RESUMEN
The distribution and variance of respiratory disease produced with aerosols of bovine herpesvirus 1 (BHV-1) and Mannheimia haemolytica in control (183 calves in 44 experiments) and vaccinated calves were studied in experiments conducted at the Animal Diseases Research Institute, Lethbridge, Alberta, from 1975 to 1989. All calves had been born and raised at this institute and exposed similarly for 5 min by means of a face mask to viral and bacterial aerosols produced by a Collison atomizer (particles < 3 microm in diameter). We summarized the macroscopic pathological responses of pneumonia (main end point), tonsillitis, tracheitis, and other microbiologic and experimental variables. We also summarized the lobar distribution of pneumonia in 202 control and 192 vaccinated calves with this disease model and in calves similarly exposed to parainfluenza 3 virus/M. haemolytica or BHV-1/Pasteurella multocida. Pneumonia in control calves began in ventral tissues of all lobes, with lobar preferences, and progressed dorsally, the dorsal parts of both large caudal lobes being least affected. A high variance of pneumonia was evident within and among experiments. From the magnitude of variance observed in the control groups, the number of calves per group required in vaccine-challenge studies using this BHV-1/M. haemolytica disease model was estimated. Such estimates are required for any disease model used in vaccine-challenge studies.
Asunto(s)
Enfermedades de los Bovinos/prevención & control , Infecciones por Herpesviridae/veterinaria , Herpesvirus Bovino 1/inmunología , Mannheimia haemolytica/inmunología , Infecciones por Pasteurella/veterinaria , Vacunación/veterinaria , Aerosoles , Animales , Bovinos , Enfermedades de los Bovinos/patología , Femenino , Infecciones por Herpesviridae/patología , Infecciones por Herpesviridae/prevención & control , Pulmón/microbiología , Pulmón/patología , Pulmón/virología , Infecciones por Pasteurella/patología , Infecciones por Pasteurella/prevención & control , Distribución Aleatoria , Infecciones del Sistema Respiratorio/patología , Infecciones del Sistema Respiratorio/prevención & control , Infecciones del Sistema Respiratorio/veterinaria , Tamaño de la Muestra , Organismos Libres de Patógenos EspecíficosRESUMEN
The operation of the high-line speed cattle abattoir studied follows a plant-created hazard analysis and critical control point (HACCP) plan that is recognized by the Canadian Food Inspection Agency. Measurement of bioaerosols is not a part of this plan. In this study CFUs in air of selected abattoir processes were enumerated after impinging air onto tryptic soy agar plates with a slit air sampler for 10 to 20 min. The total viable count (TVC) per liter of air was calculated for each sample following incubation at 30 degrees C for 24 h. Monthly samples were collected on the hide removal floor and the carcass dressing floor from March 1998 to April 1999. Mud tag, dirt, and wetness of incoming hides were scored subjectively on the hide removal floor. The other processes were sampled in 3 separate months. The TVC at two locations on the hide removal floor (center of hide removal floor [CHF] and top of hide puller [THP]) had a strong association to each other (r = 0.84; P < 0.001). The mean TVC at the CHF and THP was 10.0 and 11.5, respectively, and the TVC for individual samples ranged from 2 to 42 at these locations. The TVC means for all the other processes ranged from 0.01 to 0.7. Tag and TVC on the hide removal floor had a different seasonal distribution with TVC being highest in the warm months (April to October 1998) and lowest for November to April 1999. No significant relations between TVC and the dirt and wetness variables were evident for the CHF and THP locations on the hide removal floor. It was concluded that the control of aerosols in the hide removal floor should be treated as a critical control point in the HACCP plan.
