关键词: 环境丰富度, 新西兰白兔, 应激, 动物福利

Abstract: Objective To explore the impact of environmental enrichment on animal welfare and stress levels, and the effects of different feeding environment enrichment methods ( food, environment, and cultural enrichment) on the healthy growth of animals. Method A total of 24 New Zealand white rabbits, half male and half female, were randomly divided into 6 groups with 4 pieces in each group. Specifically, negative control group ( group A, single toy, replaced once a week) , control group ( group B, without any environmental enrichment ) , and enrichment group were divided into 4 groups. The replacement frequency of toys in each group was once every 3, 6, 9, and 12 days, represented by group C, D, E, and F, respectively. The experimental period was 3 weeks, and the effects of environmental enrichment frequency on behavior, hematological indicators, cortisol and adrenocorticotropic hormone levels in urine, anti apoptotic protein ( Bcl-2) , Caspase-3 in brain tissue, and related mRNA gene expression in brain tissue of New Zealand white rabbits were studied. Result Animal behavioral observations showed that compared with Group B, Group F had a significant difference (P<0. 05) , while Group E had an extremely significant difference ( P < 0. 01) . There were no significant differences in hematological indicators and hormone levels in urine among animals within a period of 3 weeks. The expression of related genes in animal brain tissues showed that compared with group B, there was a significant difference in BDNF gene expression levels among the C, D, and F groups with rich environments ( P < 0. 05 ) . Compared with group B, there was a significant difference in GR gene expression levels in group D ( P < 0. 05 ) , and a significant difference in TH gene expression levels between groups A and B, C, and F (P<0. 05) . Compared with groups B and C, there was a significant difference in TH gene expression levels between groups D and F (P<0. 05) . In addition, there was no difference in the expression levels of POMC and TPH genes among the groups. The expression of anti apoptotic protein ( Bcl-2) in animal brain tissue showed an increasing trend in the expression levels of Bcl-2 protein in the brain tissues of groups C, D, E, and F compared to group B. The expression result of Caspase-3 protein showed that compared with Group B, the expression levels of Caspase-3 protein in brain tissues of Groups A, C, D, and E showed a decreasing trend. Conclusion Enhancing environmental and dietary enrichment can, to some extent, improve the stress resistance of rabbits without affecting their hematological parameters. When providing environmental enrichment for experimental rabbits, frequent changes to their environment should be avoided. Under the condition of maintaining toy cleanliness, a toy replacement frequency of every 6 days is optimal, as it enhances neural vitality in rabbits, improves their ability to regulate pain and fear, and increases their sense of security. However, if the toy replacement frequency is too frequent ( e. g. , every 3 days) , it may exacerbate stress in the experimental rabbits. 

Key words: environmental enrichment, New Zealand white rabbits, stress, animal welfare