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Michael R. Bedford 《British poultry science》2018,59(5):486-493
ABSTRACT1. Enzymes have been used commercially for nearly 40 years and save significant costs through sparing of expensive nutrients but the mechanism by which this is achieved is still debated.2. The research focused on non-starch polysaccharidase (NSPase) enzymes is used as an example of where greater progress could have been made if the details of the work had been described more fully and the analysis of the data generated had been broader in scope and more critical.3. Lack of standardisation of the details presented in the materials and methods has been identified as a significant barrier to meaningful retrospective analysis and thus limits advances in the understanding of the mode of action of these enzymes.4. The identity of the enzyme employed and its activity is often lacking, and more importantly the purity is rarely disclosed. Contaminant activities which are neither listed nor assayed could play a significant role in the responses observed.5. The dose optimum of most enzymes is often considerably higher than that employed in most studies. Thus studies claiming synergy between two ‘activities’ should ensure that the response is not related to each enzyme simply augmenting the dose of just one activity in the finished feed. This is a common problem, and coupled with the lack of factorial experiments to justify the presence of each enzyme in a multi-enzyme product, it is not surprising that there is still debate as to whether single or multi-enzymes are best suited poultry rations.6. The three proposed mechanisms for NSPases (viscosity, cell wall and prebiotic) are discussed, and along with their strengths and weaknesses it is suggested that a re-evaluation of each is needed. Viscosity may have to be re-evaluated as being a function not only of the cereal being fed, but of the age of the animal as well. The cell wall theory as described is poorly modelled in vitro and hence the validity of these data is questioned. The prebiotic theory may need significant modification as it appears that the quantities of oligomers produced are insufficient to generate the additional volatile fatty acids (VFA)’s reported. It is likely that all three mechanisms play a role in the responses observed, but the prebiotic mechanism probably plays by far the most important part in low viscosity diets.7. Future research would be improved if it considered all potential mechanisms when designing a trial. Significant failings are apparent as a result of adherence to tenets in explanation of the results. Most importantly, it should be emphasised that a hypothesis is there to be tested, not defended. 相似文献
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《The Journal of Applied Poultry Research》2006,15(1):136-144
The gastrointestinal tract contains within it a microenvironment of bacteria that influences the host animal in many ways. The microflora can metabolize several nutrients that the host cannot digest and converts these to end products (such as short-chain fatty acids), a process that has a direct impact on digestive physiology. The microbiota directs the assembly of the gut-associated lymphoid tissue, helps educate the immune system, affects the integrity of the intestinal mucosal barrier, modulates proliferation and differentiation of its epithelial lineages, regulates angiogenesis, modifies the activity of the enteric nervous system, and plays a key role in extracting and processing nutrients consumed in the diet. Despite these important effects, the mechanisms by which the gut microbial community influences host biology remain almost entirely unknown. Recent molecular-based investigations have confirmed the species diversity and metabolic complexity of gut microflora, although there is much work to be done to understand how they relate to each other as well as the host animal. It is almost a century ago that Eli Metchnikoff proposed the revolutionary idea to consume viable bacteria to promote health. Since that time, the area known as probiotics has made dramatic progress, particularly during the past 2 decades. The last 20 yr have also seen the emergence of a new, related area of study—prebiotics. Use of these 2 ideas—providing live nonpathogenic bacteria as well as substrates for their growth—have potential to help optimize the health of animals by manipulating the gastrointestinal tract in positive ways. 相似文献
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《The Journal of Applied Poultry Research》2015,24(1):66-72
