Preweaning Performance of Beefmaster- and Brahman-Sired Calves from Angus and Brahman Cows on Three Forage Systems

Abstract

Three years of data from 42 purebred Angus (AA) and 50 Brahman (BB) cows bred to purebred Beefmaster (BM) and purebred Brahman (BB) bulls were used to evaluate both breed of sire effects and different forage systems. Cows and calves were managed on one of three forage systems: endophyte-infected tall fescue (E+E+), common bermudagrass and endophyte-infected tall fescue (E+CB), and common bermudagrass and endophyte-free tall fescue (E−CB). Data from 215 calves born and 197 calves weaned were used in this study. The calves were weighed and tagged at birth and were not creep-fed. They were weaned at an average of 195 d of age and their weights and hip heights were taken. There was little evidence of sire breed, forage effects, or interactions of the two on the birthweight of calves from the BM or BB sires, which averaged 39 and 37 kg, respectively. The calves from the AA cows were 7.7kg heavier at birth than those from the BB cows (P<0.01). There was evidence of a sire breed × dam breed × forage interaction (P<0.10) in calf 205-d weights. There was little evidence of any advantage in 205-d weight for calves on E+CB compared to those on E+E+ except for the BB × BB calves (P<0.10). Only the BB × AA calves seemed to benefit from the E−CB compared to E+CB (P<0.10), and 205-d weights were less for BB × BB calves on E−CB than on E+CB. Averaged over sire breed, the 205-d weights of calves on E−CB exceeded those on E+E+ by 15kg (P<0.05). Averaged over forages, there was little evidence of differences between BM and BB sires when bred to Angus cows, although predictable decreases in 205-d weights were observed in BM × BB and BB × BB compared to the Angus crosses (P<0.05). The means for hip height averaged over sire and dam breed suggest an advantage for E−CB compared to E+E+ (P<0.10). These data do not suggest any notable advantage for any of the breed groups on any particular forage system. A predictable trend for improved performance as E+ is removed from the forage system is evident as is a similar trend as heterozygosity is increased in the progeny.