FEATURE
Developing Heifers for Long-Term Success By Laura Handke
R
esearch conducted in the past decade is helping to shed light on new heifer development strategies, with management beginning early in the life of a heifer calf. Today, there is much focus on nutritional management strategies that can be applied at strategic times in a heifer’s early life. The importance of timing in attaining puberty is critical, research is proving, and nutrition is an essential component of long-term reproductive performance.
Focus on Calfhood Opportunities
To maximize lifetime productivity, heifers need to become pregnant by 15 months of age, meaning they have to reach puberty by 12-13 months of age. Additionally, heifers need 2-3 cycles to become sexually mature.
Metabolic imprinting is an early adaptation to nutritional stress/stimulus that permanently changes physiology and metabolism. These changes continue to be expressed even in the absence of the stress/stimulus that initiated them.
“Longstanding research shows that heifers bred on their third estrus cycle have greater pregnancy rates than those bred on their first,” says Philipe Moriel, University of Florida, associate professor of beef cattle nutrition and management in a recent Beef Reproductive Task Force webinar. In a recent study, researchers looked at heifers that reached puberty before breeding season and heifers that reached puberty during breeding season; 100% of heifers had the opportunity to settle, the only difference was when they came into estrus for the first time. “What we see is a very consistent response from heifers that reach puberty before the breeding season versus those that reach puberty after breeding season has begun,” Moriel says. “We can see the negative effects of later puberty on long-term reproductive performance and calving distribution.” Not only the number of heifers that settle are of concern, but the effect that a later conception has on calving distribution can be costly. Longevity is also a concern – heifers that calve within the first 21 days of their first calving season have greater pregnancy rates in the next six generations, allowing a producer more time to absorb the costs of developing a heifer and realizing profit from her calves. And, obviously, heifers that calve earlier typically wean heavier calves.
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“Feed efficiency is greatest in calfhood, the younger the calf, the more feed efficient they are. Calves are also more susceptible to environmental effects early in life. Both environment and nutrition experienced early in a heifer’s life can influence her metabolic performance throughout her lifetime,” Moriel says.
Puberty attainment is susceptible to metabolic imprinting and is influenced most between the first two to six months of a calf ’s life. Recent data shows that when you enhance nutrition between the first two to six months of a heifer’s life, she is able to achieve puberty sooner. Even better, new data has shown enhanced nutritional response and subsequent puberty attainment is possible to a greater extent when the nutrition is provided at earlier periods in the heifers life and even in the gestational phase of her dam. The study looked at heifers that were assigned to a high average daily gain (ADG) from 3-21 weeks of age and a group of heifers that were assigned a moderate ADG (.5 kilo/1 pound) from 3-21 weeks of age. What they saw was that that those heifers on a higher ADG had better developed reproductive tracts as a percentage of body weight. “By boosting nutrition in the early stages of life, we are able to help those heifers reach puberty sooner,” Moriel says of the opportunities early high average daily gains provide in heifer development.
Nutritional Strategies Early weaning, between two and three months of age, on the first day of breeding season for their mothers, is a tool that researchers are investigating. This strategy to increase reproductive performance of the cows, especially first calf heifers, is one that is proving to be effective.
