肉鸡腹水症

危害快速生长幼龄肉鸡的腹水综合症(ascites syndrome)已成为肉鸡饲养业世界性的严重问题。本病主要表现为腹腔内积聚大量血清样液体。由于许多因素可引起腹腔积液,因此这种异常仅是一种症状,而不是特异性的疾病。该症于1946年首次报道于美国,当时是雏火鸡发生腹水症。随后,腹水症便很快成为一些高海拔(>1500米)国家养鸡业的常见问题,如南美、墨西哥和南非,有时腹水症引起的死亡率高达30％。因此,有人认为腹水症与高海拔有关,而把它称作“高海拔病”(alti-     

γ射线防治美洲幼虫腐臭病在商业上的应用

引言美洲幼虫腐臭病(AFB)是一种蜜蜂幼虫病,可造成蜂蜜生产、蜂数和蜂群的重大损失。此病系幼虫芽孢杆菌(Bacilluas larvae)引起,可由受该菌孢子污染的蜂具在箱、群之间传播。用γ射线照射受污染的蜂具,可杀死上面的孢子,对养蜂业极为有益。为此,本文特谈谈这种技术。     

预防B型变异株的一种新型传染性鼻炎四价疫苗的效力

传染性鼻炎是由副鸡嗜血杆菌引起的鸡的一种急性呼吸道疾病，目前在生产上主要使用含有代表A、B、C三种血清型（按Page分类（1962））的两种或多种菌株制成的灭活疫苗。到目前为止，这些疫苗对特定血清型菌株的合并感染提供了令人满意的免疫保护。免疫失败通常与某些商品疫苗中遗漏其中些分离株进行血清分型。结果发现了多     

猪的胚胎(受精卵)移植

猪在家畜中繁殖力最高,因此胚胎移植技术对于提高猪个体繁殖能力的价值就不如对繁殖力较低的牛和羊等大。但从育种方面来说,用卵移植法在短时期内使个体母猪产生大量后代或从未成熟母猪得到受精卵以缩短世代间隔却仍然是有价值的。卵移植在猪育种工作中实     

绵羊和牛摄食行为自动记录装置的发展和使用

<正> 前言目测牧食和反刍活动是费力的强劳动,一些学者已经应用自记仪器在野外自动记录这些活动。振动器(Vibracorder)用振摆原理和钟的机械装置记录牧食时间和频率已被广泛采用(Allden,1962;Stobbs,1970;Sarker 和 Holmes,1974,Castle 等1975),移位微动开关已被用于记录颌的活     

牛弥漫性无败性蹄叶炎的病因、发生和防制

弥漫性无败性蹄真皮炎(蹄叶炎)是牛跛行和不安而造成经济损失的主要原因。蹄叶炎由多种致病因素引起,对大多数病因不十分清楚。给不习惯的牛饲喂易发酵的碳水化合物易诱发该病。被认为涉及到的有组胺、乳酸和内毒素。全身性酸中毒、组胺中毒和内毒素血症形成蹄叶炎的病理生理学特征。主要根据蹄双侧对称性损害和所有患蹄特征性跛行的观察来诊断。眼观损害有蹄背侧壁凹陷、蹄底颜色改变和蹄骨转位。蹄真皮的组织学检查都有变性变化和动脉硬化、此外还有血栓和肉芽组织。对该病可用保守疗法并应用抑制环加氧酶的非类固醇抗炎药进行治疗,通过合理的饲养管理进行防制。     

Population Structure of Phytophthora cinnamomi in South Africa

ABSTRACT Phytophthora cinnamomi isolates collected from 1977 to 1986 and 1991 to 1993 in two regions in South Africa were analyzed using isozymes. A total of 135 isolates was analyzed for 14 enzymes representing 20 putative loci, of which four were polymorphic. This led to the identification of nine different multilocus isozyme genotypes. Both mating types of P. cinnamomi occurred commonly in the Cape region, whereas, predominantly, the A2 mating type occurred in the Mpumalanga region of South Africa. A2 mating type isolates could be resolved into seven multilocus isozyme genotypes, compared with only two multilocus isozyme genotypes for the A1 mating type isolates. Low levels of gene (0.115) and genotypic (2.4%) diversity and a low number of alleles per locus (1.43) were observed for the South African P. cinnamomi population. The genetic distance between the Cape and Mpumalanga P. cinnamomi populations was relatively low (D(m) = 0.165), and no specific pattern in regional distribution of multilocus isozyme genotypes could be observed. The genetic distance between the "old" (isolated between 1977 and 1986) and "new" (isolated between 1991 and 1993) P. cinnamomi populations from the Cape was low (D(m) = 0.164), indicating a stable population over time. Three of the nine multilocus isozyme genotypes were specific to the "old" population, and only one multilocus isozyme genotype was specific to the "new" population. Significant differences in allele frequencies, a high genetic distance (D(m) = 0.581) between the Cape A1 and A2 mating type isolates, significant deviations from Hardy-Weinberg equilibrium, a low overall level of heterozygosity, and a high fixation index (0.71) all indicate that sexual reproduction occurs rarely, if at all, in the South African P. cinnamomi population.