Epidemiology of reticuloendotheliosis virus in broiler breeder flocks

Six broiler breeder flocks from two companies in Mississippi were tested at intervals for reticuloendotheliosis (RE) virus infection. Virus was isolated and antibody demonstrated in all six flocks. Infection was first detected at ages ranging from 13 to 47 weeks. Studies showed that neither congenital transmission from grandparent flocks nor treatment with contaminated vaccines was a likely source of infection; thus, exposure to RE virus was assumed to come from the environment. Virus was isolated from litter samples from two of the flocks, but no specific environmental infection source was identified. Infection rates of flocks differed between the two companies. Although adequate controls were lacking, no performance problems due to RE virus infection were apparent in breeder or broiler progeny flocks. However, the RE viruses isolated from these flocks were immunosuppressive and oncogenic when inoculated into day-old chicks. A moderate (3-16%) incidence of neoplasms was induced by contact exposure to these field isolates in the laboratory.     

Seroprevalence and identification of Ornithobacterium rhinotracheale from broiler and broiler breeder flocks in Thailand

Ornithobacteriosis is an infectious disease of avian species that has been reported in almost all countries around the world, except Thailand. The objectives of this study were to determine the seroprevalence of Ornithobacterium rhinotracheale (ORT) and to isolate and identify ORT in broilers and broiler breeders in Thailand. Chicken antibodies had been randomly checked from 17 farms (19 flocks) of broilers and 23 farms (28 flocks) of broiler breeders. The seropositive flocks were 63% and 100% in broilers and broiler breeders, respectively. The sera analysis showed that the individual 280 broiler sera antibody responses were 67.5% negative, 12.9% suspect, and 19.6% positive. The individual antibody responses of 510 broiler breeder sera revealed 12.2% negative, 38.0% suspect, and 49.8% positive samples. The bacteria were isolated and identified by polymerase chain reaction (PCR). Bacterial isolation and identification revealed that nine isolates of the 12 PCR analysis samples showed positive results to PCR analysis. All the positive PCR samples were collected from the broiler breeder farms.     

Control, prevention and eradication of Salmonella enteritidis infection in broiler and broiler breeder flocks

Salmonella enteritidis was identified by serological and bacteriological techniques in two clinically normal breeder flocks in an integrated broiler organisation in Northern Ireland. The organism was transmitted vertically to clinically affected progeny flocks. The infected breeder flocks were slaughtered and the infection throughout the organisation controlled and subsequently eradicated. A working group, consisting of the senior management of the broiler organisation and veterinary staff from the Veterinary Research Laboratories at Stormont, was formed to establish procedures to minimise the risk of the reintroduction of salmonella infection, by preventing vertical transmission from grandparent flocks, or lateral transmission from personnel, other animal species and fomites, or transmission through the feed. All feed was heated to a minimum of 70 degrees C for 12 minutes immediately before it was pelleted and subsequently transported to the flocks through a dedicated system of conveyor belts, bins and lorries. A comprehensive system for monitoring the efficacy of the preventive procedures was established and is now used throughout the poultry industry of Northern Ireland.     

Characterisation of an infectious bronchitis virus isolated from vaccinated broiler breeder flocks.

Four apparently serologically closely related isolates of infectious bronchitis virus were obtained from two flocks of vaccinated broiler breeders, one mile apart, which were experiencing increased mortality and decreases in egg production. The isolates were serologically distinct from isolates previously described and capable of causing characteristic infectious bronchitis-like respiratory infection in young chicks. In one experiment, the H120 vaccine strain of the virus did not protect the trachea against challenge with the new isolates 21 days later.     

Quantification of a sperm-egg interaction for estimating the mating efficiency of broiler breeder flocks

1. The frequency distribution of points of sperm hydrolysis (or holes) produced per unit area of the inner perivitelline layer was examined in samples of approximately 60 laid eggs, taken on the same day from each of 19 flocks of broiler breeder hens. 2. The holes counted in samples of perivitelline layer from eggs varied from 0 to greater than 100; lower numbers being found in eggs from flocks with lower fertility. 3. The median frequency of holes in the inner perivitelline layer was strongly correlated ( r = 0.92) with the median frequency of spermatozoa found trapped in the corresponding outer perivitelline layer. 4. The median frequency of holes in the inner perivitelline layer and of spermatozoa in the outer perivitelline layer were both strongly correlated ( r = 0.80 and 0.77, respectively) with flock fertility. 5. It is suggested that counting 'holes' in the inner perivitelline layer of laid eggs is a more convenient method for assessing breeding efficiency and predicting flock fertility than counting spermatozoa trapped in the outer perivitelline layer.     

