Indicators of total homeostasis in cows in different periods of lactations

Abstract

The immunomorphological parameters of cattle in different periods of lactation were studied. In the first 3 months of lactation, excluding 7 days of the colostrum period, 59.3 units of circulating immune complexes were found in the serum, in the middle of lactation (4–7 months) – 94.2 (p <0.05), at the end (8–10 months) – 94.1 units (p <0.05). The significant difference between the indicator in the first 3 months and in the subsequent periods of lactation is due to the fact that at the beginning of lactation the cows were not yet pregnant. In the colostrum period, a high rate of circulating immune complexes of 116.1 units (p <0.05) was determined as a consequence of a fetal prenatal immune attack on the cow's body, when the system of mononuclear phagocytes had not yet coped with the elimination of neutralization products. During the dry period, the number of circulating immune complexes was 87.6 units (p <0.05). The decrease in the indicator occurred due to an increase in the activity of mononuclear phagocytes and the absence of lactation effect on the body. The content of segmental, functionally mature leukocytes at the beginning of lactation was 39.4%, in the middle of lactation this indicator decreased to 24.8% (p<0.05), at the end it was 26.3% (p<0.05). A significant difference was found in the relative number of segmented neutrophils in the control group and in non-lactating cows in the dry period – 29.9% (p <0.05). During the colostrum period, the level of lymphocytes in the blood of animals was 62.0% (p <0.05) and it significantly differed from the control – 43.6%. In the middle and at the end of lactation, there was also a significant difference between the indicator and the control, up to 58.9–59.4% (p<0.05). A significant difference with the group of down-calving dry cows was established – 53.9% (p <0.05). In the first 1–3 months of lactation, cows are either not yet pregnant, or a close bond (placenta) between the mother and the fetus has not yet been formed, therefore a low activity of specific immunity at this time is caused by the absence of foreign fetal antigens in the blood of cows. The findings suggest that the birth process may be initiated by the immune system.