1日龄雏鸡中超抗原SEB和MDV后脾与胸腺淋巴细胞IFN—γ的体外诱生

为研究超抗原（SAg)在禽类诱导的免疫机理和进一步揭示MDV（马立克氏病病毒）感染的免疫学规律，采用NO－释放法，设计用雏鸡骨髓巨噬细胞为靶细胞检测1日龄雏鸡接种超抗原SEB和MDV后脾与胸腺淋巴细胞IFN－γ体外诱生的动态变化。结果发现，超抗原SEB（SAG－SEB）可提高脾与胸腺淋巴细胞IFN－γ体外诱生水平，其中，高剂量（1ng/只）引起短时加强后下降，而低剂量（0.01ng)则出现缓升缓降现象，而MDV接种则抑制脾与胸腺淋巴细胞IFN－γ体外诱生，SAg-SEB能增强雏鸡细胞免疫，主要表现于接种初期（1－10dPI)，而MDV却在接种后1－25d间降低细胞免疫，说明超抗原SEB和MDV虽然均可引起鸡T细胞增殖，但对鸡免疫细胞IFN－γ的体外诱生作用不同。     

1日龄雏鸡接种超抗原SEB和MDV后脾与胸腺淋巴细胞IFN-γ的体外诱生

为研究超抗原(SAg)在禽类诱导的免疫机理和进一步揭示MDV(马立克氏病病毒)感染的免疫学规律,采用NO-释放法,设计用雏鸡骨髓巨噬细胞为靶细胞检测1日龄雏鸡接种超抗原SEB和MDV后脾与胸腺淋巴细胞IFN-γ体外诱生的动态变化.结果发现,超抗原SEB(SAG-SEB)可提高脾与胸腺淋巴细胞IFN-γ体外诱生水平,其中,高剂量(1 ng/只)引起短时加强后下降,而低剂量(0.01 ng)则出现缓升缓降现象;而MDV接种则抑制脾与胸腺淋巴细胞IFN-γ体外诱生; SAg-SEB能增强雏鸡细胞免疫,主要表现于接种初期(1-10 d PI),而MDV却在接种后1-25 d间降低细胞免疫;说明超抗原SEB和MDV虽然均可引起鸡T细胞增殖,但对鸡免疫细胞IFN-γ的体外诱生作用不同.     

感染鸡贫血病毒雏鸡接种新城疫疫苗后免疫功能和免疫调节的变化

雏鸡1日龄感染鸡贫血病毒，8日龄接种Lasota疫苗，以未感染免疫雏鸡为对照，于免疫后7、14、28d检测血清免疫球蛋白IgG、IgM、IgA,在凝抑制抗体（HI）滴度；胸腺、法氏囊、脾脏T细胞、IgG^ 、IgM^ 、IgA^ ,抗体生成细胞数量及T、B细胞增殖反应；胸腺、脾脏细胞因子IL－2、IFN活性的变化。结果发现，感染CAV雏鸡Lasota疫苗免疫后，其血清IgG、IgM、IgA免疫球蛋白含量明显减少，HI抗体滴度降低；胸腺、法氏囊、脾脏T细胞、抗体生成细胞数量降低及T、B细胞增殖反应减弱，胸腺、脾脏IL－2及TNF诱生活性降低，表明其细胞免疫和体流免疫功能以及细胞因子免疫调节作用均未感染免疫雏鸡明显减弱。     

刺五加多糖对雏鸡主要免疫指标的影响

为了明确刺五加多糖对雏鸡主要免疫指标的影响。试验采用以下方法:选取1日龄雏鸡50只进行常规饲养至7日龄后,随机分为三组,试验组分别皮下注射高剂量(200 mg/mL)、低剂量(100 mg/mL)刺五加多糖。空白对照组注射氯化钠注射液,在试验后7 d和14 d分别检测免疫器官指数,MTT法检测T细胞活性,Griess法检测巨噬细胞释放一氧化氮(NO)能力、酶联免疫吸附实验(ELISA)试剂盒检测血清中总IgG和IL-2、IL-4水平。结果:刺五加多糖能提高雏鸡免疫器官指数、T细胞增殖活性和IL-2的水平,高剂量刺五加多糖(200 mg/mL)的作用更加明显。刺五加多糖能增强雏鸡的免疫功能,200 mg/mL的刺五加多糖效果更佳。     

