Evaluation of the efficiency of protein utilisation as additional selection criterion in pig breeding

The aim of this study was to evaluate the genetic parameters of the trait e fficiency of protein utilisation, defined as the ratio protein intake : lea n meat yield under the condition of a protein supply according to the requi rement of the pigs. The analysis is based on 164 female crossbred pigs, ori ginating from 59 AI-boars. Three progenies of each AI-boars were penned ind ividually in a choice feeding system, having access to two diets, differing in crude protein concentration (hP: 20,8%, nP: 12,2% crude protein). Along with the choice fed pigs 3 * 2 female progenies of the AI-boars were perfo rmance tested under the conditions of the traditional central station test. The results are: Choice fed pig preferred the high protein diet during the entire fattening period. Hence, protein intake exceeded the requirement, particularly from 6 0 kg body weight onwards. As compared to the traditionally performance test ed pigs, this excess in protein intake did not affect meat performance trai ts. Differences in the efficiency of protein utilisation between progeny groups of different AI-boars can be interpreted as genetically induced. The estim ated heritability for the protein utilisation was h(2) = 0.39 +/- 0.14. Genetic correlation between the efficiency of protein utilisation and other performance traits used in the breeding goal were positive. In particular the relation to the trait feed conversion efficiency was quite high (r(g) = 0.82 +/- 0.11). Hence, consideration of the traits included in traditional breeding goal Improves the efficiency of protein utilisation as well. No e cological benefit can be expected in additional consideration of the effici ency of protein utilisation. Antagonistic genetic correlation between meat quality traits and the effici ency of protein utilisation were estimated. This relationship indicates tha t a high efficiency of protein utilisation and a high meat quality are gene tically hard to combine. Because of high standard errors, the genetic correlation between homologous traits of choice fed and traditionally station tested pigs are hard to int erpret. Judged by the low genetic correlation (r(g) = 0.03 +/- 0.13) a geno type X environment-interaction is only indicated for the trait feed convers ion efficiency.