Early pregnancy tests are important every year – but this year, they’re more important than ever.
“The blood tests that are approved now for pregnancy testing are as early as 30 days, and that’s fairly accurate for a blood test. For a rectal palpation, it’s not recommended to palpate cattle much earlier than 45 days, and most of the time I don’t recommend pregnancy testing cows at anything less than about 60 days,” said Eldon Cole, University of Missouri southwest region livestock specialist at the Lawrence County office in Mt. Vernon. Cole continued 90-100 days is about the upper limit for “early” preg checking, and cited marketing benefits as another reason for testing virgin heifers that are being bred. “If you find out they’re open early, you can still put a little weight on them and sell them on the market, and they will be young enough to still qualify for certain age and source verification programs,” he explained. “If we waited several more months, preg checked them and said, ‘I’m going to have to do something with those heifers,’ they might be a little old.
As a result of the drought, feed is scarce and expensive. Dr. Tom Troxel, associate head-animal science for the University of Arkansas System Division of Agriculture, said it takes the net returns from 2.0-2.5 calves to pay for one open cow. Troxel told Ozarks Farm & Neighbor, “You surely don’t want to be paying high feed costs, shipping in hay from distances, and feed that to a cow that’s not going to produce you a calf next year.”
Early preg checking is also important during a drought year because producers tend to early wean their calves to cut feed costs.
Early testing can also help your veterinarian predict calving dates more accurately. “If you’ve done some AI work and had a clean-up bull with them, he can tell you if this calf that she’s carrying is going to be out of the AI bull or will it, more than likely, be a clean-up bull’s calf,” Cole said.
Cole said most producers prefer the certainty of a veterinarian’s ultrasound to manual palpation as a means of detecting pregnancy. “When you can actually see that embryo on the screen, it’s pretty evident that this is the right call on this heifer,” he said.
Early preg testing works best in a controlled breeding season. Cole said, “We tell people that if you don’t pull the bull out and have a gap of at least 30 days before you have the vet preg check, he may have some that he will call open, but they may be only bred 21-25 days.” In addition, during the heat of the summer of 2012, there will undoubtedly be bred heifers that will lose the fetus. “This fall, we may see some of those heifers coming back into heat,” Cole said. “But at least this gives the person a tip that the bull was working, the heifers got bred, but for some reason her body did not allow her to maintain that pregnancy.”
For whatever reason, if you find an open cow during a time of drought when forage is limited, Troxel recommended that you sell her. “If you’ve got plenty of forage and you think a bred cow would bring more value in the future, you might want to put a bull with them and sell them. But I would certainly mark that cow as one to cull, because obviously she did not breed and reproductive efficiency is genetically heritable,” he said. “Culling open cows is part of a long term program to improve the reproductive efficiency of your herd; many people will give cows another year and that usually is a mistake, because that does not improve the reproductive efficiency of your cow herd in the long haul.”
