肉仔鸡肠道微生物的日粮调控——六类饲用抗生素替代品的作用

1前言在过去数十年,抗生素被用在畜禽日粮中以维持健康和生产效率。但由于致病菌耐药性的产生,抗生素进而威胁公共卫生,所以自1986年瑞     

饲用抗生素的安全替代品——绿源素

秸秆微贮技术是一种现代生物技术。是通过一种叫“秸秆发酵活杆菌”(该菌是将木质纤维分解菌和有机酸发酵菌通过生物工程技术制备的高效复合杆菌)完成的。农作物秸秆经秸秆发酵活杆菌发酵贮存制成的优质饲料称作秸秆微贮饲料。具有成本低、效益高,适口性好,采食量高,消化率高,制作容易、无毒无害、作业季节长与农业不争化肥、不争农时等优点。1.水泥地微贮法。与传统青贮窖相似,将作物秸秆铡切碎,按比例喷洒菌液后装入池内,分层压实、封口。这种方法优点:池内不易进气进水、密封性好,经久耐用。2.土窖微贮法。选地势高、土质硬、向阳干燥、…     

辣椒素作为饲用抗生素替代品的研究进展

辣椒素作为天然植物来源的抗菌活性成分,具有安全、营养、高效广谱抗菌性和不产生抗药性的特征,在饲料领域作为饲用抗生素替代品有极高的研究和应用价值。本文主要就辣椒素作为饲用抗生素天然替代品的研究进展作一综述。     

饲用抗生素替代品的研究进展

抗生素是某些生物(主要是细菌、放线菌和真菌等微生物)在其生命活动过程中产生的,也可以人工合成,能在低微质量浓度下选择性地杀灭他种生物或抑制其机能的化学物质。1950年抗生素作为畜禽促生长添加剂在欧洲各国投入使用,在美国     

小麦日粮NSP和木聚糖酶对肉仔鸡肠道微生物区系的影响

肠道微生物菌群是所有动物消化系统的一个组成部分,由于肠道微生物都是活的有机体,也就是说它们的生存需要营养和空间,这就意味着动物的消化系统对营养物质消化和吸收的能力,部分依赖于其中寄居的微生物菌群的分布及其总量。研究表明,不同微生物菌群的分布决定了代谢过程的范围     

饲用抗生素对肠道微生物影响的研究

1饲用抗生素的起源和促生长效果1.1起源和发展饲用抗生素是在药用抗生素的基础上发展起来的。Stockstad等(1949)发现,链霉素(strepfomyces)发酵过程中得到的代谢产物,可以促进鸡只快速生长。Whitehill于1950年说明此代谢产物中含有的金霉素具有促生长效果。Jukes等(1950)试验证     

鸡肠道饲用抗生素及天然替抗产品作用机制破解

近日,中国农业科学院深圳农业基因组研究所,通过高通量测序构建了全球首个鸡肠道微生物参考基因集,对动物肠道宏基因组学研究起到了重要补充作用。该研究为开发“绿色天然”植物来源替抗产品提供了科学依据。相关研究成果在线发表在《微生物学(Microbiome)》上。为了进一步研究家禽肠道微生物功能,解释饲用抗生素和天然替抗产品与肠道微生物群落的相互作用关系,联合研究团队于2012年启动鸡肠道宏基因组研究计划,经过6年的努力,构建了第一个鸡肠道微生物参考基因集,深入分析不同肠段、不同饲养方法、不同日龄对肠道微生物群落与功能的影响,并系统比较了饲用抗生素金霉素(CTC)和天然替抗产品博落回提取物(MCE)对肠道微生物菌群的调节作用。     

