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Wednesday, September 20, 2006
How to Toilet Train Your Cats

You may link to this site, but please don't copy or reprint it — on the web or on paper — without the express written permission of the author.
cat on toilet, side view

In Loving Memory of Misha: April 1989–March 2005

There have been more books and articles about toilet-training your cat than you'd think. In the summer of 1989, when Misha was a small kitten with big ears and enough meow for five cats, I searched out and read a half-dozen of them. And then tried it myself, and discovered there were a couple of things they all failed to mention ...

Some of the advice in those books turned out to be impractical. Some of it was unnecessary. Some of it was quite sensible and worked like a charm. A lot of what works and what doesn't work depends on the individual cat — on her personality and smarts. Here's what worked for me and Misha.

The central idea is that the transition from litter box to toilet be accomplished in a series of stages. You make a small change and then give your cat time to adjust before you make another small change. If at any time Felix gives the whole thing up and pees on the rug instead, you're pushing him too far too fast; back up a stage or two and try again, more slowly.

In the following instructions, I've used the word "rest" to mean: do nothing for a period of between a day and a week, depending on how flappable your cat is. (Misha caught on fast and was completely trained in under two weeks, far in advance of what the books led me to expect.)

Ready? First start by training yourself ...

The very most important thing to remember is: Lid Up, Seat Down. Post a note on the back of the door or the lid of the toilet if you think you (or your housemates or guests) might forget. (Nowadays, if I have a guest who leaves the lid down, Misha will usually come and ask me to fix it, but you can't expect every cat to go to this much trouble. Besides, he's been using the toilet for more than six years now; when the whole idea was new to him he'd just as soon pee in the bathtub instead.) And if you are accustomed to closing the bathroom door when it's empty, you'll have to break that habit too.

Begin by moving the cat's current litter box from wherever it is to one side of the toilet. Make sure he knows where it is and uses it. Rest. Next put something — a stack of newspapers, a phone book, a cardboard box — under the litter box to raise it, say, about an inch. (Magazines are too slick; you don't want the litter box sliding around and making Felix feel insecure. Tape the litter box down if you need to.) Rest. Get another box or phone book and raise it a little higher. Rest. Continue this process until the bottom of the litter box is level with the top of the toilet seat. (For Misha I raised it about two inches per day.)

At the beginning of this process, your cat could just step into the box; later he began jumping up into it, until at some point he probably started jumping up onto the toilet seat first and stepping into the box from there. You've been diligently keeping the lid up and the seat down, of course, so by now your cat is thoroughly familiar with tromping around on the open toilet.

Lift the seat on your toilet and measure the inside diameter of the top of the bowl at its widest point. Venture forth and buy a metal mixing bowl of that diameter. Do not (I discovered this the hard way) substitute a plastic bowl. A plastic bowl will not support the cat's weight and will bend, dropping into the toilet bowl and spilling litter everywhere, not to mention startling hell out of the cat.

Now you move the litter box over so that it's sitting directly over the toilet seat. (If your cat has shown reluctance over previous changes, you might want to split this into two stages, moving it halfway onto the seat and then fully over.) Take away the stack of phone books or whatever. Rest.

Here's the cool part. Take away the litter box entirely. (Ta da!) Nestle the metal mixing bowl inside the toilet bowl and lower the seat. Fill the bowl with about two inches of litter (all of this is much easier if you have the tiny granules of litter that can be scooped out and flushed).

Naturally, any humans using the toilet at this point will want to remove the metal bowl prior to their own use and replace it afterward. The next week or two the whole process is likely to be something of an annoyance; if you begin to think it's not worth it, just remember that you will never have to clean a litter box again.

cat on toilet, back view
Misha's first attempt without the box. He scored two out of a possible four.

Watch your cat using the bathroom in the metal bowl. Count the number of feet he gets up on the toilet seat (as opposed to down in the bowl of litter). The higher the number, the luckier you are and the easier your job is going to be ...

...because next you have to teach him proper squatting posture. Catch him beginning to use the toilet as much of the time as possible and show him where his feet are supposed to go. Just lift them right out of the bowl and place them on the seat (front legs in the middle, hind legs on the outside). If he starts out with three or, heaven forbid, all four feet in the bowl, just get the front two feet out first. Praise him all over the place every time he completes the activity in this position.

(Misha is very doglike in that he craves approval and praise. If your cat is indifferent to this sort of thing, you can also reward him with small food treats and wean him from them later when the toilet behavior has 'set.' Just keep the treats as small and infrequent as possible — half a Pounce or similar treat per occasion should be plenty.)

When he is regularly using the toilet with his front feet out (and some cats naturally start from this position), begin lifting a hind foot out and placing it on the seat outside the front paws. Felix will probably find this awkward at first and try to replace the foot in the litter. Be persistent. Move that foot four times in a row if you have to, until it stays there. Praise and/or treat.

cat on toilet, front view
Misha demonstrates proper squatting posture. Note the look of firm concentration.

Repeat with the other hind foot, until your cat learns to balance in that squat. (There will actually be two different squats, a low one for urine elimination and a high one for bowel movements.) Once he's getting all four feet regularly on the seat, it's all downhill from here.

Which is fortunate, because the last bit is also the most unpleasant. I suggest that you postpone this stage until you have at least a weekend, and preferably several days, when you (or another responsible party) will be at home most of the time. I skipped through this part in about two days; I only hope that your cat allows you to move along that fast.

Begin reducing the litter in the bowl. Go as fast as he'll feel comfortable with, because as the litter decreases, the odor increases. You'll want to be home at this point so that you can praise him and dump out the contents of the bowl immediately after he's finished, to minimize both the smell and the possibility that your cat, in a confused attempt to minimize the smell on his own, tries to cover it up with litter that no longer exists and ends up tracking unpleasantness into the rest of the house.

By the time you're down to a token teaspoonful of litter in the bottom of the bowl, your next-door neighbors will probably be aware of the precise instant your cat has used the toilet. This is as bad as it gets. The next time you rinse out the metal bowl, put a little bit of water in the bottom. Increase the water level each time, just as you decreased the litter level. Remember — if at any point Felix looks nervous enough about the change to give the whole thing up and take his business to the corner behind the door, back up a step or two and try the thing again more slowly.

Once the water in the mixing bowl is a couple of inches deep and your cat is comfortable with the whole thing, you get to perform the last bit of magic. Take the mixing bowl away, leaving the bare toilet. (Lid Up, Seat Down.)

Voila! Your cat is now toilet-trained.

Got questions? Visit the How to Toilet Train Your Cat FAQ page for more information.

In Loving Memory of Misha: April 1989–March 2005


Posted at 07:38 pm by VetPractice
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which are smarter, cats or dogs?

Again, from one of my favorite writers in encarta:
 
 
 
Which Are Smarter, Cats or Dogs?
Which is brainier, me or my pal here? (Image Credit: Corbis)

In the cartoon world, dogs and cats are natural enemies. In that two-dimensional universe, cats are smarter than dogs. And the humans all have three fingers and a thumb.

You can't use the cartoon world to determine which are smarter, cats or dogs. In my house, which is inhabited by two cats and a dog, I would have to say that the dog is the smarter creature.

Even though she sometimes tries to walk through doors that are only open a crack, therefore shutting them on her head, my dog clearly demonstrates her superior intelligence by following me everywhere I go and generally making me feel like the center of the universe. That's a smart thing to do because it guarantees many treats and lots of affection.

The cats pretty much ignore me except when they're hungry. The male cat has, however, trained my husband to let him out every morning at the brutal hour of 5 AM, which means the cat--at least in some ways--is smarter than my husband.

I know my household is not a science lab. The intellectual pecking order we have established won't necessarily hold up against the rigors of scientific inquiry.

It's an important question, though, one that Cat People and Dog People have debated forever. If you're a Cat Person, you know that cats are smarter because they're independent and clean, and they have an uncanny sense of where they are and how to get home. If you're a Dog Person, you know that dogs are smarter because they're easier to train. In fact, dogs are so smart they sometimes even wear police badges and perform important jobs for people with disabilities, among other things.

Is one of our favorite pets smarter than the other? Can we finally put this question to rest? I think I have an answer. But we need to get a bunch of other stuff straight first.

Part II: What is intelligence?
You'd think defining intelligence would be easy. But it's not, not even with humans.

Early human intelligence tests, performed in the late 1800s, tried to link smarts with body proportions, reaction time, and sensitivity to smells, sounds, weights, and other stimuli. The problem was that the test results didn't correlate with how well a subject performed in school. In hindsight, it seems goofy to believe that someone with a good sense of smell would be smarter. But that just shows how difficult it has been to come up with a good way of measuring intelligence.

Later intelligence tests focused on practical knowledge, memory, reasoning, vocabulary, and problem solving. These tests turned out to be better predictors of academic success.

They still weren't perfect, however, because they focus mainly on how well someone will do in school--and that's only one arena for achievement. Think for a minute about the smartest people you know. What makes them smart? That they know a lot of words? That they're good at math? That they can fix toasters and program VCRs?

