瘤胃保护性蛋氨酸对奶牛的营养作用

瘤胃保护性蛋氨酸(RPMet)经过瘤胃后在小肠转化为蛋氨酸(Met),可增加进入小肠的Met数量,改善小肠氨基酸平衡,提高血清中必需氨基酸浓度、奶牛氮的利用率及其生产性能等.本文综述了RPMet对奶牛的营养作用.     

日粮中不同维生素A和维生素E添加水平对肉仔鸡维生素生物学利用率的影响

本文旨在研究肉仔鸡日粮中添加不同水平维生素A、维生素E对其生物学利用率的影响.选用1日龄爱拔益加(AA)肉仔鸡960只,随机分为4个处理,每个处理3个重复,每个重复80只鸡.试验日粮参照AA肉仔鸡推荐标准配制,4个处理的日粮维生素A、维生素E添加水平分别为:6 375和37.5 IU/kg、8 500和50 IU/kg、10 625和62.5 IU/kg、12 750和75 IU/kg.试验期49 d.研究表明:增加日粮维生素A、维生素E水平可以改善肉仔鸡增重和料重比.肉仔鸡血清和肝脏中维生素A、维生素E水平均随日粮添加水平的增加而提高.维生素A、维生素E水平从AA肉仔鸡推荐量(8 500和50 IU/kg)降至6 375和37.5 IU/kg时,肉仔鸡血清中维生素A、维生素E水平降低了8.42%(P>0.05)和12.14%(P<0.05),肝脏中维生素A、维生素E降低了9.04%和5.12%(P>0.05);维生素A、维生素E水平分别增加至12 750和75 IU/kg时,血清维生素A、维生素E水平提高了6.44%(P>0.05)和42.21%(P<0.01),肝脏维生素A、维生素E提高了192.58%和65.03%(P<0.01).由此可知,提高日粮维生素A、维生素E水平可提高肉仔鸡血清和肝脏中维生素A、维生素E的水平.     

鸭茅的营养价值评定

以宝兴鸭茅(Dactylis glomerata L.)为对照,对鸭茅新品系YA02-116、YA01-101、YA01-103、02123、01071的营养价值及其刈割影响进行了评价。结果表明:刈割对鸭茅营养有直接影响,刈割后再生草的蛋白质含量较初次刈割材料有明显下降,纤维含量显著升高(P<0.05),营养价值降低。通过隶属函数法对所有供试材料综合评价表明,材料YA 02-116、YA 01-101的营养价值较好,高于对照品种宝兴鸭茅,具有一定开发利用价值,为鸭茅新品种的选育提供了参考。     

中国肉牛业现状和发展对策

本文介绍了中国肉牛业的现状，分析了中国肉牛业生产中存在的3个方面的问题，提出了中国肉牛业发展的5个对策，即继续开展肉牛改良，加快肉牛良种培育和扩繁；提高肉牛饲养管理水平，促进优质肉牛生产；提高牛肉产品质量；实现产业化生产；实施牛肉品牌战略。     

大通县马属动物住肉孢子虫感染情况调查报告及形态学观测

作者等于2007年4月至2007年10月期间,在大通县宰马场的马胴体中进行了住肉孢子虫感染情况的调查,结果被检查的200匹马胴体中,检查出住肉孢子虫的21匹,感染率为10.5%;每0.1克肌肉中,感染强度在1-12之间,平均感染强度3.6;从不同部位的感染来看,膈肌、心肌、食道肌的感染率分别为:5.5%、6.5%、10.5%,从其它肌肉中未发现住肉孢子虫;不同部位的形态膈肌主要以长紡锤形为主,心肌以长椭圆为主,食道肌以长形为主,并对各部位发现的虫体形态进行了拍照,以供同行参考。     

放牧对草地植物群落的影响

从放牧强度、放牧制度、家畜采食习性等方面综述了放牧对草地植物群落的影响.适宜的放牧强度可促进草地的健康发展,丰富草地的生物多样性;放牧制度在不同地区的应用有差别,合理的放牧制度有利于维持草地生态平衡和草地生产力的提高.     

Changes in peripheral blood leukocyte subpopulations in piglets co-infected experimentally with porcine reproductive and respiratory syndrome virus and porcine circovirus type 2

Porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2) are pathogens, which can significantly affect the swine industry worldwide. Field surveys suggest that simultaneous PRRSV and PCV2 infection is common in pigs. The objective of this study was to measure the changes in peripheral blood leukocyte subpopulations in piglets co-infected experimentally with PRRSV and PCV2, in order to analyze the synergistic influence of co-infection on the immune system. Changes in peripheral blood leukocyte subpopulations were systematically measured by flow cytometry (FCM). The levels of antibodies to PRRSV and PCV2 were detected by indirect Enzyme-Linked ImmunoSorbent Assay (ELISA) and the indirect fluorescent antibody test (IFA), respectively. Serum viral loads were measured using real-time PCR. The results showed that piglets co-infected with PRRSV and PCV2 exhibited slower generation and lower levels of antibodies to PRRSV and PCV2, and increased amounts and a prolonged presence of both PRRSV and PCV2 in serum, in comparison to the piglets infected with either virus alone. The major finding in our study was that the total and differential leukocyte counts, including white blood cells (WBCs), monocytes, granulocytes and lymphocytes (T, B and NK cells, as well as T-cell subpopulations), dramatically decreased early during co-infection with PRRSV and PCV2 for about two weeks, in contrast with animals singly infected with either PRRSV or PCV2. These results suggest that PRRSV and PCV2 co-infection results in a synergistic decrease in immune cells in the peripheral blood of piglets. These data contribute to the understanding of the immunosuppressive effects resulting from PRRSV and PCV2 co-infection in pigs.     

家蚕原种人工饲料适应性品系的选拔

研究了家蚕中、日系原种与杂交种对人工饲料适应性的差异；经累代定向选择，建立了苏５、青松人工饲料适应性品系，该品系对人工饲料适应性比非选拔系有明显提高，配以优良的原种饲料，进行原种稚蚕人工饲料育，综合成绩基本达到桑叶育水平。     

复方中药发酵液对肉鸡大肠杆菌病的防治效果及免疫调节作用

试验旨在研究复方中药发酵液对肉鸡大肠杆菌病的防治效果及免疫调节作用。选择健康1日龄AA白羽肉鸡240羽,分别进行大肠杆菌O78半数致死剂量和复方中药发酵液对大肠杆菌病的防治试验。在28日龄评价治疗效果,并在28、42日龄分别检测免疫器官指数、抗氧化指标和肠道菌群等指标。结果显示,经过植物乳杆菌和枯草芽孢杆菌等菌株发酵后的复方中药发酵液能够将大肠杆菌的感染时间由4 h延迟至24 h,高剂量组（1.0 g/mL）、中剂量组（0.5 g/mL）、抗生素组（硫酸新霉素）有效率分别为80.0%、76.7%和80.0%,治愈率分别为80.0%、70.0%和70.0%;高剂量组与感染组和抗生素组相比,28日龄时胸腺指数分别提高了165.6%（P<0.05）、25.4%（P>0.05）,法氏囊指数分别提高了82.6%和94.3%（P<0.05）,42日龄时胸腺指数分别提高了97.4%和82.0%（P<0.05）,法氏囊指数分别提高了43.4%和27.5%（P<0.05）,28、42日龄时抗氧化指标T-AOC、TP含量及GSH-Px、T-SOD活性差异显著（P<0.05）,能够显著提高肠道内乳酸菌含量,降低大肠杆菌含量（P<0.05）。综上,中剂量组（0.5 g/mL）复方中药发酵液抗菌效果明显,能够替代抗生素,高剂量组（1.0 g/mL）复方中药发酵液对肉鸡其他指标明显优于抗生素。     

Estimation of genetic parameters for reproductive traits in connectedness groups of Duroc,Landrace and Yorkshire pigs in China

The objective of this study was to estimate group- and breed-specific genetic parameters for reproductive traits in Chinese Duroc, Landrace, and Yorkshire populations. Records for reproductive traits between April 1998 and December 2017 from 92 nucleus pig breeding farms, which were involved in the China Swine Genetic Improvement Program, were analysed. Due to weak genetic connectedness across all farms, connectedness groups consisting of related farms were used. Three, two and four connectedness groups for Duroc, Landrace and Yorkshire were firstly established according to the genetic connectedness rating among farms. For each connectedness group a five-trait animal model was implemented, and via restricted maximum likelihood procedure the genetic parameters were estimated for five reproductive traits i.e., total number born (TNB), number born alive (NBA), litter weight at farrowing (LWF), farrowing interval (FI) and age at first farrowing (AFF). The average of heritabilities among connectedness groups ranged from .01 (for FI in Yorkshire) to .30 (for AFF in Duroc). Estimates of repeatability for litter traits ranged from .14 to .20 and were consistent for each breed, and for FI, the estimates varied from .01 to .11 across breeds and groups. The estimated genetic correlations among litter traits (i.e., TNB, NBA and LWF) were all significantly high (>.56) and similar across breeds. Averaged genetic correlations over three breeds were −.25, −.27, −.18, −.04, −.10, −.02, and .28 for FI-TNB, FI-NBA, FI-LWF, AFF-TNB, AFF-NBA, AFF-LWF and FI-AFF, respectively. The standard errors of the estimates were all very low (<0.01) in most situations. Results from this study suggest that selection based on TNB which is currently used in dam line selection index can improve NBA and LWF simultaneously. However, care should be taken on FI and AFF as they are both greatly influenced by non-genetic factors such as management and measurement.