Estimation of Genetic Parameters and Trends for Milk Production in a Libyan Holstein Population under Arid Mediterranean Subtropical Conditions

Abstract Text: Heritabilities for the mean of the first 6 highest 3-wk test-days (M6HTD), 120-d milk yield (MY120), and 305-d milk yield (MY305), genetic correlations, and phenotypic correlations among these traits were estimated in a Libyan dairy population of 3,345 dairy cows that were progeny of 294 sires and 2,540 dams. Heritabilities were medium for M6HTD (0.20 ± 0.04) and MY120 (0.25 ± 0.04) and low for MY305 (0.14 ± 0.03). Genetic correlations were high and positive and phenotypic correlations were moderate and positive for all traits. Genetic trends for cows, sire, and dams were mostly negative and small or near zero suggesting that selection and breeding strategies were unsuccessful in this Libyan population during the period of the study.

Keywords:

Dairy

Genetic Parameters

Subtropical