Dam type: maternal effects upon dam reproductive performance, calf mortality to weaning and preweaning growth parameters

Three dam types (straightbred (SB), single cross (2x), three-breed cross (3xX)), located in three Virginia herds (Bland, Hanover, State Farm) were bred to a combination of Angus, Limousin x Shorthorn and Maine Anjou x Shorthorn bulls. Over four calf crop years, 1978-1981, 1040 matings were recorded.

Reproductive performance of the dam, calf livability, average daily gain, weaning conformation and condition scores, adjusted 205-day weight, actual weaning weight and total damn productivity (kg. calf weaned/cow exposed) were assessed with regard to dam type, as well as individual dam breed effects. Three-breed cross cows were evaluated for both maternal sire and grandsire effects.

Pregnancy rates were similar among the three cow types, but 3X dams produced the highest weaning rates, due to lower death losses. Weaning weights of 2X and 3X progeny were comparable. Straightbred dams were the least productive, weaning slower-gaining, lighter-weight calves. Three-breed cross dams weaned an additional 30 and 17 kg. over SB and 2X cows, respectively. Dam breed effects were significant among SB, 2X and 3X maternal sires. State Farm was the most productive location and Angus sires out-produced the two larger-framed bull types.

Results of this experiment indicate that among the three dam types, maternal efficiency was maximized within the 3X cow. Use of a larger type sire breed was not necessarily indicative of escalated weaning weights and improved dam productivity. An increase in dam reproductive ability and a decrease in calf mortality may prove more advantageous than striving for increased growth in crossbreeding programs.