Analysis of Lifetime Traits for Crossbred Dairy Cattle in the Central Highland of Ethiopia
The objective of this study was to analyze the lifetime performance of crossbred dairy cattle in the Central highland of Ethiopia. Birth year records of 502 cows maintained at Holetta Agricultural Research Centre from 1974 through 2015 were used to estimate longevity traits. The fixed effects considered were genetic groups, season of birth, and birth year groups. Least squares mean analyses were performed using general linear model procedure of SAS software, version 9.4. The overall means for total life (TL), herd life (HL), productive life (PL), lifetime milk yield (LTMY), lifetime milk yield per day of total life (LTMYTL), lifetime milk yield per day of herd life (LTMYHL), lifetime milk yield per day of productive day (LTMYPL) and calf crop (LTC) were 3294.6±54.16 days, 2046.2±47.19 days, 1367.8±37.7 days, 9314.14±314.2 kg, 2.71±0.06 kg, 4.45±0.08 kg, 6.56±0.10 kg and 4.5±0.10, respectively. Both genetic group and birth year were found to be the factors that significantly influenced (p < at least 0.05) all studied traits. The study revealed that the first generation 50%, and 75% Friesian x Boran crossbred dairy cows performed better in most of the lifetime traits than Borana and later generations (F2 and F3) which implies that segregation effect can be minimized through upgrading. The result may show that about 438.40 days were wasted without production during calf and heifer growth period compared with an ideal situation (24 to 27 months considered as the cow starts production). In addition, cows spent 90.76 days per calving without milk production unnecessarily. The higher gap between TL and HL and between HL and PL could show that more milk and calf production can be obtained through selection and enhancing heifer rearing and cow management. In conclusion, the first generation 50% and 75% Friesian x Boran crossbred dairy cows had performed better in lifetime traits than Boran and later generations (F2 and F3). This could be associated with a reduction in adaptation potential of up-graded generation and reduction in hybrid vigor and recombination losses in inter se generation. Enhancing the farm husbandry practices and optimizing breeding programs that encompass the lifetime traits are essential to reduce the effect of environmental factors, reduce segregation and further genetic improvement.