Chicken anemia virus in broilers: dynamics of the infection in two commercial broiler flocks

Chicken anemia virus (CAV) can cause a disease syndrome characterized by severe anemia, bone marrow atrophy, and severe immunosuppression in young chicks. Maternal antibodies prevent these clinical signs but do not prevent infection, transmission of the virus, or immunosuppression. The clinical disease is rare today because of the widespread practice of vaccinating breeders, but the subclinical form of the disease is ubiquitous. The dynamics of CAV infection, CAV antibody responses, relative lymphoid organ weights, and associated lesions were studied in two broiler flocks from a commercial producer. Both groups had detectable CAV antibodies at hatch, which waned over the first 3 wk of life. Both groups had detectable CAV DNA in both thymi and bursae over the same period. At 35 days of age, virus was detectable by polymerase chain reaction in 16 of 20 chickens, and 7 of 20 had detectable antibodies. By 42 days of age, virus was detectable in 18 of 20 chickens, and 18 of 20 had antibodies to CAV. We observed a decrease in relative thymic weights beginning at 35 days of age, coincidental withthe detection of CAV in the thymus. Bursal sizes began to decrease at 28 days of age, coincidental with a rise in antibody titers to infectious bursal disease virus. In this study, we demonstrated that under typical field conditions CAV infections in broilers have unique dynamics unlike those reported in egg laying strains of chickens managed under specific-pathogen-free conditions.     

Assessing the breeding efficiency of broiler breeder flocks by measuring sperm transfer into laid eggs

1. The breeding efficiency of broiler flocks was assessed by estimating the numbers of spermatozoa trapped in a 5.5 mm² area of the perivitelline layer of laid eggs.

2. In samples of approximately 60 eggs taken from flocks on the same day, the numbers of spermatozoa ranged from 0 to several hundred.

3. Within each sample of eggs, there appeared to be two distinct populations: eggs in which perivitelline spermatozoa could not be found; and eggs containing spermatozoa for which the logarithm of the number of perivitelline spermatozoa can be approximated by a normal distribution.

4. When data from 15 flocks were considered, the overall flock fertility was linearly correlated with: the median of the number of spermatozoa per 5.5 mm of perivitelline layer (r = 0.678); the mean of positive values of the logarithm of the number of spermatozoa (r = 0.620); and the proportion of sampled eggs in which the number of perivitelline spermatozoa was greater than 0 (r = 0.714).

5. Flock age was the major factor influencing fertility and all the variables of perivitelline sperm distribution.     

Pinealoma in a broiler breeder

An incidental central nervous system tumor was found in a broiler breeder. The cellular mass was histologically similar to the normal pineal gland, but it was characterized by a decreased ratio of follicular/parafollicular cells, a relative increase in mitoses, a size three times greater than a normal pineal gland, and growth and expansion into adjacent cerebellar tissue. These characteristics warranted a diagnosis of pinealoma rather than pineal gland hyperplasia.     

评估肉用种鸡

对于种鸡场的管理人员来说，如何评估肉用种鸡、监测数据是否准确、鸡群每日饲喂多少料量、何时转群、每百只母鸡配给多少公鸡，这些信息对一个种鸡群的成功与否起着至关重要的作用。业内大多数同行都认同，管理种鸡群最重要的一项指标就是鸡群的平均体重，或者说，鸡群对喂料水平的反馈。１如何对种鸡进行称重肉种鸡的个体称重应越早越好，最好从第２周龄开始。对某些称重器来说，鸡只只有达到２２０～３００g时才能有效地使用。早一些对鸡只进行称重可以确定所饲养的鸡群属于哪种类型。年轻种鸡群所产的雏鸡势必比产蛋中期或产蛋后期所产…     

Infectious bronchitis serology in broilers and broiler breeders: correlations between antibody titers and performance in vaccinated flocks

In this study, a follow-up was made between 1993 and 1997 from broiler breeders at birth down to offspring broilers at processing, through vertically integrated registration of infectious bronchitis virus (IBV) antibody titers and performance data. All measurements were used two by two in a simple correlation study to calculate the degree to which they were linearly correlated. The antibody patterns in the broiler breeders indicated frequent field infections breaking through vaccinal immunity. Significant correlations measured between antibody titers and production parameters within and between the generations strongly suggested negative effects of IBV infections on laying percentage in the breeders and on mortality and daily weight gain in the broilers. Economic losses associated with IBV infections in the broilers occurred predominantly in flocks hatched with low and erratic maternal antibody titers. We concluded that IBV vaccination strategies should aim at high and uniform antibody titers in the broiler breeders.     

