ESTIMATION OF GENETIC AND NON-GENETIC PARAMETERS FOR REPRODUCTION AND PRODUCTION TRAITS OF HOLSTEIN FRIESIAN DAIRY HERD AT ELFORA CHEFFA DAIRY FARM, OROMIA ZONE OF AMHARA REGION, ETHIOPIA

Abstract

The study was conducted at Cheffa dairy farm with the objective of estimating the effects of genetic and non-genetic factors on Age at First Service (AFS), Age at First Calving (AFC), Calving Interval (CI), Days Open (DO), Number of Service per Conception (NSC), Lactation Length (LL) and adjusted 305 days milk yield (305-dMY). A total of 2343 records were collected from 123 cows and 13 sires' progenies having greater than 93.75 % HF blood levels through the period from 1996 to 2014 for evaluation. Independent variables were year of birth and season, year of calving and season and parity while AFS, AFC, CI, DO, NSC, LL and 305-dMY were taken as dependent variables. Data were analyzed using the General Linear Models (GLM) of SAS, 2008 and using PEST and VCE software for genetic parameter estimation. The results indicated that the overall least squares means (± standard error) of AFS, AFC, CI, DO, NSC, LL and 305-dMY were 30.5 ± 0.60 months, 39.76 ± 0.67 months, 446.1 ± 6.79 days, 181.7 ± 7.01 days, 1.6 ± 0.05, 328.3 ± 5.50 days and 2305.2 ± 32.15 liters, respectively. Year of birth had highly significant (p<0.01) and significant (p<0.05) effect on AFS and AFC respectively. Year of calving had highly significant (p<0.01) effect on CI and 305-dMY and significant (p<0.05) effect on DO and NSC. Season of calving had significant (p<0.05) effect on CI and 305- dMY. Longest records of CI and highest records of 305-dMY were exhibited in short rain season while, shortest and lowest records of CI and 305-dMY were recorded in dry and long rain seasons, respectively. Parity had highly significant (p<0.01) effect on CI, DO, NSC and 305-dMY and significant (p<0.05) effect on LL. Longest value of CI, DO and LL were observed in 1st parity and highest value of NSC and highest value of 305-dMY were recorded in 7th and 5th parity respectively. The shortest value of CI, DO, LL and lowest value of 305-dMY was recorded in 9th parity while shortest value of NSC was recorded in 1st parity. Heritability values of AFS, AFC, CI, DO, NSC, LL and 305-dMY were 0.50 ± 0.05, 0.50 ± 0.06, 0.28 ± 0.04, 0.04 ± 0.009, 0.01 ± 0.006, 0.01± 0.007, and 0.40± 0.04 respectively and repeatability value of CI, DO, NSC, LL and 305-dMY were 0.30 ± 0.03, 0.06 ± 0.005, 0.04 ± 0.003, 0.02 ± 0.002 and 0.44 ± 0.03 respectively. Percent of positive breeding value of AFS, AFC, CI, DO , NSC and 305-dMY were 42.86%, 41.27%, 39.96%, 39.21% , 38.30% and 49.27%, respectively. This study revealed that genetic performance of the dairy breed in the study area was influenced by environment but selecting adaptive animal from the herd and a better management may improve all aspect of productivity. For traits of high to moderate heritability (h2) (AFS, AFC, CI and 305-dMY), repeatability (r) (CI and305-dMY) and individual animal with negative breeding value (BV) results (except for 305-dMY); selection could be one means of genetic improvement while, for traits with low h2 and r proper management should be applied. Hence, complete record keeping and planned genetic and non-genetic performance evaluation of dairy traits were a prerequisite to improvement productivity of the herd and to run profitable dairy enterprise through selection and better management. Future investigation of this farm should consider development of selection index using relative economic value of traits (functional, reproductive and adaptive traits), heritability value and genetic correlation of traits.