饲粮添加新产玉米对肉仔鸡生长性能及肠道微生物区系的影响

试验旨在研究饲粮添加新产玉米对肉仔鸡生长性能及肠道微生物区系的影响。试验采用单因素完全随机设计,选取288只1日龄健康科宝肉仔鸡公雏,随机分为4组,每个处理组设6个重复,每个重复12只鸡,分别饲喂占饲粮总比例60%旧玉米(对照组)、占饲粮总比例40%旧玉米+占饲粮总比例20%新产玉米(处理Ⅰ组)、占饲粮总比例20%旧玉米+占饲粮总比例40%新产玉米(处理Ⅱ组)、占饲粮总比例60%新产玉米(处理Ⅲ组)4种饲粮。试验期为42 d,分前期(0～21 d)和后期(22～42 d)两个阶段进行。21、42日龄末测定各试验组试鸡生长性能,42日龄末采集对照组和处理Ⅲ组肉仔鸡回肠、盲肠食糜测定肠道微生物丰度。试验结果显示:(1)处理Ⅲ组显著降低了前期和后期肉仔鸡平均日增重(P<0.05),增加了前期和后期肉仔鸡料重比(P<0.05)。(2)对照组和处理Ⅲ组样本中盲肠和回肠相对丰度较高的菌门为Firmicutes和Proteobacteria;回肠相对丰度较高优势菌属为Lactobacillus、Romboutsia和Candidatus_Arthromitus;盲肠相...     

日粮添加甘露寡聚糖对肉仔鸡生产性能和肠道微生物群落的影响

本研究以酵母细胞壁来源的甘露寡聚糖为试验材料,探讨了不同添加剂量对爱拔益加肉仔鸡肠道微生物群落的影响。试验结果表明,日粮中添加酵母细胞壁来源的甘露寡聚糖可显著提高肉仔鸡生产性能,显著降低肉仔鸡肠道中大肠杆菌和沙门氏菌的数量,提高乳酸杆菌的数量,添加剂量以750mg/kg为适宜。     

Anti-nutritive effect of wheat pentosans in broiler chickens: roles of viscosity and gut microflora.

1. The mechanism of the anti-nutritive activity of isolated wheat pentosans was investigated by examining the roles of digesta viscosity and gut microflora in broiler chickens. 2. Wheat pentosans were isolated by alkaline extraction and purified by sequential treatment with pancreatin, alpha-amylase and lichenase, and high-speed centrifugation. Some of the pentosans were depolymerised using a beta-xylanase, which reduced the relative viscosity of the polysaccharides 4 fold. 3. Inclusion of 35 g alkali-extractable pentosans (containing 854 g arabinoxylans/kg DM) per kg diet significantly (P less than 0.05) depressed broiler performance and the viscosity of the digesta of these birds was significantly (P less than 0.05) higher than that of controls. Addition of the same amount of depolymerised pentosans had no significant effect on bird performance and had less effect on digesta viscosity. 4. Supplementation of the diet containing wheat pentosans (30 g/kg) with procaine penicillin (150 mg/kg) did not improve bird performance. 4. It is concluded that the wheat pentosans elicit their anti-nutritive activity predominantly through increasing the viscosity of digesta.     

Intestinal function and gut microflora of broiler chickens as influenced by cereal grains and microbial enzyme supplementation

A study was conducted to investigate the effect of the key cereal grains and a microbial enzyme supplement on broiler chicken performance, gut microflora and intestinal function. Ingestion of the barley-based diet was associated with low 28-day body weight, decreased feed intake and high FCR. The supplemental enzyme increased feed intake and weight gain of the chickens on a wheat-based diet. The pH of the gizzard and caecal contents varied with the grain type. Enzyme supplementation reduced ileal viscosity, particularly in birds that received the diet based on wheat. The birds on the barley-based diet had lower ileal digestibility of dry matter, protein and energy than those given maize and sorghum-based diets. The ileal digestibility of starch was increased by enzyme supplementation. Enzyme supplementation increased the number of total anaerobic bacteria in the gizzard of birds fed on sorghum and increased lactobacilli in the gizzard of those fed both sorghum and wheat. The birds fed the sorghum-based diet had the lowest counts of caecal total anaerobic bacteria and lactobacilli. Jejunal villus height and villus:crypt ratio of birds fed the barley-based diet were the lowest when compared with those fed the other diets. Enzyme application induced an increase in villus height and villus:crypt ratio of birds on wheat, crypt depth on barley and a reduction in crypt depth of chickens on the sorghum-based diets. The highest activity of maltase and the lowest activity of sucrase were observed in tissue from birds fed on maize and sorghum-based diets respectively. The differences in the performance of broilers on cereal grains could be explained by changes in intestinal morphology, enzyme activities and gut microflora as well as nutrient digestibility. The improved performance by supplemental enzyme in wheat-fed chickens was associated with beneficial changes in intestinal morphology and digesta viscosity.     

