Effects of Access to an Outdoor Yard on Hematological Values, Serum Biochemical Values and Peripheral Blood Mononuclear Cell Viability in Japanese Black Cattle

We investigated the effects of outdoor yard access in farm-reared Japanese Black breeding cattle. Sixteen cattle were randomly divided into a yard group allowed six hours of daily access to an outdoor yard but otherwise kept in an indoor barn (n = 8) and a control group kept exclusively in the indoor barn (n = 8), and were evaluated through an eight-week (week 0 to week 8) study period. As a result, there was no difference between the yard and control groups or week 0 and week 8 values in hematological values or serum biochemical values. Peripheral blood mononuclear cells (PBMCs) viability showed a statistically significant difference in the interaction effect between the group and measurement date (P < 0.05), and was significantly decreased in the control group from week 0 to week 8 (P < 0.01). Additionally, the cell viability significantly differed between the groups at week 8 (P < 0.05). These results suggest that outdoor yard access might improve PBMC cellular function in Japanese Black cattle.