茯苓多糖对雏鸡细胞免疫活性的影响及其抗肿瘤作用

给1日龄AA雏鸡经腹腔注射马立克氏病病毒(MDV)强毒株(0．2mL／只)，并从当日开始给试验组雏鸡以3个剂量连续肌肉注射茯苓多糖1周，分别于7、14、28、42、56日龄取脾组织，制备脾细胞悬液，用ELISA法检测了雏鸡淋巴细胞转化率、NK细胞活性及MФ活性，并与对照组比较。结果表明，3个剂量均可显著提高雏鸡的淋巴细胞转化率、NK细胞活性及MФ活性，且中剂量组效果优于其他2个剂量组。证实茯苓多糖能提高MDV强毒株感染雏鸡的细胞免疫活性．并具有抗肿瘤作用。     

中药加味麻杏石甘汤对传染性支气管炎病毒感染雏鸡的保护作用及其机制分析

为研究中药组方加味麻杏石甘汤对人工感染传染性支气管炎病毒(Infectious bronchitis virus,IBV)雏鸡的保护作用及其作用机制,将240只15日龄雏鸡随机分为6组:健康对照组、IBV接种组、利巴韦林治疗组及加味麻杏石甘汤高、中、低剂量治疗组。IBV接种组及各治疗组雏鸡的接种病毒量为3×10-5.68EID50/0.3 mL,于攻毒后48 h进行治疗,剂量分别为0.01%利巴韦林和0.6%、0.4%、0.2%加味麻杏石甘汤。ELISA方法检测各组雏鸡血清中细胞因子γ干扰素(interferonγ,IFN-γ)与白介素4(interleukin 4,IL-4)含量。结果显示:IBV接种组雏鸡血清中IL-4水平显著升高,IFN-γ水平显著降低;经过药物干预治疗以后,血清中IL-4水平降低,IFN-γ水平提高。各药物治疗组之间,中药高、中剂量组IFN-γ水平高于低剂量组和利巴韦林组,IL-4水平较之偏低。可见,加味麻杏石甘汤可使IBV感染雏鸡血清中IFN-γ含量上调,IL-4含量下调,其保护机制可能是通过改善IBV感染导致的Th1/Th2失衡而起作用。     

雏鸡接种超抗原SEB和MDV后免疫细胞TNF-α的体外诱生

超抗原由某些细菌、病毒、支原体和寄生虫产生，其中金黄色葡萄球菌肠毒素(SE)中SEB具有代表性；已知超抗原(SAg)可大量激活人和小鼠T细胞(CD4^ 和CD8^ )和抗原递呈细胞(APC)，并诱导IL-1、IL-2、IL-6、TNF、IFN-γ等Th-1细胞因子，乃至免疫无反应、细胞凋亡和免疫抑制；超抗原SEB诱导CD8^ T细胞成为细胞毒性T细胞，启动NK细胞的细胞因子产生，有研究发现，SEB具有双相激活作用，高剂量诱导迅速，低剂量诱导长期而长期的激活状态。     

中药复方板青可溶性粉防治鸡传染性支气管炎的效果研究

为研究复方板青可溶性粉防治传染性支气管炎病毒感染雏鸡的功效与影响，本试验将鸡随机分为预防组、治疗组、双黄连治疗对照组、麻杏石甘治疗对照组、模型对照组和空白对照组。其中预防组和治疗组分别设高、中、低剂量组。除空白对照组不做处理外，预防组从12日龄起连续3 d通过饮水给药，随后各处理组将0.2 mL/只剂量的传染性支气管炎病毒通过滴鼻使15日龄的雏鸡染毒，染毒后治疗组连续6 d饮水给药。试验期间统计鸡发病数和治愈数，计算其发病率、保护率和治愈率；并检测各组鸡只的免疫器官指数、淋巴细胞增殖能力、血清中细胞因子IL-2、IL-4、TNF-α和IFN-α水平，探究复方板青可溶性粉对IBV感染雏鸡的防治效果。试验结果显示，复方板青可溶性粉预防高剂量组保护率可达66.67%，治疗中剂量组治愈率可达83.33%，另一方面提高了感染雏鸡的免疫器官指数，增强了淋巴细胞增殖能力，在染毒后4和10 d，各给药组的T淋巴细胞和B淋巴细胞增殖能力显著高于模型对照组（P<0.05）；还可以调节血清中IL-2、IL-4、TNF-α和IFN-α水平，使其维持动态平衡，其中在攻毒后5和11 d，治疗中剂量组的IL-4和IFN-α水平显著高于模型对照组（P<0.05）。综合试验数据，复方板青可溶性粉具有较好的预防和治疗传染性支气管炎的作用，且治疗作用优于预防作用，其中预防高剂量组及治疗中剂量组效果最为显著。     

