Off-campus UNL users: To download campus access dissertations, please use the following link to log into our proxy server with your NU ID and password. When you are done browsing please remember to return to this page and log out.
Non-UNL users: Please talk to your librarian about requesting this dissertation through interlibrary loan.
Output/input differences among Bos indicus - Bos taurus and Bos taurus - Bos taurus sources of germ plasm
Abstract
Four F$\sb1$-cross groups of cows from Cycle III of the Germ Plasm Evaluation program at the Roman L. Hruska United States Meat Animal Research Center were evaluated on the basis of biological efficiency. The cows were the result of mating either Hereford (H) or Angus (A) dams to Brahman (Bm), Pinzgauer (Pz), Sahiwal (Sw), H or A (HA) sires. Comparison of these four breed-cross types allowed evaluation of two Bos indicus-Bos taurus (Bm-X and Sw-X) versus two Bos taurus-Bos taurus (HA-X and Pz-X) sources of germ plasm. 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$\sb1$ females for an annual production cycle in the Nebraska environment. The cows were producing three-way terminal-cross progeny with a segment of the herd devoted to producing replacement females. One evaluation was made for efficiency measured as calf weaning weight/total annual energy requirements (CALFEFF, g/Mcal) while a second also included cull cow weight (TOTEFF, g/Mcal). Results for CALFEFF were 16.9, 16.4, 15.4 and 15.5 g/Mcal and 27.7, 27.8, 27.1 and 26.5 g/Mcal for TOTEFF for systems utilizing Sw-X, Bm-X, HA-X and Pz-X sources of germ plasm, respectively. The overall results from this study indicated substantial differences to exist between these four breed-cross groups in efficiency of production to weaning.
Subject Area
Genetics|Livestock|Veterinary services
Recommended Citation
Green, Ronald David, "Output/input differences among Bos indicus - Bos taurus and Bos taurus - Bos taurus sources of germ plasm" (1988). ETD collection for University of Nebraska-Lincoln. AAI8911112.
https://digitalcommons.unl.edu/dissertations/AAI8911112