INFLUENCE OF GROWTH-HORMONE GENOTYPES ON BREEDING VALUES OF SIMMENTALBULLS

A leucine/valine substitution of growth hormone amino-acid 127 was gen otyped in 221 Bavarian Simmental bulls by PCR/RFLP. Gene frequencies f or leucine (L) and valine (V) were 0.68 and 0.32, respectively. Breedi ng values for meat traits were significantly different between genotyp es. The heterozygous genotype LV was superior to LL and VV in both car cass gain (p < 0.01) and meat value, an index which includes carcass g ain and classification score (p < 0.05). In relation to classification score, genotype W was significantly better (p < 0.05) than LV and VV. No effects on milk breeding values were apparent even though those of milk composition approached significance.