玉屏风煎剂对雏鸡十二指肠黏膜的免疫调节作用

为了研究玉屏风煎剂对雏鸡十二指肠黏膜的免疫调节作用,试验将120只1日龄雏鸡随机分成4组,分别为玉屏风煎剂低、中、高剂量组和对照组,每组30只。7日龄时,雏鸡采用滴鼻和点眼方法2倍量接种LaSota系疫苗,21日龄重复免疫一次。首次免疫前2天,玉屏风煎剂低、中、高剂量组分别按0.125,0.25,0.5 g/mL三个浓度灌服玉屏风煎剂1 mL/只,对照组灌服等量生理盐水,连续灌服5 d。各试验组于10,30,50日龄时分别剖杀10只并摘取十二指肠,测定各组雏鸡十二指肠单位面积IgA分泌细胞的阳性表达率以及分泌性免疫球蛋白A(SIgA)的含量。结果表明:与对照组相比,中、高剂量玉屏风煎剂能显著或极显著提高雏鸡十二指肠IgA分泌细胞的阳性表达率及SIgA含量(P0.05或P0.01)。说明玉屏风煎剂可增强雏鸡十二指肠黏膜免疫功能,以0.25,0.5 g/mL剂量为佳。     

二烯丙基二硫化物对马立克氏病鸡血清生化指标的影响

评估抗肿瘤药物二烯丙基二硫化物(DADS)对仔鸡马立克氏病(MD)血清生化指标的影响及其抗肿瘤效果。将75只1日龄雏鸡随机平均分为5组,分别为空白组,对照组和二烯丙基二硫化物低剂量组、中剂量组、高剂量组。1日龄时对照组和试验组肌内注射马立克氏病病毒(MDV)进行攻毒,15日龄时分别以低剂量、中剂量、高剂量的DADS皮下注射作为药物试验组,40日龄时比较5组试验鸡血清白蛋白(ALB)、总蛋白(TP)、球蛋白(GLO)、总胆红素(TB)、天门冬氨酸氨基转移酶(AST)、丙氨酸氨基转移酶(ALT)和血糖(GLU)的变化。结果显示,MDV对鸡体的ALB、TP、GLU呈下调作用,其他检测项呈上调作用;DADS对感染MDV鸡指标有恢复正常值的作用,并且随浓度的增大呈上升到下降的趋势,最适浓度在100μmol/mL。提示DADS能有效抑制MDV的早期感染,增强肝功能。     

白术、微米白术和白术多糖对断奶仔猪生长性能和肠道形态及微生态区系的影响

试验选用96头平均体重14.82 kg左右的杜×长×大断奶仔猪,随机分成4组,每组3栏,每栏8头(公母各半)。对照组饲喂基础日粮,试验1、2、3组分别添加1%80目白术、0.2%白术多糖和1%微米白术。试验期30 d。结果表明:在生长性能方面,与对照组相比,1%微米白术添加组可显著提高日增重(P0.05)、降低饲料增重比和腹泻率,而且效果优于1%80目白术组和0.2%白术多糖组,在肠道形态和肠道微生态区系方面,与对照组相比,日粮添加1%80目白术、0.2%白术多糖、1%微米白术均可不同程度的提高十二指肠和空肠的绒毛高度,加深十二指肠和空肠的隐窝深度,并且增加肠道微生态区系的多样性,其中以1%微米白术添加组的效果最佳。     

Prevalence and seasonal incidence of nematode parasites and fluke infections of sheep and goats in eastern Ethiopia