Characterisation and response of intestinal microflora and mucins to manno-oligosaccharide and antibiotic supplementation in broiler chickens

1. An experiment was conducted to characterise and evaluate, in comparison to zinc bacitracin (ZnB), the response of intestinal microflora and mucins to manno-oligosacchares (MOS, Bio-MOS®, Alltech Biotechnology, Nicholasville, Kentucky, USA).

2. Supplementation of MOS and ZnB selectively increased the intensity of sulphomucins. As revealed by the plate culture method, MOS accelerated the maturation of gut microflora by promoting the growth of lactobacilli in the ileal mucosa and vice versa on ileal and caecal clostridia. Unlike MOS, ZnB suppressed the growth of intestinal bacteria, especially those of lactobacilli and clostridia. Use of T-RFLP further revealed that MOS increased the diversity of lactobacilli in the ileum and ileal mucosa but the opposite was observed for ZnB. It also appears that MOS and ZnB possessed a common property in differentially favouring the growth of certain Lactobacillus species. There was also evidence to show that both MOS and ZnB also increased the homogeneity of the gut microflora, possibly through the regulation of the overall gut bacterial communities.

3. Improvement in intestinal microbial homogeneity and mucin synthesis, coupled with the differential selections for certain specific beneficial bacterial species, may ultimately be proven to be the target mechanisms in the search for more effective alternatives to antibiotics.     

Effect of different concentrations of Bacillus subtilis on growth performance, carcase quality, gut microflora and immune response of broiler chickens

1. An experiment was conducted to study the effects of different Bacillus subtilis concentrations on productivity, carcase quality, immune response and the gut microflora of broiler chickens. 2. There were 5 treatment groups: control, with no added Bacillus subtilis supplementation; and 4 treatment groups receiving feed supplemented with different concentrations of B. subtilis. 3. Weight gain was significantly higher and the feed conversion rate was significantly better in all groups receiving feed supplemented with B. subtilis, regardless of its concentration. The groups given B. subtilis supplementation produced relatively bigger breasts, and smaller carcases and thighs, compared with the control group. 4. The appearance of increased diffuse lymphohistiocytic infiltration and solitary lymphoid follicles in the mucosa, and a stronger response to NDV vaccination, indicate increased immunological responses in chickens fed with the B. subtilis supplemented diet. 5. The higher inclusion rate of B. subtilis did not increase Lactobacillus concentrations in the ileum or in the caecum, but decreased the E. coli population significantly.     

Erythropoiesis regulation during the development of ascites syndrome in broiler chickens: a possible role of corticosterone

The ascites syndrome in broiler chickens is attributed to metabolic burdening, which results from intensive genetic selection for rapid growth coupled with exposure to extreme environmental conditions, such as low ambient temperature. These conditions impose on the broilers difficulties in fulfilling tissue demands for oxygen, and the birds exhibit a decrease in blood oxygen saturation and high hematocrit values. It is unknown whether the increase in hematocrit results from alteration in erythropoiesis or from fluid exudation out of the blood system to the abdominal cavity. The present study was conducted to examine the association between abnormal stress response and erythropoiesis process in ascitic broilers. Ascitic chickens revealed a uniquely continuous stress response: expressing an increase (P < or = 0.05) in plasma corticosterone concentration 2 to 3 wk before death. At 5 wk of age, ascitic broilers exhibited an increase (P < 0.05) in hematocrit, blood cell count, and packed cells and blood volumes, with no significant change in plasma volume. These results confirm an accelerated erythropoiesis process in ascitic birds. Increased blood cell production in ascitic birds was matched by an increase (P < 0.05) in the proportion of immature red blood cells (23%) in comparison with broilers that remained healthy (7%), and by decreased (P < 0.05) hemoglobin content relative to red blood cells. We conclude that continually increased corticosterone concentrations, as an inducer of erythropoiesis proliferation and differentiation arrest, in ascitic chickens, resulted in increased production of red blood cells (partially immature) with decreased hemoglobin content; this decrease in hemoglobin might have contributed to enhanced development of hypoxemia and to aggravation of the syndrome.     

