ESTIMATION OF GENOMIC BREEDING VALUE FOR HEAT TOLERANCE (HT GEBTV)IN WADARA DAIRY CATTLE

Abstract

The research was conducted to estimate the genomic breeding value for heat tolerance (HT GEBV) in wadara dairy cattle breed at Abubakar Tafawa Balewa University Dairy Research and Development Center Gubi campus, Bauchi state, Nigeria. A total of thirty five (35) Wadara dairy cattle were used for the study. The basic parameters measured in the experiment were; rectal temperatures (Morning Rectal Temperature MRT, Evening Rectal Temperature ERT and Increased Rectal Temperature IRT) and subsequent day milk yield (SDMY). Variations were recorded within wadara breed in the basic parameters at P < 0.05. The cow with tag number W383 recorded the highest mean IRT of 1.2 ^oC, while W368 recorded the lowest mean IRT of 0.3 ^oC.  W362 and W358 recorded highest mean SDMY of 2.4 l, while W354 recorded the lowest mean SDMY of 0.5 l. W360 recorded the highest mean estimated percentage decline in SDMY per unit increase in IRT of 61.3%/ ^oC, while W359 record the lowest (22.0 %/ ^oC). W359 had the highest HT GEBV of +16.7%/⁰C while W360 had the lowest of -22.6%/⁰C. The coefficients obtained from correlation analysis between the IRTs and SDMYs of all the lactating wadara cows were used to develop the prediction equation of HT GEBV for all the wadara cattle breed in the farm. Mean regression coefficient of -0.66 l/^oC, intercept of 1.70 l and error of estimation of 0.1 were obtained through the analysis. The prediction equation  was developed using genomics best linear unbiased prediction (GBLUP) equation as follow; Y_ij =1.75 – 0.64X_ij + 0.1.The findings from this study showed that there were significant (P<0.05) genomic variations in HT GEBV within the wadara  dairy cattle at Abubakar Tafawa Balewa University Dairy Research and Development Center. Thus selective breeding is recommended in order to improve the population mean of HT GEBV of wadara cattle breed in the farm.