Treatment of cow affects calf
A three-year University of Nebraska–Lincoln (UNL) study, conducted at the Gudmundsen Sandhills Laboratory and the West Central Research and Extension Center in North Platte, demonstrates what a cow eats during late pregnancy affects her calf, said a UNL specialist.
Fetal programming, or the affect on the calf made by treatment of the pregnant cow, can be economically significant, said Rick Funston, beef reproductive physiologist at UNL’s West Central Research and Extension Center. Both birth and weaning body weights can be affected by manipulating the cow’s ration.
Steers’ harvest quality grade and heifers’ time of puberty can also be influenced.
During the study, four similar groups of cows grazed winter range. Two received a protein supplement; two did not. Four groups of cows grazed corn residues, two with protein supplement and two without. This study was repeated over three years.
Study results revealed cows grazed on corn residues and supplemented with protein had slightly heavier calves at birth than any of the others. At weaning, the apparent effect of supplementation had nearly disappeared from the corn residue system. Supplemented cows on winter range weaned calves equal those on corn residue. Unsupplemented winter range cows’ progeny, however, were 30 pounds lighter on average at weaning than those from any of the other treatments.
Although steers’ average daily gain in the feedlot was similar among treatments, both final live body weight and hot carcass weight were greater for steers from supplemented cows grazing winter range but not corn residue. More steers from supplemented cows achieved USDA quality grades of Choice or greater regardless of grazing system.
Heifer calves achieved similar weight gains regardless of dam treatment, but those born to cows grazing winter range without supplement were lighter at breeding and pregnancy diagnosis then any others. Although heifers from supplemented cows were younger at puberty, treatment did not affect final pregnancy rate.
Unsupplemented cows grazing winter range were lighter when the calving season started. By the time they weaned their calves, however, the effect of supplemental protein had disappeared. The cows that grazed corn residues were heavier, despite similar body condition scores. Their subsequent pregnancy rates were not affected by treatment.
For more information about this study, go to www. beef.unl.edu and click on reports in the left menu bar. Choose 2009 from the drop down menu under Nebraska Beef Reports and click on “Effect of Winter Grazing System and Supplementation on Beef Cow and Progeny Performance.” — WLJ