Absence of a role for selenium deficiency in the runting syndrome of broiler chickens in Australia

The role of selenium deficiency in the etiology of the runting-stunting syndrome (RSS) of broiler chickens in Australia was investigated. Commercial broiler chickens maintained on selenium-deficient developed signs consistent with selenium deficiency of exudative diathesis and markedly reduced plasma glutathione peroxidase activity, but they did not develop pancreatic atrophy and fibrosis or elevated plasma amylase activity, which are the other lesions associated with RSS. Supplementation of the diets of birds from a RSS-susceptible flock with a mixture of selenium, vitamin E, cysteine, and sulfate had no effect on the incidence of runting in the treated birds. In field outbreaks of RSS there were no observable differences between affected and unaffected birds in the concentration of selenium in tissue samples. Furthermore, evidence is presented which suggests that in cases of RSS, pancreatic atrophy and elevations in plasma amylase precede reductions in plasma glutathione peroxidase activity.     

Proventriculitis in broiler chickens: effects of immunosuppression

Proventriculitis in broilers causes carcass condemnation when swollen proventriculi tear during evisceration. The cause of this proventriculitis is unknown, but several infectious agents have been associated with it. One such agent, infectious bursal disease virus (IBDV), has been implicated as a cause of proventriculitis, but a direct effect of this virus on the proventriculus has not been proven. The role of IBDV in proventriculitis may be indirect as a result of its ability to cause immunosuppression. The objective of this study was to understand how immunosuppression affects the incidence of proventriculitis in broiler chickens. Immunosuppression was induced in commercial and specific-pathogen-free broiler chickens using chemicals (cyclophosphamide and cyclosporin) or virus (IBDV). All groups were then exposed to a proventricular homogenate produced from diseased birds. At 7 and 14 days postinoculation, the incidence of proventriculitis in these groups was compared to that produced by homogenate exposure in immunocompetent broilers. All birds exposed to the proventricular homogenate from diseased birds developed proventriculitis. Cyclophosphamide and IBDV, both B cell suppressors, did not significantly affect the incidence or characteristics of the proventriculitis observed, although they did have an effect on the size of the proventriculus at 7 days postinoculation. Chickens immunosuppressed with cyclosporin, a T cell suppressor, developed more severe lesions and had a higher incidence of proventriculitis. These findings indicate that both B and T cells are involved in the immune response against proventriculitis, but cell-mediated immunity appears to have a more important role in controlling the disease. IBDV affects both humoral and cellular immunity in the chicken, so although under experimental conditions it didn't have a major effect on proventriculitis, it may explain why control of IBDV in the field seems to reduce the incidence of proventriculitis.     

