MT. VERNON, Mo. — Fall calving is becoming more popular each year in southwest Missouri, according to Eldon Cole, a livestock specialist with University of Missouri Extension.
“This means females will be bred around Nov. 20 for a Sept. 1 calf. We’re only two months away from that target date,” said Cole.
With such an exact timeline, Cole says more producers are using fixed-time artificial insemination on their herds this fall.
It results in a more uniform calf crop that should be born earlier in the season. Earlier birth dates usually mean heavier calves at weaning.
University of Missouri researcher Dr. David Patterson, and his team, have helped develop several fixed-time artificial insemination protocols that have been highly successful on both heifers and cows. The average conception rate for the fixed time females runs in the low 60 percent range.
Some producers may feel the 60 to 65 percent conception is not satisfactory for the effort and expense.
However, compared to natural service and the uncertainty of using an unproven bull, those rates stack up pretty well.
“It would take an exceptional bull battery to get 60 percent or more of the natural service calves to hit the ground in roughly a two-week period,” said Cole.
The protocols have varying lengths of time you must plan ahead to use them. On the cow side, the duration of the protocol is either eight or 10 days from the CIDR insertion to actual AI service.
It involves three or four trips through the chute. Heifers require a bit more time and their three protocols vary from nine to 36 days. They also involve the vaginal CIDR insert and three or four trips through the chute.
One of these protocols uses the feeding of MGA, rather than the inserts and that saves one trip through the chute.
Charts that outline the various protocols are available from MU Extension centers, AI semen catalogs, some veterinarians and are online.
“It is important when using heat synchronization protocols that exact timing is adhered to. It’s definitely more effective to use AI sires that have a proven track record as a fixed-time AI breeder,” said Cole. “Be sure and talk to the AI company to assure the bull, or bulls, of your choice have a good history for timed AI.”
In addition to timed AI success on the bull, Cole says it is important to study the expected progeny differences (EPDs) on prospective sires.
“Be realistic about the traits your herd will benefit from then look for sires with high accuracy values for those traits. An accuracy of .80 or higher insures less variation in progeny,” said Cole.
Semen cost is reasonable for many bulls used in commercial herds. Excellent bulls can be found for commercial use in the $15-$20 range. Volume discounts can drop the cost even lower.
“Economics may cause some to shy away from heat synchronization and AI but comparisons for the overall cost of natural compared to AI breeding, on a per calf basis, is similar,” said Cole.
Since late November weather can be cold and rainy, Cole says producers should consider using a breeding barn on the day AI is done.
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