In February's Beef Cattle Comment, Cornell University Extension Beef Specialist Mike Baker, Beef Extension Specialist, shared some good news for cow-calf producers concerned over the high-cost of grain concentrates. Ohio State University researchers studied the impact of three ration sources to cows in their last trimester before spring calving.
Three cow groups were 1) full fed hay, or 2) 4.4 pounds of hay plus 8.5 pounds of dried distillers grains with solubles (DDGS) and 2.2 pounds of protein/mineral supplement or 3) 4.8 pounds of hay, 10 pounds of dry shelled corn plus 2.2 pounds of supplement.
Steer calves from the cows were weaned at about six months of age, backgrounded on stockpiled fescue for 28 days, then placed on a common high-energy diet. They were harvested when bakfat registered at 0.5 inches via ultrasound.
Birth weights of calves born to cows on the all-hay diet were smaller than the others. Weaning weights of calves from corn supplemented cows was greater than calves from hay-fed cows, while those from DDGS fed cows were intermediate.
Milk production was measured using the weigh-suckle-weigh procedure and found not to be different between treatments. Therefore differences in weaning weights were not due to milk production as might be expected.
Feedlot measures of initial weight, dry matter intake, average daily gain or feed efficiency weren't different due to how the cows were fed in last trimester. And, hot carcass weight, ribeye area, and yield grade were not affected by maternal nutrition.
However, the carcasses from calves out of cows fed the low starch (hay and DDGS) diets had higher marbling scores and fewer USDA Select carcasses than cows receiving corn supplemented diets. So it appears, surmised Baker and the study authors, that maternal nutrition during gestation may affect fat deposition.
Bottom line: Maternal late gestation dietary energy source seems to alter fetal growth, affecting birth weight and having long-term effects on metabolism and body composition. Feeding a low-starch diet in late gestation appears to be associated with greater intramuscular fat deposition. And that can be good for the beef producer's bottom line.