LAUSR

BACKGROUND This study evaluated the effects of citrus extract (CE) on growth performance, plasma amino acid (AA) profiles, intestinal development, and small intestine AA and peptide transporters expression levels in broilers. A total of 540 1-day-old yellow-feathered broilers were fed a basal diet without any antibiotic (control group), or a basal diet containing 10 mg/kg of zinc bacitracin (antibiotic group), or a basal diet supplemented with 10 mg/kg of CE (CE group). After 63-day feeding, 2 broilers per pen were slaughtered to collect tissues for further analysis. RESULTS Results showed that CE increased (P < 0.05) the final body weight and average daily gain from day 1 to 63, and decreased (P < 0.05) the feed/gain ratio from day 1 to 63. Dietary CE supplementation increased (P < 0.05) plasma total protein, albumin, and glucose concentration, and decreased (P < 0.05) urea concentration. CE supplementation increased (P < 0.05) the villus height in the ileum and the V/C in the jejunum and ileum, but decreased (P < 0.05) the crypt depth in the jejunum and ileum. CE supplementation increased (P < 0.05) most plasma essential AAs concentrations. Additionally, CE supplementation upregulated (P < 0.05) ASCT1, b0,+ AT, B0 AT1, EAAT3, rBAT, y+ LAT2, and PepT1 expression in the jejunum, and b0,+ AT, EAAT3, rBAT, y+ LAT2, and CAT1 and PepT1 in the ileum. CONCLUSION Collectively, our results indicated that CE supplementation promotes intestinal physiological absorption of AA by upregulating gene expression of small intestinal key AA and peptide transporters, thereby enhancing the growth performance of broilers. This article is protected by copyright. All rights reserved.