| Abstract: | Results comparing crossbred bulls relative to straightbred bulls for various reproduction traits (such as puberty, sperm concentration, pregnancy rate and weaning rate) and progeny growth traits (birth and weaning weight) were summarized separately for Bos taurus X Bos taurus (Bt X Bt) and Bos indicus X Bos taurus (Bi X Bt) crosses. The Bt X Bt and Bi X Bt crossbred bulls were 1.8 and 5.0% younger, respectively, at puberty than straightbred bulls. Also, sperm concentration of Bt X Bt and Bi X Bt crossbred bulls was greater than straightbred bulls by 36.4 and 56.0%, respectively. Pregnancy rate and weaning rate of cows exposed to straightbred and crossbred bulls indicated advantage values of .2 and 4.0%, respectively, for Bt X Bt crossbred bulls. Corresponding advantage values for Bi X Bt crossbred bulls over straightbred bulls were 1.4 and 3.7%, respectively, for these two traits. Birth and weaning weights were similar for calves sired by straightbred and Bt X Bt crossbred bulls as well as for calves sired by straightbred and Bi X Bt crossbred bulls. |
