Researchers found that restricting feed of heifers might improve their efficiency throughout their lives. They also noticed interesting traits in second and third generations produced from cows in the restricted feed study, which began in 2001. "The feed restriction seems to have made the second generation of calves able to withstand restriction with greater efficiency," Roberts says.
While third-generation feed-restricted calves were lighter at birth and at weaning than calves from cows fed at the industry standard, feed-restricted animals themselves were slightly fatter and heavier at the calves' weaning, he adds. "Physiologically, the second-generation restricted cow is conserving some of the nutrients taken in for body reserves, which may result in more efficient reproduction and better survivability in the herd," Roberts says.
“This is important because it potentially positions the heifers to withstand subsequent periods of nutrient deprivation due to naturally occurring phenomena such as drought," MacNeil says.
Tracking marbling traits for high-quality beef
To improve the quality of beef, LARRL scientists are taking a closer look at the streaks of fat in lean meat, known as marbling—a longtime indicator of palatability and basis for determining the price of beef. Marbling, which is measured either at slaughter or by ultrasound of live animals, is an inherited trait and thus amenable to genetic improvement, MacNeil says. "Cattle breeders would benefit greatly from having genetic indicators of superb marbling and other sought-after traits," he says.
Geneticist Lee Alexander and his colleagues are studying these genetic traits. They used a panel of molecular genetic markers to locate specific locations in the genome of a Wagyu-Limousin cross population that contain genes that influence traits such as marbling and fatty acid composition. Those breeds were specifically chosen because Wagyu is a heavily marbled beef, and Limousin is leaner.
"Genetic markers successfully identified a region of the genome associated with the amount of marbling and relative quantities of saturated and monounsaturated fats," Alexander says.
Scientists believe these findings may lead to healthier and better-tasting products for consumers through breeding methods that result in an improved fat profile in beef.