抑制素基因免疫对小鼠生殖的影响

用编码抑制素α（1－32）的基因与pcDNA3.1真核表达质粒进行重组，构建抑制素基因疫苗NH。将30只2周龄ICR小鼠随机分为3组（每组10只），试验Ⅰ，Ⅱ组分别经脂质体介导肌肉注射iINH15μg()0μL,25μg(100μL)，对照组注射免疫空载体pcDNA3.115μg(100μL)。首次免疫后间隔3周加强免疫1次。小经pINH基因免疫后，用ELISA可从血浆中检测到抑制素抗体，表明pINH可在活体肌细胞内表达，表达产物具有制素抗原性，能激活免疫系统产生抑制素抗体。抑制素抗体P／N＞2视为阳性，阳性率为30％（6／20）。抑制素抗体阳性小鼠与阴性小鼠的产仔数，初生重和窝重等没有显著差异（P＞0．05）。抗体阳性组首次免疫后，雌鼠血浆FSH浓度略有升高，经过加强免疫后显著升高（P＜0．05）。由此可以看出，抑制素基因免疫可以诱导产生抗抑制素抗体，并促进促卵泡素的分泌。     

抑制素与乙肝表面抗原融合基因免疫对大鼠生殖能力的影响

90只大鼠随机分为5组(n=18),分别肌肉注射10、50、100μg抑制素与乙肝表面抗原融合基因表达质粒(pCIS)、50μg空载体(pcDNA3.1)和100μL生理盐水。20 d后加强免疫1次,对每组中的12只大鼠进行2次加强免疫。结果发现抑制素抗体P/N值随着免疫次数的增加而提高。100μg剂量组2次和3次免疫的成熟卵泡发育数分别比对照组多6.9和7.5个(P<0.05)。3次免疫后大鼠成熟卵泡发育数比2次免疫后显著提高(35.2±2.73 vs 31.0±0.92,P<0.05)。抑制素基因免疫组的胎盘数和窝产仔数高于对照组(P>0.05),抗体阳性鼠高于阴性鼠(P<0.05)。pCIS 3次免疫后抗体阳性鼠的抗体水平与成熟卵泡发育数的相关系数为0.45(P>0.05),与胎盘数的相关系数为0.77(P<0.05)。pCIS免疫大鼠动情期和产后血浆FSH水平高于对照组,抗体阳性鼠的血浆FSH水平高于阴性鼠,其中2次免疫后阳性组动情期FSH浓度极显著高于阴性组(P<0.01)。这些结果表明,抑制素基因免疫大鼠可促进大鼠的卵泡发育,提高血浆FSH水平,为抑制素基因免疫大动物提供了试验依据。     

抑制素基因免疫大鼠的免疫应答与基因表达

为了研究抑制素基因免疫对大鼠免疫应答和发情的影响及免疫后抑制素的组织分布,将60只大鼠分为5组,每只分别肌肉注射10（T1）、50（T2）、100μg pCIS（T3）,50μg pcDNA3.1（V）和生理盐水（S）。ELISA检测抑制素抗体水平,阴道涂片法检测大鼠的发情状况,免疫组化分析抑制素的组织分布。结果显示,不同剂量抑制素基因2次免疫10 d后抗体P/N值均显著升高（P〈0.05）,3次免疫10 d后T2和T3组抗体P/N值进一步显著升高（P〈0.05）,T3组抗体水平有高于T1和T2组的趋势（P〉0.05）;抑制素基因免疫对大鼠的发情无显著影响;3次免疫2周后心脏、肝脏、接种肌肉部位均未检出抑制素;卵巢、肾脏和垂体部位均检出抑制素;而脾脏部位,抑制素质粒免疫组检出抑制素,对照组则未检出抑制素。这些结果表明,免疫剂量和次数的增加没有导致大鼠产生明显的抑制素免疫耐受,抑制素基因免疫大鼠是相对安全的,抑制素的组织分布结果亦为抑制素基因免疫的作用机理研究提供了理论依据。     

