首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
精氨酸是一种条件性必需氨基酸,在肉羊的繁殖性能和生长性能上表现出良好的改善作用。N-乙酰谷氨酸(NAG)是动物机体内天然存在的精氨酸内源激活剂,N-氨甲酰谷氨酸(NCG)作为其结构类似物,能促进肉羊机体精氨酸的内源合成,在肉羊饲养上具有替代精氨酸的潜在价值。本文阐述了NCG的作用机理和代谢途径,并综述了精氨酸和NCG对肉羊繁殖性能、生产性能和屠宰性能等方面影响的研究进展,以期为NCG在今后肉羊实际生产中的应用提供参考。  相似文献   

2.
<正>精氨酸是动物体内一种重要的碱性氨基酸,在许多代谢过程中发挥重要作用。近年来,国内外研究证实,日粮中添加L-精氨酸能提高猪的日增重,能降低料肉比、改善肉品质和提高抗氧化能力,同时通过提高细胞免疫和体液免疫改善机体免疫功能,但受添加成本和配方空间的影响,外源添加精氨酸的方法未能在实际生产中得到应用。N-氨甲酰谷氨酸(NCG)是N-乙酰谷氨酸(NAG)的结构类似物,NAG是精氨酸内源性合成途径中  相似文献   

3.
肠道是机体内外环境的交汇点,易受外界环境变化诱导产生活性氧自由基,严重时造成机体氧化还原系统失衡,从而诱发肠道氧化应激。N-氨甲酰谷氨酸(NCG)是N-乙酰谷氨酸(NAG)的结构类似物,可以促进肠道内源精氨酸的合成。近些年研究发现,NCG在缓解猪肠道氧化应激和维持肠道健康方面发挥重要作用。本文综述了NCG缓解猪肠道氧化应激的作用机制,也为NCG在缓解生猪氧化应激上的应用提供参考。  相似文献   

4.
作为内源性精氨酸合成促进激活剂的N-乙酰谷氨酸(NAG)的结构类似物——N-氨甲酰谷氨酸(NCG),是一种新型、安全、高效、持久的可促进精氨酸内原合成的添加剂。本文综述了精氨酸的功能和补充方法、NCG的特点以及NCG对反刍动物的作用等内容。  相似文献   

5.
N-甲酰谷氨酸对仔猪内源性精氨酸的合成调控   总被引:4,自引:0,他引:4  
精氨酸(Arg)具有重要的生理、代谢和营养作用,几乎机体中所有组织均利用Arg合成胞浆蛋白和核蛋白,精氨酸在促进肌肉蛋白质合成,增强机体的免疫力,促进细胞分裂、伤口复原和激素分泌等各种生理过程中,也都有着重要的角色。Arg为条件性必需氨基酸,在应激状态下和特殊生长阶段为必需氨基酸,仔猪体内合成的精氨酸不能满足生理代谢需要。但是精氨酸的吸收与赖氨酸等拮抗,因此,对精氨酸及其内源性合成调控研究具有极大的应用价值和实践意义。N-乙酰谷氨酸(N-acetylglutamate,NAG)是内源性精氨酸合成途径中的必需辅助因子和限制因素之一。本文就NAG特别是其类似物N-甲酰谷氨酸(N-carbamoylglutamate,NCG)等对机体内源性精氨酸合成调控作一综述。  相似文献   

6.
精氨酸是一种条件性必需氨基酸,在动物细胞信息传递和营养代谢中起重要作用。N-氨甲酰谷氨酸(N-carbamylglutamate,NCG)能够促进内源性精氨酸的合成,其成本为精氨酸的10%,可广泛利用于实际生产中。本文主要介绍精氨酸功能、NCG和内源性精氨酸合成、NCG在猪生产各阶段的应用情况与展望。  相似文献   

7.
<正>N-氨甲酰谷氨酸(NCG)是一种白色细小粉末,不溶于水,有效成分含量为98.3%。国内外研究资料表明,NCG作为一种绿色高效的功能性氨基酸促进剂,具有极高的药用价值[1]。作为精氨酸(Arg)内源激活剂可以提高机体Arg含量,改善动物生产水平和健康状况。NCG是尿素循环中鸟氨酸生成瓜氨酸的中间体N-乙酰谷氨酸(NAG)的类似物,是内源性Arg合成途径中的必需辅助因子和限制性因素之一[2]。而  相似文献   

