Output/input differences among Bos indicus - Bos taurus and Bos taurus - Bos taurus sources of germ plasm.

摘要

Four F;The first phase of this evaluation involved an 18-wk experimental period where non-pregnant cows of each breed-cross were pen fed in drylot while nursing calves sired by Charolais males. This was done in order to estimate the maintenance and lactation energy requirements and efficiency (g calf gain/total Mcal metabolizable energy consumed by cow and calf) for this phase of the annual production cycle for each breed-cross group. The results for efficiency were 35.2, 34.6, 31.6 and 31.5 g/Mcal for the Sw-X, Bm-X, HA-X and Pz-X groups, respectively, indicating an approximate 10% advantage for the two Bos indicus-X groups relative to their Bos taurus-X counterparts.;The second phase of the study was in the development of a deterministic model which attempted to combine all input and output information available from previous study results into two measures of biological efficiency of cow-calf production to weaning. The model simulated a theoretical herd of 200 F;The overall results from this study indicated substantial differences to exist between these four breed-cross groups in efficiency of production to weaning.