Feed Lot

AUG 2017

Feedlots and cow/calf operations in the beef industry who feed 500 or more has annually on grains and concentrates; maintain 500 or more beef cows; backgrounder, stocker/grower, preconditioner; veterinarian, nutritionist, consultant

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When raising heifers, it pays to have a short breeding season—if breeding by natural service—and to preg- nancy test as soon as possible after the breeding sea- son or an AI protocol. Yearling heifers should have a short breeding season (45 days at most—the equiva- lent of 2 heat cycles—and some producers only give heifers 30 days to breed). This is the best age to cull, regarding fertility and efficiency. You should never keep a yearling that's a slow breeder. Rectal palpation is the traditional method of preg- nancy testing. Pregnancy can sometimes be detected as early as 30 days and definitely by 45 days of gesta- tion, feeling the uterus, ovaries, and uterine arteries through the rectal wall. For checking early, however, many producers prefer ultrasound. An experienced technician using ultrasound can detect pregnancy ear- lier than palpation, at about 21 days. A blood test is also useful for early pregnancy de- tection. There have been several tests developed using hormone measurements in blood and milk to confirm pregnancy. A commonly used blood test was developed by Dr. Garth Sasser, University of Idaho. He discovered a protein produced by the placenta of ruminant animals, detectable in their blood, and founded a com- pany called BioTracking. His blood test called Bio- PRYN (Pregnant Ruminant Yes/No) for cattle, sheep, goats, and other ruminants became commercially available in 2002 and today there are more than 50 labs in North America that process blood samples. There are now two other blood tests besides the BioPRYN test. One text is from IDEXX Laboratories, with headquarters in Westbrook, Maine. According to Frank Winslow, Director of Worldwide Marketing for IDEXX, this test was launched in August 2011, using ELISA assays to check for pregnancy-associated gly- coproteins (PAG). The IDEXX test is accurate 28 days after breeding. "This test delivers 99.3% sensitivity and up to 95.1% specificity after breeding, so clients can know with more than 99% certainty that a cow is open," says Winslow. In 2016 IDEXX launched a rapid visual pregnancy test—a 21-minute assay that can be read by a veterinarian without laboratory equipment—utilizing blood samples previously collected. The other blood test is by Genex, called DG29. This test targets a different protein in the blood, but works on the same principle. According to Laurie Lancaster of AgSource Laboratory (Jerome, Idaho), the DG29 test is accurate as early as 29 days post breeding. "There are two labs that process the blood samples: the AgSource Laboratories located in Menomonie, Wis- consin, and our lab here in Jerome. We also have a milk test—which is probably more practical for dairy cows, but can be used in beef cattle. With a milk sample we can determine pregnancy with accuracy any time after 35 days post-breeding," says Lancaster. Two years ago, BioTracking introduced a new tool for checking heifers, called the BioPRYNhfr-25 blood pregnancy test. At 25 days post-breeding, BioPRYN- hfr-25 is an early, accurate open detection for heifers. Research in commercial settings confirms BioPRYN is 99.9% accurate when a heifer is identified as open 25 days post-breeding. Dr. Fred Muller's Ag Health Laboratories in Sunny- side, Washington, handles many BioPRYN blood tests. He says this is a great tool to determine if heifers set- tled to an AI breeding or bred later to a cleanup bull— if you wait two weeks after a synchronized AI breeding before putting a cleanup bull with the heifers. "If you AI the heifers, you can still put them with a bull in a couple weeks, but 25 days after they've been AI'd you can pull a blood sample and see if they were AI bred," explains Muller. Any heifer that settled to the AI breed- ing will be confirmed at that time by the blood test, whereas any that settled two weeks later to the cleanup bull wouldn't show positive yet. Many producers want to know if they settled to AI or the cleanup bull, and an early test allows you to cull 20 FEED•LOT  August 2017 COW/CALF CORNER Early Pregnancy Testing Heifers Has Value By HEATHER SMITH THOMAS

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