Abstract
This systematic review aims to evaluate the effectiveness of various physical environmental enrichment items such as brushes, ropes, teats, chains, balls, cowhides/blocks, at improving the welfare of indoor-housed calves, heifers, and cattle. This review of 33 peer-reviewed papers and one industry report evaluated different welfare-related outcomes following physical environmental enrichment, including feed intake, lying time, play and exploratory behaviour, aggression, stereotypic behaviour and cross-sucking behaviour. The results of the meta-analysis revealed that calves and heifers enrolled in experimental studies using enrichment items had significantly improved growth rates, and increased locomotor play, but the overall reduction in cross-sucking behaviour was small and non-significant. The effect of enrichment on feed intake, aggression/stereotypic behaviour, play behaviour, cleanliness score contrasted between studies, with some reporting improvements while others showed no effect of environmental enrichment in these parameters. The risk of bias assessment revealed limitations in researcher blinding, sequence generation, and allocation concealment across the literature assessing the effectiveness of environmental enrichment on animal welfare. Overall, this review underscores the significant positive impact of physical enrichment on the welfare and behaviour of indoor-housed cattle, while highlighting the need for further research to optimise enrichment strategies across different cattle age groups and housing conditions.