Researchers at the USDA’s Agriculture Research Station are learning that feeding heifers more in their first year may not be the best way to get the best pregnancy rates or cattle performance. According to scientist Andy Roberts, “For the last 3 to 4 decades, the mantra has been ‘feed them to breed them,’ which means providing enough feed during the first year to ensure that young heifers reach puberty to start reproducing. But our studies indicate this doesn’t seem to be optimal in the long run. Our research shows that by feeding to get all the animals bred, you are also propping up the inefficient animals—those that won’t consistently produce calves when put in nutrient-limited environments later in life.”
The researchers looked at two groups of heifers (50 percent Red Angus, 25 percent Charolais, and 25 percent Tarentaise) in two lifetime treatment groups. The control group was fed according to industry guidelines. The restricted group was fed 80% of the amount of feed consumed by animals in the control group (on a body weight basis) for 140 days, ending when they were a year old. From breeding through late fall, the heifers were managed as one group, and then during the winter they were separated back into their groups: control and restricted. Every winter, the heifers in the restricted group were fed 20% less supplemental feed than the control group.
The feed restricted heifers grew more slowly and weighed less, and their pregnancy rates were lower: 87 % compared to 91% for the controls. But feeding the restricted heifers cost less, and also improved their efficiency throughout the rest of their lives and the lives of their offspring. “An interesting thing occurred,” says Roberts. “The feed restriction seems to have made the second generation able to withstand restriction [of feed] with greater efficiency.” By the third generation of the project, calves from restricted-feed cows were lighter at birth and at weaning than calves from control cows. But their mothers themselves were slightly heavier when the calves were weaned.
“Physiologically, the second-generation restricted cow is conserving some of the nutrients taken in for body reserves, which may result in more efficient reproduction and better survivability in the herd,” explains Roberts. Cows maximum production peaks at age 5 (as measured by calf weaning weight). In this study, the proportion of cows that became pregnant, and thus stayed in the herd until age 5 was greatest for restricted cows out of restricted dams. In comparison, restricted cows from control-fed dams had the lowest rate of survival to age 5.
What Does This Mean For You?
This is good news for folks ranching and farming in areas where drought and other weather changes mean that forage for livestock isn’t always as dependable or plentiful as we’d like. By feeding less, you can save money and create a cow herd that is resilient and successful even when forage is limited. It also means that you can identify cows early that aren’t going to be successful in your operation. As Andrew Roberts says, “Early elimination of inefficient breeders allows them to be harvested for the high-quality meat market.”
This article was drawn from “Improving Production Efficiency” in the Agriculture Research Magazine.
Any similar studies with breeding ewe lambs?
Finally researchers are catching up with what astute ranchers have known for 20 years.
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