Newswise — Manipulating a cow’s nutrition level during the second trimester can alter the carcass composition of her offspring, according to associate professor of animal science Amanda Blair of South Dakota State University.
Fetal programming is the concept that during fetus development important biological parameters can be manipulated by environmental events and these alterations can carry through to maturity.
Using this concept to influence beef production by altering maternal nutrition is a fairly new area of research, the meat scientist explains. “We focus primarily on the second trimester because that’s when the bulk of the muscle development occurs.”
With more than $411,000 in funding from the U.S. Department of Agriculture and the South Dakota Beef Industry Council, Blair and her team began a 4-year project in 2010 to determine how limiting a cow’s energy intake during the second trimester affected her calf.
She worked with former SDSU ruminant nutrition expert Aimee Wertz-Lutz, Extension meat specialist Keith Underwood, feedlot nutritionist Robbie Pritchard and genetics experts Michael Gonda from SDSU and James Reecy, director of Iowa State University’s Office of Biotechnology.
Their goal was to use fetal programming as a tool to alter carcass composition, according to Blair. In the long term, the researchers hope to improve the quality and quantity of beef.
Energy levels altered
The team split 151 cows at the Cottonwood Field Station into two groups. Both groups were bred in June 2010 and treated the same until the second trimester. During that 90-day period, the positive energy group was fed to maintain an average body condition score of five, meaning they maintained their weight or gained slightly. The negative group was fed to lose about a body condition.
Protein was held constant, so the only variable was energy, Blair explains. In the third trimester, the cows were then given the same rations.
“We didn’t want to be extreme,” Blair explains. “We wanted to mimic what could normally happen in a production setting. Losing one-half to one body condition score during the winter is classically OK.” Then producers typically increase the nutritional levels in the third trimester.
The calves were born in April and May 2011, weaned in October and then brought to the SDSU feedlot. One set of 12 was harvested at the SDSU meat lab one month after weaning and a second dozen in May 2012, so they could be analyzed for changes in gene expression. The remaining steers and heifers were processed in May at Tyson Foods in Dakota City, Nebraska, where carcass data and meat quality attributes were recorded.
Fat distribution improved
Overall, the study showed that “altering maternal energy during mid-gestation impacts the fat deposition of the offspring,” Blair explains. 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 producer standpoint, that’s fabulous.”
But, she cautions, “we don’t know what would happen long term with the females.” A University of Nebraska study suggests that these females will be negatively affected as breeding stock.
The yield grade of the offspring from the negative energy cows who cost less to feed also was improved, Blair says. This measure looks at carcass weight, back fat, percentage of kidney, pelvic and heart fat and ribeye area. Meat tenderness and color were unaffected by the maternal diets.
Though this looks good to cattle producers, Blair isn’t ready to issue any recommendations.
Further analysis needed
“We have a lot to learn,” she says, particularly when it comes to breeding stock. “Fat is very important to reproduction, both the age at which the animals reach puberty and their fertility.”
Next, Blair, ruminant nutritionists Derek Brake and Ken Olson, Underwood and Gonda will investigate the effects of reducing protein intake during mid and late gestation through funding from the South Dakota Beef Industry Council. The project will be done in collaboration with reproductive physiologist Rick Funston of the University of Nebraska.
“These types of studies allow us to look at the whole beef system from conception to consumption,” Blair says. 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.
About South Dakota State University
Founded in 1881, South Dakota State University is the state’s Morrill Act land-grant institution as well as its largest, most comprehensive school of higher education. SDSU confers degrees from eight different colleges representing more than 175 majors, minors and specializations. The institution also offers 29 master’s degree programs, 13 Ph.D. and two professional programs. The work of the university is carried out on a residential campus in Brookings, at sites in Sioux Falls, Pierre and Rapid City, and through Cooperative Extension offices and Agricultural Experiment Station research sites across the state.