脂多糖和地塞米松对肉鸡生长性能、养分代谢、血清生化指标及肠道形态发育的影响

摘要

试验旨在探讨脂多糖(LPS)和地塞米松(DEX)对肉鸡生长性能、养分代谢、血清生化指标及小肠形态发育的影响.选取1日龄健康状况良好、体重相近的AA肉仔鸡224只,随机分为4个处理组,每个处理7个重复,每个重复8只,分为无免疫组(NV组)、正常免疫组(CV组)、免疫抑制组(DEX组)和免疫亢进组(LPS组),DEX组和LPS组分别于15、17和19 d肌肉注射2.5 mg/kg体重的DEX或500 μg/kg体重的LPS,NV组和CV组于相应日龄注射等体积的生理盐水.预试期7 d,正试期35 d.结果显示,DEX组和LPS组能够显著降低肉鸡平均日采食量(ADFI)和平均日增重(ADG)(P<0.05),提高料重比(P>0.05);DEX和LPS对干物质(DM)表观代谢率无显著影响(P>0.05),但可显著降低36~42 d日粮中的有机物(OM)、粗蛋白质(CP)、钙(Ca)和磷(P)的表观代谢率(P<0.05);21和42 d时,各组血清葡萄糖(GLU)、尿酸(UA)和丙二醛(MDA)水平均无显著差异(P>0.05).21 d时,DEX组和LPS组血清中的白细胞介素-6(IL-6)和肿瘤坏死因子-α(TNF-α)含量显著高于NV组和CV组(P<0.05),但在42 d,各组间的血清IL-6和TNF-α含量无显著差异(P>0.05).DEX和LPS可降低21和42 d十二指肠、空肠和回肠的肠壁厚度、黏膜厚度,绒毛高度和绒毛高度/隐窝深度.综上所述,DEX和LPS使肉鸡的肠道形态结构受损,降低了养分表观代谢率,从而影响采食量及体增重,使生长性能下降.%This research was to study the effect of bacterial lipopolysaccharide (LPX) and dexamethasone (DEX) on the growth performance,nutrient metabolism and blood biochemical indexes and intestinal morphology development of broiler chickens.224 AA broilers with similar body weight and 1-day-old were chosen and divided into 4 groups randomly,which were immune group (NV group),normal immune group (CV group),immunosuppression group (DEX group) and immune hyperthyroidism group (LPS group) with 7 replicates per group and 8 broilers per replicate.At 15,17 and 19 d,chicken of LPS and DEX groups were intramuscular injected with 500 μg/(kg·BW) LPS or 2.5 mg/(kg·BW) DEX,respectively,while chicken of NV and CV groups was injected with normal saline in the same volume.The experiment was lasted for 42 d with 7 d preliminary trial period.The results showed that the average daily feed intake (ADFI) and average daily gain (ADG) were decreased significantly (P<0.05) by LPS and DEX immunological stress,there were was no significant difference in feed to gain ratio (F/G) among experimental groups (P>0.05).The apparent metabolic rate of organic matter (DM) was no significantly affected by LPS and DEX immunological stress,while that of dry matter (OM),crude protein (CP),Ca and P were declined significantly at 36-42 d (P<0.05).At 21 and 42 d,GLU,UA and MDA levels were not significantly different among experimental groups (P>0.05).At 21 d,the contents of serum IL-6 and TNF-α in DEX and LPS groups were significantly higher than those in NV and CV groups (P<0.05),but there was no significant difference at 42 d (P>0.05).The wall thickness,mucosa thickness, villus height and the ratio of villus length to crypt depth were reduced by LPS and DEX at 21 and 42 d of broilers.In summary,LPS and DEX had an important influence on the apparent digestibility of DM,CP,Ca and P.DEX and LPS could damage the intestinal morphology of broilers,reduce the apparent metabolic rate,affect the feed intake and body weight,decrease growth performance.