蛋氨酸羟基类似物的生产工艺及其在动物营养中的应用

蛋氨酸羟基类似物(MHA)作为蛋氨酸(Met)替代物被广泛应用于饲料添加剂中。M HA因其特殊的结构性质,不仅具备M et的营养功能,而且可以发挥M et不具备的酸化剂、抗生素等功能。随着我国畜牧和饲料添加剂行业的发展,MHA合成方法的研究及应用必将得到进一步的关注,因此,本文概述了MHA的生产工艺及其在动物营养中的应用。     

蛋氨酸羟基类似物在饲料中的应用进展

蛋氨酸羟基类似物(methionine hydroxyl analog,MHA)不仅具备蛋氨酸的营养功能,且能够发挥蛋氨酸不具备的酸化剂、抗生素等生物学功能。文章综述了MHA的理化性质、生物学作用、吸收代谢机制及其在养殖生产中的应用,为其在畜牧及饲料添加剂中的发展和应用提供参考。     

羟基蛋氨酸螯合矿在畜禽生产中的应用研究进展

羟基蛋氨酸螯合矿是由蛋氨酸羟基类似物(methionine hydroxyl analogue,MHA)与微量元素金属离子螯合而成的产物.它既可以给畜禽提供必须的微量元素,还具备蛋氨酸的营养功能,是具有双重营养特性的饲料添加剂.饲粮中添加羟基蛋氨酸螯合矿既可以提高畜禽的生产性能、增强抵抗力,提升畜禽健康水平,又能实现资...     

蛋氨酸及其羟基类似物的饲用效果

随着动物营养学、畜牧业和饲料工业的发展,随着人类生活水平提高对畜产品数量和质量提出的更高需求,蛋氨酸(Met)及其羟基类似物(MHA)在动物饲养上的使用将日趋广泛,其产量和质量也将大幅度提高,现将其饲用效果等问题作如下综述。一、蛋氨酸及其羟基类似物作饲料添加剂的发展。     

甜菜碱替代蛋氨酸研究

近来有人提倡用甜菜碱(Bet)取代畜禽日粮中蛋氨酸(Met).作为一种饲料添加剂,甜菜碱的诱人之处最初是它比蛋氨酸的价格便宜.胆碱、甜菜碱和蛋氨酸都是非稳态甲基供体,它们在许多代谢过程中扮演着十分重要的角色.然而,只有蛋氨酸直接参与蛋白质的合成,与畜禽生产性能的表达(生长、产蛋和泌乳)密切相关.本文就三者之间的相互关系,针对其作为饲料添加剂的价值进行评价.1 蛋氨酸、胆碱和甜菜碱的代谢功能1.1蛋氨酸的三大代谢作用1.1.1作为必需氨基酸(EAA),蛋氨酸直接参与     

DL-蛋氨酸与DL-蛋氨酸羟基类似物生物效能比较

摘要:增加日粮蛋氨酸水平致使肉仔鸡体增重和饲料转化率明显提高。通过比较DL—蛋氨酸与DL—蛋氨羟基类似物表明后者提高体增重和饲料转化率的平均效率分别为前者的66％和59％。目前,两种不同类型添加剂蛋氨酸补充配合饲料中是有效的,即DL—蛋氨酸和DL—蛋氨酸羟基类似物(DL—MHA)。DL—蛋氨酸是     

半体内法研究DL-蛋氨酸和过瘤胃蛋氨酸的稳定性

选择带有瘤胃、十二指肠前端和回肠末端瘘管、体况良好的 4头肉牛 ,通过小尼龙袋法 ,研究DL Met、吸附MHA、动物油包被Met和脂肪酸包被Met在瘤胃和肠道中的消失率和利用率。结果表明 ,DL Met在瘤胃中 4h便完全消失 ,不宜直接饲喂反刍动物 ;吸附MHA和动物油包被Met稳定性最好 ,脂肪酸包被Met次之 ;几种形式Met在瘤胃、瘤胃后、小肠、大肠和总消化道中的消失率以及蛋氨酸在肠道的利用率差异不显著 (P >0 .0 5 )。     

MHA和蛋氨酸在肉用仔鸡配合饲料中应用方法

实践中,人们对于蛋氨酸和蛋氨酸羟基类似物(MHA)在配合饲料中的使用方法并非十分明确,本项试验旨在实地了解65份固体蛋氨酸替代100份液体蛋氨酸(MHA)的可靠性。 1 材料与方法 1.1 试验动物与试验处理 将1400只健康1日龄商品代肉用仔鸡随机分成蛋氨酸和MHA两组,     

蛋鸡饲粮添加蛋氨酸及其羟基类似物的试验

<正> 国外已普遍利用蛋氨酸或其羟基类似物(简称MHA),作为蛋鸡的营养添加剂,以节省动植物蛋白质饮料和平衡饲粮中的含氨基酸.二者作用     

不同蛋氨酸添加剂对蛋鸡生产水平的影响

当前，饲料工业中广泛应用的蛋氨酸添加剂可分为两种：消旋蛋氨酸（DL－Methionine，简称蛋氨酸即DLM）和消旋蛋氨酸羟基类似物（DL－MethionineHydroxyAnalogue，简称MHA）。虽然，蛋氨酸和蛋氨酸羟基类似物都有液体和固体产品，但市场上常见的是固体消旋蛋氨酸（DLM）和液体蛋氨酸羟基类似物自由酸（MHA－FA）。从分子结构看，蛋氨酸（DLM）分子碳链α位为一个氨基（—NH２），而MHA—FA分子相应位置上则为一个羟基（—OH），故MHA—FA不是蛋氨酸。理论上MHA—FA在动物体内须经转氨酶的作用，用其他来源的氨基代替其分…     

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