The influence of genotypic factors on the forming of the economic use of values of ukrainian bleck and wheat milk breeds

The evaluation of dairy cows` exterior plays a key role in the system of breeding because well-defined breed typology and high exterior evaluation cause high production efficiency. The objective of the study was to evaluate the exterior of the cows in Ukrainian Black and White dairy breed, to analyze the effectiveness of the selection of first-calf cows according to the body measurements and to study the influence of genotype factors on the formation of the exterior. For research purpose animal groups were formed on the principle of analogues, taking into account the part of Holstein inheritance, parentage, linear belonging, and age. Depending on the part of Holstein inheritance researched livestock was divided into three groups: 75,0-87,4 %, 87,5-99,9 % and 100 %. As a result of our own research it has been established that simultaneously with an increasing of the part of Holstein inheritance the body measurements increase too. It indicates about the improving effect of the Holstein breed on the formation of the exterior in the Ukrainian black-and-white milk breed. The first-calf cows with part of Holstein inheritance 100 % have advantages over the cows with the same age with part of Holstein inheritance 75,0-87,4 % with the withers height – 4 cm (P < 0,001), sacrum height – 4 cm (P <0.001), depth of chest – 1 cm, width of chest – 1 cm, width of hips – 1 cm, length of thoracic – 3 cm, chest girth – 2 cm, width of pins – 1 cm (P <0,001); the advantage over the first-calf cows with part of Holstein inheritance 87,5-99,9 % was 3 cm in withers height, 2 cm in sacrum height and 1 cm in all other cases. An increasing of the part of Holstein inheritance is accompanied by an increasing of milk yield, milk fat and milk protein. The higher milk yield had cows with the part of Holstein inheritance 100 % – by 294 kg compared to cows of the same age with the part of Holstein inheritance 87,5-99,9 % and by 2017 kg (P < 0,001) compared to cows of the same age with the part of Holstein inheritance 75,0-87,4 %. Fat content in milk of cows with the part of Holstein inheritance 100 % was lower by 0,02 % compared to cows with the part of Holstein inheritance 87,5-99,9 % and 0,21 % (P < 0,001) compared to cows with the part of Holstein inheritance 75,0-87,4 %, it was expected – the higher milk yield, the lower fat content in milk. The effectiveness of the simultaneous complex selection of dairy cattle on several grounds depends on the existence of correlation between them. The correlation between the body measurements of cows and 305-milk yield is positive, but varied in strength. The average strength of the correlation is observed between the milk yield and withers height (r = +0,233, P < 0,001), milk yield and length of thoracic (r = +0,332, P < 0,01), in other cases, the strength of the correlation is weak, but with sacrum height (P < 0,01), chest girt (P < 0,01) and depth of chest (P < 0,05) is significant. One-factor dispersion analysis was carried out to determine the level of determinism of live weight and body measurements by genotype factors. According to the results it was established that the influence of the bull's origin on the live weight of their first-calf daughters was 72,8 %, on the body measurements – 31,5- 91,3 %, the influence of line belonging amounted 81,0 % and 36,1-69,4 %, the influence of the part of Holstein inheritance was 26,3 % and 15,9-39,5 %, respectively. All genotypic factors have a significant effect on the live weight of the first-calf cows (P < 0,05 ... 0,001), withers height (P < 0,05...0,01), width of chest (P < 0,01...0,001) and width of pins (P < 0,05...0,001). Thus, the greatest influence on the body measurements and live weight of first-calf cows has the bull's origin, just below – the line belonging, the lowest – the part of Holstein inheritance, but in all cases it is rather high. It was established that for improvement of the cows` exterior will be promote the using of bulls and lines that have the desirable indicators of live weight and body measurements of daughters, as well as animals with a high part of Holstein inheritance, which have by good exterior characteristics. For effective selection it is needed to use of detected correlations between milk yield and body measurements. Key words: exterior, body measurements, part of Holstein inheritance, bull's origin, milk productivity.