All of these things represent different types of intelligence. Some people might have some types of smarts, but lack others. And whether or not we recognize something as intelligence has a lot to do with what we value or what we're seeking.

For example, let's look at the old stereotype of the dumb athlete. (It's a lame stereotype, I know. There are plenty of people who display talent on playing fields and in the classroom.) But, just as there are people who do well in school but can't shoot a basket, there are others who are more successful on the sports field than in class. So why do we have the expression "dumb jock" but no counterpart for someone who is a nonathletic scholar? The term "nerd" comes close, but a nerd can be athletic. (I should know--I consider myself a nerd, yet I earned many varsity letters in high school.) The reason we have the dumb jock putdown is because in school, academic intelligence counts for more than athletic intelligence.

Similarly, in the cat and dog debate, people will generally define intelligence as what they value. Do they want a fastidious pet? Then a cat is probably going to seem "smarter," because cats--unlike dogs--do not roll around in dead fish and then come bounding in the house to show off their glorious odor. Or, perhaps they want a pet that obeys voice commands? Even though cats can be trained to use toilets (not just litter boxes), dogs are easier to train, and therefore will likely be considered more intelligent creatures.

In order to become less biased about measuring intelligence, we have to know more about how cats and dogs think.

Which Are Smarter, Cats or Dogs?

Part III: How cats think
Some of my favorite reading about the world of the cat is by the late Roger Caras, who wrote more than five dozen books on animals and served as president of the American Society for Prevention of Cruelty to Animals. He also hosted the Westminster Dog Show, so he can't be described as biased.

In A Cat is Watching, Caras says that cats and dogs are probably equally intelligent. (Other experts disagree with this, but I'll get to that later.)

Cats and humans have similar brains. They're so similar, in fact, that more cats have been used for neurological studies than any other animal. The big difference is that human brains have a neocortex and cat brains do not. The neocortex functions as our center for speech and memory associations. Apart from that, however, our more primitive underlying brain structures are just about the same.

Cats' brains are wired to be sensory, Caras writes. So what does that mean? Caras defines a sense as something that alerts a cat to changes in its environment--changes that will ideally be handled so that the cat comes out on top. They rely on whiskers and noses and other tools to feel and perceive the world around them. Most of all, they observe and respond.

Cats are almost mystical in their ability to perceive the world. You've probably heard the folk wisdom that cats always land on their feet, and that they always find their way home. Although "always" is a risky word to use, it is true that cats are graceful. Unlike seeing-eye dogs, cats can't lead a blind person across the street. But they often demonstrate an uncanny talent for navigation.

When I was about six years old, a black stray cat took a liking to our little gray cat, Cloudy. We called him The Yowl, because he would howl love songs outside our windows at night. After a litter of unplanned kittens arrived, my parents took The Yowl to some farmland 20 miles away, crossing a freeway to get there. And yet, a few weeks later, the cat came back. He kept coming back, even after we had Cloudy spayed.

So, how did The Yowl do this? Caras believes cats have sun-based direction finders--solar global positioning systems, if you will. And it's not just that they scan the horizon for the sun's angle--it's also possible, Caras writes, that cats are absorbing data that we can't absorb ourselves and therefore don't know to measure.

So, while some people would say, "If we can't measure it, it doesn't exist," I share Caras's fascination with the unknown. And if some cats are better at using this mysterious information than others, why couldn't that be a form of intelligence?

Part IV: How dogs think
Probably the best-known expert on the intelligence of dogs is Stanley Coren, a psychology professor at the University of British Columbia and the author of several books about dogs.

In The Intelligence of Dogs, Coren outlines three types of smarts that can be measured: instinctive, adaptive, and working. Instinctive intelligence describes what dogs are genetically designed to do. This is why some can herd sheep and others are good at retrieving tennis balls. Adaptive intelligence describes how well dogs can figure out what's going on around them--for example, how quickly they can find a hidden treat. Working intelligence describes how quickly they learn commands.

The book even contains instructions for measuring your dog's smarts. Even so, says Coren, the tests are biased against the dogs--they're only testing how well dogs understand us, not how well they understand each other.

Dogs, like humans, are social animals. They think in terms of how they relate to others. Domestic cats are not pack animals, which is why people laugh when someone trots out the old expression, "It was like herding cats!" This is also why many people, Coren included, make a strong case for dogs being smarter, paws down.

"The reason is very simple," he says. "If you have two animals that are roughly at the same evolutionary level and roughly the same [classification]--cats and dogs are both carnivores--the one that has the more complex social structure is almost always brighter."

Want to Learn More?

Find out pretty much everything you'd want to know about dogs on Encarta.

Check out two books by Stanley Coren: How to Speak Dog and The Intelligence of Dogs.

Pack animals have to read signals and anticipate the effect of their actions. It's kind of like being a chess player. If you look at it in human developmental terms, a dog is about equivalent to a human two-year-old, which means it knows about 260 words or signals. The average cat, meanwhile, is more like an 18-month-old, which means it knows about 50 words. The more words a creature knows and the better it's able to communicate, the more it is apt to succeed in a social environment.

It's not that cats are too regal to perform tricks or obey commands, Coren says. It's that they don't understand how to do them. They just aren't able to learn language and read social cues as well as dogs.

Dogs, on the other hand, are champs at it. Maybe this is why dogs joined human families about 14,000 years ago, while cats were first domesticated 4,500 years ago. Dogs were quicker to figure out how to hop on board the human gravy train. In any case, this is why my dog always knows when she's going for a walk, even without my using the word--there's some signal I'm giving off without even knowing it.

This isn't to say that dogs are perfect at reading the body language of all species. In fact, in How to Speak Dog, Coren explains that this is one reason why cats and dogs often don't get along. A frightened or submissive dog will roll over, exposing its stomach. A cat, on the other hand, will roll on to its back when killing prey, or defending itself with its powerful hind legs. So, a dog might look at a cat on its back and think, "Hey. I won. Better go sniff and make peace." The cat, meanwhile, is thinking, "I'll disembowel Fifi if it's the last thing I do."

Despite this, dogs' skill at language and communication with humans has enabled them to not only be companions, but also to perform crucial jobs. In addition to helping police officers and people with disabilities, some dogs can even detect cancer with their noses.

Despite the pleasure they provide as pets and the rodents they dispatch for us, there's no evidence that cats can do anything like this. So, if intelligence is a measure of the complexity of a task an animal can perform, then dogs really do take first prize.

Someday, when we understand more of the things we can't measure, the answer to the Who's smarter? question might be different. Or maybe we'll just stop asking the question, because the important thing already is clear: Cats and dogs both think.

And until we're able to catch tennis balls in our mouths and kill mice with our bare hands, we should be impressed with them both.


Posted at 07:28 pm by VetPractice
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Friday, August 18, 2006
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Posted at 07:31 pm by VetPractice
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Wednesday, August 02, 2006
HCG hormone postings

How to cite:
Electronic Document Format (ISO)
CASTILHO, C., GAMBINI, A.L.G., FERNANDES, P. et al. Synchronization of ovulation in crossbred dairy heifers using gonadotrophin-releasing hormone agonist, prostaglandin F2a and human chorionic gonadotrophin or estradiol benzoate. Braz J Med Biol Res. [online]. 2000, vol. 33, no. 1 [cited 2006-08-03], pp. 91-101. Available from: <http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2000000100013&lng=en&nrm=iso>. ISSN 0100-879X. doi: 10.1590/S0100-879X2000000100013.
Electronic Document Format (ABNT)
CASTILHO, C. et al . Synchronization of ovulation in crossbred dairy heifers using gonadotrophin-releasing hormone agonist, prostaglandin F2a and human chorionic gonadotrophin or estradiol benzoate. Braz J Med Biol Res.,  Ribeirão Preto,  v. 33,  n. 1,  2000.  Available from: <http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2000000100013&lng=en&nrm=iso>. Access on: 03  Aug  2006.  doi: 10.1590/S0100-879X2000000100013.
Electronic Document Format (Vancouver)

Castilho C., Gambini A.L.G., Fernandes P., Trinca L.A., Teixeira A.B., Barros C.M.. Synchronization of ovulation in crossbred dairy heifers using gonadotrophin-releasing hormone agonist, prostaglandin F2a and human chorionic gonadotrophin or estradiol benzoate. Braz J Med Biol Res.  [serial in the Internet]. 2000  Jan [cited 2006  Aug  03];  33(1): 91-101. Available from: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2000000100013&lng=en&nrm=iso. doi: 10.1590/S0100-879X2000000100013.