Asunto(s)
Mataderos , Microbiología del Aire , Bacterias Aerobias/aislamiento & purificación , Manipulación de Alimentos , Crianza de Animales Domésticos , Animales , Bacterias Aerobias/crecimiento & desarrollo , Bovinos , Recuento de Colonia Microbiana , Femenino , Higiene , Masculino , Estaciones del AñoRESUMEN
The efficacy of cold storage of raw, bagged, boxed beef was assessed microbiologically at a high-line-speed abattoir (270 carcasses per h). At the time of this study, plant management was in the process of creating a hazard analysis critical control point plan for all processes. Aerobic bacteria, coliforms, and type 1 Escherichia coli were enumerated (5 by 5-cm excision samples, hydrophobic grid membrane filter technology) before and after cold storage of this final product produced at six fabrication tables. In addition, the temperature-function integration technique (TFIT) was used to calculate the potential number of generations of E. coli during the first 24 or 48 h of storage of the boxed beef. Based on the temperature histories (total of 60 boxes, resulting from 12 product cuts, five boxes from each of two fabrication tables on each of 6 sampling days, and six types of fabrication tables), TFIT did not predict any growth of E. coli (with or without lag) for the test period. This was verified by E. coli mean log10 values of 0.65 to 0.42 cm2 (P > 0.05) determined by culture before and after the cooling process, respectively. Counts of aerobic bacteria and coliforms were significantly reduced (P < 0.001 and P < 0.05, respectively) during the initial period of the cooling process. There were significant microbiological differences (P < 0.05) between table-cut units.
Asunto(s)
Mataderos/normas , Bacterias/crecimiento & desarrollo , Manipulación de Alimentos/normas , Carne/microbiología , Animales , Bacterias/aislamiento & purificación , Bovinos , Frío , Recuento de Colonia Microbiana , Manipulación de Alimentos/métodos , Control de Calidad , Factores de TiempoRESUMEN
To enhance food safety and keeping quality, beef carcasses are cooled immediately after leaving the slaughter floor. Within hazard analysis and critical control point (HACCP) systems, this cooling process needs to be monitored by the industry and verified by regulatory agencies. This study assessed the usefulness of the temperature-function integration technique (TFIT) for the verification of the hygienic adequacy of two cooling processes for beef carcasses at one abattoir. The cooling process passes carcasses through a spray cooler for at least 17 h and a holding cooler for at least 7 h. The TFIT is faster and cheaper than culture methods. For spray cooler 1, the Escherichia coli generations predicted by TFIT for carcass surfaces (pelvic and shank sites) were compared to estimated E. coli counts from 120 surface excision samples (rump, brisket, and sacrum; 5 by 5 by 0.2 cm) before and after cooling. Counts of aerobic bacteria, coliforms, and E. coli were decreased after spray cooler 1 (P < or = 0.001). The number of E. coli generations (with lag) at the pelvic site calculated by TFIT averaged 0.85 +/- 0.19 and 0.15 +/- 0.04 after emerging from spray coolers 1 and 2, respectively. The TFIT (with lag) was considered convenient and appropriate for the inspection service to verify HACCP systems for carcass cooling processes.
Asunto(s)
Mataderos/normas , Bacterias/crecimiento & desarrollo , Manipulación de Alimentos/normas , Inspección de Alimentos/métodos , Carne/microbiología , Animales , Bacterias/aislamiento & purificación , Bovinos , Recuento de Colonia Microbiana , Medios de Cultivo , Manipulación de Alimentos/métodos , Control de Calidad , TemperaturaRESUMEN
The effect of washing on the bacterial contamination of beef carcasses in a modern abattoir was evaluated. Twenty-six carcasses were evaluated at the end of the slaughter process before and after washing, and 13 other carcasses were evaluated only after being washed. An excision sample (5 x 5 x 0.5 cm) was collected from 10 sites on each carcass immediately before washing and at an adjacent site immediately after washing. Aerobic bacterial colonies were enumerated, using hydrophobic grid membrane filter technology. After washing, the log10 of the most probable number of growth units/cm2 decreased (P < 0.01) at the lateral rump site, increased (P < 0.01) at the thorax and neck sites, but was unchanged at the other 7 sites, compared with before washing. The sample size required to estimate, within 0.5 log10 units, the mean log10 most probable number of growth units/cm2 at a site for use in future group-carcass evaluations was determined and compared with a previously used sample size definition. It was concluded that the washing process described did not result in a major change in the bacterial contamination of carcasses.
