Cattle Today

Cattle Today



by: Heather Smith Thomas

Modern technology and new techniques in reproduction are making some aspects of cattle production easier. One innovation that is gaining popularity is pregnancy checking via blood samples.

Brandon Critendon (Wolf Point Ranch, at Port LaVaca, Texas -- on the Gulf Coast between Houston and Corpus Christi) has been using this means of pregnancy checking for almost two years and feels it has several advantages over palpation or ultrasound. The blood test can be done as early as 30 days post breeding, which is sooner than you can tell when using palpation. The cow or heifer must be at least 45 days pregnant before you can tell by palpation, with any accuracy, that she is pregnant.

A blood sample is taken from a vein under the tail, sent to the lab to check for presence of a certain hormone produced by the placenta, and the results are available (via phone, e-mail, fax or whatever the producer desires) within 48 hours. BioTracking, the company doing the BioPRYN test, now has 15 labs around the country; the number of cattlemen using this test has grown tremendously since it became available in 2005. The first year, they processed about 85,000 samples and now they are doing this amount monthly.

"I really like using the blood test on my heifers. I use it in my cow herd, as well, but it's not as convenient to check them that quickly. The advantages of the blood test include better accuracy, not having to manually enter the cow through palpation (which in some instances may disrupt a pregnancy), and the ease of collecting the blood samples," says Critendon.

"My cows are all individually identified with visual and electronic ID so this makes the procedure very easy for us. Here in Texas, where in the past we've done a lot of testing for brucellosis, it's easy for me to find people who have a lot of experience in bleeding cattle," he says. It's quick and easy to take a blood sample, taking less time than checking a cow with rectal palpation.

"You need someone to manage the paperwork and record the cows' numbers, but the people at the lab are very careful and accurate in what they are doing. We've calved out several sets of cows now, that we've preg tested via blood test, without any palpation, and the accuracy is very good," says Critendon. A very small percent may lose the pregnancy after they've been blood tested, but the test is much more accurate than palpating.

Ranches in that area of Texas are very large and it's hard to see all the cattle on a daily basis. A few may abort at some point between testing and calving. "But I know that my calf crop is a lot larger since we've moved to the blood testing, and I think this is due to better accuracy. Even with very experienced people doing palpation, they miss a few; it seems like we ended up with more open ones when we relied on palpation to check them."

His heifer program has greatly benefitted from the blood test. "I can time my breeding season, with one round of AI and cleanup bulls. With the accuracy of this test at 30 days post breeding, I can check them at day 75 from the first day I started AI, and pick the heifers from a 45 day breeding season. I calved out a set of heifers doing it that way, and they all calved in a short time frame," he explains.

"You can still come back afterward and have a later group. If you pull blood at 30 days and they show not bred, it doesn't always mean they are open; the test may not have picked up a very early pregancy on those. You can always come back on those cattle and bleed them again later. I'm trying to get my heifers to calve in a 45 day window, so this really helps."

A person putting together groups of heifers guaranteed to calve at a certain time could use this blood test to determine the groupings. The ones bred later can be checked later. You can pull blood again 30 days later and find the ones that bred during the next increment. It's hard to get a large group of heifers all mature and bred early, and this is a way to sort them very quickly as to which ones settled at certain stages of the breeding season.

Critendon also likes the fact that with the blood test there's no possibility of disease transfer from animal to animal, since each one has an individual needle and blood vial. "There is always some risk of spreading disease when using palpation. Ideally you'd change gloves between every animal, but no one takes time to do that. I got picky enough to do that once, but it drags the day out longer and you end up with a big pile of dirty gloves," he says.

The biggest disadvantage to the blood test is that you have to wait two days for results. For some producers who are only working their cows once in the fall when cattle are coming off pasture or the calves are being weaned or sold (and must make a decsion about culling as the cows are preg checked), this won't work. They must know immediately if that cow is pregnant or open when she goes through the chute, to know whether to give vaccines, dewormers, etc. since they don't want to administer those products to a cow they are going to sell. But for anyone who will have those cows around awhile before sale, with another chance to run them back through, the blood test works nicely.

"We started using the blood test on a trial basis in February 2006 and since then I have gone strictly to pulling blood rather than palpation or ultrasound. We've run many series of samples through the lab, and can't say enough good things about the people at Biotracking. We had an issue once with some samples; the company called to tell me the results would be delayed, and I complained a little since I had all my cowboys lined up to work cattle again on the day I was expecting to have the results back.

They showed up on my computer at 3 a.m. that next morning. I went to bed not knowing whether or not we'd be able to work the cows the next day, but the results showed up. Those guys work overtime to make it work for you," he says.

Usually he sends about 200 samples at a time to the lab, but has sent as many as 700 at a time. "They'll report it back to me in an Excel spread sheet, and I can put that into my computer and sort my cattle by opens or by ear tag number or take all the opens and put them in one area and put ear tag numbers back in chronological order so we can see them as the cows are coming down the chute and find them easier," explains Critendon.

