Estimation of genetic parameters for fertility and prolificacy in the Lacaune meat sheep population carrying a hyperprolific gene

From an economic perspective, meat sheep farms depend on several components, such as reproductive traits, which can be influenced by numerous factors of variation. In this study, the effects of two kinds of oestrus, a) induced oestrus (IO) and b) the first natural return oestrus (FRO), and of the genotype encoding a hyperprolific gene (FecL) on prolificacy and fertility were tested. The genetic parameters of these two traits were also estimated using BLUP animal models with ASReml software. The data related to 68,652 matings were recorded from 2010 to 2020 for 20,770 ewes from the Lacaune Ovi-Test population. The oestrus type, which is associated with the use of hormonal treatment, improved the two reproductive traits studied. As expected, one copy of the mutated allele of the FecL gene had an effect on the prolificacy of +0.5 lambs per lambing but had no effect on fertility. Moreover, the animal variances estimated during this study for prolificacy and fertility after IO and on FRO were low but still explained a share of the phenotype variance of ±0.5 lambs per litter and ±0.20 fertility points around the average. The repeatabilities and heritabilities of prolificacy and fertility were low but consistent with the literature. Owing to the structural relationship between the oestrus type in our dataset, less data were available on FRO, making its genetic evaluation less accurate than the genetic evaluation on IO. • Reproduction results according to the oestrus type differed in this study. • Hormonal treatments, used to synchronize oestrus, improved fertility and litter size. • Mutation of an allele of the FecL gene increased litter size by + 0.5 lambs. • The FecL gene had no impact on fertility. • The repeatability and heritability of prolificacy and fertility were low.