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How to cite this article

Braz J Med Biol Res, January 2000, Volume 33(1) 91-101

Synchronization of ovulation in crossbred dairy heifers using gonadotrophin-releasing hormone agonist, prostaglandin F2a and human chorionic gonadotrophin or estradiol benzoate

C. Castilho1, A.L.G. Gambini1, P. Fernandes1, L.A. Trinca2, A.B. Teixeira1 and C.M. Barros1

Departamentos de 1Farmacologia and 2Bioestatística, Instituto de Biociências, Universidade Estadual Paulista, Botucatu, SP, Brasil

down.gif (51 bytes) Abstract
Introduction
Material and Methods
Results
Discussion
References
Acknowledgments
Correspondence and Footnotes


Abstract  

Girolando (Gir x Holstein) is a very common dairy breed in Brazil because it combines the rusticity of Gir (Bos indicus) with the high milk yield of Holstein (Bos taurus). The ovarian follicular dynamics and hormonal treatments for synchronization of ovulation and timed artificial insemination were studied in Girolando heifers. The injection of a gonadotrophin-releasing hormone (GnRH) agonist was followed 6 or 7 days (d) later by prostaglandin F2a (PGF2a). Twenty-four hours after PGF2a injection either human chorionic gonadotropin (hCG, GPh-d6 and GPh-d7 groups) or estradiol benzoate (EB, GPE-d6 and GPE-d7 groups) was administered to synchronize ovulation and consequently allow timed artificial insemination (AI) 24 and 30 h after hCG and EB injection, respectively. Follicular dynamics in Girolando heifers was characterized by the predominance of three follicular waves (71.4%) with sizes of dominant follicles (10-13 mm) and corpus luteum (approximately 20 mm) similar to those for Bos indicus cattle. In the GnRH-PGF-hCG protocol, hCG administration induced earlier ovulation (67.4 h, P<0.01) compared to the control group (GnRH-PGF) and a better synchronization of ovulation, since most of it occurred within a period of 12 to 17 h. Pregnancy rate after timed AI was 42.8 (3/7, GPh-d6) to 50% (7/14, GPh-d7). In contrast, estradiol benzoate (GnRH-PGF-EB protocol) synchronized ovulation of only 5 of 11 heifers from the GPE-d7 group and of none (0/7) from the GPE-d6 group, which led to low pregnancy rates after timed AI (27.3 and 0%, respectively). However, since a small number of Girolando heifers was used to determine pregnancy rates in the present study, pregnancy rates should be confirmed with a larger number of animals.

Key words: follicle, corpus luteum, ovulation, hCG, GnRH, artificial insemination


Introduction

Zebu cattle (Bos indicus) is predominant in Brazil and other tropical and subtropical regions. Girolando (Gir x Holstein) is a very common dairy breed in Brazil because it combines the rusticity of Gir (Bos indicus) with the high milk yield of Holstein (Bos taurus). One of the most important factors for a successful artificial insemination (AI) program is the detection of estrus, which requires time and trained personnel. In the last decade the characterization of bovine follicular dynamics by ultrasonography has provided a rational basis for pharmacological manipulation of the estrous cycle in order to synchronize ovulation and allow AI at a predetermined time (timed AI) regardless of estrous behavior.

The gonadotrophin-releasing hormone (GnRH) analogs have been shown to induce follicle luteinization or ovulation, followed by the emergence of a new follicular wave (1). GnRH analog administration followed 7 days (d) later by prostaglandin F2a (PGF2a) is a synchronization system whereby the animals show a better homogeneity of follicular development at the time of induced luteolysis (2). If a second injection of GnRH agonist is administered 36 to 48 h following PGF2a administration the ovulation is synchronized (3-5) and timed AI 16 to 24 h after the second dose of GnRH results in pregnancy rates similar to those observed in cows bred during normal estrus (4-7). Pursley et al. (3) reported that pregnancy rates after timed AI were similar to those for cows bred 12 h after estrus detection (37.8 vs 38.9%). On the other hand, Roy and Twagiramungu (8), waiting only 6 days between the first GnRH injection and PGF2a administration, observed a high pregnancy rate (62.2%) in fixed-time AI beef heifers.

Therefore, the main objectives of the present study were to characterize follicular dynamics in Girolando heifers and to develop hormonal treatments for the efficient synchronization of ovulation to allow timed AI in heifers.


Material and Methods

Location and animals

The experiments were carried out on a private farm (Americana) located 50 km from Botucatu, São Paulo State, Brazil (latitude 22o 51' S, longitude 48o 26' W). During the last 20 years, the mean annual temperature in Botucatu was 20.6oC and the mean temperatures for the warmest and coldest months were 23.6o and 17.4oC, respectively.

Girolando heifers aged 20 to 30 months were used in four experiments (Exp.). Body weights were approximately 300 kg (Exp. I and II), 295 ± 6.6 kg (Exp. III) and 392 ± 9.4 kg (Exp. IV). The animals were maintained on pasture (Brachiaria decumbens) with ad libitum mineral salt supplementation. Heifers from Exp. I and II also had access to a ration of 30% napier grass, 50% corn and 20% soybean (4 kg heifer-1 day-1) for the duration of the experiments.

Experiment I

Girolando heifers (N = 20) had their estrous cycle synchronized by two intramuscular (im) injections of PGF2a (dinoprost trometamine, 25 mg, Lutalyse®, Upjohn, São Paulo, SP, Brazil) administered 11 days apart. After estrus detection, follicle and corpus luteum (CL) development was monitored by daily ultrasonography (Aloka SSD-500, 7.5 MHz linear transducer) in 14 heifers during a complete estrous cycle. Ovarian maps were drawn to record the relative position of follicles (³4 mm) and CL as described previously (9).

Experiment II

Approximately ten days after the end of Exp. I (i.e., 7 to 12 days after ovulation) the same heifers (N = 14) were treated intramuscularly with 8 µg of buserelin acetate, a GnRH agonist (Conceptal®, Hoechst Roussel Veterinária, São Paulo, SP, Brazil, d 0), followed 7 days later by PGF2a (25 mg dinoprost trometamine, im, Lutalyse®, Upjohn, d 7), and 24 h after PGF2a administration they received human chorionic gonadotropin (hCG) (1,000 IU iv; 2000 IU im; Vetecor®, Serono Veterinária, São Paulo, SP, Brazil, d 8, GPh-d7 group). The hCG dose was split, and 1,000 IU was given iv to simulate the quick increase in luteinizing hormone (LH) that occurs at the time of the ovulatory surge, and 2,000 IU was given im to maintain LH-like activity for an extended period of time. All heifers were inseminated artificially 20 h after hCG injection without estrus detection. Pregnancy was diagnosed by ultrasonography at approximately 30 days postinsemination.

Follicular development was examined daily by ultrasonography until hCG injection and then every 6 h until ovulation during the following 6 days. The time of ovulation was considered as the average between the last time the ovulatory follicle was seen and the first time that it was not observed on the ultrasound screen.

Blood samples (10 ml) were collected into heparinized tubes just before each hormonal treatment and immediately placed on ice. Plasma was separated by centrifugation within 4 h and then stored at -20oC until the time for progesterone radioimmunoassay (RIA). The CL was considered to be undergoing regression when plasma progesterone concentration declined 50% or more from mid-luteal phase levels to concentrations £1.5 ng/ml (10).

Experiment III

Twenty-three cycling heifers (with a visible CL by ultrasonography) were allocated to two groups: GP-d7 (control, N = 12) and GPE-d7 (N = 11).

The animals were treated at random stages of the estrous cycle with a GnRH analog (8 µg Conceptal®, im, d 0) followed by PGF2a 7 days later (25 mg Lutalyse®, im, d 7). After PGF2a injection heifers from the GP-d7 (control group) were observed three times a day to detect estrus and AI was performed 12 h later. Twenty-four hours after PGF2a injection heifers from the GPE-d7 group received estradiol benzoate (EB, 0.75 mg, im, Estrogin®, Farmavet, São Paulo, SP, Brazil, d 8) and were inseminated 30 h later without estrous detection. Blood samples and ultrasonography were performed as indicated in Exp. II.

Experiment IV

Twenty-one heifers at random stages of the estrous cycle were divided into three groups (GP-d6, GPE-d6 and GPh-d6) and received hormonal treatments similar to those described in Exp. II (group GPh-d7) and III (groups GP-d7 and GPE-d7), except that PGF2a injection occurred 6 days after GnRH administration instead of 7 days as in Exp. II and III. Heifers from groups GP-d6, GPE-d6 and GPh-d6 were inseminated approximately 12 h after heat detection, 24 h after EB injection and 30 h after hCG injection, respectively. Blood samples were obtained and ultrasonography was performed as indicated in Exp. II.

Progesterone radioimmunoassay (RIA)

Progesterone RIA was performed according to a method previously described (9). Antiserum to bovine progesterone was a gift from Dr. Magaly Manzo (Faculdade de Ciências Veterinárias Maracay, Venezuela) The intra- and the inter-assay coefficients of variation were 4.4 and 11.9%, respectively, and the sensitivity of the assay was 0.23 ± 0.02 ng/ml.

Statistical analysis

Data were analyzed using the Statistical Analysis System (11). ANOVA considering animal as a block and comparisons of averages (Tukey test) were used to analyze wave length, maximum diameter, growth and atresia rate of the dominant follicle in heifers with 3 follicular waves (Exp. I). The F-test was used to compare the synchronization of ovulation among groups in Exp. III and IV. The Wilcoxon-Mann-Whitney test (12) was used to compare the interval from PGF2a administration to ovulation.


