A TEAM of South Dakota State University (SDSU) researchers is asking questions about how changes to a beef cow's energy intake during the second trimester of pregnancy might affect the quality of beef from her offspring.
Known as fetal programming, this concept suggests that, during development of the fetus, important biological parameters can be manipulated and that these alterations can carry through to maturity. While fetal programming has been studied in human health, it's a relatively new area of research in the beef industry, SDSU associate professor of animal science Amanda Blair explained.
With more than $411,000 in funding from the U.S. Department of Agriculture and the South Dakota Beef Industry Council, Blair and her colleagues began a four-year project in 2010 to determine how limiting a cow's energy intake during the second trimester affects her calf.
"We focus primarily on the second trimester because that's when the bulk of the muscle development (of the fetus) occurs," Blair said.
She is working with SDSU extension meat specialist Keith Underwood, feedlot nutritionist Robbie Pritchard and geneticists Michael Gonda from SDSU and James Reecy, director of Iowa State University's Office of Biotechnology.
The team divided 151 cows at the Cottonwood Range & Livestock Field Station near Philip, S.D., into two groups. All cows were bred in June 2010, and the groups were managed the same until the second trimester.
During that 90-day period, one group was fed a "positive" energy diet to maintain an average body condition score of five, meaning the cows maintained their weight or gained slightly. The second group was fed less energy — a "negative" energy diet — to lose body condition.
Protein was held constant, so the only variable was energy, Blair explained. In the third trimester, the cows were all given the same rations.
The calves were born in April and May 2011, weaned in October and brought to the SDSU feedlot. In the spring of 2012, 24 head were harvested at the SDSU Meat Lab and analyzed for changes in gene expression. The remaining steers and heifers were processed at Tyson Foods in Dakota City, Neb., where carcass data and meat quality attributes were recorded.
Overall, the study showed that "altering maternal energy during mid-gestation impacts the fat deposition of the offspring," Blair said. The calves from cows in the negative energy group had a more favorable distribution of carcass fat.
"They had an increase in marbling relative to back fat," Blair noted. "From a beef production standpoint, that's exciting."
The yield grade of the offspring from the negative energy cows also improved, Blair said. Meat tenderness and color were unaffected by the maternal diets.
Next, the researchers will investigate the effects of reducing protein intake during mid- and late gestation.
"These types of studies allow us to look at the whole beef system from conception to consumption," Blair said.
Only when researchers know more about the mechanisms and what's changing will they be able to advise producers on using fetal programming as a management tool.