LIFESPAN OF DAIRY CATTLE DEPENDING ON THE LEVEL OF EVALUATION OF UDDER LINEAR TRAITS

Abstract

The dependence of cows lifespan of Ukrainian Black-and-White dairy (UBWD) and Holstein (H) breeds on the level of evaluation of linear type traits that characterize udder morphological qualities in the general system of linear classification was studied. Descriptive traits of the evaluated conformation type were: front udder parts attachment, height of rear udder parts attachment, central ligament, udder depth, front teats placement and length. A certain correlative variability was established between level of evaluation of linear type traits and lifespan of animals. The highly reliable difference between evaluated cows for linear type trait of front udder parts attachment with 1 and 9 scores is significant and was 841 (UBWD; P<0.001) and 810 (H; P<0.001) days. An interbreed comparison of cows lifespan, depending on the evaluation, testified in favor cows of Holstein breed with variability within 43-159 days by an unreliable difference. Difference between the lowest and highest scores for type trait of height rear udder attachment in cows of experimental breeds was 740 (UBWD; Р<0.001) and 810 (H; Р<0.001) days. Animals with an assessment for trait development of central udder ligament lower than 1-3 scores live, according to evaluated breeds, from 2089 to 2401 (UBWD) and from 2154 to 2468 (H) days. Cows with 9 scores for both breeds had the highest lifespan – 2663 days (UBWD), inferior to cows with the lowest score by 754 (Р<0.001) and 2803 days (H) with significant increase on 649 days (Р<0.001). Difference between the average lifespan in cows of Ukrainian Black-and-White dairy breed with 9 and 1 scores for linear type trait of udder depth was 739 (Р<0.001) and 832 days (Р<0.001) in Holstein cows. Lifespan of cows both breeds in the herd was characterized by slight curvilinear variability, depending on the assessment of linear type trait of front teats placement. Consequently, cows of both breeds with an average score of 7 were used in the herd for the longest period. Evaluation of correlative variability of the front teats length with lifespan of cows in controlled breeds indicated that animals with an average score of 5, which was equal to their teats length at 5 cm, had longer functional life. Research results showed that each of evaluated descriptive traits in cows of both breeds has an impact on lifespan with different variability within individual body part, so better expression of linear type trait can be a breeding trait as an indirect predictor of longevity.