Polymorphism of Growth Hormone Gh1-Alui in Jersey Cows and Its Effect on Milk Yield and Composition (Report‪)‬

ABSTRACT: To analyze genetic effects on milk production traits, 164 unrelated Italian Jersey cows reared in 15 farms located in Southern Italy were characterized at the growth hormone locus. Using a Polymerase Chain Reaction-Restriction Fragment Length Polymorphism protocol all three possible genotypes for the Leucine/Valine polymorphism were identified even if in the considered population the number of homozygous animals (Leucine/Leucine = 36; Valine/Valine = 28) was smaller than Leucine/Valine (n = 100) cows; the Hardy-Weinberg equilibrium as verified. Statistical analysis showed that daily milk yield in the Leucine/Leucine genotype was higher (p0.01) than in Leucine/Valine (22.76 kg vs. 16.96 kg); cows with Leucine/Valine genotype differed significantly from Leucine/Leucine and Valine/Valine genotypes particularly in fat (4.95% vs. 4.13% and 4.82%, respectively) and protein content (4.00% vs. 3.47% and 3.79%, respectively). No significant effect on lactation length was observed. (Key Words : Growth Hormone, Polymorphism, Jersey, Milk Traits) INTRODUCTION