Effect of oat hulls on performance, gut capacity and feed passage time in broiler chickens

1. Two experiments were conducted to study effects of oat hulls and their interaction with soluble fibre in broiler chickens. 2. In experiment 1, wheat or naked oats based diets with or without NSP-degrading enzymes were mixed with 0, 40 or 100 g/kg oat hulls which replaced a maize starch/soy isolate mixture, and the diets were fed to broiler chickens from 7-21 d of age. 3. Production results, AMEn determined between 14 and 16 d of age, and ileal digestibility indicated no negative effect of oat hulls on nutrient digestibility or weight gain. 4. Feed consumption increased significantly when oat hulls were included in the diet and relative gut weight increased correspondingly (P<0.05). 5. No interaction effects were found between soluble and insoluble fibres, except for a possible effect on starch digestibility in wheat diets. 6. In experiment 2, mash diets were fed unsupplemented, or were supplemented with coarsely or finely ground oat hulls which replaced a maize starch/soy isolate mixture. 7. Faecal titanium dioxide excreted between 1 and 48 h after feeding of a gelatin capsule containing titanium dioxide, was used to calculate feed passage time. 8. There was a tendency (P=0.08) for faster feed passage with inclusion of coarsely ground oat hulls, but no effect of finely ground oat hulls was found.     

Influence of dietary mushroom Agaricus bisporus on intestinal morphology and microflora composition in broiler chickens

In this study, we evaluated the intestinal morphology and bacteria populations in broiler chickens fed for six weeks diets that contained different amount of the mushroom Agaricus bisporus. Ninety day-old female chicks were randomly divided into three dietary treatments, each with three replicates kept in floor pens and fed a basal diet supplemented with the dried mushroom at levels of 0, 10 or 20 g/kg fresh feed. Feed and water were offered to birds ad libitum. The morphological examinations of the intestine were carried out on 1-cm long excised segments from duodenum, jejunum and ileum. The populations of total aerobes, total anaerobes, Lactobacilli spp., Bifidobacteria spp., Escherichiacoli, Bacteroides spp. and Enterococci were enumerated in ileum and caecum by conventional microbiological techniques using selective agar media. The results of the study showed that dietary mushroom supplementation did not significantly affect intestinal morphology at either level of inclusion. Morphometrical parameters of depth of duodenum, jejunum and ileum crypt and height of villi revealed no differences amongst dietary treatments. In the ileum, Lactobacilli spp. were higher in birds supplemented at the level of 20 g/kg compared to controls; however, other measurements of bacteria loads were similar amongst the three dietary treatments. In the caecum, Lactobacilli spp. and Bifidobacteria spp. loads were higher in birds supplemented at either level of inclusion compared to control birds, although these did not differ between the two levels of supplementation. In conclusion, dietary mushroom supplementation may beneficially affect intestinal health of broiler chickens.     

Comparison of the supplemental effects of Saccharomyces cerevisiae and antibiotics in low-protein and high-fibre diets fed to broiler chickens.

Two experiments were completed to compare the supplemental effects of yeast Saccharomyces cerevisiae and sub-therapeutic antibiotics in high-fibre and low-protein diets for broiler chicks. In experiment 1, yeast was added at 1.5, 3.0 and 6.0 g kg-1 while penicillin, tylosin or neoterramycin were added at 150 mg kg-1 into different batches of a high-fibre diet containing 250 g kg-1 palm kernel meal. Saccharomyces cerevisiae and antibiotics increased BW, BWG, FCR, feed intake, carcass and breast weights above the control. Small intestine weight was reduced by antibiotics, while yeast caused a lower deposition of abdominal fat. Liver weights of different treated broilers were similar. The performance indices were superior on penicillin and 3.0 g kg-1 yeast compared to other supplements evaluated. In the second experiment, 1.5 and 3.0 g kg-1 of yeast, and 0.75 mg kg-1 of procaine penicillin, zinc bacitracin and tylosin were separately added to a 180 g kg-1 crude protein diet. Performance of the chicks with additives was compared with unsupplemented negative and positive controls containing 180 and 210 g kg-1 crude protein respectively. Broilers fed with supplements had superior BW, BWG, FCR and feed intake compared to the negative control, but carcass data were similar. Dietary penicillin increased BW, BWG, feed intake more than other supplements, but yeast stimulated higher FCR. Data from both studies indicated that Saccharomyces cerevisiae comparatively increased growth and carcass weight and reduce abdominal fat, therefore, it can serve as a natural substitute for antibiotics in broiler diet.