降低奶牛养殖对环境污染的营养调控关键技术

随着我国奶牛养殖业的快速发展,在生产过程中产生的废弃物时环境的影响越来越大,其中由于氮、磷和甲烷排放所造成的污染尤为突出。降低氮磷和甲烷的排放,其本质问题是提高奶牛日粮的利用效率,本文就如何提高奶牛对氮磷的利用效率以及降低甲烷排放进行了综述。     

不同饲粮组成对泌乳荷斯坦奶牛产奶性能、血液生化指标及氮磷排放量的影响

本试验研究了减少饲粮氮磷水平或使用复合添加剂对泌乳荷斯坦奶牛的产奶性能、血液生化指标及氮磷排放量的影响,旨在不影响生产性能的前提下减少奶牛粪尿中氮磷的排放量。采用配对试验设计,将36头泌乳荷斯坦奶牛分为3组,每组12头,分别为对照(CR)(原奶牛场配方饲粮)、低氮磷(LPP)组[原奶牛场配方饲粮减少0.70%的氮(粗蛋白质)、0.03%的磷]、复合添加剂(CA)组[原奶牛场配方饲粮+复合添加剂(由活性酵母、酶制剂和有机锌混合组成)]。预试期7 d,正试期30 d。测定产奶量、乳成分、血液生化指标及氮磷排放量。结果表明:各组产奶量、干物质采食量、乳成分无显著差异(P0.05);LPP组与CR组相比,酸性洗涤纤维、磷的表观消化率分别提高了73.12%、42.94%(P0.05);与CR组相比,LPP组总氮、总磷排放量分别降低了9.11%和26.34%(P0.05),CA组分别降低了16.35%和16.10%(P0.05);LPP组与CR组之间血液生化指标差异不显著(P0.05),CA组的血液谷丙转氨酶(ALT)活性和磷含量显著高于CR组(P0.05)。结果提示,在满足正常营养需求的情况下,适当控制奶牛氮磷摄入量和使用复合添加剂均能降低氮磷的排放量。     

降低奶牛氮排泄的技术措施

伴随着我国奶牛养殖业的发展,因蛋白饲料价格提高带来的饲养成本上升问题以及奶牛养殖过程中大量的氮排放带来的环境污染问题越来越受到人们的重视。本文综述了粪尿氮的产生过程以及降低奶牛氮排泄的方法,阐述通过改变饲粮组成和加工方式、采用蛋白质包被技术等措施可提高饲粮蛋白质利用率,对提高生产性能、减少氮素排放、减轻环境污染、降低饲养成本都具有积极的意义。     

商业化牛场泌乳奶牛氮磷营养代谢调控与管理策略对环境安全的研究

研究结果表明,奶牛场日常活动中排放的过多氮和磷对环境造成一定程度的污染,而通过优化饲养和管理要素被认为是减少粪尿中氮和磷排放的重要策略。因此,本试验旨在通过评估奶牛群体中氮和磷的利用效率,研究日粮和管理要素对提高营养素的利用效率和减少氮和磷排放的影响。试验选用64个商业化奶牛场,精粗比为50∶50,基础日粮由牧草青贮和玉米青贮组成。试验结果显示,氮和磷的采食量分别为562 g/d(CP含量为16.4%)和84.8 g/d(P含量为0.4%),单产水平平均为29.7 kg/d,氮和磷的利用效率分别为25.8%±2.9%和31.9%±4.5%,通过控制日粮粗蛋白质的采食来调控日粮氮能在很大程度上降低氮的排放(R2=0.70)且优于日粮磷的调控降低磷的排放(R2=0.30)。尽管常用饲料原料中磷含量较高,但氮利用效率的提高有助于提高磷的利用效率。而分群饲喂、周期的日粮配给及选择不同的饲喂系统等管理策略在提高氮和磷的利用效率上不能产生持续的作用。但通过优化氮和磷的利用效率能降低单位乳生产中氮和磷的浪费且分别能减少氮和磷排泄的17%和35%。当考虑泌乳群体和农场土地的利用效率时,营养和群体管理策略在减少氮和磷的排放上就...     

