The heritability and correlative variability of linear traits with milk yield of Holstein firstborn cows

Abstract

Studies carried out to evaluate the firstborn cows of Holstein breed (Ukrainian Black-and-White dairy with a conditional bloodline of Holstein above 93.75%) by conformation type. The research base was the breeding farm of PE "Buryns'ke" of Pidlisnivskyi branch in Sumy district. The modern method of linear classification used by two systems: 9-score, de-scribing 18 conformation body parts and 100-score, with a set of four selection traits defining the dairy type, body, limbs and udder. The population-genetic aspect determined by the heritability and correlative variability of linear traits with milk yield of Holstein cows of domestic breeding in Sumy region. Group traits characterizing the dairy type of cows (r = 0.398), body development (r = 0.412), limb condition (r = 0.215), udder morphological qualities (r = 0.466) and final score best correlated with milk yield (r = 0.474). The highest coefficients of heritability were found for the dairy type (h2 = 0.366), body (h2 = 0.328), udder (h2 = 0.385) and final score (h2 = 0.477). The average and moderate heritability level determined for descriptive traits: height (h2 = 0.286), body depth (h2 = 0.275), angularity (h2 = 0.414), rear width (h2 = 0.295), pelvic limbs posture (h2 = 0.274), fore (h2 = 0.351) and rear (h2 = 0.296) udder attachment and central ligament (h2 = 0.294). A sufficient heritability level and correlative variability between linear traits and milk yield allowed effectively select dairy cattle in the direction of improving the conformation and productivity.