GENETICS AND BREEDING Considerations for the Specification and Statistical Estimation of Differences Among Animals in the Partial Efficiencies of Feed Energy Utilization 1
1990
The partial efficiencies of feed net en ergy use for lactation, maintenance weight change, and pregnancy are impor~ tant components of production system ef ficiency. If heritable variation in these efficiencies can be identified the efficien cies may become important 'selection cri teria in livestock. Estimates of the partial efficiencies of interest have been obtained using multiple regression procedures and data from nutrition experiments. Such ex pe~ents utilize variation among anunals, not necessarily within animals. V~ation within animals is necessary to estimate partial efficiencies for individu ~s. ~ithin-animal multiple regression YIelds mterpretable and meaningful esti mates of the partial efficiencies of energy use only when 1) the model is correctly and completely specified, 2) values of the independent variables are uncorrelated, 3;J1d ~) autocorrelation among observa tions IS accOlUlted for correctly. To obtain independent variation in weight, weight composition, weight change, pregnancy and milk yield may not be feasible wi~ animal~, especially in field data Analyses of reSIduals from prediction equations based on among animal estimates of the partial efficiencies may provide some in formation as to the amount of genetic va~ation available, but they are difficult to mterpret Alternatives, such as random coefficients models, may help in address ing the problems.
Keywords:
- Correction
- Cite
- Save
- Machine Reading By IdeaReader
8
References
0
Citations
NaN
KQI