Genetic insights into litter size in goats: A meta-analysis of KISS1 and BMP15 SNP variants

Litter size is a key trait in livestock breeding. The BMP15 and KISS1 genes have been studied in goats, but results on their association with litter size are inconsistent. The objective of this study was to employ a meta-analysis approach to investigate the genetic relationship between the BMP15 (g.735 G>A) and KISS1 (g.2540 C>T and g.2510 G>A) genes and litter size in goats. A total of five studies (including 12 breeds) were included for the g.735 G>A mutation, three studies (including nine breeds) for g.2540 C>T, and two studies (including six breeds) for g.2510 G>A in this meta-analysis. The meta-analysis was conducted under four different genetic models: recessive (GG + AG vs. AA), dominant (GG vs. AG + AA), additive (GG vs. AA) and codominant (GG + AA vs. AG) models of inheritance. Data were analyzed under either random or fixed effects models based on the estimates of I² estimates. A sensitivity analysis was performed by removing one study at a time to determine the stability of the overall results. Funnel plots and the Egger regression tests were also used to assess the publication bias among studies. Significant associations (P< 0.05) were observed between the g.2540 C>T and g.2510 G>A loci and litter size in goats under the additive (SMD = -0.469, 95 % CI = -0.908 to -0.030, P-value = 0.036) and codominant (SMD = 0.147, 95 % CI = 0.003-0.291, P = 0.046) genetic models, respectively. Our results did not identify any significant association between g.735 G>A of BMP15 and litter size under the investigated genetic models.