中国优质家禽产业化育种制种探索

当人们对禽产品在卫生、保健、风味、口感等方面有了更高需求时,就为培育具有中国特色的生态型优良家禽品种(品系)提供了广阔市场天地。文章对当前中国家禽育种制种的发展方向做了阐述,提出了几种确实有效的育种方案和方法。     

B—单型特异血清型对马立克氏病疫苗免疫效果的影响

以前的研究表明，Ｂ－单型地抵抗超强毒马立克病病毒攻击的效果依所使用的马立克氏病疫苗的种类不同而不同。为了测定同一血清型ＭＤ疫苗接种同一单型鸡后用ＭＤＭｄ５强毒攻击是否产生相似的保护性。     

蜂群的熏烟治螨技术

由于应用二—磷—氯苯基—乙醇杀螨剂治疗由武氏尘螨引起的壁虱病,所以,在蜂群中把烟当作杀螨剂的一种载体已变得非常重要。蜂群的喷烟治疗意即蜂群中的所有蜜蜂都暴露在特定浓度的烟笼罩下的特定空间内。因此,蜂群的熏烟技术必须包括以下几个方面:烟在蜂箱内均匀分布;烟的浓度;蜜蜂对熏烟治疗的抵抗力;尤其应考虑到温     

Field evaluation of melatonin implants to advance the breeding season in 1-year-old farmed red deer hinds

The efficacy of controlled-release melatonin implants to advance the onset of the breeding season was assessed in 1-year-old red deer hinds on five commercial deer farms in various localities in the North Island of New Zealand. Between 44 and 60 hinds in each of six herds were equally divided among treatment and control groups at each site. Melatonin treatment commenced between 27 November and 16 December and was achieved by the subcutaneous administration of two 18 mg melatonin implants. Three doses were given at about 30 day intervals. Two adult stags for each hind group were treated with three 18 mg melatonin implants concurrently on either two or three occasions. On each property, treated and control hinds were joined as one herd to treated stags commencing 30 January-10 February and concluding 15 May-2 June. The hinds in the four experimental herds underwent rectal ultrasound examination May-June to estimate conception rate and foetal age. Calving dates, hind and calf mortalities, weaning weights, and the antler growth cycle and harvesting data were recorded. Overall, treatment with melatonin resulted in an average advance of the median calving date of 22 days (range 12-36 days) when compared with untreated controls in the same herds. Pregnancy rates were 91.3-100% in treated hinds and 63.6-100% in untreated hinds. There were no differences in calf mortality or calf sex ratio between treated and untreated groups. No hind deaths could be attributed to melatonin treatment. The weaning weights of calves were 5.68 kg and 4.43 kg heavier for the male and female offspring of treated hinds respectively, compared with those of control hinds. Treated stags commenced rutting behaviour earlier than normal and the antler casting and growth cycle was advanced. Treatment resulted in advancement of the seasonal pattern of coat changes in hinds and stags, but no untoward side effects of the melatonin treatments were observed.     

Conservation and duplication of isozymes in plants

Many enzymes in plants have isozymes because the same catalytic reaction is often present in several subcellular compartments, most frequently the plastids and the cytosol. The number and subcellular locations of the isozymes appear to be highly conserved in plant evolution. However, gene duplication in diploid species and the addition of genomes in polyploid species have increased the number of isozymes.     

Prevalence of antimicrobial resistance among Salmonella on midwest and northeast USA dairy farms

The objective of this study was to determine the prevalence of antimicrobial resistance among Salmonella isolated from dairy herds in New York, Minnesota, Michigan, and Wisconsin, USA. Serogroup and antimicrobial susceptibility characteristics were determined for Salmonella from cattle and environmental samples collected during August 2000–October 2001 as part of a longitudinal study where 129 herds were visited at 2-month intervals. Salmonella isolates were tested (using a broth microdilution method) for susceptibility to amoxicillin/clavulanic acid, ampicillin, ceftiofur, ceftriaxone, cephalothin, chloramphenicol, ciprofloxacin, gentamicin, kanamycin, nalidixic acid, streptomycin, sulfamethoxazole, tetracycline, and trimethoprim/sulfamethoxazole. Of the 1506 isolates tested for minimum inhibitory concentrations to these 14 antimicrobial agents, 81.2% were pan-susceptible and for most herds (81.6%) the predominant antimicrobial resistance pattern was pan-susceptible. At least 1 Salmonella isolate resistant to 5 or more antimicrobial agents was found on 23.6% of herds. This resistance phenotype was most common among serogroups B and E1 and among samples from calves and farmer-designated sick cows. Resistant samples most frequently exhibited resistance to tetracycline, streptomycin, and/or ampicillin. No samples were resistant to ceftriaxone (though 13 were in the intermediate range), and very few samples were resistant to ciprofloxacin (n = 1), nalidixic acid (n = 5), or trimethoprim/sulfamethoxazole (n = 7).     