Sissay, M.M., Uggla, A. and Waller, P.J., XXXX. Prevalence and seasonal incidence of nematode parasites and fluke infections of sheep and goats in eastern Ethiopia. Tropical Animal Health and Production, XXXX. A 2-year abattoir survey was carried out to determine the prevalence, abundance and seasonal incidence of gastro-intestinal (GI) nematodes and trematodes (flukes) of sheep and goats in the semi-arid zone of eastern Ethiopia. During May 2003 to April 2005, viscera including liver, lungs and GI tracts were collected from 655 sheep and 632 goats slaughtered at 4 abattoirs located in the towns of Haramaya, Harar, Dire Dawa and Jijiga in eastern Ethiopia. All animals were raised in the farming areas located within the community boundaries for each town. Collected materials were transported within 24 h to the parasitology laboratory of Haramaya University for immediate processing. Thirteen species belonging to 9 genera of GI nematodes (Haemonchus contortus, Trichostrongylus axei, T. colubriformis, T. vitrinus, Nematodirus filicollis, N. spathiger, Oesophagostomum columbianum, O. venulosum, Strongyloides papillosus, Bunostomum trigonocephalum, Trichuris ovis, Cooperia curticei and Chabertia ovina), and 4 species belonging to 3 genera of trematodes (Fasciola hepatica, F. gigantica, Paramphistomum {Calicohoron} microbothrium and Dicrocoelium dendriticum) were recorded in both sheep and goats. All animals in this investigation were infected with multiple species to varying degrees. The mean burdens of adult nematodes were generally moderate in both sheep and goats and showed patterns of seasonal abundance that corresponded with the bi-modal annual rainfall pattern, with highest burdens around the middle of the rainy season. In both sheep and goats there were significant differences in the mean worm burdens and abundance of the different nematode species between the four geographic locations, with worm burdens in the Haramaya and Harar areas greater than those observed in the Dire Dawa and Jijiga locations. Similar seasonal variations were also observed in the prevalence of flukes. But there were no significant differences in the prevalence of each fluke species between the four locations. Overall, the results showed that Haemonchus, Trichostrongylus, Nematodirus, Oesophagostomum, Fasciola and Paramphistomum species were the most abundant helminth parasites of sheep and goats in eastern Ethiopia.     

Feline intracranial neoplasia: retrospective review of 160 cases (1985-2001)

The purpose of this study was to determine the frequency of different tumor types within a large cohort of cats with intracranial neoplasia and to attempt to correlate signalment, tumor size and location, and survival time for each tumor. Medical records of 160 cats with confirmed intracranial neoplasia evaluated between 1985 and 2001 were reviewed. Parameters evaluated included age, sex, breed, FeLV/FIV status, clinical signs, duration of signs, number of tumors, tumor location(s), imaging results, treatment, survival times, and histopathologic diagnosis. Most of the cats were older (11.3 +/- 3.8 years). Primary tumors accounted for 70.6% of cases. Metastasis and direct extension of secondary tumors accounted for only 5.6 and 3.8% of cases, respectively. Twelve cats (7.5%) had 2 or more discrete tumors of the same type, whereas 16 cats (10.0%) had 2 different types of intracranial tumors. The most common tumor types were meningioma (n = 93, 58.1%), lymphoma (n = 23, 14.4%), pituitary tumors (n = 14, 8.8%), and gliomas (n = 12, 7.5%). The most common neurological signs were altered consciousness (n = 42, 26.2%), circling (n = 36, 22.5%), and seizures (n = 36, 22.5%). Cats without specific neurological signs were common (n = 34, 21.2%). The tumor was considered an incidental finding in 30 (18.8%) cats. In addition to expected relationships (eg, meninges and meningioma, pituitary and pituitary tumors), we found that lesion location was predictive of tumor type with diffuse cerebral or brainstem involvement predictive of lymphoma and third ventricle involvement predictive of meningioma.     

Y‐chromosomal variation of local goat breeds of Turkey close to the domestication centre

Genetic variations in chromosome Y are enabling researchers to identify paternal lineages, which are informative for introgressions and migrations. In this study, the male‐specific region markers, sex‐determining region‐Y (SRY), amelogenin (AMELY) and zinc finger (ZFY) were analysed in seven Turkish native goat breeds, Angora, Kilis, Hair, Honaml?, Norduz, Gürcü and Abaza. A SNP in the ZFY gene defined a new haplotype Y2C. All domestic haplogroups originate from Capra aegagrus, while the finding of Y1A, Y1B, Y2A and Y2C in 32, 4, 126 and 2 Turkish domestic goats, respectively, appears to indicate a predomestic origin of the major haplotypes. The occurrence of four haplotypes in the Hair goat and, in contrast, a frequency of 96% of Y1A in the Kilis breed illustrate that Y‐chromosomal variants have a more breed‐dependent distribution than mitochondrial or autosomal DNA. This probably reflects male founder effects, but a role in adaptation cannot be excluded.     

