高原鼠兔消化管的解剖学形态特征

对 1 6例 (雄 1 0 ,雌 6 )高原鼠兔 (Ochotonacurzoni ae)的消化管进行了观察描述 :高原鼠兔的舌上有丝状、菌状、轮廓和叶状乳头 ;齿式为 2 2 0 321 0 2 3;单室胃 ,容积 3 2～8 0mL ;小肠平均长度为 970 1 7 88 0 8mm ,为体长的 7 31±0 2 8倍 ;大肠平均长度为 5 5 8 39± 6 6 39mm ,为体长的 4 2 1± 0 36倍 ;小肠与大肠总长度为 1 5 2 8 95± 1 4 7 78mm ,为体长 (1 32 78mm )的 1 1 5 2± 0 5 9倍 ;盲肠为 2 0 4 34±2 6 98mm ,为体长的 1 5 4倍。回盲口有盲小管 ,盲肠螺旋褶上有长丝状乳头 ,盲结口有盲结口瓣 ,盲结口下接结肠网状部。     

生物频谱对牛胚胎体外生产效率的影响

利用可调式周林生物频谱发生器对牛卵母细胞体外成熟、体外受精和体外培养过程实施辐射,以提高牛胚胎体外生产效率。频谱发生器与培养材料的距离为５ｃｍ,辐射强度根据辐射温度加以调节。结果表明,辐射温度控制在３９℃时,入孵卵母细胞的卵裂率（６３％）与对照组６１（％）无显著差异（Ｐ〉０．０５）,而囊胚发育率（３９％）显著高于对照组（１９％）（Ｐ〈０．０５）;当辐射温度达到４０℃时,试验组的卵裂率仅为１４％,囊     

氮素形态对紫花苜蓿盛花期生长及结瘤固氮的影响

在完全营养液条件下,采用砂培法,研究了3种氮素形态配比NO3--N,NH4+-N和NO3--N∶NH4+-N为1∶1和0、105、210mg/L 3个氮素水平对紫花苜蓿盛花期生长及结瘤固氮的影响。结果表明:不同形态氮素处理下紫花苜蓿的株高、生物量、根瘤数、根瘤重、固氮酶活性和全氮含量均显著高于CK。同一氮素水平下,株高表现为NO3--N和NH4+-N混合培养下效果最好,NO3--N培养下次之,NH4+-N培养下最低;生物量、根瘤数、根瘤重、固氮酶活性和全氮含量NO3--N和NH4+-N混合培养下效果最好,NH4+-N培养下次之,NO3--N培养下最低;茎叶比则是NO3--N培养下最大,NH4+-N培养下次之,NO3--N和NH4+-N混合培养下的最低,各氮素形态处理间差异显著(P0.05)。随着氮素水平的增加,各形态配比下紫花苜蓿的株高、生物量、根瘤数、根瘤重、固氮酶活性和全氮含量呈现增加的变化趋势,茎叶比呈现减小的变化趋势。NO3--N+NH4+-N的浓度为210mg/L时,紫花苜蓿的株高、生物量、根瘤数、固氮酶活性和全氮含量取得最大值,茎叶比取得最小值,根瘤重则在NO3--N+NH4+-N的浓度为105mg/L时取得最大值,紫花苜蓿在混合态氮培养下生长最好。     

Cliniconeuropathologic findings of familial frontal lobe epilepsy in Shetland sheepdogs

We examined an epileptic focus by electroencephalography (EEG) by using an international 10-20 electrode system in 11 Shetland sheep dogs affected with familial idiopathic epilepsy. We also performed an evaluation of the amino acids in the cerebrospinal fluid (CSF) and a pathologic examination of the brains of 8 dogs that died from status epilepticus. Continuous electroencephalography demonstrated that an epileptic focus was initially detected in the frontal lobe, particularly the internal area, and that paroxysmal foci developed diffusely in other lobes of affected dogs with recurrent convulsions. The EEG analyses indicated spike and sharp wave complexes, which were considered to be paroxysmal discharges. An increased value for glutamate or aspartate was found in the CSF of some epileptic dogs. Histologically, acute neuronal necrosis and astrocytosis were distributed predominantly in the cingulate cortex and internal area of frontal cortex, less frequently in other areas of the cerebrum. The results of this study suggest that, initially, the dogs have an epileptic focus in the frontal lobe, and that the focus extends gradually to other areas of the cerebrum. Based on the distribution of neuronal necrosis and astrocytosis, acute neuronal damage may be related to the superexcitation of neurons following epilepsy.     

