Milk productivity of black-and-white cows with easy and difficult calving
In the course of development and improvement, the cattle acquired a number of biological and economic-useful qualities, which allowed identifying separate groups of animals with high productivity and productive longevity. One of the main criteria for the selection of cows for further breeding is the quantity and quality of dairy products [4]. Both milk yield and reproductive ability of cows strongly influence the profitability of dairy farming. Difficult calving and subsequent diseases and complications negatively affect the body condition of animals. Health preservation and recovery of cows which had difficult calving are expensive. The goal of this research was to study data on milk production in cows with easy and difficult calving. To achieve this goal, the following parameters of cows with easy and difficult calving were analyzed: milk yield for first lactation, content of fat and protein mass fraction, amount of milk fat and protein; furthermore, data on milk productivity depending on the age of the first insemination and length of service period were studied. It was found that milk yield in cows with difficult calving was higher than in cows with easy calving. The influence of age of the first favorable insemination on further milk productivity was established: the highest yield was obtained from cows whose age of the first favorable insemination was between 15.1 and 17.0 months. Maximum values of milk yield during the first lactation - 6206 kg - were observed in cows with a relatively short service period (from 61 to 90 days).