GENETIC AND PHENOTYPIC CORRELATIONS OF SOME PERFORMANCE TRAITS OF NILI-RAVI BUFFALOES IN TROPICS

Abstract

Many traits in livestock and associated with each other positively or negatively where selection for trait effectively causes changes in the associated traits. This study was conducted to find such associations of genetic and phenotypic origin known as genetic and phenotypic correlations for some productive and reproductive traits of Nili-Ravi buffaloes kept under tropical environment. In this context data of 9003 lactation records of  Nili-Ravi buffaloes (n=2050) daughters of 173 sires over a period of 30 years were collected from four buffalo herds maintained by the Livestock and Dairy Development Department. Data were analysed by using the BLUP techniques by DFREML (univariate) and ASREMAL (bivariate) analysis. Heritability estimates for 1^st to 5^th lactation milk yields ranged from 0.06 to 0.18, and 305-day milk yield was 0.09. The genetic correlations (r_g) between 305-day milk yield and LMY for five parities ranged from 0.55±0.22 to 0.95±0.02 (all lactations), whereas respective phenotypic correlations ranged (r_p) from 0.63 to 0.70. However, the bivariate analysis showed genetic correlation (rg) of 1^st lactation milk yield with 1^st dry period, 1^st calving age, 1^st calving interval, 1^st service period and 1^st service per conception as 0.15±0.25, -0.03±0.21, -0.33±0.22, -0.23±0.22 (0.00±0.39 , respectively. Whereas, genetic correlation (rg) of 1^st lactation length with 1^st dry period, 1^st calving age, 1^st calving interval, 1^st service period   and 1^st service per conception were .14±0.29, 0.31±0.21, 0.22±0.31, 0.31±0.33,  0.15±0.25, -0.03±0.21, -0.33±0.22, -0.23±0.22,-0.56±0.22, respectively. . The higher values rg for milk yield help to select in early lactation for higher lifetime productive traits. However, reproduvtive traits had little genetic correlations, signifying that progressive management would be suitable to acquire better performance.