A brief history of the prevention of infectious diseases by immunisations

Infectious diseases have always been a terrible scourge for humans. The appearance of these plagues, as they were called without distinction, was generally connected to various conditions: asters, climatic changes or religious reasons. The concept of contagious, and then infectious, diseases came slowly. Variolation, i.e. transmission of ‘virulent’ matter to induce a natural disease and the immunity against it, was brought from Constantinople to England by Lady Montague, in 1721. This ‘variolation’ technique was also often performed in veterinary medicine against diseases like sheep-pox or pleuropneumonia. As ‘vaccination’ is the term generally accepted for ‘immunisation’, variolation can be the word designating such a technique. The second period of the history of immunisation began, in 1880, with the studies of Pasteur and his collaborators. A great number of bacterial vaccines were developed: dead, live but attenuated or only parts of pathogens. The viruses were produced in animals, then in eggs and at last, in tissue cultures. Second generation vaccines appeared with genetic engineering: recombinant vaccines, vector vaccines, nucleic acids vaccines, and markers vaccines, among others. These novel technologies can permit the development of new ones and improve the quality of the vaccines already existing.     

Micronutrient Content of Certain Tropical Conventional and Unconventional Feed Resources of Southern India

The ash, silica and certain important micronutrients were estimated in conventional and unconventional feed and fodder resources available in Southern India. Commonly used dry roughages, such as paddy straw, ragi straw, maize kadbi/stalk, jowar kadbi/stalk, bajra stalk and wheat straw, were high in ash (9.9% +/- 0.77%) and silica (6.4% +/- 0.65%) and low in most of the other micronutrients, except iron, with paddy straw containing most silica (>9%). Cultivated non-leguminous (maize, jowar) and improved green crops (hybrid napier, guinea, green panic, NB-21, CO-1) were also high in ash (10.5% +/- 0.60% and 12.5% +/- 0.51%) but were moderate sources of P, Mg and Cu and good sources of Zn (98 +/- 13.8 ppm and 55 +/- 6.7 ppm). Leguminous green fodders (stylosanthus, lucerne, cow pea, soyabean) were excellent sources of Ca (1.9% +/- 0.16%), Mg (0.40% +/- 0.05%), Cu (30 +/- 5.2 ppm), Zn (121 +/- 14.7 ppm) and Fe (1234 +/- 166 ppm) and moderate sources of P. Mixed local grasses and weeds were high in silica (6.9% +/- 1.00%) but were good sources of Cu, Zn and Fe. Cereal grains (maize, wheat, rice, ragi) were low in ash (2.9% +/- 0.33%) and were relatively poor sources of Ca (0.22% +/- 0.03%), Mg (0.19% +/- 0.03%) and Cu (13 +/- 3.1 ppm). Pulses were low to medium sources of most minerals and good sources of Fe (1230 +/- 293 ppm). Oil seed cake/extractions (groundnut cake, cotton seed cake, soyabean meal, sunflower cake, safflower cake) and cereal by-products (rice polish, rice bran, wheat bran) were excellent sources of P (1.1% +/- 0.47% and 2.3% +/- 0.19%) and good sources of Zn (65 +/- 3.9 ppm and 66 +/- 10.7 ppm) and Fe (938 +/- 130 ppm and 662 +/- 126 ppm). Among the unconventional feeds screened, orange peel, sunflower heads, meat meal, rubber seed cake, spirulina algae and sea weeds contained plentiful Ca, Zn and Fe: tree leaves/top feeds (mulberry, erythrina, glyricidia, banana, subabul, groundnut haulms) were excellent sources of Ca (1.5% +/- 0.13%), Zn (120 +/- 22.9 ppm) and Fe (1033 +/- 133 ppm) but relatively poor sources of P. Soyabean husk, cocoa seed husk, rubber seed cake and meat meal were moderate to good sources of P (1.0% and 0.33%). The high Zn and Fe values of most feeds/fodders were probably due to soil contamination. This account of the micronutrient content of feed/fodder resources should help in strategic supplementation intended to alleviate local deficiencies.     

