Comparison of phenotypic and heterotic effects affecting milk yield, composition and udder morphometry of Hair and F-1, F-2 and G(1) generation cross-breeds of Alpine x Hair and Saanen x Hair dairy goats in a semi-intensive system

This study was conducted to compare milk yield, milk components and udder traits of Hair goat, F-1, F-2 and G(1) generation cross-breeds of Alpine x Hair and Saanen x Hair goats under a semi-intensive system. The effects of genotype, parity, flock and year on milk production, physical and chemical compositions were almost all significant (between p < 0.05 and p < 0.001). The F-1, F-2 and G(1) generations produced 24 and 44% higher (p < 0.001) lactation milk yield (LMY), 12 and 35% (p < 0.001) fat yield and 19 and 35% (p < 0.001) protein yield than Hair goat. Positive heterosis was found in milk production and contents both Alpine x Hair F-1 (AHF(1)) and Saanen x Hair F-1 (SHF1) generations. The heterotic effect of the LMY was significant in the SHF1 generation (p < 0.05), but not in the AHF(1) generation. The highest correlation was found between LMY and udder circumference and then udder volume (p < 0.001; r = from 0.34 to 0.75). The coefficient of determination of the obtained equation for the estimation of the LMY in the Hair and cross-bred goats ranged from 0.48 to 0.71. These results showed that as the level of cross-breeding increased in this semi-intensive system, better quality dairy products can be obtained from goats, and udder measurements can be a helpful tool in estimating milk yield, thus reducing the pressure on the ecosystem. Thus, it was concluded that with better modelling of environmental variations, milk production characteristics of local goats can be increased much faster by cross-breeding, especially at the F-1 and G(1) generation cross-breed levels.