Abstract
Background This study investigated effects of different methionine(Met)supplementation levels in a reduced protein diet on growth performance,intestinal health,and different physiological parameters in broilers under Eimeria challenge.A total of 600 fourteen-day-old Cobb500 male broilers were challenged with E.maxima,E.tenella,and E.acervulina,and randomly allocated in a 2×5 factorial arrangement.Birds received normal protein diets(20％crude protein,NCP)or reduced protein diets(17％crude protein,LCP),containing 2.8,4.4,6.0,7.6,and 9.2 g/kg of Met.Results On 6 and 9 days post inoculation(DPI),increasing Met level linearly improved the growth performance(P＜0.05).Total oocyst shedding linearly increased as Met level increased(P＜0.05).Duodenal villus height(VH):crypt depth(CD)in the LCP groups were higher on 6 DPI(P＜0.01)while lower on 9 DPI(P＜0.05)compared to the NCP groups.Jejunal CD and duodenal VH:CD changed quadratically as Met level increased(P＜0.05).On 6 DPI,liver glu-tathione(GSH)and glutathione disulfiide(GSSG)linearly increased as Met level increased(P＜0.05).On 9 DPI,GSSG quadratically increased,whereas GSH:GSSG quadratically decreased as Met levels increased(P＜0.05).The expression of amino acid transporters linearly decreased as Met level increased(P＜0.05).The expression of zonula occludens 2 and claudin-1 linearly increased on 6 DPI whereas decreased on 9 DPI as Met level increased(P＜0.05).The expres-sions of cytokines were lower in the LCP groups than the NCP groups(P＜0.05).Interaction effects were found for the expression of IL-10 and TNFα on 6 DPI(P＜0.05),where it only changed quadratically in the NCP group as Met level increased.The expression of Met and folate metabolism genes were lower in the LCP groups than the NCP groups on 9 DPI(P＜0.05).The expression of these genes linearly or quadratically decreased as Met level increased(P＜0.05).Conclusion These results revealed the regulatory roles of Met in different physiological parameters including oxida-tive status,intestinal health,and nutrient metabolism in birds fed reduced protein diet and challenged with Eimeria.
基金项目
United States Department of Agriculture-Agricultural Research Service(6040-32000-080-000D)
万方数据