The Prevalence and Intensity of Helminth and Coccidial Infections in Dairy Cattle in Central Kenya

A survey of gastrointestinal parasite infections of young (<6 months old), immature (6–12 months old) and adult (>12 months old) dairy cattle on 16 farms in Kiambu District, Kenya was conducted during a dry season (September 1991 to January 1992) and during a wet season (March to July 1992). The survey was based on monthly coproparasitological examination of cohorts and worm counts in tracer calves. The effects of age, sex, farm and season on the prevalence and intensity of helminth and coccidial infections were determined. Faecal egg and oocyst counts revealed that the overall prevalences were: strongyles (including trichostrongyles) (85.5%), liver flukes (Fasciola gigantica) (34.0%), coccidia (30.9%) and tapeworms (9.6%). Eight species of the protozoan Eimeria were identified, the most prevalent species being E. bovis and E. zuernii. The most prevalent nematode genera were Haemonchus, Cooperia, Oesophagostomum and Trichostrongylus. Season, farm and age of the animals had a significant (p<0.05) influence on the intensity of infection with strongyles, liver flukes and coccidia, whereas the sex of the animals had no significant (p>0.05) effect on the prevalence or intensity of infections. A higher intensity of infection with strongyles and coccidia was found in the wet season than in the dry season (p<0.05). The age-specific intensity was in the following order: for strongyles, immature animals of 6–12 months of age had the highest egg counts, followed by young calves and adults. Calves had significantly (p<0.05) higher oocyst counts than immatures or adults. Liver fluke egg counts did not differ significant (p>0.05) between immatures and adult cattle.     

Bovine Mastitis in Selected Areas of Southern Ethiopia

A study on bovine mastitis, designed to determine the causal agents, prevalence of infection and impact of risk factors in three cattle breeds, was conducted in selected areas of southern Ethiopia. A total of 307 lactating and non-lactating cows, of which 162 were indigenous Zebu, 85 Jersey and 60 Holstein-Friesian, were examined by clinical examination and the California mastitis (CMT) test. Of these, 40.4% were positive by CMT and bacteriology for clinical or subclinical mastitis, with prevalence rates of 37.1% and 62.9%, respectively. Out of 1133 quarters examined, 212 (18.7%) were found to be infected, 83 (39.2%) clinically and 129 (60.8%) subclinically. The prevalence of mastitis was significantly higher in Holstein-Friesian than in indigenous Zebu, in non-lactating cows than in lactating cows, in the early lactation stage than in the mid-lactation stage, in cows with lesions and/or tick infestation on skin of udder and/or teats than in cows without this factor, and in the wet season than in the dry season. Mastitis increased with parity number (R = 0.9). Of 248 CMT and clinically positive udder quarter samples analysed microbiologically, 212 were culturally positive for known mastitis pathogens and 36 were negative. Of the 199 positive samples, Staphylococcus accounted for 39.2%, Streptococcus for 23.6%, coliforms for 14.1%, Micrococcus and Bacillus species for 8.0% each and Actinomyces or Arcanobacterium (Corynebacterium) for 7.0%. It was concluded that there was a high prevalence of clinical and subclinical mastitis, mainly caused by Staphylococcus aureus, Streptococcus agalactiae and Escherichia coli, in this study area.     

不同日粮氮水平对山羊氮代谢和微生物蛋白质合成的影响

本试验旨在探讨不同日粮氮水平对内蒙古白绒山羊氮代谢和微生物蛋白质合成(MCP)的影响,以达到提高氮利用率,减少环境污染和饲料资源的浪费。试验选用9只体况良好、体重为(43.83±2.95)kg,装有瘤胃瘘管的内蒙古白绒山羊,按体重随机分为3组,每组3只。日粮分为低氮7.5%、中氮10.5%、高氮13.5%3个氮水平。试验使用常规试验方法分析测定粪尿血液等生化指标,通过全收尿法和尿嘌呤衍生物法估测MCP。结果表明:随着氮水平增加,氨氮(NH3-N)浓度、氮摄入量、尿氮排出、尿中尿素氮(UUN)和MCP显著增加(P0.05),干物质采食量(DMI)显著降低(P0.01);沉积氮占总摄入氮的比例在中氮组最高,MCP在高氮组最高。综上所述,适当降低日粮氮水平可减少粪尿氮排放,提高反刍动物氮利用率。