饲粮物理有效中性洗涤纤维和瘤胃可降解淀粉的平衡关系及其对奶牛瘤胃液pH和生产性能的影响

奶牛饲粮物理有效中性洗涤纤维对于维持奶牛最佳瘤胃功能、减少代谢失调发生、预防生产性能下降等具有重要作用。奶牛瘤胃可降解淀粉含量与谷物类型、谷物加工处理方法、奶牛瘤网胃中食糜流通速率有很大关系。本文主要就奶牛饲粮物理有效中性洗涤纤维和瘤胃可降解淀粉的平衡关系及其对奶牛瘤胃液pH和生产性能的影响做一综述,以期为生产实践提供理论依据。     

营养和管理策略对商业化牧场氮和磷的利用效率的研究:环境因素

奶牛场排放的氮和磷,对大气产生一定的污染,因此有学者认为,优化动物的饲养和管理以减少粪便中氮和磷的排放,是减少奶牛场污染的重要措施。本试验选择64个商业化的奶牛场,评估氮和磷的利用效率和管理因素对营养素的利用效率、氮和磷的分泌的影响。日粮精粗比为50∶50（牧草和玉米青贮）。试验期间,氮和磷平均采食量分别为562和84.8 g/d,乳产量为29.7 kg/d,利用效率分别为25.8%和31.9%。通过调控粗蛋白质的采食量减少氮的分泌（R2=0.7）优于磷的营养控制减少磷的分泌作用（R2=0.30）。尽管饲料原料中磷含量较高,日粮氮的利用效率提高的同时利于提高磷的利用效率。奶牛群的管理如分周期饲喂,选择性的饲养系统在提高氮和磷的利用效率没有得到持续体现。优化氮和磷的利用效率有助于降低单位乳生产中氮和磷的分泌,降低比例在17%~35%之间。尽管日粮管理降低了11%氮的分泌和约17%磷的分泌,然而,当为了减少奶牛场氮和磷的分泌与奶牛群和农场的利用效率联系起来一起考虑时,营养和管理的作用就受到限制。因此,氮和磷之间正确的配比关系以提高奶牛生产性能的发挥,同时降低氮和磷的排泄在商业化牧场可能是可行的。     

酵母培养物对奶牛生产性能及抗氧化功能的影响

本试验旨在研究酵母培养物对奶牛生产性能及抗氧化功能的影响。选取56头泌乳期荷斯坦牛,按照胎次、泌乳天数、产奶量等基本一致的原则随机分成2组,对照组饲喂基础饲粮,酵母培养物组在对照组饲粮的基础上添加3%的酵母培养物,同时减少3%的副饲料,两组营养水平一致。预试期20 d,正试期60 d。结果表明:饲粮中添加3%酵母培养物极显著提高了奶牛干物质采食量(P0.01),显著性提高了奶牛的产奶量(P0.05);饲粮中添加3%酵母培养物可以显著提高牛奶中乳脂率与乳蛋白含量(P0.05),显著性降低鲜乳中体细胞的含量(P0.05);饲粮中添加3%酵母培养物后可以极显著提高超氧化物歧化酶活性(P0.01),显著提高奶牛机体的总抗氧化力(P0.05)。由此可知,酵母培养物可以提高奶牛的生产性能,有效增强抗氧化能力。     

影响反刍动物氮素利用效率和排放的营养实践

涉及奶牛生产系统和粪肥应用的总氨氮排放参数是影响农业源氨氮排放的最敏感的参数,如何通过精细饲养来提高奶牛的氮素泌乳转化效率,降低奶牛生产系统的氮素排放,对于缓解奶牛生产系统面临的经济与环保双重压力具有重要意义。本文从饲粮的氮素水平、碳水化合物类型、氨基酸补饲、饲料添加剂、饲粮精粗比以及新型饲料原料等方面对影响反刍动物氮素排放的研究进行了综述,同时介绍了康奈尔净碳水化合物-蛋白质体系(CNCPS)模型及其改进对奶牛场氮排放估测的影响以及尿素转运蛋白对反刍动物氮素代谢的影响。     

增加饲粮蛋白质水平可减少肉鸡体脂肪

有关文献报道,同时提高饲粮中的能量和蛋白质水平,可加快鸡的增重和改善饲料的利用效率。另有研究报告指出,饲粮能量水平提高,肉鸡屠体的脂肪也会随之增加,但提高饲粮蛋白质水平,则屠体的脂肪含量呈减少趋势。为进一步确证饲粮中蛋白质和能量水平对肉鸡生产性能及屠体脂肪量的影响,美国明尼苏达大学的贡博士等专门进行了试验。     

苜蓿鲜草和青饲玉米对奶牛生产性能和乳品质的影响

探讨日粮中添加苜蓿鲜草和青饲玉米对奶牛生产性能及其乳成分的影响,本试验选用荷斯坦泌乳奶牛20头,随机分为2组,对照组饲喂秸秆和精料补充料;试验组饲喂苜蓿鲜草、青饲玉米和精料补充料日粮。试验结果表明,日粮中添加苜蓿鲜草和青饲玉米,可极显著提高奶牛的生产性能和乳脂率(P<0.01),显著提高干物质采食量和乳蛋白含量(P<0.05)。     

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