青霉α-半乳糖苷酶基因工程菌表达条件优化

试验通过测定基因工程菌的酶活性,研究了培养基pH、摇床转速、接种量和甲醇浓度对青霉α-半乳糖苷酶表达的影响,旨在优化重组菌株的表达条件.结果表明:当培养基pH为5,摇床转速为200 r/min,种子接种量为5％,甲醇浓度为1.0％时,发酵上清液酶活性最高.     

瘤胃真菌体外产纤维素酶条件的筛选

本试验采用L9(34)正交试验设计,对崂山奶山羊瘤胃真菌进行体外培养,通过木聚糖酶和羧甲基纤维素酶的测定,筛选出以玉米秸秆为发酵底物的最佳发酵条件(N源、接种量、培养基起始pH值、发酵温度),并按筛选出的发酵条件对玉米秸秆、花生蔓、地瓜蔓和麸皮不同发酵底物的产酶活性进行比较。试验结果表明,木聚糖酶活力最优发酵条件N源为(NH4)2-SO4,接种量5mL,发酵起始pH值为5,发酵温度35℃,产酶最高的发酵底物为秸秆。羧甲基纤维素酶的最优发酵条件N源为(NH4)2SO4,接种量15mL,发酵起始pH值为7,发酵温度39℃。     

饲用大豆肽生产菌株的初步筛选及发酵条件研究

通过发酵试验对3株芽孢杆菌进行筛选,并确定该菌株的最佳接种量、种龄和摇床速度。对其发酵条件进行优化,结果表明最适条件为：加水量94％、温度30℃、180r／min旋转摇床48h。发酵液的水解度达到15．9％,比优化前提高了1．92倍。     

米曲霉生产乳糖酶发酵条件的研究

为确定产乳糖酶的米曲霉菌株的最佳发酵培养条件,研究了米曲霉产乳糖酶的发酵培养基成分及培养条件。结果表明,米曲霉产乳糖酶的最佳培养基成分为：乳糖1．1％,蛋白胨0．5％,KH2PO4 2％,麸皮粉1．5％,桔皮粉1％;最佳培养条件：接种量10％,温度30℃,初始pH5．5,装液量50mL／250mL,摇床转数180r／min,培养时间4d。在此条件下培养,乳糖酶活力达2348 U／L。是初始发酵条件下酶活力的15．6倍。     

微生物发酵法生产大豆肽工艺条件的研究

以脱脂豆粕为原料,采用地衣芽孢杆菌发酵生产大豆肽.研究菌株种龄、种子液接种量和摇床速度对多肽产量的影响,结果表明,种龄12 h,接种量5%,摇床速度180 r/min最佳.同时,对影响多肽产量的发酵温度、发酵时间及豆粕粉加水量3个主要因素用正交试验方法进行优化,正交试验结果发现,该菌株发酵产多肽的最佳条件为温度37℃,发酵时间48 h,加水量94%.优化后该菌株发酵豆粕后的多肽溶液酸性可溶氮含量达到1 384.65μg/mL,水解度DH为23.89%.     

多菌种混合固态发酵花生秸秆生产蛋白质饲料的工艺研究

为开发利用花生秸秆,探讨多菌种混合发酵花生秸秆产生蛋白饲料的可行性,确定复合菌剂发酵花生秸秆生产蛋白饲料工艺参数。试验采用多菌种混合发酵的方法,以粗蛋白含量和纤维素酶活性为考察指标,以花生秸秆为发酵对象,研究含水量、接种量、发酵时间、花生秸秆与麸皮比例和氮源比例对发酵后花生秸秆中粗蛋白和纤维素酶活性的影响。结果表明,优化后发酵花生秸秆的最佳工艺条件为:花生秸秆初始水分含量为70%,花生秸秆与麸皮比例为4∶1,接种量为5%,发酵时间为10 d,氮源比例为1%。花生秸秆经混合发酵后粗蛋白含量提高了53.39%(P0.05),粗灰分、粗纤维、中性洗涤纤维与酸性洗涤纤维含量分别降低了20.10%、57.97%、14.66%和21.53%(P0.05),花生秸秆的营养价值有明显改善。     

产β-葡萄糖苷酶芽孢杆菌降解豆粕的发酵条件优化及抗营养因子测定

试验优化得到了降解豆粕芽孢杆菌Z-1生长的最优发酵条件,并对发酵后豆粕中的抗营养因子进行了测定。采用单因素试验的方法在摇床培养的基础上对β-葡萄糖苷酶芽孢杆菌的生长主要影响因素进行了考察,其中包括发酵培养基的C源、N源、无机盐、p H值、接种量、发酵时间等。通过设计正交试验对各因素的浓度和组合以及最佳培养条件进行了优化,得到该菌株产酶的最适条件为:糊精5.0%、蛋白胨1.0%、Cu SO4·5H2O 0.1%、Fe SO4·7H2O 0.01%、接种量3%、p H值为7、培养时间72 h。用优化后的培养基进行发酵,在产酶活性上比优化前提高了35.5%,抗营养因子数量下降了61.6%。     

混菌固态发酵玉米秸秆生产蛋白饲料的工艺研究

试验研究了混菌固态发酵玉米秸秆生产蛋白饲料的工艺条件,以玉米秸秆为主要原料,麸皮为辅料,利用黑曲霉和产朊假丝酵母混合发酵生产蛋白饲料,通过对黑曲霉和产朊假丝酵母菌种配比、玉米秸秆和麸皮的配比、接种量、发酵温度、发酵时间、水分含量等条件的研究和正交试验对发酵条件进行了优化。试验结果表明:菌种配比1:1、玉米秸秆与麸皮配比4:1、接种量8%、发酵温度28℃、发酵时间96h、含水量45%为最佳发酵条件。在此条件下,粗蛋白的含量由5.62%提高到了25.67%。     

多拉菌素的复合诱变及发酵条件优化

为通过诱变获得遗传性状稳定的多拉菌素高产菌株,对多拉菌素产生菌RDL19-1进行多种诱变处理包括常压室温等离子(ARTP)诱变,紫外(UV)诱变,及ARTP-UV复合诱变.该菌株接种瓶后于28℃摇床培养32 h,以10％的接种量转入装量为35 mL/300 mL发酵瓶中,在28℃条件下发酵培养14 d,多拉菌素发酵产量...     

枯草芽孢杆菌诱变株发酵羽毛工艺条件的研究

通过对枯草芽孢杆菌紫外线和亚硝酸钠复合诱变菌株FUN30.2的发酵培养基及发酵条件的优化,得到最优的发酵培养基成分为:羽毛粉5.5%,青贮玉米秸秆粉0.8%,K+浓度0.018mol/L,Mg2+浓度0.065mol/L,Ca2+浓度0.072mol/L,Fe2+浓度0.010mol/L,Na+浓度0.088mol/L。最优的发酵条件为:培养温度33℃,培养时间72h,摇床转速170r/min,接种量6%,装液量100mL/500mL,菌体生长适宜的培养基初始pH值是7.0,菌体产酶的最适宜pH值为7.5～8.0。60h菌体产酶活力最高达1.267U/mL;发酵时间72h,羽毛降解率为69.61%;发酵液的氨基酸含量达22.66mg/mL。     

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