Chicken anemia agent in the United States: isolation of the virus and detection of antibody in broiler breeder flocks

Chicken anemia agent (CAA) was isolated from broiler chickens in Texas with a blue wing or anemia dermatitis-like syndrome. Specific-pathogen-free chicks inoculated with field material developed anemia, and CAA was isolated in MDCC-MSB1 cells from bone marrow and lymphoid tissue from inoculated chicks. One isolate, designated EF88/78/276, was further characterized. Infectivity of EF88/78/276 was resistant to treatment with chloroform and with heat at 70 C for 5 minutes. EF88/78/276 was indistinguishable from the Cux-1 and Gifu-1 isolates of CAA by cross-neutralization tests. Almost all 1-day-old susceptible chicks inoculated intramuscularly with EF88/78/276 developed anemia, but contact-infected chicks did not. Antibody to CAA was detected in broiler breeder flocks from Texas, the Delmarva peninsula, and Alabama.     

种鸭源猪丹毒丝菌分离及血清学调查

从发生生产性能异常的2个种鸭群中分离到2株革兰阳性丝状菌,经16S rRNA基因序列分析鉴定为猪丹毒丝菌。采用多重PCR对分离株编码表面保护性抗原(spa)基因进行扩增,分别获得大小约1 000 bp和900 bp的片段,判定为spaC型和spaB型。毒力检测结果表明,2个分离株对小鼠的半数致死量(LD50)分别为103CFU/0.2 mL和≤102CFU/0.2 mL。药敏试验结果表明,分离株对青霉素类和大部分头孢菌素类抗生素敏感,对氨基糖苷类等药物具有明显的抗性。为进一步了解猪丹毒丝菌对鸭群的感染情况,本研究采用生长凝集试验对来源于3个不同鸭场的种鸭群进行血清学调查,结果,抗丹毒丝菌抗体阳性率(抗体效价≥16)分别为82%、35%和20%,表明鸭群中广泛存在猪丹毒丝菌感染。     

平养肉种鸡的"挑鸡"技巧

目前,我国肉种鸡的饲养方式大部分还是以垫料平养和两高一低棚架饲养为主,但无论采用哪种饲养方式,在培育种鸡的过程中必须抓好育成期的均匀度。众所周知,良好的均匀度对生产性能的发挥至关重要,因此,后备期(1～25周)的主要任务便是抓好体重控制和保持良好的均匀度。维持和提高均匀度的方法有很多种,诸如断喙挑鸡,全群称重分出大、中、小栏,据不同的体重喂给不同的料量以及其他日常管理工作。若喂料方式是用料线自动喂料,那么均匀度控制起来要比用料桶人工喂料的好控制,也更易于维持,但无论哪种饲养方式和喂料方式,“挑鸡”是育成期不可少的…     

Observations on swollen head syndrome in broiler and broiler breeder chickens

Chickens on 14 broiler breeder farms were examined at various times throughout their laying cycle. Antibodies to the turkey rhinotracheitis virus were common although they were not always accompanied by clinical signs of the swollen head syndrome. Ninety-nine broiler flocks were tested of which only 20 were serologically positive to the virus. Some of these infections were subclinical. On nine farms where swollen head syndrome occurred several successive flocks were sampled; the syndrome occurred intermittently.     

种用肉鸡的饲养管理

种用肉鸡是用来生产肉鸡种蛋的种鸡,养好种用肉鸡是获得优质肉用雏鸡和提高肉鸡养殖效益的基础,也是促进肉鸡养殖业健康快速发展的前提,那么怎样才能养好种用肉鸡呢?一、鸡场建造,1.鸡场选址。种鸡场应建在通风良好、环境干燥、空气新鲜的位置,其与居民区、学校、医院等公共场所以及铁路、公路等交通要道的距离1000米以上,其与动物诊疗、屠宰及其他养殖场距离3000米以上。     

笼养肉种鸡泄殖腔炎的预防措施

其一,因笼养肉种鸡舍内饲养密度大,为此必须要加大鸡舍内的通风量,以减少舍内有害气体对鸡只的刺激和危害;其二,应当要及时清除舍内的鸡粪,舍内的人行道既要清洁卫生,又要避免舍内尘土飞扬;其三,要给鸡创造和提供一个适宜的温湿度生活环境;