Results

Experiment I

Follicular dynamics in Girolando heifers was characterized by three follicular waves (71.4%); two heifers exhibited 2 waves (14.3%), one showed 4 waves (7.1%) and another animal had a short estrous cycle. Consequently, statistical analysis was performed only in the animals with three follicular waves. The dominant follicle from the second wave was smaller when compared to dominant follicles from the first and third waves (P<0.01). The third wave was shorter (P<0.01) than the others and became the ovulatory follicle. Growth and atresia rates did not differ among dominant follicles. The maximum diameter of the CL was approximately 20 mm and the interovulatory interval was 20.6 ± 0.4 days (Table 1).

Experiment II

The injection of a GnRH agonist induced ovulation in 50% (7/14) of the animals and follicular atresia in the remaining ones. The emergence of a new follicular wave occurred 2.1 ± 0.1 days after GnRH injection in all heifers.

The sharp decline in progesterone concentrations (<1.5 ng/ml) indicates that PGF2a injection caused luteolysis in 11 of 14 heifers (Figure 1), i.e., 21% of the heifers did not respond to PGF2a administration.

PGF2a followed 24 h later by hCG administration induced ovulation in 12 of 14 (85.7%) heifers. The interval between hCG injection and ovulation was 31.6 ± 3.9 h and 10 of 12 ovulated within a period of 17 h. In two heifers the ovulation was not synchronized by the hormonal treatments and occurred 11.6 or 68.4 h after hCG injection. The pregnancy rate after timed AI was 50% (7 of 14).


Figure 1 - Progesterone concentrations (ng/ml, mean ± SEM) in Girolando heifers during treatment with GnRH (8 µg, day 0), PGF2a (25 mg, day 7) and hCG (3000 IU, day 8, GPh-d7, N = 14).

[View larger version of this image (5 K GIF file)]


Experiment III

The injection of GnRH induced ovulation in 43.5% (10/23) of the animals from the two groups, and emergence of a new follicular wave occurred 2.2 ± 0.2 days after GnRH administration in 74% of the heifers (17/23). In the heifers with no emergence of a new wave the follicles kept growing after GnRH injection.

The sharp decline in progesterone concentrations indicates that PGF2a injection caused luteolysis in all heifers from the GP-d7 and GPE-d7 groups (Figure 2).

In the control group (GP-d7) ovulation rate was 75% (9/12) while in the GPE-d7 group, PGF2a followed 24 h later by EB administration induced ovulation in 63.6% (7/11) of the heifers. Two heifers (one from GP-d7 and one from GPE-d7) ovulated 2 days before PGF2a injection and one ovulated on the day when PGF2a was administered (GPE-d7). Furthermore, three heifers from GP-d7 and four from GPE-d7 did not ovulate until 7 days after PGF2a administration. The injection of estradiol benzoate induced estrus behavior in all heifers from GPE-d7 in spite of the fact that 4 of 9 heifers did not ovulate after injection of EB. In the control group (GP-d7), only 58.3% of the heifers were observed in heat.

Excluding the animals that ovulated before (N = 2) or on the day (N = 1) of PGF2a administration, the intervals from PGF2a injection to ovulation were 103.7 ± 10.1 and 66.5 ± 3.5 h for GP-d7 and GPE-d7, respectively. Consequently, the administration of EB induced ovulation 37 h earlier when compared to the control group (P<0.05) and caused a more precise synchrony of ovulation, which occurred within a period of 18 and 66 h, respectively, for GPE-d7 and GP-d7 (P<0.05). The pregnancy rate after timed AI was 27.3% (GPE-d7), as opposed to 41.6% in heifers inseminated after estrus detection (GP-d7).


Figure 2 - Progesterone concentrations (ng/ml, mean ± SEM) in Girolando heifers during treatment with GnRH (8 µg, day 0), PGF2a (25 mg, day 7, GP-d7, N = 12) and estradiol benzoate (0.75 mg, day 8, GPE-d7, N = 11).

[View larger version of this image (6 K GIF file)]


Experiment IV

The injection of GnRH induced ovulation in 7 heifers (2 from GP-d6 and 5 from GPh-d6) and follicular atresia in 11 of 21 heifers (5, 2 and 4, respectively, from GP-d6, GPh-d6 and GPE-d6). The emergence of a new follicular wave occurred 2.2 ± 0.2 days after GnRH injection in 74% (17/23) of the heifers.

Progesterone concentrations indicate that 14, 71 and 100% of the heifers from GP-d6, GPh-d6 and GPE-d6 did not respond to PGF2a treatment, respectively (Figure 3). However, the percentage of animals detected in heat was 100, 0 and 85.7% for GP-d6, GPh-d6 and GPE-d6, respectively.

After the hormonal treatment all heifers from the GP-d6 and GPh-d6 groups ovulated, as opposed to only one heifer from the GPE-d6 group (63.3 h after the EB injection).

The interval from PGF2a injection to ovulation in the GPh-d6 group (56.6 ± 1.9 h) was significantly shorter when compared to the GP-d6 group (101.9 ± 7.2 h, P<0.01). Therefore, injection of hCG induced ovulation 67.4 h earlier (P<0.01) when compared to the control group and induced a more precise synchrony of ovulation, which occurred within a period of 12 and 52 h for GPh-d6 and GP-d6, respectively. The pregnancy rate was the same (42.8%) for heifers submitted to timed AI (GPh-d6) and for those that were bred after detection of estrus (GP-d6). None of the animals from GPE-d6 became pregnant.


Figure 3 - Progesterone concentrations (ng/ml, mean ± SEM) in Girolando heifers during treatment with GnRH (8 µg, day 0), PGF2a (25 mg, day 6, GP-d6, N = 7) and hCG (3000 IU, day 7, GPh-d6, N = 7) or estradiol benzoate (0.75 mg, day 7, GPE-d6).

[View larger version of this image (8 K GIF file)]


Discussion

In the present study the follicular dynamics of Girolando heifers was characterized primarily by the presence of three follicular waves. These patterns of follicular growth are similar to those observed in Bos taurus (13,14) and Bos indicus (9,15) heifers. Other investigators have reported the rare occurrence of one or four follicular waves (9,13-16) and the predominance of two waves (17). The reasons for variations between two and three follicular waves are not clear. However, some factors such as pregnancy (16), puberty (18), diet (19), heat stress (20) and energy balance (21) may influence follicular dynamics.

The detection of the first, second and third follicular waves in 3-wave Girolando heifers (0.2 ± 0.1, 7.3 ± 0.4 and 13.5 ± 0.5 days, respectively) occurred a little earlier (especially the third wave) compared with those of Holstein heifers (1.9 ± 0.3, 9.4 ± 0.5 and 16.1 ± 0.7 days; -0.5 ± 0.3 , 9.0 ± 0.0 and 16.0 ± 1.1 days, and approximately 4, 12 and 16 days; 13,14,17). The occurrence of follicular waves was very close to that observed in Nelore heifers (1.6 ± 0.2, 9.1 ± 0.5 and 15.1 ± 0.5 days; 9). As previously reported for European (6.1 days, 5.9 days, 6.8 days; 13,14,17) and Zebu breeds (6.9 days; 9), the length of the third follicular wave (6.9 days) was significantly (P<0.01) shorter than that of the other waves.

The maximum diameter of dominant follicles (10 to 13 mm) observed in Girolando heifers was smaller than that reported for Bos taurus heifers (14 to 20 mm, 13 to 18 mm, 14 to 16 mm; 13,17,22) and similar to that reported for Bos indicus heifers (10 mm, 12 mm; 9,15). The second dominant follicle, developing during the luteal phase, was significantly smaller (P<0.01) than the others in 3-wave Girolando heifers. This result agrees with those obtained for European (14) and Zebu cattle (9).

The maximum CL diameter for 3-wave Girolando heifers (19 to 20 mm) was comparable to that obtained for Zebu heifers (17 to 18 mm; 9,15). However, the size tended to be smaller than that for Bos taurus (25 to 30 mm; 22). Thus, the size of dominant follicles and CL of Girolando heifers (Gir x Holstein) may be similar to those of Zebu cattle and smaller than those of Bos taurus breeds. However, the pattern of growth and turnover of dominant follicles is similar for Zebu and European breeds.

Injection of the GnRH agonist at random stages of the estrous cycle caused ovulation in 33 to 50% of Girolando heifers and induced a new follicular wave 2 to 3 days after its administration in 91% of the heifers (49/58). A similar ovulation rate has been reported for European heifers (54%; 6) and Zebu cows (33.3%; 23), while in European cows Pursley et al. (7) showed a higher percentage of ovulation (>85%) about 2 days after the first GnRH injection.

GnRH administration induces ovulation or atresia (24) depending on the stage of follicular development (4). Silcox et al. (25) reported that GnRH induced ovulation in 100% of growing follicles (>10 mm), 33% of follicles in the plateau phase and 0% (no ovulation) of atretic follicles. In addition, LH receptors decrease as the dominant follicle develops from growth to the plateau and regression phases (26) and as atresia is clearly being manifested (27).