Asunto(s)
Mataderos/normas , Bacterias Aerobias/crecimiento & desarrollo , Microbiología de Alimentos , Carne/microbiología , Análisis de Varianza , Animales , Canadá , Bovinos , Recuento de Colonia Microbiana/veterinaria , Femenino , Modelos Lineales , MasculinoRESUMEN
A method has been developed for the bacteriological evaluation of groups of beef carcasses which can be used to measure the degree of control over hygiene during hide removal and carcass dressing in abattoirs. This method, which enumerates aerobic mesophilic bacteria automatically using a hydrophobic grid membrane filter, was applied at six abattoirs. Two hundred excision samples (5 x 5 x 0.5 cm) were taken at 10 sites on the external surface of a group of 20 carcasses (five carcasses were sampled on each of four consecutive daily visits) for group-carcass evaluation at each abattoir. For each abattoir, the mean log10 Most Probable Number of Growth Units (MPNGU) and between-carcass variance component were obtained for each site and the average over sites. Using the average within-abattoir variance of this study and previously published studies involving 76 additional carcasses (Jericho et al. 1993), it was determined that 20 carcasses are more than adequate to estimate the mean log10 MPNGU per cm2 within 0.5 units at a site. The distribution of the log10 MPNGU per cm2 over the 10 sites was compared for the abattoirs, and sites were found to cluster into 2-4 homogenous groups. The means over sites of log10 MPNGU per cm2 for the abattoirs ranged from 1.52 to 2.64 and were unrelated to line speed.
Asunto(s)
Mataderos/normas , Manipulación de Alimentos/normas , Productos de la Carne/microbiología , Alberta , Animales , Bovinos , Recuento de Colonia Microbiana , Estudios de Evaluación como Asunto , Reproducibilidad de los Resultados , Manejo de Especímenes , Estadística como Asunto , Distribución TisularRESUMEN
Numbers of mesophilic bacteria were estimated on carcasses of 25 heifers and 25 steers of beef breeds in a modern, high-line-speed abattoir. One side of each carcass from each sex was sampled at the end of the kill-floor, before the carcass wash, on each of 25 visits. Two adjacent excision samples (5 x 5 x 0.5 cm) were taken from each of ten sites and processed for automatic enumeration of aerobic bacteria on hydrophobic grid membrane filters. The effects of sex and carcass weight on bacterial counts were examined. Groups of carcasses were examined to determine the sample size required for future assessments of kill-floor hygiene. The log10 of the most probable number of growth units (MPNGU)/cm2 did not differ significantly between heifers and steers (average over the ten sites of 2.2) and there was no effect of carcass weight on bacterial counts for nine of the ten sites. There were, however, highly significant (p < 0.001) differences in the counts between sites and the counts from the ten sites clustered into five homogenous groups. The between-carcass component of variation at a site was generally larger than the within-carcass component. We conclude that, to estimate the mean log10 MPNGU/cm2 at a site to within +/- 0.5 units, future group-carcass evaluations require about 200 samples from 10 (two adjacent samples/site) or 20 carcasses (one sample/site).
Asunto(s)
Bacterias Aerobias/crecimiento & desarrollo , Bovinos/microbiología , Carne/microbiología , Mataderos , Animales , Peso Corporal , Recuento de Colonia Microbiana , Femenino , Masculino , Tamaño de la Muestra , Factores SexualesRESUMEN
The protective effect of an inactivated whole-virion bovine herpesvirus-1 (BHV-1) immunising inoculum, without adjuvant, against viral-bacterial respiratory disease was studied in three experimental treatment groups of five calves each. One group was boosted 14 days after the first vaccination and at this time the second group received their initial inoculation. Seven days later, calves were challenged with BHV-1 in aerosol and four days after this challenge all calves were exposed to Pasteurella haemolytica A1 in aerosol. Among the three groups, differences in rectal temperature responses four days after viral challenge (P less than 0.01) did not relate to protection. However the main response variable, viral-bacterial pneumonia, was reduced in boosted calves (P less than 0.05).