He tried out the blood test on a limited basis the first time. "I'm not a quick sell, on anything. I'll sit back and do my own research on anything new; I won't jump in until I'm sure it's going to work. In the beginning, I'm pretty critical on new ideas. I really put this one to the test. I took a set of fall calving cows and pulled blood on them in February 2006. I'd been running bulls on them since mid December. I sorted out all the bred cows and pulled blood again on them in May. I wanted to see how everything was looking, and got basically the same results," he says.

"We had a good summer and the cows were looking pretty good and fleshy, but I pulled blood again on them in early August. I was trying to find out early if I had any more open cows, since a lot of people start shipping cull cows in September/October and the market drops. But I had the same results on them (no opens) and calved them out. I'd given it a very good test. Since then, all my spring cows this year, and all my heifers, have calved out with this test. I've already pulled blood again on my second round of heifers in this past breeding season, and I feel extremely confident in it now," says Critendon.

"It took me a few times to work the kinks out of it on my end and get my precedure figured out, but now it works very smoothly. The first time we pulled blood, we did 175 cows, on two different ranches. We had to pen both sets of cattle. By the time we got in the chute and started the first set, it was about 9 a.m. We were trying to figure out how to keep the paper work flowing properly, etc. and were not very efficient yet, but even after taking time out for a good lunch, we were finished by 3 p.m. with both bunches. Now, of course, we can do it faster. If you have someone good at drawing the blood, it doesn't take as long as palpation," he explains. When someone is trying to determine a relatively early pregnancy with palpation, they may be in that cow awhile.

"We do a lot of AI and are good at working in these cows, but I don't feel comfortable going into a cow and looking for a 40 day pregnancy," says Critendon. There's always some risk for bruising the embryo and aborting that cow.

"I manage large numbers of heifers through the breeding season, and may have a few sorts regarding body condition and nutrition. There may be some that need a higher plane of nutrition and there may be others I'm coasting through, but I can do some preg testing (via blood test) relatively early in the breeding season and if I need to do some additional sorting, I still have time to do that, based on the results of the tests. I think this can give you a way to locate the most fertile heifers early on, and still turn around and take the open ones to the feed yard and get them fed and fattened before they reach the age when the market starts to drop," explains Critendon. This gives a better chance to hit the best heifer market, on the ones that don't settle early.

"I've recommended this to several of my neighbors down here in south Texas, and they're now using the blood test. We're in an area where 75 to 80 percent of the cattle are not individually marked. They have fire brands, but no individual ID. I'm often talking to people who can't fathom individual ID, but they have to do it, for this. Some of these guys are more intrigued by using ID so they can pull blood on these cattle to preg check, than they are on using ID for other reasons like being able to pair the cows and calves. Now they've put in ear tags and find it helpful in many different ways," he says.

He feels strongly that he'd never go back to using palpation or ultrasound, since the blood test has been very beneficial to his program. "It's not much different in cost than palpation. The test itself costs $2.25. By the time you add the equipment, needles and labor, it puts another 50 cents on it, so the total would be about $2.75 per animal. Regarding labor, we're often doing several jobs at once, which makes it more cost effective. I may have a little more labor on hand for that day, but we're generally doing more to those cattle at the same time. We send enough numbers down the chute on a day of working that we can make it very cheap," says Critendon. By contrast, it can be harder to schedule a vet to come palpate, and in some instances the cost of the farm call -- if you are a long ways from a vet who will do this -- can add a lot to the cost of palpation.

The biggest disadvantage for some people is having to wait two days for the test results. "This is not a disadvantage to me, since I'm set up to where I can turn my cows back out or have large enough traps to keep them in a couple days. I use this in my cow herd, too, though by the time I preg test them a palpator could do a good job also. Two weeks before weaning, I give my calves some vaccinations while they are still on the cow, and put the cows down the chute and pull blood. The cow has to come back in again in two weeks anyway when we wean the calves, and we can sort and work the cows at that time," he says.

This is much better than trying to preg check and work the cows in one day. All too often people are vaccinating or squirting fly spray/dewormers on the cows as they come through the chute, before they are preg checked--and then you have some open ones that you not only wasted these products on, but can't ship immediately because of the withdrawal times on those drugs. "The proper thing to do would be to hold those cows until the withdrawal times are past, but how many people are actually going to do that?" he says. It makes more sense to only work the cows you know are pregnant.

The blood test gives a person several more options in breeding management. "The cost is relatively small, so a person can use it to fine tune a breeding program. I could pull blood in conjuction with my AI program, to determine my percentage of AI calves." It can tell you which ones are bred by AI and which ones settled to the clean-up bulls.

"We heat synch everything, so we have large numbers to AI. I can't do all my heifers at once and get them all done in a day's work; I have to break them up into several groups. I'll have my cleanup bulls out on the first set by the time we AI some of the last ones. There are still a few things I need to work out on my end to be able to better manage the breeding and use the tools that are available," says Critendon.

