低乳糖脱脂鲜牛奶的研究

以新鲜的脱脂牛乳为原料,应用乳糖酶对脱脂牛乳中的乳糖进行水解,经杀菌灭酶研制了营养丰富,且具有保健功效的低乳糖脱脂牛奶。乳糖酶在脱脂牛乳中最适水解条件为：水解温度35℃,水解时间2h,乳糖酶添加量1.2g/L,脱脂牛乳经乳糖酶水解,其乳糖水解率达到65%以上。     

低乳糖液态奶水解率及褐变的研究

本文探讨了乳糖酶水解鲜乳中乳糖的工艺，确定了最佳的酶解条件为：酶解温度40℃、时间3h、pH=6．8、酶添加量0.5‰。在生产过程中通过添加褐变抑制剂来抑制因水解乳糖产生单糖而引起的褐变反应。通过本研究不仅使产品在营养上更加丰富，而且使产品在色、香、味等方面更加具有市场竟争力。     

酶解猪血制备氨基酸液体肥工艺条件优化

试验以猪血为原料,利用风味蛋白酶水解猪血中的蛋白,以水解率为指标,得到酶解血液的最佳条件.通过单因素试验研究料液比、酶添加量、pH值、温度和水解时间对猪血蛋白水解率的影响;正交试验确定水解的较佳工艺条件为:料液比1 ∶ 10.5 g/mL、pH值6、水解温度50℃、酶浓度12 000 U/g蛋白、水解时间7 h.在此条...     

猪血红蛋白酶解工艺参数优化

本试验采用酶法水解猪血红蛋白．选择水解猪血红蛋白的最优蛋白酶,并确定其最佳水解条件（包括加水倍数、酶添加比例、pH值、温度、反应时间以及沉淀血红素的pH值）。结果表明,最佳水解条件为加水倍数的2．0倍、酶添加比例4‰、pH8．5、水解温度56℃、水解时间为12h,水解后喷雾干燥产品的氨基酸总含量高达85．67％．     

乳糖诱导大肠杆菌β-D-半乳糖苷酶试验

大肠杆菌是是重要的使人罹患疾病的食源性病原微生物之一,也是重要的食品被动物排泄物污染的指标。大肠杆菌在其生长过程中会产生β-D-半乳糖苷酶,这种酶常被用于进行大肠杆菌的快速检测。本试验是探索乳糖诱导大肠杆菌产生β-D-半乳糖苷酶的最佳条件,缩短基于酶检测技术检测大肠杆菌的时间。通过单因素试验确定培养基中加入乳糖的浓度、剂量和培养时间,用L9(34)正交表设计试验因素水平,以β-D-半乳糖苷酶活力OD值为判定指标,确定乳糖诱导大肠杆菌产生β-D-半乳糖苷酶的客观条件。结果于10 m L大肠杆菌培养液中添加0.5%乳糖1 m L,诱导时间为4 h时所诱导的β-D-半乳糖苷酶量最多。说明恰当的乳糖浓度能很好地诱导大肠杆菌短时间产生β-D-半乳糖苷酶,并因此可以明显缩短利用该酶检测大肠杆菌的时间。     

酶解猪血红蛋白工艺条件的研究

试验选用中性蛋白酶水解猪血红蛋白。通过单因素试验,研究水解温度、pH值、酶加量、底物浓度、水解时间对水解效果的影响。通过正交试验,得出最佳的水解条件为:温度55℃、pH值7.5、酶加量5000U/g蛋白、底物浓度10%、水解时间3h,在此条件下的水解度为22.03%、三氯乙酸可溶性氮含量(SN-TCA指数)为63.83%。     

固定化乳糖酶在低乳糖乳制品中的应用

乳糖不耐症及低乳糖乳制品口感问题是制约乳制品消费增长的重要因素。通过固定化乳糖酶分解牛乳中的乳糖,同时调整配方,制备出口感佳、营养丰富、成本低的低乳糖乳制品。结果表明,固定化后的乳糖酶在温度50.00～70.00℃、pH值6.7左右时,具有较高的酶活力,稳定性好,金属离子对固定化酶活力影响较小。通过响应面法优化出制备低乳糖乳制品的最佳条件为:温度50.33℃,时间181.99 min,固定化乳糖酶添加量1.28 g/L,乳糖水解率为83.98%,固定化乳糖酶可重复使用8次。通过正交试验及感官评价,确认低乳糖乳制品的最佳添加剂配方为:玛卡粉0.08%,椰粉3.00%,乳清蛋白粉1.80%和果葡糖浆2.00%,为低乳糖乳制品的规模化生产奠定了基础。     

产β-半乳糖苷酶枯草芽孢杆菌BGJ222培养条件的初步优化

本文以酵母粉蛋白胨培养基为基础培养基,探讨了不同培养时间、接种量、初始pH、碳源、氮源、金属离子对枯草芽孢杆菌BGJ222表达β-半乳糖苷酶能力的影响。结果表明,菌株BGJ222最大产酶量的培养条件为:初始pH 6.6,接种量2%(V/V),培养温度37℃,培养时间24 h;培养基组成为:酵母粉0.5%(m/V),蛋白胨1.0%(m/V),NaCl 0.5%(m/V),三梨醇1.0%(m/V),MgCl20.5%(m/V)。在此条件下,菌株BGJ222表达β-半乳糖苷酶达到11456.4 Miller,比基础培养基的表达量(860 Miller)提高了12倍。     

羽毛蛋白酶解条件的初步研究

试验以羽毛粉为原料,对羽毛蛋白酶解的条件进行初步研究。以紫外分光光度计测得吸光度值为指标,得出酶解的最佳条件。进行单因素试验,以水解温度、加酶量、水解时间和pH作为4个因素,通过试验筛选每个单因素较好的数值。试验结果表明,最适酶解条件为水解温度60℃、加酶量2.5%、水解时间6 h和pH 6.5。     

乳成分对凝固型酸乳贮藏品质的影响

鲜乳的乳成分随季节、温度、挤乳时间及次数变化明显,导致用其直接加工的酸乳品质差异较大,因此,本实验研究了不同乳蛋白、乳脂肪和乳糖添加量对酸乳贮藏期间酸度和持水性的影响.结果表明:酸乳贮藏持水性随乳蛋白、乳脂肪和乳糖添加量的升高而明显增强;酸度随乳蛋白添加量的增加明显上升,而脂肪和乳糖添加量对凝固型酸乳贮藏酸度无明显影响.     

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