Reproductive capacity and milk production of cows depending on their physio-logical status during lactation

Due to violation of husbandry, feeding, milking, non-observance of sanitary requirements, especially in postpartum period, cases of endometritis, mastitis and limb diseases in cows increase in conditions of intensive cattle breeding. These diseases adversely affect reproductive and productive qualities of animals, thus causing great financial losses to agribusiness. Therefore, increasing longevity of animals, reducing percentage of their elimination due to various diseases, reducing risk of economically significant diseases in dairy herds by selecting highly productive animals with high resistance to common diseases are relevant. The aim of the research was to study phenotypic relationship between fertility level and milk production of black-motley Holsteinized cows with different diseases at the farm in Moscow region. The research materials were 1234 records of diseases - endometritis, mastitis and limb diseases - obtained from veterinary outpatient logs (2015-2021) of the breeding organization. Information about 5 signs of milk productivity and 3 signs of fertility of the studied population of black-motley Holsteinized dairy cattle was taken from ‘Seleks’ database. According to the results, significant (p < 0.01) increase was observed in sick animals in comparison with healthy ones: number of inseminations per lactation - b y 33.5 %, open days - b y 7.3 %, milk days - b y 4.35 %. Milk yield was higher by 19.4 % (p < 0.01), fat and protein mass fraction - by 0.32 and 0.33 % (p < 0.01), respectively, fat and protein yield - b y 82 and 69 kg (p < 0.01), respectively, compared to healthy animals. When comparing the indices in animals with one, two and three diseases, significant differences were obtained both between the groups with single diseases and complexes. For fertility traits, the indices increased significantly with the number of diseases from 4 to 20 % for individual traits. For milk production traits, there was a tendency for indices to decrease with increasing number of diseases.