RELATIVE VARIABILITY OF LINEAR ASSESSMENT TRAITS WITH MILK YIELD OF HOLSTEIN BREED FIRST-BORN COWS

Researches have been conducted to study conformation type of firstborn Holstein breed cows of Ukrainian selection. Cows at the age of first lactation were evaluated in the period of 2–4 months of its course using two systems of linear classification as recommended by ICAR. The 9-score system described 18 conformation traits. Four groups of conformation traits that characterize dairy type, body, limbs and udder, were assessed by the 100-score scale. It was found that firstborn cows have a good development of exterior traits that characterize dairy type, with an average estimate of 83.8 score, body condition – score 84.4, limbs – 83.3 and udder quality – score 84.2. Evaluation of descriptive traits of firstborn cows showed that the level of their development, compared with group, has a significantly higher variability in the herd with coefficients of variation of 11.2–31.4%. According to the final assessment, firstborns of Holstein breed Ukrainian selection corresponded to the desired type on the international scale “good plus” (score 84). By the 100-score system of linear assessment, all group traits and final score were positively correlated with milk yield at the age of first (0.233–0.455) and third (0.203–0.356) lactation and for the lifetime (0.278–0.468). Sufficient level for effective selection is evidenced by the relationship with milk yield: height (0.211–0.341), body depth (0.282–0.369), angularity (0.338–0.475), rump width (0.211–0.368), fore udder attachment (0.263–0.367), rear udder attachment (0.224–341), central ligament (0.233–0.362) and locomotion (0.221-0.382).