Effects of Supplementation with Bee Pollen and Propolis on Growth Performance and Serum Metabolites of Rabbits: A Meta-Analysis

SIMPLE SUMMARY: Bee pollen and propolis have been used successfully to improve performance and serum metabolites in poultry; however, their effects in rabbits have been inconsistent. Therefore, the objective of this study was to evaluate the supplementation with bee pollen and propolis on animal performance and serum metabolites of rabbits through a meta-analysis. In rabbits, supplementation with bee pollen and propolis has been shown to reduce the feed conversion rate; however, it can also increase weight gain and total antioxidant capacity in blood serum. These results suggest that bee pollen and propolis could be used as natural growth promoters and to improve rabbits’ antioxidant status. ABSTRACT: The objective of this study was to evaluate the effects of bee pollen (BP) and propolis (PRO) supplementation on rabbits’ productive performance and serum metabolites through a meta-analysis. Sixteen peer-reviewed publications were included in the data set. The rabbit strains used in the studies included in the data set were New Zealand White, V-line, Rex, and V-line crosses. Weighted mean differences (WMD) between treatments supplemented with BP or PRO and control treatments were used to assess the magnitude of the effect. BP supplementation decreased (p < 0.001) daily feed intake (DFI) and feed conversion ratio (FCR); however, increased (p < 0.001) average daily gain (ADG) and hot carcass yield (HCY). PRO supplementation reduced DFI (p = 0.041) and FCR (p < 0.001), and increased ADG (p < 0.001) and HCY (p = 0.005). In blood serum, BP supplementation increased total antioxidant capacity (TAC; p = 0.002) and decreased serum creatinine concentration (p = 0.049). Likewise, decreased serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and malondialdehyde (MDA) were detected in response to BP supplementation (p < 0.05). PRO supplementation increased the TAC in blood serum (p = 0.018); however, decreased serum concentrations of AST, ALT, and MDA were observed (p < 0.05). In conclusion, BP or PRO supplementation can be used as a natural growth promoter in rabbits, and both can also improve rabbits' antioxidant status. However, BP or PRO supplementation does not affect rabbits' renal or hepatic health status.