The findings challenge long-held beliefs about the weaning-feeding process and fit nicely into a rapidly expanding value-based marketing approach in which meat quality rather than average cattle weight drives the payments made to producers. Producers for years have weaned their animals at seven months and let them forage in pastures for up to a year before feeding a corn-based finishing diet.
The researchers’ latest study, published in the July issue of the Journal of Animal Science, documents changes in meat-fat composition over two production seasons using the two approaches. It also confirms their preliminary findings about the possible advantages of early weaning of cattle.
"This study shows that we can produce high-quality beef that consumers desire, while at the same time reducing the amount of waste fat that must be discarded," said Larry L. Berger, a professor of animal sciences. "Our approach gives farmers an alternative production system in which they can improve the quality of the meat and get a better economic return off the animals."
Berger’s team analyzed two groups of Angus-Simmenthal heifers from the same genetic line. One group (16 animals) was weaned and put to pasture in the traditional way before getting the finishing diet. Thirty-two animals born the next year were weaned early and put on the finishing diet.
Ultrasound readings taken at regular intervals let researchers see changes in both intramuscular fat and subcutaneous rib fat. Intramuscular fat, or marbling, is a barometer of beef juiciness and flavor. Subcutaneous fat is waste and is removed before meat cuts hit store shelves.
Marbling increased in the younger animals at a higher rate, and the layer of undesirable rib fat was smaller, Berger said. All animals were harvested at about the same time. For the early weaned animals, harvest came at age 13 months, which is about five months earlier than is traditionally done.
"The older traditionally fed animals had more of the calories they consumed go into trimmed fat," he said. "The younger ones had more calories go in the marbling. The early weaning group had more of the nutrients consumed in the finished product compared to the older ones."
The National Beef Quality Audit in the 1990s concluded that cattle producers should strive to adapt to consumer demand for more lean beef by reducing rib fat by 20 percent and increasing marbling. Weaning animals early, Berger said, may help producers achieve that goal and reduce their feed costs.
The new study was written by Berger and department colleagues Aimee E. Wertz, a doctoral student, and professors Dan B. Faulkner, Floyd K. McKeith and Sandra Luisa Rodriguez-Zas. The Illinois Council for Food and Agriculture Research funded the research.
Journal
Journal of Animal Science