Effects of environmental enrichment on behavior, physiology, and rumen bacterial communities in early-weaned small-tailed Han sheep

Abstract

This study evaluated the effectiveness of sensory and cognitive environmental enrichment in alleviating stress in early-weaned small-tailed Han lambs. Forty-nine lambs weaned at 35 days of age were assigned to seven groups (n = 7 per group): without environmental enrichment (Control), intermittent sensory enrichment (Int S), continuous sensory enrichment (Con S), intermittent cognitive enrichment (Int C), continuous cognitive enrichment (Con C), 24 h alternate enrichment (24 h), and 48 h alternate enrichment (48 h). Key results showed that lambs in the Int C group significantly increased the frequency of foraging and ruminating behaviors while reducing drinking, lying, and urinating or defecating behaviors (P < 0.05). The frequency of foraging, ruminating, drinking and urinating or defecating behaviors in the 48 h group was significantly decreased (P < 0.05), whereas the frequency of lying behavior was significantly increased (P < 0.05). The frequency of licking behavior in the Int S group was significantly higher than that in the 48 h group, and following behavior frequency was significantly higher in the Int S group than that in the Con S, Con C, 24 h and 48 h groups. Rubbing behavior in the Int S group was significantly higher than that in the Con S group. Interaction frequency was significantly increased in the Int C group and 24 h group (P < 0.05). The serum cortisol (CORT) level of lambs in the Con C group was significantly lower than that in the 48 h group (P < 0.05). The relative abundance of Ruminococcus in the rumen bacteria of the 24 h and 48 h groups was significantly higher than that in the control group (P < 0.01). Furthermore, the relative abundance of Ruminococcus was negatively correlated with foraging and following behaviors, whereas the abundances of Christensenellaceae_R-7_group and Rikenellaceae_RC9_gut_group were positively correlated with foraging, drinking and urinating or defecating behaviors. In conclusion, intermittent cognitive and 24 h alternate enrichment may be effective strategies for mitigating weaning stress in intensive lamb production.