Effect of complement C3 genotypes on milk production in sheep

The aim of the present study was to investigate the influence of the complement genotype affiliation (determined via the C3 complement component polymorphism) upon the milk productivity in sheep. The sheep included in this experiment were milk type crossings (n = 118 sheep) - Stara Zagora-East-Friesian and (Stara Zagora-East-Friesian) - Blackhead Pleven breed. Compared to the other C3 genotypes (SS, FF, FS and F5S), the HS genotype gave the highest milk productiveness for the whole and the milking lactation (p < 0.01). This high productivity was associated with a high daily milk yield and with the longer lactation duration. The lowest scores (milk productiveness, daily milk yield, numbers of lactation days) were observed in the 175S genotype sheep. Albeit the lactation duration was low in the FF genotype sheep, the milk productiveness was comparable to values observed with the FS and SS genotypes and this was probably due to a high daily milk yield. Moreover, the lifelong milk production was enhanced in this particular genotype. The calculations of the point serial coefficients evidenced a strong correlation between C3 genotype affiliation and milk productivity in sheep. These results suggest that a selection based on C3 genotype would improve lactation performances in sheep.