酵母β-葡聚糖的作用机制及其在养猪中的应用

酵母β-葡聚糖作为酵母细胞壁中的主要功能成分之一,其在提高动物免疫方面的功效日益引起人们的关注.本文主要从酵母β-葡聚糖对免疫细胞表面受体、免疫相关基因表达和免疫细胞信号传导的影响来阐述其提高动物免疫力的机制;并简要论述酵母β葡聚糖在生猪养殖中的应用情况.     

水溶性酵母葡聚糖的制备及应用研究进展

啤酒酵母葡聚糖是一类免疫多糖,参与生物细胞的多种生命调节,可激活免疫细胞,调节机体免疫力,具抗菌消炎、抗病毒、抗肿瘤等功能,且毒副作用低,被称为生物效应应答剂。近年来,越来越多的学者开始研究和开发酵母葡聚糖。论文对酵母葡聚糖的结构、提取方法、结构修饰和应用进行了简述,对提取方法和结构修饰中的各种方法进行了综合比较和分析;并重点介绍了提高酵母葡聚糖的水溶性的方法及相对应的鉴定方法,这将为酵母葡聚糖的开发利用奠定一定的理论基础。除此之外,论文还对酵母葡聚糖的进一步开发利用进行了展望。     

酵母β-葡聚糖的作用机制及其在养猪中的应用(续完)

上一期从“酵母β-葡聚糖与免疫细胞表面多糖受体结合发挥作用”和“酵母β-葡聚糖调节免疫相关基因的表达量发挥作用”这两个方面介绍了酵母β-葡聚糖的作用机制。     

酵母细胞壁多糖对免疫功能的作用机制

抗生素替代品的研究对提高人们的生活水平具有重要意义,在抗生素替代品研究方面,β-葡聚糖和甘露寡糖作为酵母细胞壁多糖的主要成分,在提高动物免疫方面的功效日益引起人们关注。随着多糖类免疫增强剂免疫增强效应的分子机制研究的不断深入,人们逐渐认识到了酵母细胞壁多糖对免疫功能的作用机制。从酵母细胞壁多糖组成成分β-葡聚糖和甘露寡糖2方面,分别讲述了β-葡聚糖和甘露寡糖对免疫功能的作用机制。     

口服酵母载体疫苗在畜禽疫病防控中的应用

酵母载体疫苗由于其安全性、免疫方式、生产成本等方面的显著优势,近年来受到关注。酵母细胞壁含有的β-葡聚糖可作为天然佐剂;通过将目的蛋白锚定在酵母细胞表面制成酵母表面展示疫苗、表达在胞内的全重组酵母疫苗口服免疫使用,不仅可激发机体黏膜免疫,调节微生物菌群,还可省去蛋白质纯化、免疫注射等流程,在降低人工成本,促进无抗化健康养殖方面具有重要助推作用。论文简述了酵母疫苗表达系统及其优势、免疫机制及生产应用现状,展望了酵母表达系统在动物疫病防控中的潜在应用。     

酵母多糖对养殖动物的营养和保健作用研究进展

酵母多糖是从酵母细胞壁提取的大分子多糖聚合物,主要包括葡聚糖和甘露聚糖。它具有免疫活性,能够增强动物非特异性免疫力,具有抗肿瘤、抗病毒、抗辐射、抗衰老等作用,在动物营养和动物医学领域具有重要应用价值。本文介绍了酵母多糖的组成成分,对其生物学功能和在动物营养上的应用现状进行了综述。     

酵母β-母葡聚糖在畜禽生产上的应用

酵母β-葡聚糖分布广泛,在畜禽生产上的应用潜力很大。本文主要讨论了β-葡聚糖的提取方法、生物活性,重点讨论酵母β-葡聚糖作为饲料添加剂在畜禽生产上的应用。     

β-葡聚糖及其在畜禽日粮中的应用

β-葡聚糖作为一种有潜能的免疫刺激剂,普遍分布于酵母、细菌、真菌和植物中。本文在综述了β-葡聚糖的结构、来源及提取工艺的基础上,重点论述了其应用于畜禽日粮中对畜禽生产性能、胃肠道发育和微生物菌群,以及免疫功能的影响,为β-葡聚糖在饲料中的应用提供更多的理论依据。     

酵母多糖在家禽生产中应用的研究进展

酵母多糖（YPS）是酵母细胞壁中提取的一种大分子复合多糖,其外层到内层分别为甘露聚糖层、糖蛋白层及β-葡聚糖层。β-葡聚糖和甘露聚糖（MOS）为酵母多糖的主要成分。酵母壁多糖作为新型绿色饲料添加剂,具有改善家禽肠道健康,促进机体生长,增强机体免疫,提高抗氧化性能,缓解应激及解毒等作用,因此YPS可作为饲料添加剂用于畜禽生产。文章就YPS对家禽生理、生产性能的影响及其作用机制进行综述,为YPS在家禽生产中的进一步应用提供参考。     

酵母β-葡聚糖对仔猪生产性能的影响

据有关研究表明，从酵母中提取的β-葡聚糖可能是一种很好的天然免疫增强剂。适量添加可降低动物的各种应激反应．增强疫苗的保护效果．提高动物的健康状况，进而提高动物的生产性能。研究发现．酵母β-葡聚糖能提高小鼠对细菌、真菌、病毒和寄生虫的抵抗能力。Buddle等用β-葡聚糖降低了母羊乳房炎的发生率；刘影等（2003）研究发现，β-葡聚糖能提高肉仔鸡的免疫机能．并有提高生长性能的趋势。本试验旨在考察β-葡聚糖在断奶仔猪生产上的应用效果，并探索其最适添加量。     

Phase I evaluation of CCNU (lomustine) in tumor-bearing cats

1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.     

Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects

Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.     

Prevalence of gastric lesions in racing Alaskan sled dogs

Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large.     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.     

Evaluation of biohydrogenation rate of canola vs. soya bean seeds as unsaturated fatty acids sources for ruminants in situ

An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro‐organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed.     

Serum biochemical values and mineral element contents of tissues in yaks

Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.Abbreviations Alb albumin - ALT alanine aminotransferase - AST aspartate aminotransferase - BUN blood urea nitrogen - Chol cholesterol - Glob globulin - -GT -glutamyl transpeptidase - IP inorganic phosphorus - TP total protein     

Avian brood parasitism — a growing research area in behavioral ecology (part Ⅱ)

正We are pleased to publish the second special issue on avian brood parasitism and to be responsible guest editors for the two special issues of Chinese Birds (Vol. 3, No. 4, 2012 and Vol. 4, No. 1, 2013), entitled "Avian Brood Parasitism - A Growing Research Area in Behavioral Ecology". The first issue was published in December 2012. The goal of the two special issues is to publish accumulated knowledge and some of the recent developments in     

Internal Parasites and Haematological Values in Cattle Slaughtered in Buea Subdivision of Cameroon

Tropical Animal Health and Production -