In most Girolando heifers (100% Exp. II, 74% Exp. III and 86% Exp. IV) the GnRH agonist induced a new follicular wave at approximately 2 days after its administration, and as a consequence of this follicular synchronization, 86% of the heifers had a dominant follicle (>8.0 mm) at the time of PGF2a injection (day 6 or 7). The use of GnRH, in addition to inducing ovulation or atresia, stimulates recruitment of follicles directly by follicle-stimulating hormone (FSH) release within 2 to 4 h after its administration (28) and/or indirectly by an increase in FSH concentration occurring 1 to 2 days after removal of the dominant follicle (29) that contains FSH inhibitory factors such as inhibin (27).

Administration of PGF2a induced luteolysis in 85% (day 7, Exp. II), 100% (day 7, Exp. III) and 38% (day 6, Exp. IV) of the Girolando heifers. In Experiment IV, PGF2a injection did not cause luteolysis in 5 of 7 heifers from GPh-d6 or in the 7 heifers from GPE-d6, while most animals from GP-d6 presented luteolysis (6/7).

Injection of the primary GnRH agonist induced the formation of an accessory CL in 5, 0 and 2 heifers from GPh-d6, GPE-d6 and GP-d6, respectively. Considering that PGF2a is not efficient in causing luteolysis during the first 4 days after ovulation (30), a possible explanation for the reduced number of heifers that presented luteolysis in the GPh-d6 group is the presence of accessory CL (5/7) that are too young (4 days old) to respond to PGF2a administration. However, it is surprising that none of the animals from the GPE-d6 group presented luteolysis in spite of the absence of accessory CL and the presence of functional CL (progesterone >6.0 ng/ml). Pursley et al. (7) reported the absence of luteolysis in 6 of 24 Holstein heifers treated with PGF2a 7 days after GnRH agonist injection. In Nelore cows (31), PGF2a administration did not induce estrus in 54% of the animals even in the presence of a functional CL (progesterone >5.0 ng/ml) in 23 of 28 animals.

The administration of a second dose of GnRH 24 to 48 h after PGF2a causes a more precise synchronization of ovulation in both Bos taurus (7,32) and Bos indicus cows (33) and permits timed artificial insemination (3,5,32,34,35). Pursley et al. (7) reported that all Holstein cows and 75% of the heifers ovulated within a period of 24 to 32 h after the second GnRH administration. In another study using an AI protocol of GnRH - 7 days - PGF2a - 30 to 36 h - GnRH - 16 to 24 h, the same authors (3) showed that the pregnancy rate after this treatment was similar to that for the control group (37.8 vs 38.9%). Additionally, Roy and Twagiramungu (8) observed a high pregnancy rate (62.2%) after timed AI in beef heifers treated with a similar protocol (GnRH-PGF-GnRH) except that GnRH was administered 6 days after PGF2a and the second dose of GnRH was injected 46 to 48 after PGF2a.

In the present study, the second dose of GnRH was replaced by estradiol benzoate or hCG. Estradiol benzoate in the absence of progesterone (<1.0 ng/ml) has been shown to induce an LH surge approximately 16 to 24 h after its administration (36). However, EB in the presence of a functional CL or when administered with exogenous progestagens decreases gonadotrophin secretion and induces atresia of the dominant follicle (37). In contrast, GnRH administration induces a short LH surge (approximately 5 h; 28), while plasma levels of hCG (LH-like activity) continue to be detectable up to 66 h after its im injection (32). In Girolando heifers treated with hCG (GPh-d6) ovulation occurred 67.4 h earlier (P<0.01) compared to control (GP-d6, Exp. IV) and was better synchronized since most of it occurred within a period of 12 (GPh-d6) or 17 h (GPh-d7). The pregnancy rate obtained after timed AI (50% in GPh-d7 and 42.8% in GPh-d6) was close to that obtained in Holstein heifers (56.1%) after the GnRH-PGF-hCG protocol (hCG was injected 48 h after PGF2a and all heifers were inseminated 16 h after hCG; 32). However, a small number of Girolando heifers was used. Consequently, these results must be confirmed with a larger number of animals.

The use of EB to synchronize ovulation in Girolando heifers was not as effective as hCG, because only one heifer ovulated in the GPE-d6 group and 2 of 11 heifers ovulated before the end of the hormonal treatments (GPE-d7). Excluding these 2 heifers, EB administration (GPE-d7) induced ovulation 37 h (P<0.05) earlier compared to control heifers (GP-d7) and induced a better synchrony of ovulation, which occurred within a period of 66 and 18 h for GP-d7 and GPE-d7, respectively. The low ovulation rate observed in GPE-d6 can be explained by the fact that none of the heifers presented luteolysis after PGF2a administration, showing that EB in the presence of elevated progesterone concentrations (>2.0 ng/ml) did not induce an LH surge and ovulation. On the other hand, although five of seven heifers from GPh-d6 did not undergo luteolysis, all of them ovulated after hCG injection. This may be explained by the fact that hCG, which has LH-like activity, induces ovulation acting directly on the follicles (32,38).

In the control groups the percentage of animals showing estrus was 58.3 and 100% for GP-d7 and GP-d6, respectively. These results agree with those obtained in other studies in which PGF2a administered 6 or 7 days after GnRH injection induced heat in 70 to 83% of the animals (4,5).

Estradiol benzoate injection induced estrus in most Girolando heifers (100% in GPE-d7 and 86% in GPE-d6) while none of them showed estrus after hCG injection (GPh-d6). It has been shown that administration of estrogens induces behavioral estrus in cattle (39), whereas GnRH agonist reduces the occurrence of spontaneous estrus due to functional alterations in the dominant follicles (1), which could lead to lower estradiol concentrations in the blood stream (4). Considering that both GnRH and hCG induce ovulation through LH-like activity, it is possible that hCG reduces spontaneous estrus in a similar manner as GnRH.

The pregnancy rates obtained after EB administration in groups GPE-d7 (27.3%) and GPE-d6 (0%) were lower than those reported for Nelore cows treated with GPE-d7 protocol (45.5%; 35) and closer to those observed in Nelore heifers (N = 64) treated with the GPE-d6 protocol (33%; Barros CM, Figueiredo RA and Fernandes P, unpublished results). The high percentage of heifers showing estrus after EB administration (GPE-d7 and GPE-d6) followed by low pregnancy rates after timed AI indicates that the occurrence of heat in response to estradiol benzoate injection may not be linked to the actual time of LH surge or ovulation time. In spite of the small number of heifers used, the low pregnancy rates observed after GPE-d6 and GPE-d7 indicate that these treatments are not as promising for heifers as they are for adult cows (35).

In Experiment III, 14.3% of the animals (2 in GPE-d7 and 1 in GP-d7) ovulated before the injection of PGF2a, while no animal from GPE-d6 or GP-d6 exhibited estrus or ovulated before PGF2a administration. Results reported by Canadian researchers (8) indicate that a 6-day interval between GnRH and PGF2a injection improves estrus synchronization and reduces the occurrence of estrus before PGF2a administration.

Schmitt et al. (32) treated Holstein heifers with the GnRH-PGF-GnRH protocol for timed AI and reported a lower pregnancy rate in animals injected with GnRH 24 h after PGF2a (25.8%) when compared to those that received GnRH 48 h after prostaglandin (45.5%). Additionally, they observed that the low pregnancy rate was associated with a high incidence (34.8%) of heifers returning earlier to estrus (<16 days) after timed AI in the group of animals that received GnRH 24 h after PGF2a. In contrast, delaying the second GnRH injection (48 vs 24 h) allowed the ovulatory follicle to be exposed for a longer time to the increased basal pulsatile release of LH. This may have permitted the ovulatory follicle to differentiate into a normal CL with a higher steroidogenic capacity. This normal CL was capable of maintaining pregnancy and consequently the number of animals returning earlier to estrus decreased (32). Likewise, it may be possible to improve pregnancy rates in Girolando heifers treated with GnRH-PGF-EB by extending to 48 h the interval between PGF2a administration and EB injection.

Although hCG (GPh-d6 and GPh-d7 groups) and EB (GPE-d6 and GPE-d7 groups) were administered 24 h after PGF2a, the synchronization of ovulation and pregnancy rates after hCG treatment was much better than that observed after EB administration. At least two factors may have contributed to these results: hCG is capable of inducing ovulation even in the presence of a functional CL (32,40), and second the CL induced by hCG is larger and produces more progesterone than the GnRH-induced CL (40). Consequently, it may have a better capacity to maintain pregnancy.

In summary, hCG administration in both protocols, GPh-d6 and GPh-d7, was effective in synchronizing ovulation and allowed successful timed AI in crossbred heifers. On the other hand, estradiol benzoate synchronized ovulation in only 5 of 11 Girolando heifers from the GPE-d7 group and in none from the GPE-d6 group, which led to low pregnancy rates after timed AI. However, since a small number of Girolando heifers was used to determine pregnancy rates, pregnancy rates should be confirmed with a larger number of animals.


