植物乳杆菌BLPS-9中试发酵工艺优化及冻干保护剂筛选

本研究以植物乳杆菌BLPS-9为研究对象,对其中试发酵工艺进行优化,采用正交因素对其保护剂配方进行筛选。结果表明:经优化后植物乳杆菌BLPS-9中试发酵液活菌数可达50×10^8 cfu/mL,确定最佳离心条件10000 r/min、离心10 min活菌数最高,保护剂配方为脱脂奶粉25%、海藻糖7.5%、甘油0.75%;在最适离心条件下采用最佳冻干保护剂进行冷冻干燥,植物乳杆菌BLPS-9存活率可达91.01%,菌粉活菌数为6.0×10^11 cfu/g。在4℃和-20℃条件下贮存28 d,活菌数无明显损失。本研究为进一步提高乳酸菌制品的货架期提供了参考。     

笼养成年蛋鸡盲肠中乳酸菌的分离与鉴定

试验从笼养蛋鸡盲肠内容物中分离乳酸菌,采用MRS平板分离乳酸菌,经过革兰氏染色、菌落形态观察及糖发酵生化管鉴定为乳酸菌种属。结果显示,分离出15株革兰氏阳性菌,经抑菌试验选出7株乳酸菌,发酵生化鉴定为绿色乳杆菌、瑞士乳杆菌、果糖乳杆菌、德氏乳杆菌、肠膜明串珠菌葡聚糖亚种、假肠膜明串球菌和肠膜明串珠菌乳脂亚种。     

植物乳杆菌冻干保护剂的筛选及冻干工艺的研究

本试验对植物乳杆菌的冻干保护剂进行了筛选,同时对冻干工艺进行了优化。结果表明:最佳冻干保护剂配方是奶粉20%,海藻糖10%,甘油2%,低聚木糖5%;最佳的预冻温度和时间分别是-70℃,6 h;菌泥与水不同比例混合冻干后,随着水分的增加,植物乳杆菌的存活率缓慢下降,建议水与菌泥最佳比列为0.5:1。经过冻干保护剂和冻干条件的优化,植物乳杆菌的存活率达到80%以上。     

3株瘤胃源乳酸菌冻干保护效果初步研究北大核心

试验旨在确定最佳保护剂组合及保藏温度,提高乳酸菌制剂冷冻保藏效果。试验以戊糖片球菌、海氏肠球菌、戊糖乳杆菌为研究对象,采用真空冷冻干燥技术,探究不同保护剂及保藏温度对乳酸菌冻干存活率及保藏存活率的影响。结果显示,保护剂3 (脱脂乳9.51%、葡萄糖7.56%、麦芽糊精7.77%)对戊糖片球菌和戊糖乳杆菌冻干保藏效果最好,冻干后存活率分别为81.80%和79.90%;保护剂1 (脱脂乳12%、海藻糖1%、谷氨酸钠1%、甘油3%)对海氏肠球菌冻干保藏效果最好,冻干后存活率为84.83%。乳酸菌冻干粉在-80℃条件下保藏效果更好。研究表明,采用保护剂1、-80℃保藏对3种乳酸菌制剂的长期保藏效果最好。     

乳双歧杆菌U9冷冻保护剂的优化研究

乳双歧杆菌U9是一株具有优良益生功能的乳杆菌。为了保证U9菌株活性,为工业化益生菌制剂生产提供稳定菌种,利用液氮深冷方式对U9菌株进行冷冻保藏。以冷冻存活率为评价指标,对冷冻保护剂种类进行筛选,并对保护剂配方进行正交试验优化。结果表明,甘油、海藻糖、脱脂乳粉及维生素C 4种保护剂能对乳双歧杆菌U9起到良好的保护作用;正交试验优化确定的保护剂配方为甘油2%、海藻糖7.5%、脱脂乳粉7.5%、维生素C 0.1%,菌体冷冻后存活率达到94%。     

保加利亚乳杆菌B9冷冻保护剂的优化

保加利亚乳杆菌B9(Lactobacillus delbrueckii subsp.bulgaricus B9)是一株具有优良酸乳发酵性能的乳杆菌。为开发B9菌株活性,为工业化发酵剂生产提供稳定菌种,本研究利用液氮深冷的方式对B9菌株进行冷冻保藏。以冷冻存活率评价指标,在对冷冻保护剂种类进行筛选,对保护剂配方进行正交优化,并确定菌体与保护剂最佳混合比例。结果表明,脱脂乳粉、甘油、海藻糖及Vc四种保护剂能对保加利亚乳杆菌B9起到良好的保护作用;正交优化确定保护剂配方为脱脂乳粉10%、甘油3%、海藻糖5%、Vc 0.075%(m:m),可使菌体解冻后存活率达到91%。     