Asunto(s)
Vacunas Bacterianas , Herpesvirus Bovino 1/inmunología , Rinotraqueítis Infecciosa Bovina/inmunología , Mannheimia haemolytica/inmunología , Pasteurelosis Neumónica/prevención & control , Aerosoles , Animales , Anticuerpos Antibacterianos/sangre , Bovinos , Enfermedades de los Bovinos/inmunología , Enfermedades de los Bovinos/prevención & control , Herpesvirus Bovino 1/aislamiento & purificación , Inmunización Secundaria/veterinaria , Rinotraqueítis Infecciosa Bovina/complicaciones , Rinotraqueítis Infecciosa Bovina/prevención & control , Laringe/patología , Pulmón/microbiología , Pulmón/patología , Masculino , Mannheimia haemolytica/aislamiento & purificación , Mucosa Nasal/microbiología , Tonsila Palatina/microbiología , Tonsila Palatina/patología , Pasteurelosis Neumónica/complicaciones , Organismos Libres de Patógenos Específicos , Tráquea/patología , Vacunación/veterinaria , Vacunas de Productos InactivadosRESUMEN
Formalin-inactivated and sonicated Pasteurella haemolytica bacterins were prepared from 1 h cultures of bacterial pellets in RPMI-1640 medium containing 7% fetal calf serum. The bacterial pellets were obtained from logarithmic phase growth of the organism by centrifugation. The protective effect of the vaccine was evaluated in 43 specific-pathogen-free Hereford crossbred calves and yearlings in three experiments. Cattle were either single vaccinated or boosted via three routes; intratracheally (i.t.), intranasally (i.n.) or intramuscularly (i.m.), using low or high doses. The two low-dose groups were also given supernatant by the same routes and volume as the bacterin. Cattle were challenged by P. haemolytica in aerosol at 24 or 39 days after last vaccination. To enhance the susceptibility of the cattle to this challenge, the cattle were exposed to bovine herpesvirus-1 aerosol 4 days before the bacterial challenge. The extent of pneumonia was significantly less in three groups of cattle (i.n.-i.n.,i.m.-i.n.,i.m.-i.m.) boosted with high dose of the bacterin than in the controls. Protection was observed when challenge isolates were heterologous or homologous to the isolates used to prepare the bacterins. It was also observed that the level of complement fixing antibody or anticytotoxin activity to P. haemolytica did not correlate with the degree of protection.
Asunto(s)
Vacunas Bacterianas/inmunología , Herpesvirus Bovino 1/inmunología , Infecciones por Pasteurella/prevención & control , Pasteurella/inmunología , Vacunas de Productos Inactivados/uso terapéutico , Administración Intranasal , Aerosoles , Animales , Anticuerpos Antivirales/inmunología , Temperatura Corporal/efectos de los fármacos , Bovinos , Femenino , Herpesvirus Bovino 1/aislamiento & purificación , Rinotraqueítis Infecciosa Bovina/prevención & control , Pulmón/microbiología , Masculino , Tonsila Palatina/microbiología , Sonicación , Vacunas de Productos Inactivados/farmacologíaRESUMEN
An experiment was designed to study the interaction of Pasteurella haemolytica with an attenuated bovine herpesvirus 1 in calves. Low titre of the virus culture used for aerosol exposure failed to produce measurable interaction. However, the experiment provided the first opportunity to study the light-microscopic changes in lungs of calves (n = 3) to a low-dose exposure (5-min aerosol) of P. haemolytica A1 from a fresh 5-h log-phase culture. The histopathological study was confined to tissue exposed to only P. haemolytica. A limited macroscopic pneumonia was produced in ventral parts of cranial lobes. Four days after exposure, a typical reaction featured four zones. Zone 1a at the centre with acute inflammatory processes and necrosis of phagocytic cells was surrounded by a broad band of compacted, largely necrotic macrophages and polymorphonuclear leucocytes (PMNL) in alveoli of zone 1b. Necrosis was confined to zone 1. Zone 2a frequently occupied the remainder of the lobule with irregular distribution of congestion, oedema with a fibrinous component, and infiltration by numerous PMNL, macrophages and other mononuclear inflammatory cells. The narrow zone 2b was located between zones 1b and 2a and had oedema with a fibrinous component, numerous fibrocytes, few inflammatory cells and empty capillaries. It is suggested that zone 2 served to isolate zone 1 by surrounding it with nonfunctional tissue. The pathogenicity of P. haemolytica is discussed for uncompromised lungs and lungs compromised by virulent BHV1 infection.
