Development of New Indicator Traits for Selection for High Milk Yield of Indigenous Dual-Purpose Cows in Hot-Humid Environment, Ghana

Records on association of milk yield and morphological traits, particularly parts distal to the knee/hock joints (fore/hind shank length and circumference) in dual-purpose cows, are hardly available. This makes the selection for milk yield potentials in favour of these traits difficult. The objectives of this study were to estimate the relationship between average milk yield (AvMY) and morphological traits (MT) and determine the best MT predictor of average milk yield in dual-purpose cows of the hot-humid environment in Ashanti Region of Ghana. Three hundred and eighty-four (384) cows were purposively selected to measure the association between AvMY and MT in 20 farms from April 2015 to July 2017. Analysis of data revealed that phenotypic correlations between AvMY and MT (i.e., head length, horn length, horn tip spacing, and muzzle circumference) were low (0.14 to 0.24), whilst that of heart girth, ear length, tail length and pelvic width were medium (0.34 to 0.46). High correlations were observed among AvMY, body length, body height at withers, height at rump, hock circumference, and fore/hind-shank length and circumference (0.50 to 0.84). The best predictor of AvMY was the hind-shank circumference, followed by the fore-shank circumference, hind-shank length, fore-shank length, and hock circumference in descending order. It was concluded that there was an association between AvMY and MT. Breeders and producers should consider fore- and hind-shank circumference and length when selecting for improvement in AvMY potential.