Evaluation of Salmonella-lytic properties of bacteriophages isolated from commercial broiler houses

Because of recent interest in bacteriophage therapy in poultry, information regarding the interaction of bacteriophages and potential host bacteria in the environment should be collected. The present studies were initiated with a rather typical commercial broiler integrator within the south-central United States to examine environmental Salmonella levels in two broiler complexes, attempt to isolate Salmonella-lytic bacteriophages, and elucidate a possible reason for differing apparent Salmonella prevalence. Significantly (P < 0.05) less Salmonella was isolated from houses in complex 1 (15/44 [34%] Salmonella-positive drag swabs) as compared to houses in complex 2 (22/24 [92%]). A total of seven Salmonella-lytic bacteriophages were isolated from Salmonella-positive environments, and two bacteriophages were isolated from a single Salmonella-negative house. During the initial bacteriophage isolation, individual bacteriophages did not replicate in the Salmonella host isolated from the same environment, and lysis of additional Salmonella hosts relied on high numbers of bacteriophage to be present. This suggests that the presence of these bacteriophages in the environment of a commercial broiler house had little to no effect on the presence of Salmonella. This study highlights the need to find additional bacteriophage sources, more effective isolation methods, and more innovative approaches to using bacteriophages to treat enteric disease.     

Prevalence of Clostridium perfringens in commercial broiler hatcheries.

Clostridium perfringens, a cause of human foodborne and poultry disease, has been isolated from the intestinal tract of poultry and from the processed carcass. Little is known about the incidence and sources of this pathogen in the poultry production environment. To determine if the broiler hatchery is a possible source of C. perfringens, we collected samples from three hatcheries, each operated by a different poultry integrator, and the presence of C. perfringens in these samples was determined. For each sampling period, eggshell fragments, chick fluff from the hatcher, and paper pads stored in the hatchery before use with chicks and after placement beneath chicks for 1 hr were evaluated. Clostridium perfringens was found in eggshell fragments, fluff, and paper pads in each of the three hatcheries. The percentages of C. perfringens-positive samples from the three hatcheries ranged from 13% to 23%, with an overall incidence of 20%. Positive samples were consistently found, i.e., detected on each of the nine sampling days (three sampling days for each of three hatcheries). These results suggest that the hatchery is a potential source/reservoir for C. perfringens in the integrated poultry operation.     

Compatibility of dimmers and alternative technology lamps for commercial broiler houses

The use of artificial lighting has become an integral component of the commercial broiler industry, as chickens possess visual acuity superior to that of humans. A variety of new light emitting diode (LED) lamps have become available specifically for use in poultry houses to reduce energy costs, causing many broiler growers to consider implementing LED technology. Lamp dimmers help maximize bird performance by reducing light intensity and often have multiple settings (profiles) used to accommodate different lamps. Because of the investment required to replace lamps in a broiler house, growers have requested information to assist in selecting an appropriate lamp-profile combination. This study evaluated the impact of 8 different commercial dimmers with 21 profiles total on the performance of 15 different LED lamps, one incandescent (INC), and one cold cathode fluorescent lamp (CCFL). Approximately 350 lamp-profile combinations were individually tested for multiple criteria as the lamps were dimmed. A scoring metric was developed that considered linearity, re-fire, luminous output, and efficacy. Dimmer and profile selection impacted lamp luminous output and efficiencies. No one lamp worked effectively with all dimmers and profiles, and no one dimmer or profile worked effectively with all lamps. There were statistically significant differences in scores based on technology, lamp, dimmer, and profile, suggesting that a multifaceted approach is necessary when evaluating the performance of lamps, dimmers, and profiles. A publically available selection tool website allows access to the combination scores. Growers can use this website to make informed decisions, promoting energy savings and agricultural sustainability.     

Pathogenicity of serotype 1 fowl adenovirus in commercial broiler chickens.