Bovine respiratory disease in feedlot cattle: phenotypic, environmental, and genetic correlations with growth, carcass, and longissimus muscle palatability traits

Bovine respiratory disease (BRD) is the most costly feedlot disease in the United States. Selection for disease resistance is one of several possible interventions to prevent or reduce the economic loss associated with animal disease and to improve animal welfare. Undesirable genetic relationships, however, may exist between production and disease resistance traits. The objectives of this study were to estimate the phenotypic, environmental, and genetic correlations of BRD with growth, carcass, and LM palatability traits. Health records on 18,112 feedlot cattle over a 15-yr period and slaughter data on 1,627 steers over a 4-yr period were analyzed with bivariate animal models. Traits included ADG, adjusted carcass fat thickness at the 12th rib, marbling score, LM area, weight of retail cuts, weight of fat trim, bone weight, Warner-Bratzler shear force, tenderness score, and juiciness score. The estimated heritability of BRD incidence was 0.08 +/- 0.01. Phenotypic, environmental, and genetic correlations of the observed traits with BRD ranged from -0.35 to 0.40, -0.36 to 0.55, and -0.42 to 0.20, respectively. Most correlations were low or negligible. The percentage of carcass bone had moderate genetic, phenotypic, and environmental correlations with BRD (-0.42, -0.35, and -0.36, respectively). Hot carcass weight and weight of retail cuts had moderate, undesirable phenotypic correlations with BRD (0.37 and 0.40, respectively). Correlations of BRD with LM palatability and ADG were not detected. Low or near zero estimates of genetic correlations infer that selection to reduce BRD in feedlot cattle would have negligible correlated responses on growth, carcass, and meat palatability traits or that selection for those traits will have little effect on BRD susceptibility or resistance.     

巴氏新小绥螨章鱼胺受体基因鉴定与表达模式分析

为明确巴氏新小绥螨(Neoseiulus barkeri)章鱼胺受体基因的分子特征,探明其药理学和生理功能,运用转录组数据和生物信息学软件分析并鉴定章鱼胺受体基因的cDNA全长,利用qRT-PCR(Quantitative real-time polymerase chain reaction)比较章鱼胺受体基因在巴氏新小绥螨不同发育阶段、不同温度及饥饿胁迫条件下的表达模式.结果表明：于转录组数据库筛选鉴定到6个章鱼胺受体基因,分别命名为NbOctα1R1,NbOctα1R2,NbOctTyrR,NbOctβ2R1,NbOctβ2R2,NbOctβ3R,其完整开放阅读框为936～1 983 bp,编码312～661个氨基酸,在进化关系上与西方静走螨(Galendromus occidentalis)最为接近.NbOctα1R1,NbOctα1R2,NbOctTyrR,NbOctβ2R1,NbOctβ3R都具备G蛋白偶联受体的典型特征. 6个章鱼胺受体基因在巴氏新小绥螨不同螨态均有表达,且在幼螨和若螨中表达水平较高.在不同温度胁迫条件下,不同章鱼胺受体基因在成螨和幼螨中受低温、高温影响后...     

香根草对铜绿微囊藻的生长抑制及其成分分析

随着水体富营养化程度的加剧,藻类等大量繁殖,在对水体造成破坏的同时,藻类产生的藻毒素会使动物中毒或通过食物链传递,威胁人类的健康。为控制富营养化水体中蓝藻的数量,减少水华的发生,利用生态浮床技术,以浮床植物香根草为研究对象,通过在铜绿微囊藻培养中添加香根草种植水,研究香根草对铜绿微囊藻的抑制效应。每3 d使用血球计数板计算藻细胞密度,记录接种微囊藻的种植水和对照处理下的藻类数量;并用分光光度法测定培养液中铜绿微囊藻的叶绿素a含量,使用固相萃取方法收集香根草种植水中的根系分泌物,经气质联用仪(GC-MS)分析香根草种植水中的化学物质。结果表明:以蒸馏水培养5 d收集获得的香根草种植水对铜绿微囊藻的生长有明显的抑制作用。与对照组相比,香根草种植水中培养的铜绿微囊藻生长缓慢。其中培养6 d后,香根草种植水开始对铜绿微囊藻的生长产生抑制作用,且抑制作用随时间的推移而增加,在与铜绿微囊藻共培养21 d后,抑制率达到76%。种植水中藻类叶绿素a含量为447. 62 mg/L,对照组铜绿微囊藻叶绿素a含量则高达3 592 mg/L,为试验组的8倍。香根草根系分泌物中有24种化合物,其中己酸、棕榈酸、硬脂酸等脂肪酸对铜绿微囊藻等藻类有抑制作用。2-羟基丙酸相对含量最高,为50. 71%;其次是棕榈酸,相对含量为23. 2%。香根草种植水通过抑制铜绿微囊藻的光合作用,对铜绿微囊藻的生长产生抑制作用。