日粮中添加玉米油对肉牛瘤胃发酵的影响

3头装有瘤胃瘘管的成年杂种牛 ,按 3× 3拉丁方试验设计 ,饲以添加 0 %、4 %和 8%玉米油的稻草和精料混合料 ( 2 1 )日粮。在饲喂后 2、4、6、8h采集瘤胃液样品 ,分别测定瘤胃液pH值、NH3-N和VFA浓度。结果表明 ,添加 4 %和 8%玉米油对瘤胃液pH值、NH3-N浓度没有显著影响 (P >0 .0 5) ;添加玉米油 4 %对瘤胃总VFA浓度没有显著影响 (P >0 .0 5) ,但添加 8%玉米油使瘤胃总VFA和乙酸浓度显著下降 (P <0 .0 5)。添加 8%以下的玉米油对丙酸、丁酸浓度没有影响 (P >0 .0 5) ,结果使乙酸 /丙酸比值从 3.75分别下降到 3.2 6和 3.1 4 (P <0 .0 5)。     

Pathogenesis of GIII.2 bovine norovirus,CV186-OH/00/US strain in gnotobiotic calves

The pathogenesis of GIII.2 bovine norovirus (BoNoV) is not well understood. Our study demonstrated persisting diarrhea and prolonged fecal shedding, but with a lack of significant intestinal lesions in gnotobiotic (Gn) calves infected with GIII.2 BoNoV, CV186-OH/00/US strain. Nine 4 to 7-day-old Angus/Jersey crossbred Gn calves were orally inoculated with 10.0–11.9 log₁₀ genomic equivalents (GE)/calf of CV186-OH (n = 7) or mock (n = 2). Calves were euthanized at post-inoculation day (PID) 1 (n = 1) when moderate to severe lethargy was observed and at PIDs 2–6 (n = 4) after lethargy had subsided. Two calves were kept longer term (until PID 30) for monitoring fecal shedding patterns by TaqMan real-time RT-PCR (qRT-PCR). Most infected calves exhibited two clinical signs: (i) acute but persisting diarrhea and (ii) acute moderate to severe lethargy. The two infected calves, followed longer-term, had prolonged fecal viral RNA shedding [peak average titer of 11.8 (±0.2) log₁₀ GE/ml] at least until PID 20. By qRT-PCR, 5 infected calves had low viral RNA titers in serum, ranging from 4.0 to 5.8 log₁₀ GE/ml, at PIDs 1–5, but not (<2.7 log₁₀ GE/ml) at PIDs 6–30. The latter observation coincided with the presence of serum IgG antibody to BoNoV at PIDs 8–30. Collectively, the GIII.2 BoNoV strain CV186-OH induced only mild enteropathogenicity, evident by the lack of significant intestinal lesions, but it led to persisting mild diarrhea and prolonged fecal virus shedding in Gn calves. The prolonged fecal shedding of GIII.2 BoNoV might partially explain how this virus is maintained as endemic infections in cattle.     

Physiology and Treatment of Retained Fetal Membranes in Cattle

Retained fetal membranes (RFM) in cattle have adverse effects on fertility and production. Understanding the pathophysiology and causes of RFM is important for managing this disease. The hormonal processes that lead to normal placental separation are multifactorial and begin before parturition. A variety of risk factors, including early or induced parturition, dystocia, hormonal imbalances, and immunosuppression, can interrupt these normal processes and result in retention of the placenta. Current research does not support the efficacy of many commonly practiced treatments for RFM. Systemic administration of antibiotics can be beneficial for treating metritis after RFM, but antibiotic administration has not been shown to significantly improve future reproduction in cows with RFM. Collagenase injected into the umbilical arteries of retained placentas specifically targets the lack of placentome proteolysis and might enhance placental release. However, such therapy is costly and its benefits in terms of improving subsequent reproductive function have not been evaluated.     

牛体尺影响因素及其应用

牛体尺指标在一定程度上可以评价品种优劣及生产性能的高低。本文对影响牛体尺的因素做一综述,并从体尺与估测体重、屠宰性能、种公牛繁殖性能、奶牛产奶性能4个方面概述牛体尺应用情况,以期为今后生产中评估牛的肉用经济价值、群遗传选育、改善群体繁殖性能和提高生产性能提供一定的借鉴和指导。     

我国肉牛生产发展之管见

本文通过对目前我国肉牛生产发展概况的介绍并与世界主要国家和地区情况的对比，阐述了自己对核问题的看法。对存在问题的原因进行了初步分析，并提出了建设性意见。     

Results of a Preliminary Trial with Sphaerophorus necrophorus Toxoids to Control Liver Abscesses in Feedlot Cattle

