Genetic and nongenetic effects on plasma insulin like growth factor I (IGF-I) concentration and production traits in Angus cattle.

Abstract

Plasma insulin-like growth factor-1 concentration (IGF-I) was measured at weaning on 1756 Angus beef cattle from herds in the New England and surrounding regions of NSW to estimate the heritability of IGF-I and phenotypic and genetic correlations with other production traits. Average IGF-I was 253.9 ng/mL measured at the mean age of 237 days. IGF -I had a moderate heritability of 0.36. Phenotypic correlations were essentially zero between IGF-I and birth weight, 200-day weight and pre-weaning average daily gain. IGF -I concentration was not genetically correlated with birth weight and scanned eye muscle area, but was correlated with both 200-day weight and average daily gain with genetic correlations of –0.40 and –0.52, respectively. Daily feed intake and IGF-I concentration were estimated to have a negative genetic correlation of –0.33. Scanned rump and rib fat depth, intramuscular fat content and residual feed intake were all estimated to have positive genetic correlations between 0.31 and 0.33 with IGF-I concentration. These estimates indicate that plasma IGF-I concentration measured in seedstock herds at weaning will be a suitable trait to indirectly select for fat and feed efficiency traits.