Physiological, immunological, and behavioral responses in cows housed under confinement conditions after grazing✰

Abstract

Grazing is thought to contribute to animal health and welfare. However, cattle are often moved from grazing to confinement conditions at the end of the grazing season or due to their production stage. The aim of this study was to clarify the physiological, immunological, and behavioral responses that occur in cows when they are moved from grazing to confinement conditions. Ten Japanese black cows were used in this experiment. Five of the cows grazed on a 1.8-ha field composed of sown pasture and forest land, while the remaining cows were fed under confinement conditions with tethering for two months. Two months later, the grazing cows were moved to confinement conditions with tethering and for two weeks. They were exposed to the same conditions as the confined cows. Blood samples were collected from all cows, and complete blood cell count, leukocyte differentiation, biochemical analysis, and oxidative stress marker analysis were conducted. Behavioral observations were also carried out. The concentrations of blood urea nitrogen (BUN) and magnesium (Mg) and the activity of glutathione peroxidase (GPx) were lower (P ≤ 0.05), while the numbers of red blood cells (RBCs) and lymphocytes, the hematocrit (HCT) percentage, and the concentration of hemoglobin (HGB) were higher after cows were moved to confinement conditions (P < 0.05). The number of monocytes was lower (P = 0.08), and the number of neutrophils decreased on day 3 before increasing on day 14 after the cows were moved to confinement conditions (P = 0.1). The results of the present study suggest that moving the cows from grazing conditions to confinement conditions induced temporary stress, resulting in a reduction in plasma Mg concentrations and eliminating the high levels of immune and antioxidant enzyme activities observed in grazing cows within two weeks. However, the change in feeding conditions recovered blood parameters, such as the number of RBCs and lymphocytes, the HCT percentage, and the concentration of HGB, and these changes were accompanied by improvement in protein and energy status in cows.