'If heifers are slighted nutritionally, it's going to have an impact'
By TIM HEARDEN
WILLOWS, Calif. -- Aggressively tracking and managing the reproductive capacity of bulls and replacement heifers can bolster a cattle operation's long-term economic health, two experts say.
Tools such as measuring reproductive tract scores and synchronizing heifers' estrus cycles can help producers get the most out of calving season, said David Patterson, a reproduction and beef cow management specialist at the University of Missouri.
Further, proper nutrition for heifers will maximize their productivity, he said. He noted ranchers in the Midwest lost a lot of pregnancies last year because of drought conditions.
"A lot of that goes back to the nutritional stress during that period of time," Patterson told about 50 cattle producers during a workshop here Feb. 22.
Ranchers should keep in mind that a heifer's target weight at puberty should be about 65 percent of the average weight of mature cows, he said.
"If heifers are slighted nutritionally, it's going to have an impact on their age and weight of puberty," he said. "If you're managing a later-maturing breed and you compromise their nutritional development ... you've unknowingly set those heifers up for reproductive failure."
Generally, heifers that calve earlier produce more offspring during their lifetimes, he said. Patterson strongly discouraged using growth-promoting implants on replacement heifers, but said synchronizing the heifers with controlled intravaginal drug release devices helps with reproduction management.
"More heifers will become pregnant early in the breeding season," he said.
For bulls, a multiyear study of about 150 angus bulls at a commercial ranch found they averaged about 20 calves in a season, but some sired as many as 54, said Alison Van Eenennaam, a University of California Cooperative Extension biotechnology specialist based in Davis.
There aren't yet many ways to predict the "superstars," she said, but two things many of them had in common were scrotal circumference and favorable scores in the American Angus Association's cow energy value index.
When measuring total dollars per sire per calf crop, the researchers found one bull could bring $45,000 back to the ranch if you sold all of his progeny as feeders, Van Eenennaam said.
"Income is very directly related to the number of calves a bull produces," she said.
In some cases, a rancher may find it's more cost effective to artificially inseminate their heifers than to have them naturally serviced, she said. A Siskiyou County study found that calves sired through artificial insemination arrived a little earlier in the season and had a higher weaning weight, she said.
Patterson and Van Eenennaam were taking part in one of several cattle health seminars being put on throughout the state by the UC Cooperative Extension.
Patterson told producers that while much of the beef cattle industry is "steeped in tradition," it's important for ranchers to embrace new methods. He said competitors such as Brazil are doing so.
"The fact is we've got a lot of technology that's not difficult to use that can make a big impact," he said.
University of California-Davis Department of Animal Science: http://animalscience.ucdavis.edu/
University of Missouri Extension Animal Sciences Unit: http://animalsciences.missouri.edu/