References

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2. Thatcher WW, Drost M, Savio JD, Macmillam KL, Entwistle KW, Schmitt EJ, de la Sota RL & Morris GR (1993). New clinical uses of GnRH and its analogues in cattle. Animal Reproduction Science, 33: 27-36.

3. Pursley JR, Wiltbank MC, Stevensom JS, Ottobre JS, Barverick HA & Andersom LL (1997). Pregnancy rates per artificial insemination for cows and heifers inseminated at a synchronized ovulation or synchronized estrus. Journal of Dairy Science, 80: 295-300.
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7. Pursley JR, Mee MO & Wiltbank MC (1995). Synchronization of ovulation in dairy cows using PGF2a and GnRH. Theriogenology, 44: 915-923.

8. Roy GL & Twagiramungu H (1996). A fixed time AI program using the GnRH-PGF-GnRH method for beef females. Journal of Animal Science, 74 (Suppl 1): 222 (Abstract).

9. Figueiredo RA, Barros CM, Pinheiro OL & Soler JMP (1997). Ovarian follicular dynamics in Nelore breed (Bos indicus). Theriogenology, 47: 1489-1505.

10. Ambrose JD, Pires MFA, Moreira F, Diaz T, Binelli M & Thatcher WW (1998). Influence of deslorelin (GnRH-agonist) implant on plasma progesterone, first wave dominant follicle and pregnancy in dairy cattle. Theriogenology, 50: 1157-1170.
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14. Sirois J & Fortune JE (1988). Ovarian follicular dynamics during the estrous cycle in heifers monitored by real-time ultrasonography. Biology of Reproduction, 39: 308-317.
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15. Rhodes FM, De'ath G & Entwistle KW (1995). Animal and temporal effects on ovarian follicular dynamics in Brahman heifers. Animal Reproduction Science, 38: 265-277.

16. Murphy MG, Boland MP & Roche JF (1990). Pattern of follicular growth and resumption of ovarian activity in post-partum beef suckler cows. Journal of Reproduction and Fertility, 90: 523-533.
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17. Ginther OJ, Knopf L & Kastelic JP (1989). Temporal associations among ovarian events in cattle during oestrous cycles with two and three follicular waves. Journal of Reproduction and Fertility, 87: 223-230.
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18. Evans ACO, Adams GP & Rawlings NC (1994). Follicular and hormonal development in prepubertal heifers from 2 to 36 weeks of age. Journal of Reproduction and Fertility, 103: 463-470.

19. Murphy MG, Enright WJ & Crowe MA (1991). Effect of dietary intake on pattern of growth of dominant follicles during the oestrous cycle in beef heifers. Journal of Reproduction and Fertility, 92: 333-338.
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20. Wolfenson D, Thatcher WW, Badinga L, Savio JD, Meidan R, Lew BJ, Braw-Tal R & Berman A (1995). Effect of heat stress on follicular development during the estrous cycle in lactating dairy cattle. Biology of Reproduction, 52: 1106-1113.
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21. Lucy MC, Savio JD, Badinga L, de la Sota RL & Thatcher WW (1992). Factors that affect ovarian follicular dynamics in cattle. Journal of Animal Science, 70: 3615-3626.
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22. Adams GP, Kot K, Smith CA & Ginther OJ (1993). Effect of the dominant follicle on regression of its subordinates in heifers. Canadian Journal of Animal Science, 73: 267-275.

23. Moreira MBP (1997). Sincronização da ovulação em vacas da raça Nelore. Master's thesis, Instituto de Biociências, Universidade Estadual Paulista, Botucatu, SP.

24. Macmillan KL & Thatcher WW (1991). Effects of an agonist of gonadotropin-releasing hormone on ovarian follicles in cattle. Biology of Reproduction, 45: 883-889.
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25. Silcox RW, Powell KL & Kiser TE (1993). Ability of dominant follicle (DF) to respond exogenous GnRH administration is dependent on their stage of development. Journal of Animal Science, 71: 219 (Abstract).

26. Rolosson MM, Crim JW, Silcox RW & Kiser TE (1994). Density of [125I] hCG binding to the dominant follicle of the first wave of the estrous cycle in cows. Journal of Dairy Science, 77 (Suppl 1): 231 (Abstract).

27. Guilbault LA, Rouiller P, Matton P, Glencross RG, Beard AJ & Knight PG (1993). Relationships between the level of atresia and inhibin contents (a subunit and a-ß dimer) in morphologically dominant follicles during their growing and regressing phases of development in cattle. Biology of Reproduction, 48: 268-276.
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28. Chenault JR, Kratzert DD, Rzepkowski RA & Goodwin MC (1990). LH and FSH response of Holstein heifers to fertirelin acetate, gonadorelin and buserelin. Theriogenology, 34: 81-88.

29. Adams GP, Matteri RL, Kastelic JP, Ko JCH & Ginther OJ (1992). Association between surges of follicle-stimulating hormone and the emergence of follicular waves in heifers. Journal of Reproduction and Fertility, 94: 177-188.
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30. Rowson LEA, Tervit R & Brand A (1972). The use of prostaglandin for synchronization of estrus in cattle. Journal of Reproduction and Fertilily, 29: 145-149.

31. Pinheiro OL, Barros CM, Figueiredo RA, Valle ER, Encarnação RO & Padovani CR (1998). Estrous behavior and the estrus-to-ovulation interval in Nelore cattle (Bos indicus) with natural estrus or estrus induced with prostaglandin F2a or norgestomet and estradiol valerate. Theriogenology, 49: 667-681.
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32. Schmitt EJP, Diaz TC, Drost M, Roomes C & Thatcher WW (1996). Use of a GnRH agonist on human chorionic gonadotropin for timed insemination in cattle. Journal of Animal Science, 74: 1084-1091.

33. Gambini ALG, Moreira MBP, Castilho C & Barros CM (1998). Dinâmica folicular e sincronização da ovulação em vacas da raça Gir. Revista Brasileira de Reprodução Animal, 22: 201-210.

34. Momcilovic D, Archbald LF, Walters A, Tran T, Kelbert D, Risco C & Thatcher WW (1998). Reproductive performance of lactating dairy cows treated with gonadotrophin-releasing hormone (GnRH) and/or prostaglandin F2a (PGF2a) for synchronization of estrus and ovulation. Theriogenology, 50: 1131-1139.
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35. Fernandes P (1998). Inseminação artificial com tempo predeterminado em vacas Nelore tratadas com acetato de buserelina, prostaglandina F2a e benzoato de estradiol. Master's thesis, Faculdade de Medicina Veterinária e Zootecnia, Universidade Estadual Paulista, Botucatu, SP.

36. Lammoglia MA, Short RE, Bellows RE, Bellows RA, Macneil MD & Hafs HD (1998). Induced and synchronized estrus in cattle: dose titration of estradiol benzoate in peripubertal heifers and postpartum cows after treatment with an intravaginal progesterone-releasing insert and prostaglandin F2a. Journal of Animal Science, 76: 1662-1670.
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37. Bo GA, Adams GP, Pierson RA, Tribulo HE, Caccia M & Mapletoft RJ (1994). Follicular wave dynamics after estradiol-17ß treatment of heifers with or without a progestogen implant. Theriogenology, 41: 1555-1569.

38. Seguin BE, Oxender WD & Britt JH (1977). Effect of human chorionic gonadotropin-releasing hormone on corpus luteum function and estrous cycle duration in dairy heifers. American Journal of Veterinary Research, 38: 1153-1156.
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39. McGuire WJ, Larson RL & Kiracofe GH (1990). Syncro-mate B induced estrus in ovariectomized cows and heifers. Theriogenology, 34: 33-37.

40. Schmitt EJP, Diaz TC, Barros CM, de la Sota RL, Drost M, Fredriksson EW, Staples CR, Thorner R & Thatcher WW (1996). Differential response of the luteal phase and fertility in cattle following ovulation of the first-wave follicle with human chorionic gonadotropin or an agonist of gonadotropin-releasing hormone. Journal of Animal Science, 74: 1074-1083.
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Acknowledgments

The authors express their appreciation to Zeide Sab, Americana Farm, São Paulo, for providing the cows and support. We are also indebted to Dra. Magaly Manzo (Maracay, Venezuela) for providing progesterone antiserum and to Luiz A. Oliveira for technical assistance.


Correspondence and Footnotes

Address for correspondence: C.M. Barros, Departamento de Farmacologia, Instituto de Biociências, UNESP, 18618-000 Botucatu, SP, Brasil, Fax: +55-14-821-3744, E-mail: cmbarros@ibb.unesp.br

Presented at the "30th Annual Meeting of the Society for the Study of Reproduction", Portland, Oregon, USA, August 1997 (Biology of Reproduction, 56 (Suppl 1): 450). Research supported by FAPESP (No. 98/01186-9) and CAPES. Received March 31, 1999. Accepted November 4, 1999.

 


 

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Monday, June 19, 2006
beef cuts


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Sunday, June 18, 2006
veal

Veal Meat, Diagram of Calf

The body and parts of calves or veal meat.

