Antimicrobial peptides as an additive in broiler chicken nutrition: a meta-analysis of bird performance, nutrient digestibility and serum metabolites

The present meta-analysis evaluated the effect of the level of antimicrobial peptides (AMPs) on broiler chicken growth performance, digestibility, small intestine morphology and blood serum parameters. The database was developed from 29 articles comprising 36 experiments. Data were analyzed using a mixed model methodology considering the levels of AMPs as fixed effects and different studies as random effects. It was shown that an increased AMPs addition level quadratically influenced body weight (BW), average daily gain (ADG) and feed conversion ratio (FCR) (P < 0.05). Simultaneously, it linearly reduced mortality (P < 0.05) both in the starter and finisher periods. There was a linear increase in metabolizable energy (P < 0.05). Small intestine morphology in the duodenum, as indicated by villus height and villus height to crypt depth ratio linearly increased, while the crypt depth was linearly decreased (P < 0.05). The mucosa thickness was quadratically affected in the jejunum, while the crypt depth linearly decreased (P < 0.05). Categorical analysis showed that AMPs had a comparable effect with antibiotics on broiler performance (BW, ADG, FCR) (P > 0.05); a similar improvement was shown in the control group (P < 0.01). In conclusion, it is evidenced that AMPs can be used as an effective replacer of antibiotic growth promoters (AGP) because they can improve growth performance, digestibility, small intestine morphology and blood serum parameters of broiler in all rearing periods. Also, the optimal doses of dietary AMPs addition at 337 and 359 mg/kg of diet for the starter and finisher phases, respectively, are suggested.