Genetic Analysis of Lifetime Traits of Crossbred Dairy Cattle in the Central Highland of Ethiopia

Abstract

Data collected from 1974 to 2015(42 years) on crossbred dairy cows maintained at Holetta Agricultural Research Centre were used to estimate genetic parameters for lifetime traits. These traits were total life, herd life, productive life, lifetime milk yield, lifetime calf crop, lifetime milk yield per total life (LTMYTL), lifetime milk yield per productive life (LTMYPL), and lifetime milk yield per herd life (LTMYHL). The VCE (6.0.2) and PEST (4.2.5) software were employed for genetic parameter estimations. The heritability estimates for lifetime traits observed in the present study were medium to high ranging from 0.19±0.04 to 0.62±0.06. The estimates of heritability for total life, productive life, herd life, lifetime milk yield, LTMYTL, LTMYPL, LTMYHL and lifetime calf crop were 0.25 ±0.05, 0.20±0.04, 0.19±0.04, 0.21±0.04, 0.31±0.05,0.31±0.06, 0.27±0.07 and 0.62±0.06, respectively. The genetic correlation estimates between traits vary in magnitude ranging from 0.02 between lifetime calf crop and LTMYPL to 0.94 between LTMYTL and lifetime milk yield. Similarly, the phenotypic correlation estimates between the traits also vary from lower to high, ranging from 0.02 between lifetime calf crop and LTMYHL to 0.94 between herd life and total life. It can be noted from estimated heritability values that including the lifetime trait in the selection program can bring genetic progress to the herd. The genetic and phenotypic correlations among the total life, productive life, herd life, and lifetime milk yield were high and imply that selection on total life and lifetime milk yield would bring positive improvement on most of the lifetime traits. From the study it was concluded that including the lifetime trait in the selection program can bring genetic progress in this herd through choosing the best young sire. Based on the conclusion it was recommended that TL and LTMY need to be considered as important trait in cross breed dairy selection program.