Exterior special characteristics of cows and their descendants of different generations at high-producing herds
Abstract
The results of studies of the exterior characteristics of first-calf cows and their descendants of different generations are presented. The studies were conducted at high-producing herds (average yields per a cow about 10000 kg) LLC “Veleten” of the Glukhiv district of Sumy region and PJSC “Plemzavod “Stepnoy” of the Kamyansko-Dniprovskyy district of Zaporizhzhya region created out of the absorption crossing of the Ukrainian Black-and-White dairy breed females with Holstein breeders, first-calf cows and their descendants of the first, second, and at PJSC “Plemzavod “Stepnoy” – also of third generations. The sample of animals includes 62.5–100% share of Holstein inheritance. There was some differentiation between the cows of the controlled herds according to the investigated body measurements: the first-calf cows of PJSC “Plemzavod “Stepnoy” were highly dominated the herdmates of LLC “Veleten” by height at the withers by 3.2, chest depth by 1.4, chest girth by the shoulder by 1.2 and oblique body length – by 1.7 cm, but were inferior to them in chest width by 0.8 (P < 0.05), width of oysters – by 0.4 and girth of wrist – by 0.3 cm (P < 0.001). The cows of both farms, by all studied exterior characteristics, outweighed their descendants of different generations, which is explained by the lower age of first calving for daughters, grandchildren and great-grandchildren than the cows from which they came. However, such a slight, although in most cases, probable differentiation between the exterior features of the cows and their descendants of the above generations appears to be the result of a better level of animal production of each successive generation, as indicated by their milk yields for the first lactation. However, according to all the investigated measurements (exception – width of oysters of cows of all generations and girth of wrist in the descendants of the second and third generations) animals of both controlled herds outperformed the target parameters of exterior characteristics for the first-calf cows of the desired type of Ukrainian Black-and-White dairy breed. The analysis of body structure indices shows that the first-calf cows under control and their descendants of different generations were characterized by the type of body structure characteristic of dairy cattle. Between the body measurements of animals and their descendants of different generations, different strengths and directions of communication are established. The correlation coefficients between the exterior characteristics of cows and their daughters in LLC “Veleten”, depending on the size, were in the range -0.05 – +0.15, in cows and their granddaughters, within -0.15 – +0.06, and the regression coefficients are within -0.05 – +0.19 and -0.15 – +0.05, respectively. In PJSC “Plemzavod “Stepnoy” the relative variability of body measurements in cows and their descendants of the first, second and third generations was -0.07 – +0.23, respectively; -0.19 – +0.14 and -0.33 – +0.26, and regression coefficients ranged from -0.04 to +0.14; from -0.17 to +0.07 and from -0.47 to +0.16. It should be noted that in both farms the correlation coefficients between the exterior features of animals of different generations were by no means probable, and the regression coefficients were only reliable between the chest depth behind the shoulders of cows and their daughters in LLC “Velyten” and between heights in the cows' hedge and their great-grandchildren at PJSC “Plemzavod “Stepnoy”.
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