The genetic and phenotypic associations between lamb survival outcomes and other traits recorded at lambing

Context Australian sheep breeding values (ASBVs) for lambing ease (LE) are estimated by Sheep Genetics, using a threshold animal model at the lamb level, in tri-variate analysis that includes data on birth weight, gestation length and score. The implications of these traits survival, or use other indirect to improve accuracy ASBVs LE, not currently being considered. Ultimately, it is desirable extend outcomes individual survival.Aim present study investigated LE survival outcomes, accounting litter size, examined associations with recorded shortly after maternal breeds.Methods Equivalent linear models were used compare lamb- ewe-level various combinations additional random effects. In particular, was treated as different trait single-born twin-born lambs, identify changes genetic correlations associated size between traits. Other included lambs dead birth, weaning, behaviour score.Key results Individual inferred from field lowly heritable influenced both direct Lamb positively correlated but negatively length, score (increasing difficulty) lambs. Genetic phenotypic demonstrated weight antagonistic traits, more so moderate (0.40–0.45 singles; 0.15–0.36 including twins) (−0.63 −0.81 −0.00 −0.23 can add evaluation contrast, predominantly an ewe trait, will therefore only Lamb-level appeared underestimate heritability, sometimes compensated larger variance, over-estimate some relative models.Conclusions Expanding current include records would provide detailed options breeders develop goals ewes Further work required expand analyses continuous understand contributions traits.Implications Relative selection emphasis must be considered light expected which born, ensure favourable overall. Accuracy improved birth. possible. Completeness pedigree, availability informative level integration also factors consider choice operational versus systems.