Veal - Hindquarter

  1. Loin, the choicest cuts used for roasts and chops.
  2. Fillet, used for roasts and cutlets.
  3. Loin, chump-end used for roasts and chops.
  4. The hind-knuckle or hock, used for stews, pot-pies, meat-pies.

Veal Fore Quarter

  • 5. Neck, best end used for roasts, stews and chops.
  • 6. Breast, best end used for roasting, stews and chops.
  • 7. Blade-bone, used for pot-roasts and baked dishes.
  • 8. Fore-knuckle, used for soups and stews.
  • 9. Breast, brisket-end used for baking, stews and pot-pies.
  • 10. Neck, scrag-end used for stews, broth, meat-pies, etc.

    In cutting up veal, generally, the hindquarter is divided into loin and leg, and the forequarter into breast, neck and shoulder.

    The parts of a moderately sized, well fed calf, about eight weeks old, are nearly of the following weights:
    Loin and chump, 18 lbs.; fillet, 12½ lbs.; hind knuckle, 5½ lbs.; shoulder, 11 lbs.; neck, 11 lbs.; breast, 9 lbs., and fore knuckle, 5 lbs.; making a total of 144 lbs. weight.

    http://www.internationalstyles.net/recipes/meat-cutting/veal-meat.htm


  • Posted at 09:34 pm by VetPractice
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    Friday, June 16, 2006
    Bubonic plague

    Plague
     
    Plague is a zoonotic disease circulating mainly among small animals and their fleas. The bacteria Yersinia pestis can also infect humans. It is transmitted between animals and humans by the bite of infected fleas, direct contact, inhalation and rarely, ingestion of infective materials. Plague can be a very severe disease in people, with a case-fatality ratio of 30%-60% if left untreated.
    Infected persons usually start with “flu-like” symptoms after an incubation period of 3-7 days. Patients typically experience the sudden onset of fever, chills, head and body-aches and weakness, vomiting and nausea. Clinical plague infection manifests itself in three forms depending on the route of infection: bubonic, septicaemic and pneumonic.
    • Bubonic form is the most common form of plague resulting from the bite of an infective flea. Plague bacillus enters the skin from the site of the bite and travels through the lymphatic system to the nearest lymph node. The lymph node then becomes inflamed because the plague bacteria, Yersinia pestis or Y. pestis, will replicate here in high numbers. The swollen lymph node is called a "bubo" which is very painful and can become suppurated as an open sore in advanced stage of infection;
    • Septicaemic form of plague occurs when infection spreads directly through the bloodstream without evidence of a "bubo". More commonly advanced stages of bubonic plague will result in the presence of Y. pestis in the blood. Septicaemic plague may result from flea bites and from direct contact with infective materials through cracks in the skin.
    • Pneumonic form of plague is the most virulent and least common form of plague. Typically, pneumonic form is due to a secondary spread from advanced infection of an initial bubonic form. Primary pneumonic plague results from inhalation of aerosolized infective droplets and can be transmitted from human to human without involvement of fleas or animals. Untreated pneumonic plague has a very high case-fatality ratio.
    Plague is endemic in many countries in Africa, in the former Soviet Union, the Americas and Asia. In 2003, 9 countries reported 2118 cases and 182 deaths. 98.7% of those cases and 98.9% of those deaths were reported from Africa. Today the distribution of plague coincides with the geographical distribution of its natural foci.
    Treatment
    Rapid diagnosis and treatment is essential to reduce complications and fatality. Effective treatment methods enable almost all plague patients to be cured if diagnosed in time. These methods include the administration of antibiotics and supportive therapy.
    Prevention
    The objective of preventive measures is to inform people to be aware of the areas where zoonotic plague is active and to take precautions against flea bites and handling carcass while in plague-endemic areas. People should avoid having direct contact with infective tissues, or from being exposed to patients with pneumonic plague.
    Case recognition, medical intervention and field investigation
    • Identify the most likely source of infection in the area where the human case(s) was exposed, typically looking for clustered areas with large numbers of small animal die-offs. Institute appropriate sanitation and control measures to stop the exposure source;
    • Ensure dissemination of information concerning areas with active plague transmission, the clinical features of plague and the case definition to health workers;
    • Verify that patients have been placed on appropriate antibiotic treatment and that local supplies of antibiotics are adequate to handle further cases;
    • Isolate pneumonic plague patients;
    • Obtain specimens for laboratory confirmation.
    Laboratory testing
    Diagnosis and confirmation of plague requires laboratory testing. Recovery and identification of Y. pestis culture from a patient sample is optimum for confirmation. Depending on the presentation of the form on plague: bubo aspirates, blood, and sputum are the most appropriate specimens for rapid testing and culture. Serum taken during the early and late stages of infection can be examined to confirm infection. Rapid dipstick tests have been validated for field use to quickly screen for Y. pestis antigen in patients. Specimens should be collected and forwarded to laboratories for plague testing.
    Vaccination
    Plague vaccines at one time were widely used but have not proven to be an approach that could prevent plague effectively. Vaccines are not recommended for immediate protection in outbreak situations. Vaccination is only recommended as a prophylactic measure for high-risk groups (e.g. laboratory personnel who are constantly exposed to the risk of contamination).
    Surveillance and control
    • Conduct investigation to identify animals and flea species that are implicated in the plague enzootic cycle in the region and develop a programme on environmental management to limit its potential spread.
    • Active long-term surveillance of zoonotic foci and rapid response to reduce exposure during epizootic outbreaks have been successful in reducing human plague.
     

    Posted at 12:49 am by VetPractice
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    Thursday, June 15, 2006
    Food tech and Poultry med

    Poultry and Rabbit Med

     

    Epidemiologic Triad

    a) Host

    b) Pathogen

    c) Environment

     

    Gallus gallus- Jungle Fowl

     

     

    DL biosecurity of the Poultry Facility

     

     

    Food Tech.

     

    Food tech, application of modern technique to minimize undesirable changes of food.

     

    Cryogenics

     

    salitre


    Posted at 03:58 am by VetPractice
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    Wednesday, June 14, 2006
    Vet Thesis I- seriously need ideas

    i seriously need ideas for my thesis...

    Some ideas: Tx. of mange in a different way, oral vaccine, nutrition, herbal medicine, bacteria, euthanasia, anesthesia


    Posted at 05:00 am by VetPractice
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    Vet Thesis I- thesis writing guide

    How to Organize your Thesis
    Prof. John W. Chinneck
    Dept. of Systems and Computer Engineering
    Carleton University
    Ottawa, Canada

    email: chinneck at sce dot carleton dot ca

    Latest Revision: September 29, 1999
    (original document dates to 1988, and undergoes periodic minor revisions)

    Home for this document is: http://www.sce.carleton.ca/faculty/chinneck/thesis.html

    Translations into other languages are available.

    Introduction
    This note describes how to organize the written thesis which is the central element of your graduate degree. To know how to organize the thesis document, you first have to understand what graduate-level research is all about, so that is covered too. In other words, this note should be helpful when you are just getting started in your graduate program, as well as later when you start to write your thesis.

    What Graduate Research is All About
    The distinguishing mark of graduate research is an original contribution to knowledge. The thesis is a formal document whose sole purpose is to prove that you have made an original contribution to knowledge. Failure to prove that you have made such a contribution generally leads to failure.

    To this end, your thesis must show two important things:

    you have identified a worthwhile problem or question which has not been previously answered,
    you have solved the problem or answered the question.
    Your contribution to knowledge generally lies in your solution or answer.

    What the Graduate Thesis is All About
    Because the purpose of the graduate thesis is to prove that you have made an original and useful contribution to knowledge, the examiners read your thesis to find the answers to the following questions:

    what is this student's research question?
    is it a good question? (has it been answered before? is it a useful question to work on?)
    did the student convince me that the question was adequately answered?
    has the student made an adequate contribution to knowledge?
    A very clear statement of the question is essential to proving that you have made an original and worthwhile contribution to knowledge. To prove the originality and value of your contribution, you must present a thorough review of the existing literature on the subject, and on closely related subjects. Then, by making direct reference to your literature review, you must demonstrate that your question (a) has not been previously answered, and (b) is worth answering. Describing how you answered the question is usually easier to write about, since you have been intimately involved in the details over the course of your graduate work.

    If your thesis does not provide adequate answers to the few questions listed above, you will likely be faced with a requirement for major revisions or you may fail your thesis defence outright. For this reason, the generic thesis skeleton given below is designed to highlight the answers to those questions with appropriate thesis organization and section titles. The generic thesis skeleton can be used for any thesis. While some professors may prefer a different organization, the essential elements in any thesis will be the same. Some further notes follow the skeleton.

    Always remember that a thesis is a formal document: every item must be in the appropriate place, and repetition of material in different places should be eliminated.

    A Generic Thesis Skeleton
    1. Introduction

    This is a general introduction to what the thesis is all about -- it is not just a description of the contents of each section. Briefly summarize the question (you will be stating the question in detail later), some of the reasons why it is a worthwhile question, and perhaps give an overview of your main results. This is a birds-eye view of the answers to the main questions answered in the thesis (see above).

