Productivity energy level of cows of Gray Ukrainian breeds and their reproductive qualities

Abstract

We have studied the reproductive abilities of the animals and the development of the offspring during the post-sucking period on cows of the Gray Ukrainian breed in the 1st–3rd lactations. To evaluate the cows and the offspring, in addition to traditional signs, indicators of net energy of body maintenance and net energy of growth were introduced, as integrated indicators of the state of the organism, which depend to a greater extent on the origin than on the conditions of keeping. We have established that the researched population of animals of the Gray Ukrainian breed in the ecological and fodder conditions of the steppe zone of Ukraine shows excellent maternal instincts, reproductive function and small foetus rate not lower than the standard for the breed, almost equal distribution of offspring by sex. The yield of calves per 100 cows is 97–98%, live weight of calves at birth is 25–26 kg for heifers and 27–28 kg for bulls; high milk yield: the weaning live weight at 8 months of age is 200 kg for heifers and 230 kg for bulls, the service period of cows for 1–3 lactation period is 155–91 days, the intercalving period is 433–371 days, the small foetus coefficient is 0.54–0.49, net energy for maintaining vital activity in cows is 40–45 MJ and in newborn calves — 4.5–4.6 MJ, the net energy of growth of young calves when weaned from their mothers is 19–20 MJ and for the entire period of suckling is 3800–4900 MJ. In the section of lactations, correlational dependences were established between the net energy of maintaining cows and their offspring, which makes it possible to carry out more purposeful selection and selection of animals for further breeding and preservation of the herd of this breed.