Outbreak of avian tuberculosis in 48-week-old commercial layer hen flock

This report describes an outbreak of tuberculosis in a flock of 38,500 48-wk-old layer hens. Clinical characteristics of the process included a gradual drop in egg production and feed intake, as well as an increased mortality rate. Two well-defined clinical features were observed. On the one hand, a number of birds displayed good body condition and continued to lay but presented granulomatous nodular lesions, particularly in the infraorbital sinus, liver, and intestine. In contrast, other hens were emaciated and presented granulomatous lesions of various sizes throughout the internal organs. The lesions observed in the various organs of all the affected birds consisted of granulomas containing acid/alcohol-fast bacilli. The presence of Mycobacterium avium was confirmed through polymerase chain reaction techniques. This report describes the epidemiologic and histopathologic characteristics of the outbreak.     

Comparison of Salmonella isolation rates in different types of egg-layer hen houses in Chiba, Japan

This study investigated the differences in Salmonella isolation rates in environmental samples taken from several types of hen houses in Chiba, Japan. In addition, for the detailed epidemiologic survey, environmental samples, hens, and rodents were collected from Salmonella-contaminated windowless houses on three farms. As a result, Salmonella was isolated from four (80%) of five farms with windowless hen houses; Salmonella enteritidis was isolated from a single windowless house. In contrast, only one serotype of Salmonella was isolated from 1 (6.7%) of 15 farms with open hen houses. In the S. enteritidis-contaminated windowless hen house, the isolation rates of S. enteritidis as compared with the other serotypes were 90.9% of environments, 94.1% of hens, and 86.4% of roof rats (Rattus rattus) that resided in the environments. In reference to the phage type (PT) of these isolates, PT1 was detected in environments and roof rats, and PT9 was detected in both these samples and in hens. Thus, the Salmonella isolation rate in hen houses seems to be associated with whether the premises are windowless or open. Moreover, roof rats appear to be the most important vectors in the spread of S. enteritidis in the windowless hen house because the S. enteritidis PTs coincide with each other.     

Increment of egg weight with hen age in various commercial avian species

1. The present study indicates that a common biological pattern exists for egg weight increase with hen age for the various commercial avian species, breeds and strains at their first laying cycle. Therefore, one common equation can be used for the estimation of egg weight increase.

2. The parameters estimated for this equation are based on (a) egg weights in terms of percentage of seasonal mean egg weight, and (b) age as percentage of maximum age of the hen. Therefore, if the season's mean egg weight is known for any species, breed or strain, the increase in egg weight can be easily predicted for the whole season, or for any particular hen age. For early prediction, egg weight expressed as a percentage of initial egg weight can be used, although such prediction will be somewhat less accurate.

3. The use of egg weight as a percentage of seasonal mean egg weight, and age as a percentage of maximum age, was found to overcome the differences between strains, breeds and even species, by applying the same denominators for egg weights and periods of lay.

4. At each point of hen age (mean egg weight), the egg weight grades can be easily estimated by employing the computerised Burr's (1967) equation. These values showed excellent fit with extensive field data, provided that only normal eggs and those originating from a single flock and from no more than two weeks of collection are counted.     

Necrotic enteritis in cage-reared commercial layer pullets

Necropsy of five 12-week-old pullets from a flock of 99,300 suffering from an increased mortality rate revealed enlarged, gas-filled intestines, the mucosal surfaces of which had the "dirty turkish towel" appearance typical of necrotic enteritis. Although the pullets had been raised entirely in cages, intestinal scrapings revealed the presence of Eimeria maxima. Histopathological findings were compatible with necrotic enteritis. Clostridium perfringens was isolated by anaerobic culture from the intestines. Mortality returned to normal after bacitracin and amprolium were added to the feed.     

