The influence of maternal igf-1 genotype on birthweight and growth rate of lambs

Abstract

The present study was designed to determine the effect of IGF-1 selection on lamb birth-weight and to establish the role of the maternal IGF-1 genotype on foetal growth. Nineteen high (H) line ewes were mated to high line rams (HH), 21 low (L) line ewes were mated to H line rams (LH), 25 control (C) line ewes were mated to control rams (CC), 35 H ewes were mated to L rams (HL) and 24 L ewes were mated to L rams (LL); the resultant lambs were used in this study. HH lambs were significantly (P < 0.05) lighter at birth than both LL and CC lambs. HL and LH lambs did not differ in birthweight from either LL or HH lambs. HH lambs grew significantly (P < 0.05) faster than LH lambs and faster than LL lambs (P = 0.05). HH lambs had significantly (P < 0.05) higher IGF-1 concentrations than LL lambs post-weaning. HL and LH IGF-1 concentrations were intermediate and differed significantly (P < 0.05) from both LL and HH lambs. The results of this study suggest that the difference in foetal growth between the selection lines is not influenced by maternal genotype, but is instead influenced by foetal genotype, and this warrants further examination. © 2007 Taylor & Francis Group, LLC.