What do we know about it and how can we manage it?
DES MOINES, Iowa (Sept. 8, 2016) — What affects the cow affects her calf, but what kind of management is necessary for optimal performance of both? Robert Cushman, research physiologist at the U.S. Meat Animal Research Center (USMARC), explained that when cattlemen talk about this phenomenon, they are really discussing developmental programming, which includes fetal programming and nutritional programming. These have events that occur both before and after birth.
Robert Cushman, research physiologist at the U.S. Meat Animal Research Center (USMARC).
“If we are going to use it for management, it is important that we understand this,” he noted.
He spoke to attendees of the 2016 Applied Reproductive Strategies in Beef Cattle symposium Sept. 7-8 in Des Moines, Iowa.
He shared part of the Barker Hypothesis: “Numerous animal experiments have shown that poor nutrition during periods of rapid growth in early life may permanently change the structure and physiology of a range of organs and tissues.”
Often, cattlemen think of developmental programming in a negative sense, as in what happens to the calf when the female has a nutrient-restricted diet. He suggested that we look at it to improve management in health, productivity and reproduction.
Female reproductive traits expressed early in life have the greatest heritability. A high antral follicle count correlates to increased fertility and has an average heritability of 0.4, he said. While genetic selection for these females with a larger ovary reserve is an option to increase reproductive production, he said several studies have shown that developmental programming — including targeted feeding — can increase or decrease the size of this ovarian reserve.
Poor maternal nutrition during early pregnancy decreases the daughter’s follicle number. In theory, he granted, there may be ways to feed a dam in the first trimester during drought or negative environmental situations to increase the daughter’s antral follicle count. Conversely, he shared data showing maternal nutrition during late pregnancy did not alter the daughter’s follicle count.
Therefore, he said, third-trimester nutrient intake can positively influence the unborn heifer’s conception date, but it does not alter the antral follicle count. So, drought conditions occurring in the first trimester could potentially decrease the daughter’s ovarian reserves, but he adds that an earlier calving day could lead to increased reproductive longevity in the absence of a change in follicle number. Having a controlled calving season with more females calving earlier will help the reproductive rate of the daughters.
Cushman spoke during Thursday’s ARSBC session focusing on genetics. Visit the Newsroom at www.appliedreprostrategies.com, which features comprehensive coverage of the symposium, to view his PowerPoint, read the proceedings or listen to the presentation. Compiled by the Angus Media editorial team, the site is made possible through sponsorship by the Beef Reproduction Task Force.
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