INFLUENCE OF PHENOTYPIC TRAITS OF COWS ON THEIR MILK PRODUCTION

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The research was conducted in LLC JV "Imeni Volovikova", Rivne region (Polissya zone, n=1840), SE DG "Oleksandrivske", Vinnytsia region (Forest-Steppe zone, n=714) and SE "Experimental farm "Askaniyske" (Steppe zone, n=926) on firstborn and full-grown cows (III lactation) of the Ukrainian Black-and-White dairy breed. In the controlled cows, by retrospective analysis of zootechnical accounting data for the last 10 years, the signs of milk production were studied depending on phenotypic traits (live weight of newborns, 6-, 12- and 18-month-old animals), age and live weight at first calving, duration of the first service period).
 It has been established that animals of the Ukrainian Black-and-White dairy breed in different farms are characterised by rather high live weight during the period of their rearing. The highest values of this trait in newborn and 18-month-old heifers were observed in the Forest-Steppe zone, and in 6- and 12-month-old heifers - in the Polissya zone. The best average daily growth from birth to 6 months of age was observed in heifers from the Polissya zone, and in all subsequent age periods and from birth to 18 months - in animals from the Forest-Steppe zone. The highest values of the relative speed and tension of live weight growth of heifers were noted in the period from birth to 6 months, and these indicators decreased with age. Intergroup differentiation in terms of reproductive capacity was observed in the first-born heifers of the controlled farms. Animals from the Steppe zone had the highest live weight at first calving and the shortest duration of the first service period, while animals from the Forest-Steppe zone were the fastest maturing. Cows from the Steppe zone were also the best in terms of milk yield.
 The formation of milk production of first-born cows was significantly influenced by their live weight during the growing period. In the Forest-Steppe zone, the most productive were the first-born cows with a live weight of 40-42 kg at birth, 181-190 kg at 6 months of age, 321-335 kg at 12 months of age and 421-435 kg at 18 months of age; in the Polissya zone - 43 kg and more, 181-190 kg, 321-335 kg and 421-435 kg, respectively; in the Steppe zone - 43 kg and more, 191-200 kg, 336 kg and more and 421-435 kg. Multidirectional relationships were observed between the live weight of first-born heifers at different ages during their rearing and signs of milk production. In animals from the Forest-Steppe zone, they were insignificant and in almost all cases unreliable, while in first-born cows from the Polissya and Steppe zones these relationships were somewhat more significant and in most cases reliable.