AIRDRIE, Alta. – The development of replacement heifers is a long-term project that does not yield a return until the first calves are sold.
Young animals require special care and feeding because they are still growing but are also expected to start reproducing.
Proper nutrition influences growth and reproduction, says Airdrie veterinarian Nathan Erickson.
“The overall goal of feeding is to meet the energy and protein requirements, otherwise they are just burning hay,” he told an Oct. 5 seminar on winter feeding programs sponsored by the Foothills Forage Association.
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The main objective is to develop heifers to the point where they reach puberty and are cycling regularly at the start of the breeding season.
Most reach puberty at 55 to 60 percent of their mature weight so poor nutrition delays puberty. Age, weight and breed influence the onset of puberty.
Hereford, Angus and Limousin reach puberty at 60 percent of mature weight while Braunvieh, Red Polls and Gelbvieh reach it at 55 percent of mature weight.
Heifers don’t need too much fat in their diet because it just goes to the udder, resulting in poor milkers.
They also don’t need bypass protein at this time, but they will need higher levels for breeding the second time. Too much protein can create a form of acidity in the uterus that affects progesterone production and fertility.
Ionophores may help them reach puberty by breeding season and improves ovulation for the second breeding season.
Heifers should calve at 80 to 85 percent of their mature weight so they need an increasing plane of nutrition. About 50 percent of fetal growth occurs in the last 35 days of pregnancy.
Peak milk production is about 60 days after calving, which puts added pressure on young females because they are still growing and supporting a calf.
They must also start cycling on schedule, which means they need extra care and good feed. This places second-calf heifers at risk of being culled because they were not fed adequately and do not get pregnant on time.
Early weaning can result in better performance of the dam and subsequent calf in all age groups. If they have more recovery time, heifers can increase body condition and weight before and after calving. This improves the weight of the next calf because the mother is in better condition.
Young bulls that do not get enough energy in their diet have a delayed release of hormones that may hold back puberty.
“If they are delayed, it is hard to compensate later,” Erickson said.
Low energy may delay puberty to 57 weeks of age rather than 40 weeks. They also need higher levels of protein in their feed.
A deficiency in vitamin A and zinc can cause testicular degeneration.
With proper diet, a 1,200 pound yearling bull is likely to double its weight at maturity.