The pathogenicity of a serotype 1 fowl adenovirus (FAV-99ZH), isolated from broiler chickens exhibiting gizzard erosion, was investigated in commercial broiler chickens. Five-, 3-, and 1-wk-old commercial broiler chickens were inoculated with FAV-99ZH by both oral and ocular routes. In the 5-wk-old chickens (trial 1), none of which had the maternal antibody to FAV-99ZH, severe gizzard erosions were observed on days 5, 7, and 10 postinoculation (PI). Among the 3-wk-old chickens (trial 2), which were separated into a control group and three treatment groups according to their maternal antibody titer levels, some chickens showed clinical signs such as depression and anorexia. Compared with the control group, all the treatment groups showed decreased weight gain. One treatment group, moreover, showed significantly decreased (P < 0.05) weight gain on day 10 PI. Severe gizzard lesions, such as erosion or ulcers, were observed from day 4 PI in all treatment groups regardless of their maternal antibody levels. The 1-wk-old chickens (trial 3) were separated into a control group and two treatment groups according to their titer levels of the inoculated virus. In spite of high maternal antibody levels, severe gizzard lesions were observed in both treatment groups, which also showed decreased weight gain. One treatment group, inoculated with the higher dose, showed significantly decreased (P < 0.05) weight gain on days 10 and 14 PI compared with the control group. Fowl adenovirus was recovered mainly from gizzard and rectal (including feces) samples from inoculated chickens but was not recovered from liver samples in any of the trials or in any of the control chickens. Although the reproduced disease was similar to that described in a previous report of experimental infection of specific-pathogen-free (SPF) white leghorn chickens with fowl adenovirus, the pathogenicity of FAV-99ZH in commercial broiler chickens was more severe than that in the SPF white leghorn chickens. The results of the present study indicate that FAV-99ZH isolated from gizzard erosion had pathogenicity and produced severe lesions in the gizzards of broiler chickens and that FAV-99ZH could infect and produce illness in broiler chickens with maternal antibodies against this virus.     

Evaluation of an autogenous Salmonella bacterin and a modified live Salmonella serotype Choleraesuis vaccine on a commercial dairy farm.

OBJECTIVE: To compare the efficacy of a Salmonella bacterin and a modified live Salmonella ser. Choleraesuis vaccine on a commercial dairy. ANIMALS: 450 cows in late gestation and 80 calves. PROCEDURE: Group-1 cows (n = 150) were vaccinated once with a modified live S. Choleraesuis (serogroup C1) strain 54 (SC54) vaccine, group-2 cows (150) were vaccinated on enrollment and 30 days later with a Salmonella ser. Montevideo (serogroup C1) bacterin, and group-3 cows (150) served as unvaccinated controls. One gallon of colostrum harvested from the first 80 cows to calve was fed to each calf. Outcome assessments included fecal shedding of Salmonella spp for the first 10 days after parturition (cows) or birth (calves), milk production, involuntary culling rate, mastitis incidence, antimicrobial use, and mortality rate. RESULTS: Salmonellae were isolated from 306 of 309 (99%) cows and 64 of 74 (86.5%) calves. Shedding frequency was less in SC54-vaccinated cows and calves that received colostrum from those cows, compared with the other groups, and vaccination was specifically associated with less shedding of serogroup C1 salmonellae. Production data were similar among groups. CONCLUSIONS AND CLINICAL RELEVANCE: Vaccination of pregnant cows with an autogenous Salmonella bacterin had no effect on fecal shedding of salmonellae, whereas vaccination with a modified live S. Choleraesuis vaccine reduced the frequency of fecal shedding of serogroup C1 salmonellae during the peripartum period. A commercial S. Choleraesuis vaccine licensed for use in swine may be more efficacious than autogenous Salmonella bacterins on dairies infected with serogroup C1 salmonellae.     

A questionnaire-based,retrospective field study of persistence of Salmonella Enteritidis and Salmonella Typhimurium in Danish broiler houses

A questionnaire-based, retrospective field study was conducted in 78 Danish broiler houses (analytical units) on 42 farms. In spring 1997, all these broiler houses had been infected with Salmonella Enteritidis, phage type 8, and/or Salmonella Typhimurium, definitive-type 66, by day-old chicks delivered from the same hatchery. Because these two salmonella types had not been detected in the Danish broiler sector before and the broiler houses were infected in a period of low salmonella prevalence, the study could focus on farm-related factors, without being distorted by other salmonella infections.

The same person visited all 78 broiler houses, and farm-related factors were listed both from personal observations and by interrogating the person in charge of attending to the broilers. Additional factors (noted at the visits) were recorded in a later telephone interview. Altogether, 187 variables were analyzed.

Broiler houses were divided into single-infection houses (which had one or both of the salmonella types in only one crop), and multiple-infection houses (where infection occurred in multiple crops). This was done both generally and separately for each of the salmonella types.

Factors associated with house status—but that were beyond the control of the farmer—were the salmonella type and the percentage of salmonella positive samples in the first crop. Factors which could be controlled by the farmer and which were associated with reduced prevalence of multiple-infection houses included antiseptic soap and water for washing hands in the anteroom, hygiene barriers when removing dead broilers, gravel alongside the broiler house, systematic checks of indoor rodent-bait depots, and combined surface and pulse-fogging disinfection.     

