Background:Over the past years, antibiotic growth promoter had been restricted in animal husbandry production in many countries because of antimicrobial resistance and foodborne antibiotic residues. However, the problems of poor intestinal health and low growth efficiency of piglets have not been solved completely in an antibiotic-free diet, and it is urgent to explore alternatives to antimicrobial growth promoters. Methods:Here, a total of 532 weaned pigs were assigned to one of 4 treatments, the low amino acid (AA) level diet (d 1 to d 14 is 1.35％, d 15 to d 42 is 1.25％) (Low AA), the low AA level diet supplementation with a carvacrol–thymol blend (50 mg carvacrol and 50 mg thymol/kg of diet) (CB) (Low AA+CB), the high AA level diet (d 1 to d 14 is 1.50％, d 15 to d 42 is 1.40％) (High AA), and the high AA level diet supplementation with a CB (High AA+CB), respectively. Then we measured growth performance and intestinal health indicators of weaned pigs. Results:Results showed that high AA level significantly reduced plasma urea nitrogen, plasma Interleukin-6 (IL-6) and fecal lipocalin-2 contents (P< 0.05), significantly increased the relative abundance of fecal Lactobacillus and Enterococcus, and had a trend to increase the fecal secretory immunoglobulin A (sIgA) and mucin 2 (MUC 2) contents (P< 0.05) in piglets, thereby alleviating the diarrhea of piglets and reducing the feed conversion ratio (FCR) of piglets during d 1～14 after weaning. Dietary supplementation with CB significantly increased the activity of plasma antioxidant enzymes T-SOD and GSH-px (P< 0.05), while significantly reduced plasma malondialdehyde (MDA), plasma interleukin-1β(IL-1β), plasma endotoxin and D-lactic acid contents (P< 0.05). Meanwhile, CB significantly decreased fecal lipocalin-2 contents and the abundance of fecal Escherichia coli (P<0.05). Thus, we hypothesis that dietary supplementation with CB significantly increased the average daily gain (ADG) of piglets (P<0.05) during d 1～14 after weaning through promoting intestinal health. Conclusion:These results suggest that high AA level and dietary supplementation with CB improved the growth performance of weaned pigs in an antibiotic-free diet by improving AA metabolism and intestinal antioxidant capacity.

Yanan Wang;Zhipeng Yang;Yuanfei Zhou;Jiajian Tan;Haiqing Sun;Defa Sun;Yuyun Mu;Jian Peng;Hongkui Wei

Department of Animal Nutrition and Feed Science,College of Animal Science and Technology,Huazhong Agricultural University,Wuhan 430070,China;Guangxi Yangxiang Co.,Ltd,Guigang 537000,China;Novus International Trading(Shanghai)Co.Ltd,Shanghai 200080,China;The Cooperative Innovation Center for Sustainable Pig Production,Wuhan 430070,China

畜牧与生物技术杂志（英文版）

[1]Yanan Wang;Zhipeng Yang;Yuanfei Zhou;Jiajian Tan;Haiqing Sun;Defa Sun;Yuyun Mu;Jian Peng;Hongkui Wei-.Effects of different amino acid levels and a carvacrol–thymol blend on growth performance and intestinal health of weaned pigs)[J].畜牧与生物技术杂志（英文版）,2022(05):1428-1439

AA+CB

Effects,different,amino,acid,levels,carvacrol,thymol,blend,growth,performance,intestinal,health,weaned,pigs,Background,Over,past,years,antibiotic,had,been,restricted,animal,husbandry,production,many,countries,because,antimicrobial,resistance,foodborne,residues,However,problems,poor,low,efficiency,piglets,have,not,solved,completely,free,urgent,explore,alternatives,promoters,Methods,Here,total,were,assigned,one,treatments,Low,supplementation,high,High,respectively,Then,measured,indicators,Results,showed,that,significantly,reduced,plasma,urea,nitrogen,Interleukin,fecal,lipocalin,contents,increased,relative,abundance,Lactobacillus,Enterococcus,trend,secretory,immunoglobulin,sIgA,mucin,MUC,thereby,alleviating,diarrhea,reducing,feed,conversion,ratio,FCR,during,after,weaning,Dietary,activity,antioxidant,enzymes,GSH,px,malondialdehyde,interleukin,endotoxin,lactic,Meanwhile,decreased,Escherichia,coli,Thus,hypothesis,dietary,average,daily,gain,ADG,through,promoting,Conclusion,These,results,suggest,improved,improving,metabolism,capacity

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