Some people in his area use the blood test on cows they've heat synched for AI. "They pull blood on them very quickly and can know which ones settled. If you can't afford to buy a set of expensive heifers, you can find some cows being sold because of drought. They may be open, but if they are only open because of poor nutrition due to drought, these cows may be purchased inexpensively. Using heat synch and AI or even turning a bull out with them for a little while, you could then pull blood and determine which ones settled, and resell the open ones," he says.

"I think this is a wonderful tool and I'm trying to get all my neighbors to try it. I'd like to see the cattle operations in this area improve. Where we live, we're a long way from feed yards. We're always in a fight to get good buyers down here. The biggest thing we run into down here is lots of operations running their bulls year round because they feel a small calf is better than no calf. But this makes it tough for a person palpating those cows for preg checking, because he's palpating cows anywhere from nine months pregnant to maybe only bred a few hours," says Critendon.

This blood test, utilized early in the season, can help a person tell which cows were bred early. "You could put uniform lots together -- cows that would calve in a certain time period. I'm trying to get more people to look at some of these options--like finding some of the shorter bred cattle. There's always something that fits someone's operation, somewhere. There may be producers who want summer calves, for instance. Ranchers could sell those cows and make their own calving season more uniform," he says.

The blood test detects a level of this protein, and there may be a way to determine how long the cow has been pregnant, and be able to pinpoint how soon she'll calve. "I've talked to the company about this and I think they do this with the dairy cattle to see how close they can pinpoint it," he says. Since the dairy cows are bred AI and there's always an accurate breeding date, this gives a good way to test the accuracy of the blood test for determining length of pregnancy.

"Crossbred cattle may be more varied in gestation length, however, than dairy cattle that are so pure, and it might not be quite as accurate. We do so much crossbreeding here, it could make a difference. We personally have black Brangus, but they are not registered, and some of our older cows have mixed linage," he says. Some of the cattle in the area are Beefmaster and mixes of several other breeds. Gestation lengths may vary by 10 or 12 days.

"I try to work with BioTracking all I can, to give them as much information as possible. Most cattlemen would love to work with them more, to get things like estimated calving dates. People like my neighbors who run their bulls year round, could pull blood samples on those cows and get a good idea when they will calve."

He says taking blood samples is a lot easier than most people think. Many are hesitant to try because they aren't sure how it would work in their herd. "I read about it several years ago when it was brand new, and contacted the company and asked questions and didn't think I could make it work. But the more I kept thinking about it, I realized it wouldn't be that hard to do. Once I applied it, it actually went very well," says Critendon.

"The samples are easy to handle. You don't have to refrigerate them, just protect them so they don't get broken. I ship them in the styrofoam boxes I get vaccine in, or go to Walmart and buy shipping boxes and bubble wrap. I put the samples in groups of 10 and wrap them with a rubber band, put them in a ziplock bag, and protect it with bubble wrap," he says.

He likes to divide them into groups of 10 because if one vial gets broken inside the bag and it's contained, the people at the company can find the one that's broken and recover the blood from the bag, and test it. "If they all get broken, you can't do that, but still, it's just 10 of them rather than the whole box."

There are plastic vials available that don't break as readily, but he prefers to use the glass vials because they are larger (7 ml rather than 3), just so he can get the 3 ccs of blood very easily.

"The 3 or 4 cc vials are the only ones that come in plastic, as far as I know. I use the larger ones because our cows are not very docile and if they are jumping around or don't bleed readily, we're able to get 3 or 4 ccs before we completely lose the vacuum on the vial. By contrast you probably should fill a 3 cc. vial completely to get the sample they need. I think they can do it with less, but it's better to have plenty than not enough. If a test fails, they have enough sample to go back and run it again. It beats having to go back and find that cow again," he says.

"If we pull blood on a cow and lose the vacuum on it and feel we don't quite have enough, I'd rather throw that tube away and take another sample. Or I may grab one of the syringes I keep on hand and pull another couple cc of blood out of the cow and shoot it into that vial so I have enough," he explains. With all the labor already has invested in the process, he feels it doesn't make sense to shortcut it by not having enough blood in the sample.

"You can have problems if you are trying to go too fast when putting the cows through the chute and pulling blood, so I always keep slowing everyone down a bit. You don't want to compromise it in any way," he says.

Critendon really likes the test and says the people at the company help you out a lot. He makes sure his records are accurate and easy to read, and keeps an extra list of the numbers as well as writing them on the vials. "If someone can't read my writing on the numbers, we can always refer back to my list. I make copies of all my paperwork, so we can always go back and see that sample number 20 is cow 519, or whatever. It's working really well and I am happy with the procedure. The first day we did it, it was a bit overwhelming, but once you get comfortable with it, it goes very smoothly."


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