This study was designed to investigate the growth promoting effects of supplementing different sources and concentrations of prebiotic yeast cell wall (YCW) products containing mannanoligosaccharides in starter broilers under an immune stress andClostridium perfringens challenge. Through a series of 6 individual studies either 240 or 288 newly hatched chicks were randomly distributed to specific dietary treatments. All birds received a commercial infectious bursa disease vaccine at 10 or 15 d age followed by an orally administeredClostridium perfringens challenge on d 15, 16, and 17; or 18, 19, and 20. Weekly BW, feed consumption, and daily mortality were recorded per pen. Each study was terminated after 21 d. Pooled data analysis of all studies revealed no effect between different product sources of YCW. Products from both sources produced a significant improvement in growth rate compared to control birds fed no YCW. However, a blend of two YCW products showed an approximate 15% improvement in growth rate and a 10% reduction in FCR. The optimum dose of any YCW product among those tested was determined to be approximately 250 ppm. Prebiotic YCW additives increased BW and improved feed conversion and may be considered as alternative growth promoters for starting broilers. 相似文献
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益生元在促进益生菌生长、调节肠道微生态平衡方面发挥着重要作用。为探究兰州百合粗低聚糖（crude lily oligosaccharides, CLOs）的益生元特性,以兰州百合干为原料,提取、表征CLOs;以低聚果糖和菊粉作为阳性对照,测定CLOs在人工胃肠溶液的水解度,以及对嗜热链球菌ATCC-14485和保加利亚乳杆菌ATCC-11842的产酸、增殖作用的影响。结果表明：CLOs分子量为1 194 Da,主要由甘露糖、阿拉伯糖和葡萄糖组成,摩尔比为1:3.57:16.40;CLOs经人工胃肠溶液消化后水解度是26.96%,显著低于菊粉（P <0.05）;CLOs促进乳酸菌发酵产酸的效果显著优于菊粉和低聚果糖（P <0.05）;当CLOs的添加量为1.0%(W/V)时,能有效促进嗜热链球菌和保加利亚乳杆菌的增殖,并减缓二者在货架期的死亡速率。研究结果说明CLOs具有益生元特性,可为新型共生发酵乳的研发提供理论依据。 相似文献
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J.L.P. MOURIÑO F.
Do NASCIMENTO VIEIRA A.B. JATOBÁ B.C.
Da SILVA G.F.A. JESUS W.Q. SEIFFERT M.L. MARTINS 《Aquaculture Nutrition》2012,18(1):73-80
The dietary supplementation of prebiotics, probiotics and symbiotic in hybrid surubins (a Pseudoplatystoma corruscans and P. fasciatum cross) was evaluated for the effects on their autochthonous intestinal microbiota and on haematological and immunological parameters. A total of 160 fish were divided into four treatment groups with four replicates each. The treatment groups were fed with the following diets for 15 days: control diet without supplementation; 0.5% inulin (prebiotic) supplementation; Weissella cibaria (CPQBA 001‐10 DRM 02) (7.87 ± 0.2 log CFU g?1) supplementation; or 0.5% inulin and W. cibaria supplementation (symbiotic group). The midgut intestines of the fish with the symbiotic diet supplementation had higher concentrations of lactic acid bacteria (7.07 ± 1.11 log CFU g?1) and low levels of Vibrio spp (1.90 ± 0.60 log CFU g?1) and Pseudomonas spp (2.23 ± 1.48 log CFU g?1). In addition, increased erythrocytes and reduced circulating neutrophils were observed in this group. No differences in blood glucose, serum protein or lysozyme levels were detected between treatment groups. However, a higher concentration of total immunoglobulin was observed in fish fed with the probiotic and symbiotic diets. The addition of 0.5% inulin (prebiotic) thus W. cibaria (probiotic) to the diet of Pseudoplatystoma hybrid surubins reduce the number of pathogenic bacteria and stimulate the beneficial intestinal microbiota and may possibly alter their immune defence system. 相似文献
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The effects of dietary inulin on growth performances,survival and digestive enzyme activities of common carp (Cyprinus carpio) fry 
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下载免费PDF全文 This study was conducted to investigate the effects of dietary inulin on growth performance, diet utilization, survival rate, carcass composition and digestive enzymes activities (amylase, lipase and protease) of carp (Cyprinus carpio) fry (0.55 ± 0.02 g). After acclimation, fish were allocated into 9 tanks (40 fish per tank) and triplicate fish groups were fed, control diet (0 g) or diets containing 5 g and 10 g inulin kg?1 for 7 weeks. No significant effect on growth performance and diet utilization of fish fed inulin compared with the control group was observed. However, supplementation of inulin significantly increased survival rate and carcass lipid content, while carcass protein content significantly decreased. Dietary inulin had no significant effects on digestive lipase, protease and amylase activities. 相似文献