Unexpected newcastle disease virus in day old commercial chicks and breeder hen

Newcastle disease virus (NDV) specific antigen in the gut contents and NDV specific antibody in blood circulation were seen in day old chicks belonging to nine different commercial hatcheries of Tamil Nadu, India. Antigen disappeared by 4th week and antibody by 6th week of age. Fourteen NDV isolates obtained from the gut contents of day old chicks of different commercial hatcheries, one NDV isolate from dead in shell eggs and one NDV isolate from breeder hen were characterized and grouped under velogenic, mesogenic and lentogenic pathotypes. Four isolates were grouped under F and another four isolates were grouped under E based on reaction with monoclonal antibodies (Mabs) but found to be velogenic based on pathogenicity tests. In one particular flock velogenie NDV was isolated from breeder hen, dead in shell embryos and day old chicks and they all belong to Mabs group E. Vertical transmission of velogenic, mesogenic and lentogenic NDVs and role of NDVs in the gut contents have been discussed.     

Salmonella contamination in commercial layer feed in Japan

A total of 4,418 samples of commercial layer feeds obtained in 1998 were investigated for the presence of salmonellae. A total of 146 strains of salmonellae which consisted of 32 serovars, including 20 strains of Salmonella Enteritidis, were isolated from 143 feed samples.     

商品蛋鸡育雏期饲养管理

在蛋鸡养殖中,“五周定终身”的观点已被业内人士普遍认可。根据笔者近年处理客户养殖过程中发生问题的情况看,大多问题都发生在饲养管理上,即没有按照规范的程序进行。因此,笔者建议广大养殖户在养殖过程中可参照以下程序。     

A chronicle of serologic response in commercial layer chickens to vaccination with commercial F strain Mycoplasma gallisepticum vaccine

Vaccination of multi-age layer operations, wherein one million plus commercial layer chickens are housed, has been spurious until the development of a self-propelled, constant-speed spray vaccinator. Still, even with its use, live Mycoplasma gallisepticum (MG) vaccinations have been questionable in terms of seroconversion. Using the vaccinator as a research tool over the past 5 yr, factors have been elucidated which impact seroconversion to one live MG vaccine in particular, the F strain of MG (FMG). These factors include the type of nozzle used to spray the vaccine, the temperature of the water used to rehydrate and administer the vaccine, and the pH and osmolarity of the fluid used to apply the vaccine. In the present study, one farm was monitored for its seroconversion rates over 4 1/2 yr, during which time the FMG vaccination protocol was amended as factors were identified that enhanced seroconversion rates. The results of this study showed that implementation and inclusion of the optimized factors into the vaccination protocol for FMG enhanced seroconversion rates because they went from an initial 50%-55% positive seroconversion rate to a consistent 100% positive seroconversion rate over the 56-mo study period.     

Concentrations and emission rates of aerial ammonia,nitrous oxide,methane, carbon dioxide,dust and endotoxin in UK broiler and layer houses

1. A survey of the concentration and emission rates of aerial ammonia, nitrous oxide, methane, carbon dioxide, dust and endotoxin was undertaken in 4 examples each of typical UK broiler, cage and perchery houses over 24 h during winter and summer.

2. Overall the air quality within the poultry houses was unsatisfactory as judged by the dual criteria of farmer health and bird performance.

3. Mean concentrations of ammonia ranged from 12.3 to 24.2 ppm while concentrations of methane and nitrous oxide were close to ambient levels. Mass concentrations of aerial dust ranged from 2 to 10 rag/m³ and 0.3 to 1.2 mg/m³ for inspirable and respirable fractions respectively, while endotoxin concentration was typically about 0.1 ^g/m³ (inspirable fraction).

4. Emission rates of gaseous ammonia were rapid (9.2 g (NH₃/h per 500 kg live body weight) and uniform across the three types of building, while emissions of methane and nitrous oxide were slow. Rates of dust emission ranged from 0.86 to 8.24 g/h per 500 kg live body weight in the inspirable size fraction.     