响应面法优化乳双歧杆菌Z-1冷冻干燥保护剂配方

采用响应面法对乳双歧杆菌Z-1冷冻干燥保护剂配方进行优化。通过Plackett-Burman试验与最陡爬坡试验确定影响乳双歧杆菌Z-1冷冻干燥后活菌数的显著因素及最优响应值区间，再通过Box-Benhnken试验优化得到乳双歧杆菌Z-1冷冻干燥保护剂最佳配方。结果表明：海藻糖、蔗糖、L-半胱氨酸盐酸盐添加量是影响乳双歧杆菌Z-1冷冻干燥后活菌数的显著因素；经响应面试验设计建立活菌数和海藻糖、蔗糖、L-半胱氨酸盐酸盐添加量的回归模型，得到乳双歧杆菌Z-1冷冻干燥保护剂最佳配方为海藻糖添加量200.51 g/L、蔗糖添加量46.16 g/L、L-半胱氨酸盐酸盐添加量2.31 g/L，其他成分不变（脱脂乳粉添加量100 g/L、乳清蛋白粉20 g/L、甘油4 g/L、异抗坏血酸钠10 g/L、谷氨酸钠8 g/L）。     

不同发酵类型乳酸菌对玉米青贮发酵品质的影响

为探讨同型乳酸菌和异型乳酸菌对饲料专用玉米青贮发酵品质和体外消化率的改善效果,以饲料专用玉米为原料,植物乳杆菌和肠膜状明串株葡聚糖亚种为添加剂,分别设置无添加组(CK组)、添加植物乳杆菌组(LP组)和添加肠膜状明串珠菌聚糖亚种组(LD组),塑料罐密封青贮60 d后分析。结果表明:在添加乳酸菌的各组中,pH都明显降低,其中LP组产乳酸最多,LD组产乙酸和粗蛋白的量显著高于其他组(P0.05)。在各组中LP组产生乳酸菌最多,霉菌和酵母的数量最少。中性洗涤纤维、酸性洗涤纤维、中性洗涤木质素、半纤维素和灰分的含量LP组最高。LP作为青贮添加剂在处理饲用玉米时体外消化率最高。     

酸奶生产用直投式乳酸菌发酵剂研究

对酸奶常用发酵剂菌种德氏乳杆菌保加利亚乳杆菌亚种S-1、嗜热链球菌G1208的高密度细胞培养条件,低温真空冷冻干燥中抗冷冻保护剂的选择等进行了研究。结果发现,德氏乳杆菌保加利亚乳杆菌亚种S-1在改良MRS培养基中的最佳培养条件为:培养温度43℃,起始pH值6.0,最高活菌数为1.2×109cfu/mL;采用3%蔗糖+3%海藻糖+10%β-环糊精+10%甘油+1%酵母膏+10%脱脂奶作为冻干保护剂,经低温冷冻干燥后,存活率为40.8%。嗜热链球菌G1208的最佳培养条件为:培养温度37℃,起始pH值7.0,对培养基配方进行优化后,最高活菌数为1.7×109cfu/mL;采用3%海藻糖+1%酵母膏+10%脱脂奶作为保护剂经低温冷冻干燥后,存活率可达96%。     

植物乳杆菌WL-R-02冻干保护剂配方的优化

以植物乳杆菌WL-R-02为研究对象,将冻干存活率提高到90%以上。通过正交试验法对现有的保护剂成分进行优化,筛选出最优保护剂组合。获得的最佳保护剂配方组合为：脱脂乳粉13%,海藻糖4%,乳糖3%,L-半胱氨酸1%;以最佳复合保护剂配方对植物乳杆菌WL-R-02进行-40℃预冷冻2 h,-30℃,20 Pa条件下冷冻干燥38 h,活菌数为6.70×10¹⁰CFU/g,冻干存活率91.6%,4℃冷藏保存10 d,活菌数为6.63×1010CFU/g。该研究可为开发商品化专用直投式发酵菌剂提供技术支撑。     

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.     

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

Tropical Animal Health and Production -     

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.     

Chemotaxis of macrophage in inflammation

Our particular attention in this article was given to natural mediators for macrophages isolated from the sites of tissue injury. A number of chemotactic factors, which may satisfy many criteria making them acceptable as inflammatory leucocyte chemotactic factors, has been separated. Among them, our laboratory has isolated three macrophage (monocyte) chemotactic factors (MCF-a, -b and -c). Their purification, characterization and functional specificity are discussed.     

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