Barekatain Reza, Chrystal Peter V, Nowland Tanya, Moss Amy F, Howarth Gordon S, Hao Van Thi Thu, Moore Robert J
South Australian Research and Development Institute, Roseworthy Campus, Roseworthy, SA, Australia.
School of Animal and Veterinary Sciences, Roseworthy Campus, University of Adelaide, Roseworthy, SA, Australia.
Anim Nutr. 2023 Feb 20;13:216-228. doi: 10.1016/j.aninu.2023.01.011. eCollection 2023 Jun.
The consequences of feeding broiler chickens with reduced protein (RP) diets for gut health and barrier function are not well understood. This study was performed to elucidate the effect of reducing dietary protein and source of protein on gut health and performance parameters. Four experimental diets included 2 control diets with standard protein levels either containing meat and bone meal (CMBM) or an all-vegetable diet (CVEG), a medium RP diet (17.5% in growers and 16.5% in finisher), and a severe RP diet (15.6% in grower and 14.6% in finisher). Off-sex Ross 308 birds were assigned to each of the 4 diets and performance measurements were taken from d 7 to 42 post-hatch. Each diet was replicated 8 times (10 birds per replicate). A challenge study was conducted on additional 96 broilers (24 birds per diet) from d 13 to 21. Half of the birds in each dietary treatment were challenged by dexamethasone (DEX) to induce a leaky gut. Feeding birds with RP diets decreased weight gain ( < 0.0001) and increased feed conversion ratio ( < 0.0001) from d 7 to 42 compared with control diets. There was no difference between CVEG and CMBM control diets for any parameter. The diet containing 15.6% protein increased ( < 0.05) intestinal permeability independent of the DEX challenge. Gene expression of claudin-3 was downregulated ( < 0.05) in birds fed 15.6% protein. There was a significant interaction between diet and DEX ( < 0.05) and both RP diets (17.5% and 15.6%) downregulated claudin-2 expression in DEX-challenged birds. The overall composition of the caecal microbiota was affected in birds fed 15.6% protein having a significantly lower richness of microbiota in both sham and DEX-injected birds. Proteobacteria was the main phylum driving the differences in birds fed 15.6% protein. At the family level, Bifidobacteriaceae, Unclassified Bifidobacteriales, Enterococcaceae, Enterobacteriaceae, and Lachnospiraceae were the main taxa in birds fed 15.6% protein. Despite supplementation of synthetic amino acids, severe reduction of dietary protein compromised performance and intestinal health parameters in broilers, evidenced by differential mRNA expression of tight junction proteins, higher permeability, and changes in caecal microbiota composition.
给肉鸡饲喂低蛋白（RP）日粮对肠道健康和屏障功能的影响尚不清楚。本研究旨在阐明降低日粮蛋白质水平和蛋白质来源对肠道健康及生产性能参数的影响。四种实验日粮包括两种标准蛋白水平的对照日粮，一种含肉骨粉（CMBM），另一种为全植物性日粮（CVEG），一种中等RP日粮（生长鸡为17.5%，育肥鸡为16.5%），以及一种低RP日粮（生长鸡为15.6%，育肥鸡为14.6%）。将非种用罗斯308肉鸡分配到这四种日粮中，在孵化后第7天至42天进行生产性能测定。每种日粮重复8次（每次重复10只鸡）。从第13天至21天对另外96只肉鸡（每种日粮24只）进行攻毒试验。每种日粮处理的鸡中有一半用 dexamethasone（DEX）攻毒以诱导肠道渗漏。与对照日粮相比，从第7天至42天，给肉鸡饲喂RP日粮会降低体重增加（<0.0001）并提高饲料转化率（<0.0001）。CVEG和CMBM对照日粮在任何参数上均无差异。含15.6%蛋白质的日粮会增加（<0.05）肠道通透性，且与DEX攻毒无关。饲喂含15.6%蛋白质日粮的鸡中，claudin - 3的基因表达下调（<0.05）。日粮和DEX之间存在显著交互作用（<0.05），两种RP日粮（17.5%和15.6%）均下调了DEX攻毒鸡中claudin - 2的表达。饲喂含15.6%蛋白质日粮的鸡盲肠微生物群的总体组成受到影响，在假手术组和DEX注射组中，微生物群丰富度均显著降低。变形菌门是导致饲喂含15.6%蛋白质日粮鸡出现差异的主要菌门。在科水平上，双歧杆菌科、未分类双歧杆菌目、肠球菌科、肠杆菌科和毛螺菌科是饲喂含15.6%蛋白质日粮鸡中的主要分类群。尽管补充了合成氨基酸，但日粮蛋白质的大幅减少仍损害了肉鸡的生产性能和肠道健康参数，紧密连接蛋白的mRNA表达差异、更高的通透性以及盲肠微生物群组成的变化都证明了这一点。