Digestible valine-to-digestible lysine ratios in brown commercial layer diets

Considering that Val may potentially be a limiting amino acid for laying hens, an experiment was carried out to determine the ideal digestible Val-to-Lys ratio in the diets of 42- to 54-wk-old brown layers. Literature reports are divergent, with ratios varying between 86 and 102%, which suggests that further research is needed. Five different digestible Val-to-Lys ratios were evaluated: 84 (0.555% digestible Val), 88, 92, 96, and 100%. Feed intake (g/hen per day), egg production (%), egg weight (g), egg mass (g), FCR (kg/dozen and g/g), egg quality (yolk, eggshell, and albumen %), and egg weight (g) were evaluated. Egg weight, egg internal quality, and weight gain were not influenced by the different dietary digestible Val-to-Lys ratios. The evaluated ratios linearly affected feed intake and had a quadratic effect on egg production, egg mass, and FCR (kg/dozen and g/g). Based on the evaluated parameters, the ideal digestible Val-to-Lys ratio is 92%, corresponding to 0.607% digestible Val or 567 mg/hen per day of digestible Val.     

Longitudinal monitoring of two commercial layer flocks and their environments for Salmonella enterica serovar enteritidis and other Salmonellae

Between August 20, 2001, and September 17, 2002, 1429 samples including drag swabs, egg belt or egg rollout swabs, fan-blade swabs, rodent organ and intestinal pools, beetle (Alphitobius diaperinus) pools, housefly (Musca domestica) pools, chicken organ and intestinal pools, and egg pools were obtained for Salmonella culture from two flocks from two different commercial layer ranches. The two ranches were purposefully selected for the study based on their previous status of Salmonella Enteritidis isolation using environmental drag swabs in cooperation with practicing veterinarians. Salmonella sp. was isolated from 337 out of 979 (34.42%) non-egg samples. No Salmonella was isolated from 450 egg pools collected from either ranch. S. enteritidis was isolated from samples obtained from ranch 1 from manure drag swabs, 4/284 (1.4%); rodent organs, 1/24 (4.2%); and housefly pool cultures 1/21 (4.8%). Salmonella Enteritidis was isolated from ranch 2 from mouse organ and intestinal pool samples, 1/24 (4.2%). Salmonella group B was isolated from all sample types except the insects. There was a statistically significant difference in isolation rates among seven serogroups of Salmonella: groups B, C1, C2, D, E, K, and untypeable (Pearson chi-square 18.96, P = 0.002). Overall, statistically significant differences were observed with respect to Salmonella isolation among the types of samples taken (Pearson chi-square 118.54, P < 0.0001). Intensive monitoring for Salmonella Enteritidis can be used to optimize a Salmonella reduction program for an individual poultry biosecurity unit.     

Serological monitoring on layer farms with specific pathogen-free chickens

To monitor the existence of avian pathogens in laying chicken flocks, specific pathogen-free (SPF) chickens were introduced into two layer farms and reared with laying hens for 12 months. SPF chickens were bled several times after their introduction and examined for their sero-conversion to avian pathogens. As a result, antibodies to eight or ten kinds of pathogens were detected in SPF chickens on each farm. Antibodies to infectious bronchitis virus (IBV), avian nephritis virus, Mycoplasma gallisepticum and M. synoviae were detected early within the first month. Antibody titer to IBV suggested that the laying chickens were infected with IBV repeatedly during the experiment on both farms. However, antibodies to infectious bursal disease virus and 6 pathogens were not detected.     

Salmonella enteritidis in commercial layer farms in New York state; environmental survey results and significance of available monitoring tests.

Seven hundred fifty-one environmental samples were collected from 76 chicken layer houses in a voluntary Salmonella enteritidis (SE) survey study carried out in New York state between January 15 and April 8, 1991. SE was recovered from both houses on 1 farm. Sampling of manure pits and mice in hen houses was useful for SE screening. Phage types of SE from the environment, birds, and mice were identical. The rapid whole-blood test was unreliable, and culture of cloacal swabs was inadequate for detection of SE carriers. Culture of organs from chickens did not correlate well with results of environmental samples.