One-step RT-PCR for the Detection of Infectious Bursal Disease Virus in Clinical Samples

A single-tube, non-interrupted, one-step RT-PCR has been standardized to amplify the hypervariable region of the VP2 gene sequence of infectious bursal disease virus (IBDV). The technique standardized on purified viral RNA was successfully applied to the detection of the virus directly in clinical samples. The amplified products were confirmed to be IBDV specific by their size in ethidium bromide-stained agarose gel, nested PCR and restriction enzyme digestion. Digestion of the amplicons with StyI restriction enzyme also differentiated classical virus from six very virulent field isolates. The sensitivity of the one-step RT-PCR was found to be 0.2 pg of viral RNA.     

硼中毒对固始鸡空肠发育的影响

120只1日龄固始鸡随机分为2组，分别饮用添加硼0、400mg／L的水，研究了硼中毒对固始鸡空肠发育的影响。试验期为6周，每周定时每组取鸡10只，颈静脉放血致死，取空肠，Bouin’s液固定，制作石蜡切片，HE染色，显微镜观测与拍照。结果：（1）试验组空肠绒毛长度极显著低于同周龄对照组（P〈0．01）；肠腺长度第1周龄极显著低于对照组（P〈0．01），第2周龄显著低于对照组（P〈0．05）。（2）试验组1～4周龄空肠出现上皮细胞肿胀、脱落，绒毛中抽结缔组织水肿、毛细血管扩张，肠腺囊肿等痛变。试验表明，硼中毒对固始鸡小肠绒毛及肠腺发育有明显抑制和毒害作用，对机体消化吸收功能产生严重影响。     

胸腺素α_1对墟岗黄鸡免疫器官组织学结构的影响

本试验研究了不同剂量的胸腺素α1(Tα1)对墟岗黄母鸡免疫器官指数和组织学结构的影响。结果表明:0.015mg/kg体重剂量的Tα1可显著提高鸡免疫器官指数,可使胸腺皮质增宽,髓质胸腺小体数和胸腺细胞数增加;脾脏胸腺依赖区和法氏囊依赖区细胞增殖;高剂量Tα1则引起法氏囊髓质局部细胞变性和坏死。     

NDV和IBV感染对肉鸡大肠杆菌病发病的影响

为了解新城疫弱毒苗和传染性支气管炎弱毒苗接种对肉鸡大肠杆菌病发病的影响。对8日龄肉仔鸡用不同剂量NDVclone-30株或IBV-H120株进行滴鼻及饮水,48h后相同途径接种2株不同“O”血清型的致病性大肠杆菌。结果表明,致病性大肠杆菌单独接种鸡死亡率在20%-25%之间,而NDVclone-30株或IBVH120株与致病性大肠杆菌联合接种鸡死亡率有明显增加达40%-75%。     

Effects of High-tannin Sorghum and Bentonite on the Performance of Laying Hens

The effects of feeding high-tannin sorghum (HTS) (5% catechin equivalents (CE)) on the performance of laying hens were examined in two experiments. In experiment 1, the effects of including varying levels of HTS in layer diets were investigated. Sixty-three Isabrown hens were randomly assigned to each of the seven diets over a period of 56 days. In experiment 2, the effects of bentonite on the utilization of HTS (3.74% CE) by laying hens were investigated. Forty-five Isabrown hens were randomly assigned to each of five diets over a period of 42 days. In both experiments, weekly measurements were made for feed intake (FI), percent hen-house production (% HHP), egg weight and egg specific gravity (ESG). The results of experiment 1 showed that the different sorghum inclusion levels had no effect (p>0.05) on HHP, egg weight and ESG, while those of experiment 2 showed that maize and LTS diets gave similar weight gain, FI and FE (p>0.05). However, HHP was higher (p<0.05) for the LTS diet than for the other diets. The addition of bentonite of 0.25% or 0.5% to the HTS diet did not improve (p>0.05) layer performance. When all the results were considered together, it was concluded that HTS can be used in layer diets without adverse effects on performance. The use of bentonite to deactivate sorghum tannins is not considered necessary.     

Growth and Apparent Absorption of Minerals in Broiler Chicks Fed Diets with Low or High Tannin Contents

Sorghum grains with low (0.28 per cent catechin equivalent (%CE) or high (1.36 %CE)) tannin contents were used to study the effect of tannin on growth and on the apparent absorption of Ca, P, Mg, Na, K, Fe and Co by chickens. High-tannin sorghum caused a highly significant (p0.01) reduction in the weight gain and feed intake of broiler chicks compared to low-tannin sorghum and increased the feed conversion ratio (p0.01). The amount of tannin did not affect mortality. The apparent absorption of Ca, P, Mg, Na, K, Fe and Co was reduced (p0.01) by feeding sorghum grains with a high tannin content.     

The Value of Tissue Imprint Hybridization for Rapid Detection of Infectious Bursal Disease Virus from Field Outbreaks

The use of a peroxidase labelled PCR generated probe followed by enhanced chemiluminescence hybridization assay detected infectious bursal disease virus directly from bursal imprints on a nylon membrane. Tissue imprint hybridization proved to be a simple, rapid and safe means of detecting IBD virus for screening large numbers of field samples. The PCR generated probe was highly specific for IBD virus and did not hybridize with cellular nucleic acids in control imprints. Tissue imprint hybridization was found to be a more sensitive method than conventional antigen detection assays.     

Efficacy of Sarafloxacin in Broilers after Experimental Infection with Escherichia coli

Infections of chickens with Escherichia coli serotypeO78 can be treated with the antibiotic sarafloxacin. Three experiments were conducted on the administration of this drug to chickens that had been experimentally infected with E. coli. The birds were monitored for 10 days after infection for their average daily gain (ADG) and feed conversion ratio (FCR), and the post-mortem pathology was assessed. In the first experiment, sarafloxacin (20 mg/L, equivalent to 5 mg/kg live weight per day), given in the drinking water for 3 days after infection, led to a reduction in the mortality from 75% to 27%, but the ADG of the treated birds was still less than that of the uninfected controls. In the second experiment, when the sarafloxacin was administered at the same dose in the water but over only 2 h, there was also a considerable reduction in mortality, and the ADG and the FCR also improved significantly. In the third experiment, the dose dependence of the drug was tested. The birds were given 5 and 10 mg/kg per day sarafloxacin in each group, starting within 2 h after infection. This rapid administration of the drug completely prevented mortality, while the ADG and FCR were similar to those of the uninfected controls.     

Response of Chickens to Infection with Newcastle Disease Virus Isolated from a Guinea Fowl

An isolate of Newcastle disease virus obtained from a guinea fowl was characterized as a viscerotropic velogenic strain based upon pathogenicity index studies. Following inoculation of the viral isolate oronasally into 3-week-old chickens, clinical signs appeared after an incubation period of 4–5 days and included dullness, depression, dyspnoea, diarrhoea and leg paralysis. The virus caused a mortality of 56% with haemorrhages at the tip of the glands of the proventriculus and caecal tonsil. Histopathological changes were prominent in the lymphoid organs, being characterized by depletion, degeneration and necrosis of the lymphoid tissues. The brain was the first organ affected, with changes being noticed 3 days after infection. Isolation of virus from various organs was more frequent from 5 to 10 days after infection, but the virus persisted in some of the organs until 21 days after infection. In spite of the high mortality, a good immune response was elicited by the isolate, as was evident from the antibody titre.     

Immune Responses to Intermediate Strain IBD Vaccine at Different Levels of Maternal Antibody in Broiler Chickens

Tropical Animal Health and Production -