8.
N-氨甲酰谷氨酸(N-carbamylglutamate,NCG)是一种新型的猪用饲料添加剂,在饲料中按一定比例添加可显著提高猪的繁殖性能和生产性能。N-氨甲酰谷氨酸(NCG)主要通过促进精氨酸的内源合成,提高母猪窝产仔数和初生重,增强公猪的繁殖力,促进仔猪的生长和发育。作者将NCG在养猪生产中的应用进行了综述,以期为提高养猪生产效率提供参考依据。  相似文献   

9.
精氨酸对于幼龄仔猪是一种必需氨基酸,具有重要的生理代谢和营养作用。作为一种营养调节剂,无论是在日粮中添加精氨酸,还是添加精氨酸生素(AAA),N-氨甲酰谷氨酸(NCG),N-乙酰谷氨酸(NAG)调节内源性精氨酸的合成,都是提高仔猪体内精氨酸含量、促进断奶仔猪生长发育的有效措施。本文就精氨酸对断奶仔猪生长性能、肠道健康、抗氧化应激的影响等三方面进行综述。  相似文献   

10.
N-氨甲酰谷氨酸(NCG)是N-乙酰谷氨酸的结构类似物,具有促进哺乳动物内源性精氨酸合成的作用。NCG以饲料添加剂的形式应用于农业生产中。最初发现NCG具有提高哺乳动物繁殖性能的作用,随着研究的深入,发现NCG还可以提高畜禽的生产性能、缓解氧化应激反应和炎症反应的作用。本文论述了NCG在畜禽养殖中的研究进展,为畜禽业使用NCG提供了参考依据。  相似文献   

11.
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.  相似文献   

12.
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.  相似文献   

13.
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.  相似文献   

14.
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.  相似文献   

15.
16.
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.  相似文献   

17.
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  相似文献   

18.
A knowledge of the microbiological status of milk and of the different structures in the mammary glands has great importance in elucidating the pathogenesis of mammary gland infections. The objective of this study was to evaluate the microbiological status of various structures in the mammary glands from naturally infected dairy cows following slaughter. A total of 94 samples of milk, 184 samples of mammary parenchyma, 168 samples of gland cisterns, and 168 samples of teat cisterns were collected for microbiological examination. Microorganisms were detected in 59.9% of all samples, 67.0% of the milk samples, 70.1% of the mammary parenchymas, 55.9% of the gland cisterns and 48.8% of the teat cistern samples. When all samples were considered, coagulase-negative Staphylococcus were the most prevalent (35.7%) followed by coagulase-positive Staphylococcus (12.2%), Corynebacterium bovis (2.4%), Prototheca sp. (1.9%), and Streptococcus dysgalactiae (1.5%). There was a significantly higher occurrence of microorganisms in the milk and mammary parenchyma compared to the gland cisterns and teat cisterns. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

19.
Four grass plots were sequentially contaminated with goat faeces containing known numbers of unembryonated eggs of predominantly Haemonchus contortus and Trichostrongylus spp. between October 1982 and April 1983. Four other plots were similarly contaminated with sheep faeces between February and May 1987. An additional plot was repeatedly contaminated with sheep faeces from February to April 1987. Populations of free-living stages in faeces and of infective larvae (L3) in the herbage were subsequently monitored until the end of April and June of 1983 and 1987 respectively. During February and May 1987 two control cultures of sheep faeces were incubated in the laboratory at 25°C–30°C and at a constant temperature of 50°C and the free-living development was also monitored. L3 developed very readily in the faeces cultured at 25°C–30°C and in those spread on a grass plot in October, at the end of the wet season, but developed less on the plot contaminated in May at the start of the wet season. Worm eggs in faeces deposited on plots during the hot dry season (December to April) or incubated at 50°C died and disintegrated after 24–48 h exposure to the high environmental temperatures. The results indicate that it is unlikely that gastrointestinal nematodes of sheep and goats can develop or survive on open pasture during the dry season in the Nigerian derived savanna zone.  相似文献   

20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号