Animal Feed Science and Technology 185 (2013) 78–84 Contents lists available at ScienceDirect Animal Feed Science and Technology journal homepage: www.elsevier.com/locate/anifeedsci Effects of dietary supplementation with an antimicrobial peptide-P5 on growth performance, nutrient retention, excreta and intestinal microflora and intestinal morphology of broilers S.C. Choi a , S.L. Ingale a , J.S. Kim a , Y.K. Park b , I.K. Kwon a , B.J. Chae a,∗ a College of Animal Life Sciences, Kangwon National University, Chuncheon 200-701, Republic of Korea b College of Natural Sciences, Chosun University, Kwangju 501-759, Republic of Korea a r t i c l e i n f o Article history: Received 18 August 2012 Received in revised form 5 July 2013 Accepted 8 July 2013 Keywords: Antibiotic Antimicrobial peptide-P5 Broiler Growth performance Intestinal morphology Nutrient retention a b s t r a c t The present study investigated the effects of dietary supplementation of antimicrobial peptide-P5 (AMP-P5) on growth performance, nutrient retention, excreta and intestinal digesta microflora and intestinal morphology of broilers. Three hundred twenty-d-old chicks (Ross 308) were randomly allotted to 4 dietary treatments, each consisting of 4 pens as replicates, with 20 chicks in each pen. The dietary treatments were: NC (negative control; basal diet), PC (positive control; basal diet supplemented with 15 mg avilamycin/kg diet) and AMP-P5 (basal diet supplemented with 40 and 60 mg AMP-P5/kg diets). The experi- mental diets were fed in 2 phases, starter (d 0–21) and finisher (d 22–35). The overall (d 0–35) body weight (BW) gain and retention of dry matter (DM) and nitrogen (N; d 20–21 and d 34–35) were greater (P<0.05) in birds fed the PC and 60 mg AMP-P5/kg diets than birds fed the NC diet. Moreover, increasing levels of dietary AMP-P5 linearly (P<0.05) improved BW gain (starter, finisher and overall), feed conversion ratio (FCR; starter) and retention of DM and N (d 20–21 and d 34–35). The population of excreta of total anaerobic bacteria (TAB, d 35) and coliforms (d 21 and d 35) and the ileal and cecal digesta coliforms (d 35) was fewer (P<0.05) in birds fed the PC and 60 mg AMP-P5/kg diets compared with birds fed the NC diet. The villus height of the duodenum and jejunum and villus height:crypt depth (VH:CD) of the duodenum, jejunum and ileum were greater (P<0.05) in the birds fed the PC and 60 mg AMP-P5/kg diets than birds fed the NC diet. Increasing levels of dietary AMP-P5 linearly (P<0.05) reduced (P<0.05) excreta TAB (d 35), coliforms (d 21 and d 35) and the coliforms in the ileal and cecal digesta (d 35). Moreover, increasing levels of dietary AMP-P5 linearly increased (P<0.05) villus height (duodenum and jejunum) and VH:CD (duodenum, jejunum and ileum) and linear reduction (P<0.05) in crypt depth of the jejunum. These results indicate that dietary supplementation with 60 mg AMP-P5/kg has the potential to improve the growth performance, nutrient retention, intestinal morphology and reduce intestinal and excreta coliforms in broilers. © 2013 Elsevier B.V. All rights reserved. Abbreviations: AMP, antimicrobial peptide; BW, body weight; CFU, colony forming unit; DM, dry matter; FCR, feed conversion ratio; GE, gross energy; ME, metabolic energy; N, nitrogen; NC, negative control; PC, positive control; TAB, total anaerobic bacteria; VH:CD, villus height:crypt depth. ∗ Corresponding author. Tel.: +82 33 250 8616; fax: +82 33 244 4946. E-mail address: bjchae@kangwon.ac.kr (B.J. Chae). 0377-8401/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.anifeedsci.2013.07.005