THE IMPACT OF PHYSIOLOGICAL FACTORS ON THE PRODUCTIVITY OF BLACK AND MOTTLED DAIRY COW BREEDS

Abstract

The purpose of the research was to examine the impact of physiological factors on the productivity and reproductive ability of cows of the Ukrainian black and mottled dairy breed at the breeding farm. The method of correlation analysis was applied in the study. The impact force (η2x) of the factors on the investigated features was studied with the help of the method of one- and two-factor dispersion analysis through the correlation of factor dispersion and general dispersion on the basis of STATISTICA 8.0 mathematical program. According to the research, the average index of milk yields in the herd of the Ukrainian black and mottled dairy cow breed is 6768.77 kg, the highest milk yield for the third lactation is 7635.84 kg (Р<0.01), and the lowest milk yield is 5053.32 kg (Р<0.001) for the first lactation. The increase in the milk yield from the first to the second lactation was 1875.28 kg or 37.1%, from the first to the third lactation it was 2582.52 kg or 51.1 % (Р<0.01). With the help of the method of two-factor dispersion analysis it has been established that a cow’s age and the duration of a service-period have a highly trustworthy share of the impact on milk yields, 20.5 and 7.18% (Р<0.001) respectively. The data of the analysis indicate a predominant impact of other factors – 67.01%. The interaction of the factors (a cow’s age × the duration of a service period) does not influence milk yields for 305 days of lactation reliably, and it has the least force of the impact at the level of 2.91%. The increase in milk yields from the first to the third lactation indicates the intensification of milking and the correspondence of the environmental conditions to genetic predispositions of the animals. In order to realize the genetic potential of the productivity of dairy cows it is necessary to observe the duration of the period between calving of 386–405 days, the dry period – to 61–80 days, aiming at full-fledged involution of udder alveolar tissue, and the service-period – to 41–80 days, that is economically expedient and profitable.