Estimates of breeding values and genetic trends for Production and reproduction traits in holsteins Friesian holeta bulldam farm: a multivariate animal Model analysis

Abstract

Animal evaluation and Genetic trend analysis was conducted in small exotic dairy cattle breeds of Holstein Friesian herd to evaluate the performance of the breed under Ethiopian condition, specifically at Holeta bull dam herd. A total number of 3733 lactation records from 1125 cows and 814 Dams sired by 137 bulls were used in this study. Performance records of animals from 1979 to 2014 archived for 35 years were analyzed for traits like. 305 day milk yield (305d MY), Total milk yield (TMY), lactation length (LL), Age at first calving (AFC), Calving interval (CI), days open (DO) and Number of service per conception(NSC) were studied by fitting GLM procedure of SAS (2010) for estimation of non-genetic factors on these traits. Genetic parameters and breeding value were estimated by multivariate BLUP procedures of multi-traits repeatability Animal Model. Estimated breeding values were used to regress the genetic and phenotypic trends for both production and reproduction traits against birth years of bulls and cows. Calving year and parity (p<0.001) and sire origin (p<0.05) had a significant effect on all milk production and reproductive traits. Season insignificantly affected all productive and reproductive traits except LL and NSC while Birth year and sire origin showed a significant (p<0.001) effect on AFC. The overall means of TLMY, 305d MY, LL, AFC, CI, DO and NSC were: 3732.3 ± 44.2kg, 3661 ± 37.4 kg, 314.3 ± 1.9 days, 40.6 ± 0.37 month, 461.1 ± 7.7 days, 173 ± 6.7 days and 1.98 ± 0.05, respectively. Estimates of heritability of milk production traits were 0.15±0.04 for TLMY and 305d MY, and 0.08+0.03for LL, whereas reproductive traits 0.38±0.025, 0.13±0.04, 0.10 ± 0.04 and 0.07±0.02 for AFC, CI, DO and NSC respectively. Genetic and phenotypic correlations between 305d MY, AFC and CI showed the existence of favorable correlation, implies that selection on 305d MY will results in early maturity which in turn helps to reduce the AFC and CI in the next generation. Estimates of all sire breeding values for 305d MY, AFC and CI ranged from (-538.4 to 946.7kg), (-13.7 to 9.4 m) and (-45.9 to 67.2 days), respectively. Aggregate genetic merit for all sires range from 119.2 to 66.3 and female line ranges 125.9 to 64.2. The rate of phenotypic and genetic change over the study period for TLMY, 305d MY, AFC and CI were (4.5kg, 22.2 kg, -0.7 and -0.5 d) and (6.1, 9.5 kg 0.6 and -0.07d) per year, whereas 10.9 kg,-7.1and -1.1d for sires respectively. Positive genetic and phenotypic trends in production traits reflected the contribution of improved management after the bull dam farm was taken by NAIC plus the slight improvement observed as a result of pedigree based selection program of the center augmented with continued import of new sire lines from xiv different country with better genetic merit overtimes. Low genetic progress of fertility traits as opposed to production trait were due to the there were not the main breeding goal traits and whatever small changes observed comes from the import of better genetics over the study period from different countries. The expected annual genetic change for 305d MY AFC and CI was 25-26kg,-5 and -3d per year if the three traits selection criteria and multi traits breeding goal is to be adopted.