卵泡抑制素与GFP融合基因疫苗免疫对大鼠卵巢和生殖激素的影响

将50只大鼠随机分为5组,分别注射0.2（T1）、0.6（T2）、1g/L（T3）pEGISI,100μg空载体pEGFP-N1（C1）和100μL生理盐水（C2）,以探讨在没有使用免疫佐剂的情况下,抑制素与GFP融合基因疫苗pEGISI免疫对大鼠卵巢和生殖激素的影响。研究结果,加强免疫能提高抗体P/N值,T3组在加强免疫期与对照组差异显著（P〈0.05）;加强免疫第2周时T3组抗体阳性鼠比例达40%,与T1和T2组差异均显著（P〈0.05）。T3组卵巢大小和卵泡数均显著高于对照组（P〈0.05）,但抗体阳性鼠大卵泡数与阴性鼠差异不显著（P〉0.05）。各剂量组促卵泡素和雌二醇均高于对照组,且在加强免疫第2周时T3组与对照组差异显著（P〈0.05）;各剂量组孕酮含量与对照组差异均不显著（P〉0.05）。结果表明,在没有使用免疫佐剂的前提下,抑制素pEGISI基因免疫可产生抗体,促进卵巢发育和FSH分泌。本试验条件下100μg是最佳免疫剂量。     

抑制素pCISI基因免疫对黄牛卵泡的影响

为提高动物繁殖力，分别用不同纯度的抑制素真核融合表达质粒pCISI，配以不同免疫佐剂后导入72头母黄牛体内。结果表明：①两次免疫后，产生抗抑制素抗体的黄牛占59．72％（4 3／72）；②pCISI能促进双大卵泡发育（68．75％，44／64），诱发排双卵（50．00％，32／64）；③加入佐剂的疫苗较未加佐剂的疫苗免疫效果明显，普鲁卡因佐剂显著优于脂质体（P〈0．05）；④纯度疫苗对牛的免疫效果略高于低纯度疫苗，但差异不明显（P〉0．05）。     

双拷贝抑制素基因疫苗pcISI的构建和表达及免疫

为构建高免疫原性的卵泡抑制素（Inhibin,INH）DNA疫苗,将INH基因片段α1-32插入到pcIS中乙肝表面抗原（HBsAg）S基因第112-113氨基酸残基密码子之间,构建含2拷贝INH的融合表达质粒pcISI。酶切和测序鉴定表明,重组质粒pcISI构建成功。脂质体包裹法将pcISI转染HeLa细胞,ELISA检测表达产物的INH免疫反应原性。结果表明,融合目的基因在HeLa细胞获得表达,ISI融合蛋白具有比IS融合蛋白更强的INH抗原抗体反应性。将pcISI免疫6只大鼠后,5/6的大鼠产生了抗INH抗体,抗体P/N值在免疫后第2-6周高于pcIS免疫组。这些结果表明,所构建的质粒pcISI可以表达抑制素,表达产物具有较强的免疫原性。     

猪生殖与呼吸综合征病毒GP5基因对小鼠的DNA免疫

将表达完整猪生殖与呼吸综合征病毒（PRRSV）GP5和融合表达泛素与GP5成熟肽的真核重组表达质粒（pCI—GP5和pcDNA—U—GP5）分别肌肉注射免疫BALB／c小鼠，共免疫3次。采用间接ELISA法检测血清中抗GP5的抗体水平，MTT法检测脾淋巴细胞的增殖能力，LDH释放试验检测脾NK细胞的杀伤活性，并通过流式细胞术检测脾淋巴细胞亚群的比例。结果发现，2种DNA重组质粒免疫后均可诱导小鼠产生体液免疫和细胞免疫。三免后第5周，pCI—GP5质粒免疫组诱导产生的抗GP5抗体水平及NK活性明显高于pcDNA—U—GP5质粒免疫组；而pcDNA—U—GP5免疫组的淋巴细胞增殖指数及CD4%-CD8^＋T细胞比例明显高于pCI—GP5组。表明，GP5基因可诱导产生较高的免疫反应，泛素与GP5的融合表达可增强PRRSVGP5诱导的细胞免疫反应。     

