The effect of litter materials on broiler performance: a systematic review and meta-analysis

1. Divergence in outcomes from studies on the effects of litter materials on body weight, feed intake, feed conversion and mortality in broilers has led to a need for a meta-analysis to quantify their effects.2. A systematic search of published quantitative research relating to wood shavings and alternative bedding litters was conducted using databases.3. Means, standard deviations and sample sizes were extracted from each study. The response variables were analysed using the standardised mean difference (SMD, control treatment minus alternative litters).4. The literature demonstrated that alternative materials have no impact on feed intake in broilers, compared to wood shavings (SMD = 0.064, 95% CI = -0.101-0.229, P = 0.44).5. There was a positive overall effect of wood shavings on body weight (SMD = 0.253, 95% CI = 0.073-0.433, P = 0.006), feed conversion (SMD = -0.169, 95% CI = -0.327 - -0.012, P = 0.03) and mortality (SMD = -1.069, 95% CI = -1.983 - -0.155, P = 0.02) of broilers, compared to other litter types.6. Subgroup meta-analysis revealed that straw, when used as an alternative litter material to wood shavings, may be responsible for lower body weight (SMD = 0.654, 95% CI = 0.162-1.146, P = 0.009), worse feed conversion (SMD = -0.487, 95% CI = -0.828 - -0.145, P = 0.005) and higher mortality rates of broilers (SMD = -3.25, 95% CI = -5.681 - -0.819, P = 0.009). Rice husks impaired body weight compared to wood shavings (SMD = 0.535, 95% CI = 0.065-1.004, P = 0.02).7. It was concluded that different litter types do not affect the broilers' feed intake. Conversely, broilers kept on straw showed lower body weights, worse feed conversion and higher mortality rates, in comparison to wood shavings. Rice husks decreased body weight compared to wood shavings.