Maternal influence on sheep production: a study of some birth traits of lambs

Abstract

SummaryA study was made of the birthcoat and the birth weight of Merino lambs, coarsewoolled Ossimi and the reciprocal crosses. The pre-natal maternal environment had a clear effect on the fineness of the birthcoat of cross-bred lambs born to Merino ewes (Ossimi × Merino) where 22·6% had fine arrays, whereas those out of coarse wool Ossimi dams (Merino × Ossimi) were all coarse like pure Ossimi lambs.Merino birthcoats were the most highly evolved, having the highest curly tip/precurly tip ratio, whereas the Ossimi were the least evolved. Ossimi × Merino lambs had more evolved birthcoats than Merino × Ossimi. CT/Pre-CT ratios were 1·00, 2·35, 4·41 and 8·06 in Ossimi, Merino × Ossimi, Ossimi × Merino and Merino lambs, respectively.Ossimi birthcoats had almost straight fibres. Merino × Ossimi showed a low incidence of crimp post natally, Ossimi × Merino exhibited more post-natal crimp and that in Merino predominant crimp occurred throughout.Strong (coarse) fibres were more frequent in Merino × Ossimi whereas Ossimi × Merino possessed higher frequencies of the less strong fibres and CT/Pre-CT ratio than the other cross. The difference between the two means of the crosses was highly significant in all fibre types.Lambs with strong fibre type arrays were heavier at birth than those with finer ones.