Presentation of postweaning Escherichia coli diarrhea in southern Ontario, prevalence of hemolytic E. coli serogroups involved, and their antimicrobial resistance patterns

Post-weaning Escherichia coli diarrhea (PWECD) in Ontario was investigated using a case-control study involving 50 Ontario nurseries. The clinical signs and the impact on productive parameters were determined by means of a producer survey. The hemolytic E. coli serogroups involved in PWECD (O149:K91:K88) were examined in this study. Based on a polymerase chain reaction test, the hemolytic E. coli from 82% of the case herds were positive for 3 enterotoxins (STa, STb, and LT), those from 12% of the case herds were positive for STb and LT only, and those from one herd (6%) were positive for 3 enterotoxins, as well as for verotoxin and F18 pili. The E. coli involved in disease were resistant to multiple antibiotics. Case farms commonly used a wide variety of antibiotics either in the feed or water, or as injectable drugs. The most common antibiotic used to treat PWECD on the study farms was apramycin, but evidence of resistance to this antibiotic was noted. The PWECD problem was commonly seen within a week of weaning but onset of diarrhea was reported as late as the grower-finisher stage. Growth rate was poorer in case herds and mortality was higher than in control herds, demonstrating that PWECD is an economically important disease in Ontario.     

Improved immunobinding test using monoclonal antibodies for detection of Mycoplasma bovis in milk

The aim of this study was to evaluate an improved immunobinding test (IBT) using monoclonal antibodies to identify Mycoplasma bovis in naturally infected milk. The IBT and the improved IBT were highly specific and had an immunologic sensitivity of 5 × 10³ colony-forming units per milliliter. The results for the 2 methods agreed in the 130 milk samples tested. However, the IBT required 158 min, whereas the improved IBT required only 110 min. In addition, the improved IBT used smaller quantities of antibodies and conjugates.     

Avirulence and immunogenicity in mice of a bovine mastitis Staphylococcus aureus mutant.

An avirulent mutant, designated RC122, was derived from Staphylococcus aureus bovine mastitis strain RC108 after N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis. Mutant RC122, which was isolated on the basis of reduced colony size, showed diminished virulence in mice (LD50 of RC122: 3.1 x 10(10) cfu vs LD50 of RC108: 2.3 x 10(7) cfu). Mutant RC122 grew more slowly than its parental strain and showed decreased production of several exoproteins, such as alpha- and beta-hemolysin, DNAse and coagulase. The production of its capsule was induced only under in vivo growth conditions. Clearance studies performed in the mouse kidney revealed that the kinetics of disappearance of the mutant was similar to that of its parental strain. Protection experiments carried out by intraperitoneal administration in mice showed that mutant RC122 conferred a good degree of protection from challenge with homologous and heterologous strains.     

鸽新城疫病毒毒价的血凝价,ELD50和TCID50值相关性比较

本文比较了用血凝反应（ＨＡ）,在鸡胚成纤维细胞上的ＴＣＩＤ５０及用发育鸡胚做ＥＬＤ５０来测定鸽新城疫病毒（ＮＤＶ）毒价的相关性。结果表明,鸽ＮＤＶ毒价的ＴＣＩＤ５０和ＥＬＤ５０的值基本相同。ＨＡ滴度虽然与ＴＣＩＤ５０值有一定的相关性,但远不如ＴＣＩＤ５０准确。接种病毒后死亡鸡胚的新鲜尿囊液经冻融后,其中鸽ＮＤＶ的ＨＡ滴度和ＴＣＩＤ５０均逐渐下降。每经一次冻融,毒价几乎减少５０％。     

新型饲料添加剂—7—异丙氧基异黄酮的合成

７－异丙氧基异黄酮为一种新型饲料添加剂。用间苯二酚与苯乙酸直接酰化制得２,４二羟基苯基苄基酮,在吗啉、吡啶存在条件下与原甲酸三乙酯反应环合,再与乙－溴丙烷反应生成７－异丙氧基异黄酮,总收率为５６％。     

全国桑蚕一代杂交种质量调查及行业标准实施评价Ⅱ.良卵率、良卵数调查及评价

依据 1999- 2 0 0 3年监督抽查春用桑蚕一代杂交种质量的检验结果 ,分析良卵率和良卵数质量指标的测试成绩认为 :散卵种良卵率≥ 97%的指标比较合理 ,而平附种良卵率≥ 90 %的指标偏低 ,可提高到 94 %～ 95 % ;良卵数 (粒 ) /盒 (张 )连续 5年合格率都在 5 0 %以下 ,说明这一指标不适合目前的生产情况 ,可考虑将这一指标改为规定下限 ,允许有不同的卵量。