Asunto(s)
Aerosoles/efectos adversos , Pulmón/patología , Infecciones por Pasteurella/veterinaria , Pasteurella/aislamiento & purificación , Animales , Bovinos , Enfermedades de los Bovinos/microbiología , Enfermedades de los Bovinos/patología , Herpesvirus Bovino 1/aislamiento & purificación , Herpesvirus Bovino 1/metabolismo , Rinotraqueítis Infecciosa Bovina/complicaciones , Rinotraqueítis Infecciosa Bovina/patología , Pulmón/microbiología , Pasteurella/metabolismo , Infecciones por Pasteurella/complicaciones , Infecciones por Pasteurella/patologíaRESUMEN
Eight calves (2 calves in each of 4 groups) were exposed to an aerosol of bovine herpesvirus-1 (BHV-1) and 4 days later to an aerosol of Pasteurella haemolytica. Samples of tracheal and exhaled air were taken simultaneously beginning 1 day before viral exposure and once a day up to 3 to 4 days after the bacterial exposure. Samples were also taken during the period of aerosol exposure. Only 0.04% to 0.42% of P haemolytica-carrying droplets of the bacterial aerosol passed beyond the cranial part of the respiratory tract to the trachea. Nevertheless, numbers of bacteria as few as 1 bacterium/L of tracheal air were sufficient to produce fatal disease in the lungs of BHV-1-infected calves. In 1 of 4 groups, BHV-1 was isolated from most daily samples of exhaled and tracheal air. Pasteurella haemolytica was isolated 7 times more frequently from air when calves were kept at 1 C than when calves were kept at 23 C. The number of P haemolytica-carrying droplets in exhaled air was low (less than 1/L of air); however, samples obtained during the time that calves were coughing contained up to 10 P haemolytica-carrying droplets/L of air. It was learned that the cranial part of the respiratory tract serves as an efficient filter on inhalation and exhalation, but this filter is deficient in the animal when coughing occurs. This process expels infective droplets of size suitable for inhalation by other cattle in close proximity.
Asunto(s)
Rinotraqueítis Infecciosa Bovina/microbiología , Infecciones por Pasteurella/microbiología , Aerosoles , Microbiología del Aire , Animales , Bovinos , Herpesvirus Bovino 1/aislamiento & purificación , Rinotraqueítis Infecciosa Bovina/patología , Pasteurella/aislamiento & purificación , Infecciones por Pasteurella/patología , Respiración , Tráquea/microbiologíaRESUMEN
Immunity against pneumonic pasteurellosis was studied in calves after recovery from experimental respiratory disease with Pasteurella haemolytica. Nine calves were exposed to aerosols of parainfluenza-3 virus and Pasteurella haemolytica A1 six days apart to produce respiratory disease. After recovery from the disease, these nine principal and four control calves were challenged with aerosols of bovine herpesvirus 1 and P. haemolytica A1 four days apart. With this viral-bacterial challenge, the nine principal animals failed to develop clinical responses to this bacterial challenge and their lungs did not show the growth of P. haemolytica on cultures, whereas two of four control calves had elevated temperatures and developed necropurulent pneumonia with the isolation of P. haemolytica from the lungs. The principal calves had developed high levels of cytotoxin neutralizing antibodies in their sera following parainfluenza-3 virus-P. haemolytica infection. This demonstrated that immunity against pneumonic pasteurellosis can be achieved, with a suggestion that further search for an effective vaccine for P. haemolytica is warranted.
Asunto(s)
Anticuerpos Antibacterianos/biosíntesis , Enfermedades de los Bovinos/inmunología , Infecciones por Pasteurella/veterinaria , Neumonía/veterinaria , Aerosoles , Animales , Anticuerpos Antivirales/biosíntesis , Vacunas Bacterianas/administración & dosificación , Bovinos , Enfermedades de los Bovinos/patología , Citotoxinas/inmunología , Herpesvirus Bovino 1/inmunología , Virus de la Parainfluenza 3 Humana/inmunología , Pasteurella/inmunología , Infecciones por Pasteurella/inmunología , Infecciones por Pasteurella/patología , Neumonía/inmunología , Neumonía/patologíaRESUMEN
Ninety-three calves comprising 16 experimental groups were exposed to viral (bovine herpesvirus-1 or parainfluenza-3 virus) and Pasteurella haemolytica aerosols. Serum samples from these calves were tested before and after exposure for antibodies to P haemolytica by a modified direct complement-fixation test. At slaughter of the calves, the extent of pneumonia produced was estimated for each calf and compared with the results of the modified direct complement-fixation tests. The extent of pneumonia was not related (P greater than 0.05) to the amount of anti-P haemolytica antibody produced by either naturally occurring or experimentally induced infection.