A preliminary field experiment was undertaken to evaluate the efficacy of alum precipitated toxoids of Sphaerophorus necrophorus prepared from sonicated whole cells and cell fractions to reduce the incidence of bovine abscesses. A total of 108 calves were divided into five groups and treated as follows: I. uninoculated control, II. adjuvant inoculated control, III. 15.5 mg protein of sonicated (fragmented cells) toxoid, IV. 10.5 mg protein of cytoplasmic toxoid. V. 15.5 mg protein of cytoplasmic toxoid. All animals were maintained under similar conditions to those prevailing in feedlots in Alberta. Livers were examined at slaughter. The most promising result was achieved with the injection of 15.5 mg protein of cytoplasmic toxoid. In this treatment group, no scars (healed lesions) were found in the liver and the incidence of liver abscesses was reduced to 10% from the average 35% liver abscesses and scars found in the uninoculated and adjuvant inoculated groups. The toxoid from sonicated whole cells did not reduce liver abscess incidence. These data suggest that the incidence of liver abscesses in cattle fattened in feedlots may be reduced by immunization.     

反刍动物瘤胃酸中毒及其防治

瘤胃酸中毒是由于反刍动物突然超量采食谷粒等富含可溶性糖类物质的饲料,瘤胃内急剧产生、积聚并吸收大量乳酸等物质所致的一种急性消化性酸中毒,并可继发蹄叶炎、瘤胃炎等一系列疾病,严重影响反刍动物生产。本文从其影响因素、发病机理、防治等方面进行了综述,以期为反刍动物瘤胃酸中毒的防治提供参考依据。     

河南省三种地方牛种超数排卵结果与分析

［目的］为了分析河南三种肉牛超数排卵效果。［方法］分别选择夏南牛、郏县红牛、南阳牛作为试验母牛,采用两次PG+促卵泡素(FSH)的方法对试验母牛进行超数排卵,观测试验母牛获得总胚胎数、可用胚数分析超数排卵效果。［结果］结果显示,夏南牛可用胚9.86枚/头,南阳牛可用胚7.71枚/头,郏县红牛为6.75枚/头,可用胚中夏南牛最高与郏县红牛和南阳牛有显著性差异。可用胚率郏县红牛最高79.41%,显著高于夏南牛和南阳牛。［结论］结果表明,PG+FSH法可以用于夏南牛、郏县红牛和南阳牛的超数排卵。     

Dynamics of verotoxin-producing Escherichia coli isolated from German beef cattle between birth and slaughter

A total of 85 cattle from three German beef farms were followed between birth and slaughter during a period of 2 years and monthly faecal samples were submitted for bacterial culture. Verotoxin-producing Escherichia coli (EC) were detected using a standard diagnostic cascade. Potentially pathogenic VTEC (_pVTEC) were defined as: positive for (1) verotoxin 1 (vt1) and eae, (2) positive for verotoxin 2 (vt2) and eae, (3) positive for both verotoxins 1 and 2 and eae, while verotoxinogenic EC (EC_vt1,2) were defined as: (1) positive for vt1, (2) positive for vt2 or (3) positive for both vt1 and vt2. There were 1587 observations (1462 valid) available for the statistical analysis including 6 (0.4%) samples from 6 (7.1%) different animals positive for VTEC O157, 78 (5.3%) pVTEC isolates and 389 (26.6%) EC_vt1,2 isolates. The median day of the study at first detection was 280 days for EC_vt1,2 and 315 days for pVTEC. The median age at first detection was: 121 days for EC_vt1,2 and 215 days for pVTEC. Time series analysis, survival analysis, and stochastic SI models were used to find differences in the population dynamics of EC_vt1,2 and pVTEC.

There was a strong farm and age effect for the first detection of EC_vt1,2 and for pVTEC while the seasonal effect was significant for the first EC_vt1,2 detections only.

With increasing age at first and all consecutive detections, EC_vt1,2 and pVTEC were detected less frequently. The serotype O157 was found more frequently together with detection of other serotypes of pVTEC in the same sample. The EC_vt1,2 were found more often together with pVTEC. The first EC_vt1,2 were on average found before the first pVTEC's and positive cross-correlations existed between EC_vt1,2 and pVTEC.

The critical duration for the shedding period above which the VTEC could propagate themselves on the farms by f.e. transmission between animals was found to be between 8 and 18 sampling intervals of 28 days (224–504 days) for EC_vt1,2, and between 5 and 6 sampling periods of 28 days each (140–168 days) for the pVTEC which is smaller than all critical shedding periods for EC_vt1,2. The reasons for EC_vt1,2 being isolated from faeces earlier than pVTEC are discussed.