Evaluation of recovery of Salmonella from trachea and ceca in commercial poultry

Unpublished data from our laboratory suggest that the respiratory tract may be a viable portal of entry for Salmonella infection. Further, field reports have indicated that tracheal sampling can be a sensitive tool for monitoring for Salmonella incidence in commercial flocks. In the present study we conducted a series of field trials in North and South America to evaluate the association between cecal and tracheal recovery of Salmonella in chickens and turkeys from commercial flocks. Environmental humidity and temperature were measured to evaluate their effects on frequency of isolation from the organs. Salmonella was recovered from tracheal samples in all trials. In 3 of the 4 trials in which both trachea and ceca were sampled, the incidence of Salmonella recovery was higher in tracheal samples. Though Salmonella was not recovered from ceca in trial 2, 5% of liver and spleen samples indicated infection. Environmental conditions were not associated with incidence of Salmonella recovery. These data suggest that tracheal contamination can be a good indicator of Salmonella infection under commercial poultry conditions.     

肉鸡舍的最佳气候条件与通风方式

近30年来,全球的家禽业获得了长足的发展.其中的许多成就来源于对肉鸡快速生长和理想饲料报酬的选育.目前,肉鸡在42日龄的体重要比10年前高出0.45千克.遗传学家和大型肉鸡场已把最大的重点放在进一步提高肉鸡的生长率、饲料报酬和胸肉产量上.他们估计到2005年,肉用仔鸡在28日龄时体重可达到1.8千克.但只有在生产者放弃传统的饲养系统,采用现代饲养技术,使肉鸡的饲养环境和管理达到最佳水平才能取得这些遗传进展.在获取肉鸡最佳生产性能的许多变量中,最重要的因子之一是通过正确通风获取较好的空气质量.     

Cell-mediated and humoral immune responses to a virulent plasmid-cured mutant strain of Salmonella enterica serotype gallinarum in broiler chickens

One-week-old Salmonella-free broiler chicks were subcutaneously immunized and subsequently boosted two weeks later with 2x10(7)cfu 0.5ml(-1) of an 85-kb virulent plasmid-cured spectinomycin-resistant mutant strain (SG9VP(-)Spc(r)) of Salmonella gallinarum 9 (S. enterica serotype gallinarum 9) along with a control group of mock-immunized chickens. The chicks were subcutaneously challenged at 5 weeks of age with 5x10(10)cfu 0.5ml(-1) (5xLD(50)) of wild-type S. gallinarum var. Duisburg (S. enterica serotype gallinarum var. Duisburg). The cellular and humoral immune responses were measured at weekly intervals post-immunization (PI) and post-challenge (PC) using lymphocyte stimulation test (LST), delayed type hypersensitivity (DTH) test, serum tube agglutination test (STAT) and enzyme-linked immunosorbent assay (ELISA). High stimulation indices suggestive of a potent lymphocyte transformation response and high persistent serum IgG titres were recorded in immunized chickens at the termination of the experiment. These findings indicate that the live attenuated mutant vaccine induced a strong cellular and humoral immunity, which may play a role in the protection of fowl typhoid in broiler chickens.     

商品肉鸡饲养管理与疫病防治

为了提高商品肉鸡的成活率,减少疾病的发生和传播,饲养商品肉鸡应特别注意以下几个问题:1环境安全饲养人员应做到不串场、不串舍、尽量做到全进全出,保持适宜的空舍期,一般为3周。清除鸡舍周围的杂草,保持鸡舍良好的小气候环境。2卫生消毒环境卫生对鸡群的健康成长起重要作用,卫生好不好直接关系着育雏的成败,一定要做好雏鸡的饮水、饲料、垫料、饲养器具及环境等方面的卫生工作,同时搞好鸡舍内外的消毒,防止各种病原菌的繁殖和传播。3温度育雏前1周温度很重要,建议育雏温度32℃左右,以后每周降2～3℃,直至21℃。夏天至少提前1d,冬季至少提…     

Performance of broiler breeder pullets as influenced by composition of grower and layer diets 1

An experiment was conducted to determine the influence of three grower systems upon the subsequent performance of broiler type breeder pullets. The grower systems were full feeding a 10 per cent protein diet, full feeding a 16 per cent protein diet, and a skip‐a‐day feeding of the 16 per cent diet. One‐third of the pullets fed according to each of the feeding programmes were fed on each of three different layer diets. The use of the low protein and the skip‐a‐day feeding resulted in delaying age at sexual maturity. Total rate of egg production was not affected by the grower diet; however, the number of “ settable “ eggs was increased when maturity was delayed.

Performance of the laying hens was not influenced by the composition of the layer diet. Fertility or hatchability was not influenced by composition of either the grower or layer diet. These data would indicate that the low protein diet or the skip‐a‐day feeding system can be effectively used with feeding replacement broiler type birds.