苜蓿鲜草中提取叶蛋白最佳工艺研究

该研究以北方寒冷地区龙牧801苜蓿鲜草为原料,用酸化加热法提取苜蓿叶蛋白。研究提取温度、提取液pH值、提取时间三因素对苜蓿叶蛋白提取率的影响。在单因素实验基础上,采用三因素三水平正交试验确定酸热法提取苜蓿叶蛋白的最佳工艺条件为:提取温度为60℃、pH值为4.0、提取时间为12min,在此工艺条件下,粗蛋白提取率为45.32%。     

不同处理条件对苜蓿叶蛋白凝聚效果的研究

以现蕾期新鲜苜蓿Medicago sativa为材料,采用温度、pH值单因素处理及温度、加热时间、pH值和NaCl质量分数多因素处理,探讨不同方法对苜蓿叶蛋白凝聚效果的影响。结果表明,在单因素条件下,温度以75℃为宜,pH值4.0对苜蓿叶蛋白产量、叶蛋白纯度和粗蛋白提取率有显著影响。而在多因素条件下,叶蛋白的最适凝聚组合条件为温度85℃,时间2min,pH值4.0,以及NaCl质量分数0.4%。     

不同提取条件对苜蓿叶蛋白凝集的影响

采用不同的加热时间和溶液酸度提取苜蓿叶蛋白 ,对苜蓿叶蛋白凝集量和苜蓿叶蛋白中粗蛋白含量进行测定。结果表明 :提取苜蓿叶蛋白的加热时间在 7～ 9min较为适宜 ,提取时溶液pH值应当控制为 3.5。苜蓿叶蛋白中粗蛋白含量的变化不大 ,在 5 4%～ 6 5 %之间     

不同提取条件对苜蓿叶蛋白凝集的影响

采用不同的加热时间和溶液酸度提取苜蓿叶蛋白，对苜蓿叶蛋白凝集量和苜蓿叶蛋白中粗蛋白含量进行测定。结果表明：提取苜蓿叶蛋白的加热时间在7～9min较为适宜，提取时溶液pH值应当控制为3．5。苜蓿叶蛋白中粗蛋白含量的变化不大，在54％～65％之间。     

不同提取条件对苜缩叶蛋白凝集的影响

采用不同的加热时间和溶液酸度提取苜缩叶蛋白，对苜蓿叶蛋白凝集量和苜蓿叶蛋白中粗蛋白含量进行测定。结果表明：提取苜蓿叶蛋白的加热时间在7-9min较为适宜，提取时溶液pH值应当控制为3．5。苜缩叶蛋白中粗蛋白含量的变化不大，在54％－65％之间。     

紫花苜蓿黄酮的提取与纯化工艺初探

为探讨紫花苜蓿(Medicago sativeL.)黄酮的提取与纯化工艺,采用不同乙醇浓度和不同pH进行提取,然后用不同来源和型号的大孔树脂进行纯化,以得出苜蓿黄酮的最佳提取和纯化方法.结果表明:30％乙醇、水浸提(pH为7.5)对紫花苜蓿黄酮的浸出率最高,分别为0.46％和0.49％,pH在9.0时所得提取物黄酮含量最高为1.61％;pH为2.2～2.4时,对紫花苜蓿黄酮有最好的沉淀效果,所得沉淀物中黄酮含量为9.80％;9种型号的大孔树脂中DS-17对乙醇提取物中紫花苜蓿黄酮有较好的分离效果,所得提取物黄酮为5.87％;在大孔树脂对碱溶酸沉提取物中黄酮的分离中,2组试验均以DM130的效果最好,所得分离物黄酮含量最高分别为24.25％和29.35％.     

铝和酸胁迫对苜蓿根瘤菌生长和抗氧化酶系的影响

在铝和酸胁迫下,比较分析了天蓝苜蓿和紫花苜蓿根瘤菌的生长及SOD(超氧化物歧化酶)、CAT(过氧化氢酶)、POD(过氧化物酶)、及GR(谷胱甘肽还原酶) 等抗氧化酶系响应特点。铝胁迫设5个梯度,即0,25,50,75,100 μmol/L;酸胁迫设4个pH水平,即4,5,6,7。结果表明,铝和酸胁迫下,2种苜蓿根瘤菌的OD_A600均显著降低,生长受到抑制,且天蓝苜蓿根瘤菌的OD_A600显著高于紫花苜蓿根瘤菌。在pH水平为4和5时,紫花苜蓿根瘤菌没有生长。在铝毒胁迫下,天蓝苜蓿根瘤菌的SOD酶活性一定程度减小后缓慢上升,而CAT、POD和GR酶活性随铝浓度增大显著下降;紫花苜蓿根瘤菌的SOD,CAT及GR酶活在低Al胁迫下无显著变化,在高铝胁迫下显著下降。随着pH水平的下降,天蓝苜蓿和紫花苜蓿根瘤菌均表现为SOD、CAT、POD、GR酶活性的显著下降。在不同铝及酸胁迫下,天蓝苜蓿根瘤菌各抗氧化酶活性显著高于紫花苜蓿根瘤菌。综合分析认为天蓝苜蓿根瘤菌较之紫花苜蓿根瘤菌有较强的耐酸、耐铝性。     

植物叶蛋白提取技术及开发利用研究

研究了6种不同的叶蛋白提取方法，采用不同浓度（饱和度）的（NH4）2SO4盐析法和加热法，通过调节原液的pH值（5．0－8．0）并分别从光叶紫花苕、紫花苜蓿、白三叶、多花胡枝子、大叶胡枝子、葛藤及多年生黑麦草中提取叶蛋白，结果表明，上述植株均是较好的原料，其中光叶紫花苕、紫花苜蓿、白三叶LPC提取率较高，分别为89．51％、89．2％、76．32％。单位提取量为19、17．5、16．35g/110g鲜草。就方法论，（NH4）2SO4处理随浓度增高而提取率增高，加热法（60－80℃）中以快速加热效果最好。     

紫花苜蓿叶蛋白正交提取工艺模式的研究

为优选紫花苜蓿叶蛋白的提取工艺条件,对不同品系的苜蓿叶蛋白进行差异性分析,本试验利用单因素极差分析,以280nm紫外光测测定并计算提取率,L9（33）正交试验设计确定最佳提取工艺。结果表明,通过单因素试验确定的各因素影响能力大小为：pH〉浸泡时间〉料液比〉温度,正交试验最佳组合为A2B1C1。结果中三得利（兰州）对照和MA-7中叶蛋白的含量相对较高,分别为21.91%和19.42%。     

pH和氮素形态对紫花苜蓿根瘤特性的影响

采用砂培方法,在营养液条件下研究了pH和不同氮素形态对接种中华根瘤菌的甘农3号紫花苜蓿根瘤特性的影响。结果表明,苜蓿对碱性条件的耐受性强于酸性条件。过低或过高的pH对苜蓿与根瘤菌的共生固氮效果具有抑制作用;同时,铵态氮下培养的紫花苜蓿根瘤数、根瘤重、固氮酶活性、根系全氮含量和生物量均高于硝态氮下培养。表明pH接近于中性和铵态氮条件更有利于紫花苜蓿的结瘤固氮和植株的正常生长。     

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