畜牧业可持续发展的研究——植酸酶的应用

实现畜牧业可持续发展必须尽快推广使用植酸酶。植酸酶是能降解饲料中植酸及盐的酶，它能提高磷的利用率，降低动物排磷量，有利于环境保护。对植酸酶运用的实例分析表明：使用植酸酶能代替饲料中添加的无机磷。     

“挑战之声”饲料工业高新技术讲座暨《饲料工业》有奖阅刊(2)挑战植酸酶──矿物添加新概念

１国家“８６３”科研成果转化产品──挑战植酸酶挑战植酸酶干粉是国家“８６３”科技攻关课题中第一个对饲料行业资助项目的科研成果，由中国农科院饲料研究所承担研制，北京挑战饲料科技集团和江酉民星企业集团共同开发转化的高科技产品。挑战植酸酶是通过基因工程方法，将筛选得到的适合于在饲料中使用的植酸酶天然菌株中植酸酶编码基因进行克隆和改造，然后利用生物反应器──毕翅酵母高效表达而生产的酶制剂。其活性成分为植酸酶（Ｐｈｙｔａｓｅ），含量不低于２５００单位／ｇ。挑战植酸酶使用功效：１．１可以降解植酸盐，提高饲料…     

实用传真

植酸酶的剂型及其各自的特点受植酸酶生产技术的限制和适应饲料企业的加工工艺的要求，目前市售共有三种剂型，分别为粉状、颗粒状和液态植酸酶。由于植酸酶的温度耐受极限远不能满足大多数生产颗粒饲料的要求，所以液态植酸酶是借助后喷涂技术在颗粒饲料中使用。价格低廉，添加到饲料产品后的稳定性比较差，需要相应的喷涂设备。安装费用和日常维护费用要求较高。目前只有少数公司提供液体植酸酶。颗粒状植酸酶经过保护，适宜于生产各种饲料产品（配合饲料、浓缩饲料和预混合饲料），也可以在低温制粒时生产颗粒饲料（小于等于８２～８５℃…     

植酸酶实用指南（九）——300个问题与答案

（上接第１９期第３６页）５．何时可以全部替代无机磷？只有在很特殊的饲料配方中才有可能。即饲料背景的磷水平很高，在不添加无机磷时总磷含量已经达到０．４５％－０．５０％。如大量使用肉骨粉的口粮，植酸酶就有可能替代出全部的无机磷。６．肉鸡配合饲料中植酸酶的添加量是多少？每千克饲料添加５００FTU植酸酶，即每吨饲料添加含量为５０００FTU／g的植酸酶产品１００g。适用于所有品种、日龄的肉鸡。如果使用低含量（２５０FTU／g）的产品，每吨饲料的添加量为２kg。７．为什么肉鸡饲料中植酸酶的添加量比蛋鸡高而替代磷的量比…     

环保型饲料添加剂研制成功

中国农科院的科学家日前研制出饲料用基因工程酵母。中国农科院饲料研究所和生物技术研究中心，从１９９６年开始合作进行利用生物反应器大规模、低成本的生产饲料添加剂植酸酶的研究，从黑曲酶中克隆了适合在饲料中使用的植酸酶基因。我国饲料资源缺乏，饲料添加剂品种少，该项研究成果可用来大规模廉价生产新型饲料添加剂———植酸酶。植酸酶是一种能将饲料中的植酸水解成无机磷和肌醇的新型动物饲料添加剂。这种饲料添加剂可提高动物对磷的利用率，使畜禽粪便中磷的排出量减少４０％～７５％，能减轻江河等环境的磷污染，减少饲料用磷消…     

植酸酶替代产蛋鸡饲料中磷酸氢钙的研究

本试验目的是利用植酸酶可以水解饲料中植酸的原理，探讨在国内蛋鸡的实际生产条件下，商品植酸酶替代磷酸氢钙的效果和评价实际可应用性。试验选用22─46周龄北京红鸡，在饲料中用300FTU植酸酶替代2.2克无机磷（相当于在每吨饲料中添加60克商品植酸酶替代13.8公斤磷酸氢钙─DCP，或1.54公斤可利用磷），观测植酸酶对产蛋鸡生产性能和体况的影响。结果表明：用300FTU植酸酶替代2.2克无机磷至少可以保持产蛋鸡的生产性能不变。其中：产蛋率（＋2.2％）、日耗料量（＋l.4％）、饲料报酬（一2.0％）、破蛋率（一2．0％）、死淘率（一4.l％）和胫骨总灰分含量（＋3.6％）均优于对照组，但差异不显著；而日产蛋量（＋4.1％）、体增重（十47％）、胫骨钙含量（＋4.8％）则显著优于对照组（P＜0.05）。根据试验结果，认为可以在产蛋鸡饲料中用商品植酸酶替代目前使用的磷酸氢钙。还可以认为，根据我国目前的磷酸氢钙品质（含氟量）状况，在蛋鸡饲料中使用植酸酶能够大幅度减轻以至于杜绝磷酸氢钙导致的氟中毒问题。同时能够预见，使用植酸酶可以大幅度降低排泄物的含磷量，减少磷对自然环境的污染。植酸酶在产蛋鸡饲料中具有重要的现实应用意义。     

植酸酶使用时应注意的问题

解决饲料磷污染的最佳途径是在饲料中添加植酸酶.针对生产实践中使用植酸酶的一些误区,本文介绍了具体使用植酸酶的方法,供应用时参考.     

植酸酶在笼养蛋鸡饲料中的应用

植酸酶在笼养蛋鸡饲料中的应用Ｎｉｅｋｅｒｋ等著丁利敏陈于平摘译田野校家禽生产的小规模试验结果表明，使用植酸酶可以减少蛋鸡饲料中的总磷量。环境污染是全球性的热门话题。为了减少污染，荷兰政府通过立法限制畜禽粪便中的矿物质含量。依照这项法规，蛋鸡饲料中总磷...     

添加植酸酶提高鱼饲料磷的利用

为测定植酸酶对条纹妒实用饲料磷利用的效果，美国水产科研人员进行了试验。饲料中植物原料占70％，含磷49－7.1g／kg，非植酸磷15－1.7g／kg、试验饲料添加磷酸钾13g／kg使总磷含量为9g／kg，非植酸磷含量为6g／kR。每种饲料设3个重复，投喂条纹鲈鱼种14周，不添加植酸酶作对照；。植酸酶处理效果根据鱼体增重、饲料转换率、血清，鳞片和脊椎中的钙磷测定。磷的表现消化率使用Cr2O35g／kg测定。结果表明：投喂添加植酸酶2400U／kg饲料的鱼鳞片和脊椎中的磷浓度提高投喂添加植酸酶饲料的鱼血清中的磷浓度高、结论是条纹鲈实用饲料中添加植…     

植酸酶实用指南（七）——300个问题与答案

（上接第１７期第４０页）１０．产蛋鸡配合饲料中植酸酶的推荐量是多少？每千克饲料添加３００FTU植酸酶，即每吨饲料添加含量为５０００FTU／g的植酸酶产品６０g。如果使用低含量（２５０FTU／g）的产品，每吨饲料的添加量为１．２kg。１１．产蛋鸡饲料中使用植酸酶该怎样调整磷的水平？根据总磷调整最方便。同时考虑季节，产蛋期，采食量。例如在夏季，总磷至少应保持在０．４５％左右；而在冬季，０．４０％－０．４２％就可以了。在产蛋高峰期，总磷的水平要保持在０．４５％左右；而在４２周以后，０．４２％就可以了。对于不同的…     

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.     

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.     

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.     

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