Nov. 11 2015 08:40 AM

Veterinarian shares ready-to-use information.

"Technology is great, but you still need to manage it," shared Scott Poock, D.V.M., during the Hoard's Dairyman webinar, "An update on repro technologies and protocols."

For many years, fertility suffered in dairy herds, but that trend is changing due to selections for higher daughter pregnancy rate (DPR) and sire conception rate (SCR). But, estrus expression remains lower for cows than for heifers and beef cattle. Research hasn't confirmed any difference between Holstein and Jersey herds, or confinement versus pasture-based operations.

The University of Missouri associate professor detailed several synchronization protocols, which are available on the Dairy Cattle Reproduction Council's website,

synch protocols

A corpus luteum (CL) less than six days old doesn't respond well to prostaglandins. So, for an injection to be effective on a mature CL, you need a Day 7 to Day 17 CL.

days of estrous cycle

Cows generally have two follicular waves each cycle. It's most beneficial to presynch to get to Day 5 to 10 to increase pregnancy per AI.

There are three common presynch protocols: presynch, double ovsynch and G6G. While the longest in calendar time is presynch and the shortest is G6G, there is a downside to the quicker option. The G6G requires you to work with the animals fives times each week, as compared to four times with double ovsynch and just three times with presynch.

CIDRs, progesterone-containing devices, are used for cows with no corpus lutea. MGA, a heifer feed additive containing progesterone, works much like a CIDR, but is incorporated into delivered feed.

heifer synch protocols

"I love finding pregnant cows!" announced Poock. "However, from the herd owner's perspective, finding open cows is more important. We can do something with her."

pregnancy diagnosis

When checking for pregnancy, pregnancy-associated-glycoproteins (PAG) are measured in milk or blood. It is a placental protein found in pregnant females.

bPAGs during pregnancy

The progesterone level rises in a pregnant animal up to Day 30, then it's followed by a drop off from Day 45 to 60. There is a quick rise after 60 days. Poock recommends to those that use blood or milk tests, to use them early in the pregnancy and then recheck at 70 days to avoid the low point.

Heat detection aids include rump mounted, pedometer, radiotelemery and accelometers.

Activity monitors can have some shortcomings. "They can produce false positives and false negatives. Simple things like pen moves can mimic estrus activity, so review data and take into consideration management changes at the time. However, their accuracy is improving. They used to be about 70 percent accurate, but now are pushing 90 percent," shared Poock.

"Activity monitors are great, but when you have them, you need to utilize them to be economically feasible!" reminded Poock.

You can learn more about reproductive protocols by watching this webinar, which was sponsored by Parnell. ( Our previous webinars are also archived for viewing.

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The author is the online media manager and is responsible for the website, webinars and social media. A graduate of Modesto Junior College and Fresno State, she was raised on a California dairy and frequently blogs on youth programs and consumer issues.