    2. Background Information (optional)

    A brief section giving background information may be necessary, especially if your work spans two or more traditional fields. That means that your readers may not have any experience with some of the material needed to follow your thesis, so you need to give it to them. A different title than that given above is usually better; e.g., "A Brief Review of Frammis Algebra."

    3. Review of the State of the Art

    Here you review the state of the art relevant to your thesis. Again, a different title is probably appropriate; e.g., "State of the Art in Zylon Algorithms." The idea is to present (critical analysis comes a little bit later) the major ideas in the state of the art right up to, but not including, your own personal brilliant ideas.

    You organize this section by idea, and not by author or by publication. For example if there have been three important main approaches to Zylon Algorithms to date, you might organize subsections around these three approaches, if necessary:

    3.1 Iterative Approximation of Zylons
    3.2 Statistical Weighting of Zylons
    3.3 Graph-Theoretic Approaches to Zylon Manipulation

    4. Research Question or Problem Statement

    Engineering theses tend to refer to a "problem" to be solved where other disciplines talk in terms of a "question" to be answered. In either case, this section has three main parts:

    1. a concise statement of the question that your thesis tackles
    2. justification, by direct reference to section 3, that your question is previously unanswered
    3. discussion of why it is worthwhile to answer this question.

    Item 2 above is where you analyze the information which you presented in Section 3. For example, maybe your problem is to "develop a Zylon algorithm capable of handling very large scale problems in reasonable time" (you would further describe what you mean by "large scale" and "reasonable time" in the problem statement). Now in your analysis of the state of the art you would show how each class of current approaches fails (i.e. can handle only small problems, or takes too much time). In the last part of this section you would explain why having a large-scale fast Zylon algorithm is useful; e.g., by describing applications where it can be used.

    Since this is one of the sections that the readers are definitely looking for, highlight it by using the word "problem" or "question" in the title: e.g. "Research Question" or "Problem Statement", or maybe something more specific such as "The Large-Scale Zylon Algorithm Problem."

    5. Describing How You Solved the Problem or Answered the Question

    This part of the thesis is much more free-form. It may have one or several sections and subsections. But it all has only one purpose: to convince the examiners that you answered the question or solved the problem that you set for yourself in Section 4. So show what you did that is relevant to answering the question or solving the problem: if there were blind alleys and dead ends, do not include these, unless specifically relevant to the demonstration that you answered the thesis question.

    6. Conclusions

    You generally cover three things in the Conclusions section, and each of these usually merits a separate subsection:

    1. Conclusions
    2. Summary of Contributions
    3. Future Research

    Conclusions are not a rambling summary of the thesis: they are short, concise statements of the inferences that you have made because of your work. It helps to organize these as short numbered paragraphs, ordered from most to least important. All conclusions should be directly related to the research question stated in Section 4. Examples:

    1. The problem stated in Section 4 has been solved: as shown in Sections ? to ??, an algorithm capable of handling large-scale Zylon problems in reasonable time has been developed.

    2. The principal mechanism needed in the improved Zylon algorithm is the Grooty mechanism.

    3. Etc.

    The Summary of Contributions will be much sought and carefully read by the examiners. Here you list the contributions of new knowledge that your thesis makes. Of course, the thesis itself must substantiate any claims made here. There is often some overlap with the Conclusions, but that's okay. Concise numbered paragraphs are again best. Organize from most to least important. Examples:

    1. Developed a much quicker algorithm for large-scale Zylon problems.

    2. Demonstrated the first use of the Grooty mechanism for Zylon calculations.

    3. Etc.

    The Future Research subsection is included so that researchers picking up this work in future have the benefit of the ideas that you generated while you were working on the project. Again, concise numbered paragraphs are usually best.

    7. References

    The list of references is closely tied to the review of the state of the art given in section 3. Most examiners scan your list of references looking for the important works in the field, so make sure they are listed and referred to in section 3. Truth be known, most examiners also look for their own publications if they are in the topic area of the thesis, so list these too. Besides, reading your examiner's papers usually gives you a clue as to the type of questions they are likely to ask.

    All references given must be referred to in the main body of the thesis. Note the difference from a Bibliography, which may include works that are not directly referenced in the thesis. Organize the list of references either alphabetically by author surname (preferred), or by order of citation in the thesis.

    8. Appendices

    What goes in the appendices? Any material which impedes the smooth development of your presentation, but which is important to justify the results of a thesis. Generally it is material that is of too nitty-gritty a level of detail for inclusion in the main body of the thesis, but which should be available for perusal by the examiners to convince them sufficiently. Examples include program listings, immense tables of data, lengthy mathematical proofs or derivations, etc.

    Comments on the Skeleton
    Again, the thesis is a formal document designed to address the examiner's two main questions. Sections 3 and 4 show that you have chosen a good problem, and section 5 shows that you solved it. Sections 1 and 2 lead the reader into the problem, and section 6 highlights the main knowledge generated by the whole exercise.

    Note also that everything that others did is carefully separated from everything that you did. Knowing who did what is important to the examiners. Section 4, the problem statement, is the obvious dividing line. That's the main reason for putting it in the middle in this formal document.

    Getting Started
    The best way to get started on your thesis is to prepare an extended outline. You begin by making up the Table of Contents, listing each section and subsection that you propose to include. For each section and subsection, write a brief point-form description of the contents of that section. The entire outline might be 2 to 5 pages long. Now you and your thesis supervisor should carefully review this outline: is there unnecessary material (i.e. not directly related to the problem statement)? Then remove. Is there missing material? Then add. It is much less painful and more time-efficient to make such decisions early, during the outline phase, rather than after you've already done a lot of writing which has to be thrown away.

    How Long Does it Take to Write a Thesis?
    Longer than you think. Even after the research itself is all done -- models built, calculations complete -- it is wise to allow at least one complete term for writing the thesis. It's not the physical act of typing that takes so long, it's the fact that writing the thesis requires the complete organization of your arguments and results. It's during this formalization of your results into a well-organized thesis document capable of withstanding the scrutiny of expert examiners that you discover weaknesses. It's fixing those weaknesses that takes time.

    This is also probably the first time that your supervisor has seen the formal expression of concepts that may have been approved previously in an informal manner. Now is when you discover any misunderstandings or shortcomings in the informal agreements. It takes time to fix these. Students for whom english is not the mother tongue may have difficulty in getting ideas across, so that numerous revisions are required. And, truth be known, supervisors are sometimes not quick at reviewing and returning drafts.

    Bottom line: leave yourself enough time. A rush job has painful consequences at the defence.

    Tips
    Always keep the reader's backgrounds in mind. Who is your audience? How much can you reasonably expect them to know about the subject before picking up your thesis? Usually they are pretty knowledgeable about the general problem, but they haven't been intimately involved with the details over the last couple of years like you have: spell difficult new concepts out clearly. It sometimes helps to mentally picture a real person that you know who has the appropriate background, and to imagine that you are explaining your ideas directly to that person.

    Don't make the readers work too hard! This is fundamentally important. You know what few questions the examiners need answers for (see above). Choose section titles and wordings to clearly give them this information. The harder they have to work to ferret out your problem, your defence of the problem, your answer to the problem, your conclusions and contributions, the worse mood they will be in, and the more likely that your thesis will need major revisions.

    A corollary of the above: it's impossible to be too clear! Spell things out carefully, highlight important parts by appropriate titles etc. There's a huge amount of information in a thesis: make sure you direct the readers to the answers to the important questions.

    Remember that a thesis is not a story: it usually doesn't follow the chronology of things that you tried. It's a formal document designed to answer only a few major questions.

    Avoid using phrases like "Clearly, this is the case..." or "Obviously, it follows that ..."; these imply that, if the readers don't understand, then they must be stupid. They might not have understood because you explained it poorly.

    Avoid red flags, claims (like "software is the most important part of a computer system") that are really only your personal opinion and not substantiated by the literature or the solution you have presented. Examiners like to pick on sentences like that and ask questions like, "Can you demonstrate that software is the most important part of a computer system?"

    A Note on Computer Programs and Other Prototypes
    The purpose of your thesis is to clearly document an original contribution to knowledge. You may develop computer programs, prototypes, or other tools as a means of proving your points, but remember, the thesis is not about the tool, it is about the contribution to knowledge. Tools such as computer programs are fine and useful products, but you can't get an advanced degree just for the tool. You must use the tool to demonstrate that you have made an original contribution to knowledge; e.g., through its use, or ideas it embodies.

    Master's vs. PhD Thesis
    There are different expectations for Master's theses and for Doctoral theses. This difference is not in format but in the significance and level of discovery as evidenced by the problem to be solved and the summary of contributions; a Doctoral thesis necessarily requires a more difficult problem to be solved, and consequently more substantial contributions.

    The contribution to knowledge of a Master's thesis can be in the nature of an incremental improvement in an area of knowledge, or the application of known techniques in a new area. The Ph.D. must be a substantial and innovative contribution to knowledge.

    Back to author's homepage.

    Posted at 04:54 am by VetPractice
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