Nutritional Excess, Deficiency Can Harm
Body condition affects oocyte quality and embryo survival.
SIOUX FALLS, S.D. (Dec. 4, 2012) — For successful reproduction in the female bovine, several benchmarks must be reached. She must exhibit a normal estrous cycle. She must have functional ovaries. She must be capable of producing a viable oocyte or "egg," and she must be capable of providing a uterine environment suitable for embryo development and maintenance of pregnancy. According to Allen Bridges, University of Minnesota reproductive physiologist, for all of that to work, the female bovine must have adequate nutrition.
"It's pretty basic. We've known it for a long time. When they receive inadequate energy or protein, cows don't get pregnant," said Bridges, during the Applied Reproductive Strategies in Beef Cattle (ARSBC) conference Dec. 3-4, in Sioux Falls, S.D.
Bridges said researchers have investigated how the estrous cycle is influenced by nutrition. His research is focused on discovering what direct effects nutrition has on oocyte maturation and competence, and how nutritional status during early gestation impacts uterine function and embryo survival. He offered examples of the ways certain nutritional hormones affect reproductive tissues and how changes in nutrition and body condition during the postpartum period affect reproductive processes and pregnancy success.
Insulin, explained Bridges, is a metabolic hormone produced by the pancreas to regulate fat metabolism. Insulin level also affects production of estradiol, which is essential to reproductive function. Inadequate nutrition means lower insulin production and lower fertility.
"Too much body condition means too much insulin and the same end result," warned Bridges. "Whether females are thin and staying thin or fat and getting fatter, neither is good."
Bridges said nutritional stress also causes reduced production of insulin-like growth factor-1 (IGF-1), which plays a role in cell growth. Additionally, nutrition can affect production of leptin, which appears to be associated with insulin and IGF-1 levels.
"Nutritional stress can have dramatic effects on a developing follicle and oocyte," emphasized Bridges, recommending that females be managed for appropriate body condition — not less than body condition score (BCS) 4 and not more than 6.
"It is possible to get too much of a good thing," he added. "Nutritional excess can have the same results as deficiency."
Bridges spoke during Tuesday's ARSBC session focused on management of stress. Visit the Newsroom at www.appliedreprostrategies.com to listen to his presentation and to view the accompanying PowerPoint and proceedings paper.
Comprehensive coverage of the symposium is available online at www.appliedreprostrategies.com. Compiled by the Angus Journal editorial team, the site is made possible through sponsorship by the Beef Reproductive Task Force and LiveAuctions.tv.