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Copyright © 2015
Angus Journal

Nutrition and Reproduction

Energy, protein go hand in hand for reproductive benefits.

SIOUX FALLS, S.D. (Dec. 4, 2012) — “Reproduction is the single most important factor associated with economic success of the cow-calf producer,” said Scott Lake, assistant professor of animal science at the University of Wyoming. He explained how nutrition directly affects reproduction to the more than 300 participants at the Applied Reproductive Strategies in Beef Cattle (ARSBC) symposium Dec. 3-4, 2012, in Sioux Falls, S.D.

Scott Lake The biggest reason cows fail to conceive within 83 days of calving — the magic number to maintain a 365-day calving interval — is inadequate nutrition, explained Scott Lake.

It is important for the calving interval to be every 365 days, not just within every calving season, Lake said. The longer the postpartum anestrous period, the more likely a cow is to get culled. Generally, he added, 2- and 3-year-olds are the most likely to fall out because their continued growth demands more nutrients. The magic number is for a cow to conceive a calf 83 days after calving, and the biggest reason why cows don’t hit that number is inadequate nutrition.

If cows or first-calf heifers have a body condition score (BCS) of 5 or 6 at calving, the postpartum anestrous period shortens dramatically to 50-60 days, Lake observed. Conception rates also increase to 85%-90%.

Additionally, nutrition during pregnancy affects the calves in utero, he noted. Calves can weigh 40 more pounds (lb.) at weaning if the cow is in BCS 5-6. Granted, he said, milk production can be a factor to a degree, but nutrition of the cow greatly affects the calf’s potential.

“Cows need to be in the condition we want them in by the time they calve,” Lake emphasized. It is much harder to put on weight after calving.

“Most cases of protein, mineral and vitamin deficiencies are confounded with energy,” he said. It is very difficult to rank importance of energy and protein because of this.

As long as crude protein (CP) and total digestible nutrient (TDN) requirements are met, he explained, it doesn’t matter the source, as long as it is of good quality. Inadequate protein intake can result in reduced pregnancy rates in cows whose diets contain equal energy.

He warned that protein-supplement effects are dependent upon the environment and the cow’s age. Protein also needs corresponding energy to work properly. Protein and energy go hand in hand.

He urged producers to slow down and feed cattle correctly. He concluded it doesn’t matter the quality of semen for breeding or technicians, reproduction won’t work without proper nutrition.

Lake spoke during Tuesday's session focused on herd fertility and nutrition. Visit the Newsroom at to listen to his presentation and view the PowerPoint and proceedings paper submitted to accompany his presentation.

Comprehensive coverage of the symposium is available online at Compiled by the Angus Journal editorial team, the site is made possible through sponsorship by the Beef Reproductive Task Force and

Editor's Note: This article was written under contract or by staff of the Angus Journal. To request reprint permission and guidelines, contact Shauna Rose Hermel, editor, at 816-383-5270.