Study of the resistance of cows with mastitis depending on the age of lactation

Abstract

Relevance. The breeding stock and young cattle in the conditions of industrial technology of animal husbandry experience an increased antigenic load, which leads to disturbances in the immune status and the development of inflammatory processes manifested by endometritis and mastitis, diarrheal and respiratory syndromes. It was relevant to conduct a comprehensive assessment of the immunological reactivity of the animal’s body according to the state of resistance in cattle with clinical and subclinical mastitis, depending on the age of lactation. As a result of complex studies, the specific and nonspecific reactivity of the body of cattle in different periods of lactation was studied.Methods. The object of the study were cows of a black-and-white Holstein breed (n = 450). Groups of animals were formed according to the age of lactation:1st lactation, 2–3rd lactation, 3–4th lactation and for health reasons: clinically healthy animals, with subclinical mastitis and clinical mastitis. Milk samples were taken from cows to count the number of somatic cells, and blood to determine the quantitative content of IgG immunoglobulin and indicators of nonspecific resistance.Results. It was found that with mastitis in cows of different lactation ages, almost identical changes in the immune status were observed. Quantitative determination of IgG levels in animal blood serum is the basis for assessing the immunity of cattle. The immune status in clinically healthy animals was characterized by a higher level of the total amount of IgG immunoglobulin in the blood serum (amounted to 22.25 ± 0.70 mg/ml), whereas in cows with a subclinical form of mastitis, the level of IgG immunoglobulin decreased by 12.3%, with a clinical form of mastitis — by 17.2%. The results also showed that in cows of different lactations with subclinical and clinical mastitis, the bactericidal activity (by 10.8%) and the lysozyme activity of the blood increased significantly (by 8.22%). In cows with clinical mastitis — by 8.6% and 9.7% respectively, compared with the indicators in groups of healthy animals. Thus, mastitis, occurring in acute and subacute form, leads to a decrease in the resistance of the cows’ organism.