热带假丝酵母菌与桑叶黄酮对犊牛营养物质代谢和瘤胃发酵的影响

本文旨在研究饲粮中添加热带假丝酵母菌(CT)与桑叶黄酮(MLF)对断奶前后犊牛能量与氮代谢、瘤胃微生物蛋白合成以及瘤胃发酵的影响。选取(20±2)日龄中国荷斯坦公犊牛48头,随机分为4组,对照组(CON)饲喂基础饲粮,断奶前为代乳品和开食料,断奶后为开食料;CT组在基础饲粮中添加CT;MLF组添加MLF;CM组添加CT和MLF。犊牛于56日龄断奶(代乳品),试验期60 d。分别于犊牛28、42、56和80日龄采集瘤胃液,35和63日龄进行消化代谢试验。结果表明:与CT组相比,CM组犊牛断奶前代谢能显著提高(P0.05),较CON组,断奶后CM组氮利用率显著提高(P0.05);断奶前MLF组较CON和CT组氮的生物学价值显著提高(P0.05)。与CON组相比,CT组显著提高了28~80日龄瘤胃液p H和56、80日龄瘤胃液微生物蛋白含量(P0.05),CT、MLF和CM组瘤胃液氨态氮浓度无显著变化(P0.05);与CON组相比,56日龄M LF组总挥发性脂肪酸浓度和丁酸含量显著提高(P0.05);42日龄乙酸/丙酸CT和MLF组较CON组有提高的趋势(P=0.090),各组间乙酸和戊酸含量无显著差异(P0.05)。结果提示,饲粮添加CT有助于改善断奶前犊牛瘤胃液p H和促进瘤胃微生物蛋白的合成;添加CT和MLF有助于提高断奶前犊牛饲粮代谢能和氮的生物学价值,提高断奶后犊牛总能代谢率和氮的利用率,降低粪能和总排出氮量,同时具有改善瘤胃发酵的作用,并且CT与MLF联合使用效果优于单一添加。     

根据个体间蛋白质多位点基因型的比较分析中国黄牛的遗传关系

现行群体间遗传距离的度量方法都以等位基因频率的计算为依据，这些方法的缺点之一是在位点不多，多态笥不高时要求群体有较大的取样个体数目，另外，这些方法所建造的树素图不能反映群体是由混血引起还是由长期进化引起这一问题，针对这些问题，本文提出了以个体间蛋白质多位点基因型比较为基础的群体间遗传距离和群体内基因杂合度的度量方法，以十个主要中国黄牛群体的遗传关系分析为例，比较圆满的解决了上面几个问题。     

猪霉麦中毒和霉麦无害化处理的研究

对1983年嫩江地区某地猪喂霉麦引起的中毒进行了系统研究。通过霉菌菌相、菌量分析,明确了霉麦的优势菌为黄曲霉菌;通过流行病学调查、优势菌的产毒试验、毒素的化学确证试验、当日鸭雏的生物学确证试验以及猪的回归试验等,证明黄曲霉毒素B_1(AFT B_1)是造成猪短期内大批死亡的原因。同时,进行了霉麦无害化处理试验,初步证明用0.02％次氯酸钠处理具有杀菌、除毒效果可靠等特点。     

Metabolism of microbial nitrogen in ruminants with special reference to nucleic acids

Characteristically the metabolism of microbial nitrogen (N) compounds in ruminants involves the degradation of dietary N and synthesis of microbial protein (MP), compounds including a small amount of peptides and free amino acids, which may account for 75–85% of total N and the remainder are nucleic acids (NA: DNA and RNA). Generally rumen microbes contain 10–25% NA‐N of the total N while 70–80% is in the form of RNA. This paper describes the degradation and synthesis of NA in the rumen and their fate in the lower digestive tracts. Their physiological and nutritional significance in different types of ruminant animals is also discussed. The research works on NA metabolism in ruminants has been mainly on metabolism of purines after rumen microbial digestion and absorption in the lower gut. Subsequently, the fate of absorbed purines has been intensively investigated to assess the extent of MP synthesis in the rumen. The method for predicting ruminal synthesized MP and subsequently digested MP has been proposed using urinary purine derivative (PD) excretion in sheep and cattle fed on ordinary feed. The latter approach has now been adopted for calculation of protein supply in some feeding standards, although there are still difficulties in predicting representative samples of rumen microbes, and also uncertainties in variations of non‐renal and endogenous purine losses.     

用重组核衣壳蛋白ELISA检测PRRSV抗体的研究

ＰＲＲＳＶ重组Ｎ蛋白ＥＬＩＳＡ检测人工感染猪血清７５份,与ＩＤＥＸＸ公司ＥＬＩＳＡ试剂盒及ＩＦＡ的符合率分别为９７．３％和１００％。检测疫苗免疫猪血清,阳性率１００％。在免疫后６ｄ就能检出抗体,比ＩＦＡ敏感。检测８５份我国田间猪血清,阳性率１８．８％。     

Radiosensitivity and capacity for radiation-induced sublethal damage repair of canine transitional cell carcinoma (TCC) cell lines

Understanding the inherent radiosensitivity and repair capacity of canine transitional cell carcinoma (TCC) can aid in optimizing radiation protocols to treat this disease. The objective of this study was to evaluate the parameters surviving fraction at 2 Gy (SF(2) ), α/β ratio and capacity for sublethal damage repair (SLDR) in response to radiation. Dose-response and split-dose studies were performed using the clonogenic assay. The mean SF(2) for three established TCC cell lines was high at 0.61. All the three cell lines exhibited a low to moderate α/β ratio, with the mean being 3.27. Two cell lines exhibited statistically increased survival at 4 and 24 h in the dose-response assay. Overall, our results indicate that the cell lines are moderately radioresistant, have a high repair capacity and behave similarly to a late-responding normal tissue. These findings indicate that the radiation protocols utilizing higher doses with less fractionation may be more effective for treating TCC.     

Effects of Supplementing a Basal Diet of Chloris gayana Hay with One of Three Protein-rich Legume Hays of Cassia rotundifolia,Lablab purpureus and Macroptilium atropurpureum Forage on Some Nutritional Parameters in Goats

Growth and digestibility experiments were conducted on growing East African type goats offered Chloris gayana hay supplemented with one of three high-protein (119–128 g CP/kg DM) legume hays, Cassia rotundifolia (cassia), Lablab purpureus (lablab) or Macroptilium atropurpureum (siratro), and crushed maize to investigate the feed intake, digestibility, growth and urinary excretion of purine derivatives. Goats in the supplemented groups had higher total dry matter and nitrogen intakes and higher N retention and body mass gains than unsupplemented counterparts. The digestibility of dry matter, organic matter and neutral detergent fibre were increased by protein supplementation. Animals on supplemented diets had higher fractional outflow rates of particulate matter from the rumen. The production of protein by ruminal microbes and the efficiency of microbial N production were increased by supplementation. It was concluded that a mixture of low-quality grass hay (61.9 CP/kg DM) and either cassia, lablab or siratro hay, and maize grain can provide a productive balanced diet for growing goats.     

转基因技术在畜牧兽医中的发展前景

通过简要叙述转基因动物研究的发展简史、研究现状和存在问题 ,对转基因动物育种、药物生物反应器、组织器官移植 ,以及基因治疗和免疫等前景进行了综述。在此基础上 ,从畜牧兽医角度出发提出了追踪发展趋势的几点思考。