双拷贝抑制素基因免疫对大鼠卵泡发育、产仔及生殖激素的影响

将90只大鼠随机分为5组,分别注射10μg.100μL-1 pcISI(T1)、50μg.100μL-1 pcISI(T2)、100μg.100μL-1(T3)pcISI、100μg空载体pcMV-S(V)和100μL生理盐水(S),以探讨在不使用免疫佐剂的情况下,不同剂量的双拷贝抑制素pcISI基因免疫对大鼠卵泡发育、产仔和生殖激素的影响。结果表明,加强免疫能提高抗体P/N值,加强免疫后各剂量组平均抗体P/N值大于2,T3组抗体P/N值显著高于T1和T2组(P<0.05)。T3组成熟卵泡数显著高于对照组(P<0.05),且抗体阳性鼠成熟卵泡数比阴性鼠多12.45个(P<0.05)。除了T1组外,其他2个剂量组产仔数和胎盘数均高于对照组(P<0.05)。抗体阳性鼠胎盘数比阴性鼠多5.09个(P<0.05),产仔数比阴性鼠多5.39个(P<0.05)。抑制素pcISI基因免疫大鼠后促卵泡素(FSH)、雌二醇(E2)和孕酮(P4)含量均高于对照组,T3组的FSH含量与对照组差异显著(P<0.05),T3组的E2含量与对照组差异极显著(P<0.01),各剂量组P4含量与对照组差异均不显著(P>0.05)。这些结果说明,在没有免疫佐剂的前提下,双拷贝抑制素pcISI基因免疫可产生抗体,促进FSH分泌和卵泡发育,增加产仔数。本试验条件下100μg.100μL-1是最佳免疫剂量。     

抑制素基因免疫对南阳黄牛生殖激素的影响

选择40头南阳黄牛，用3．0毫克抑制素基因重组质粒（PCIS，免疫组，n=30）或同剂量的生理盐水（对照组，n=10）间隔21天注射2次，分别在首次免疫当天、首次免疫后第10天和第21天、加强免疫后第10天和第45天收集血清，应用放射免疫法（RIA）测定处理后不同时期血清中激素水平。结果表明：在5个采血时间点内．加强免疫后第10天抗体阳性牛比率最高．为37．5％，与其他采血时间点有显著差异。免疫组促卵泡素（FSH）平均含量比对照组高，但差异不显著；17-β雌二醇（E2）和孕酮（P4）水平在加强免疫后2组有显著性差异。     

mC3d3-DINHα（1～32）基因免疫对大鼠卯泡发育和生殖激素的影响

选择32只60日龄雌性性成熟大鼠分为4组，分别肌肉注射pcDNA-DPPISS-DINH（试验组1）50μg，poD—NA—DPPISS-DINH—mC3d3（试验组2）50μg，空载体pcDNA3．1（对照组1）50μg，生理盐水（对照组2）1mL。首次免疫20、40d后各组分别同剂量同样免疫程序加强免疫注射1次。结果发现，试验1和2组卵巢的重量都显著高于对照组1和2，但试验1和2组之间的差异不显著（P〉0．05）；试验2组卵巢成熟卵泡发育个数和FSH的浓度显著高于试验1组和对照1和2组（P〈0．05）；加强免疫第40天，试验1、2组的E1的浓度分别显著高于本试验组免疫前第0天，免疫后第20天的激素浓度；试验组与对照组在各个免疫试验时间LH的浓度在统计上差并不显著（P〉0．05）。结果证明，应用重组抑制素真核表达质粒pcDNA-DPPISS-DINH—mC3d3（试验组2）免疫动物可以促进大鼠卵泡的发育，可提高血浆FSH、E2水平，为抑制素基因免疫大动物提供了试验依据。     

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。     

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.     

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.     

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.     

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.     

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.     

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。