Risk factors for avian influenza and Newcastle disease in smallholder farming systems, Madagascar highlands

Newcastle disease (ND) and avian influenza (AI) are issues of interest to avian producers in Madagascar. Newcastle disease virus (NDV) is the major constraint for village aviculture, and avian influenza viruses type A (AIAV) are known to circulate in bird flocks. This study aims at classifying smallholder poultry farms, according to the combination of risk factors potentially associated with NDV and AIAV transmission and to assess the level of infection for each farm class. Two study sites, Lake Alaotra and Grand Antananarivo, were chosen with respect to their differences in terms of agro-ecological features and poultry productions. A typology survey involving 526 farms was performed to identify possible risk factors for (i) within-village, and (ii) between-village virus transmission. A cross-sectional serological study was also carried out in 270 farms to assess sero-prevalences of NDV and AIAV for each farm class and the link between them and risk factor patterns. For within-village transmission, four classes of farms were identified in Grand Antananarivo and five in Lake Alaotra. For between-village virus transmission, four classes of farms were identified for each site. In both sites, NDV sero-prevalence was higher than for AIAV. There was no evidence of the presence of H5 or H7 subtypes of AIAV. Sero-prevalences were significantly higher in Lake Alaotra than in Grand Antananarivo for both viruses (OR=2.4, p=0.02 for NDV, and OR=9.6, p<0.0001 for AIAV). For within-village NDV transmission in Grand Antananarivo, backyard chicken farms (OR=3.6, p<0.001), and chicken farms with biosecurity awareness (OR=3.4, p<0.01) had greater odds of having antibodies against NDV than the others. For between-village virus transmission, farms with multiple external contacts, and farms using many small markets had greater odds of having antibodies against NDV than the others (OR=5.4, p<0.01). For AIAV, there were no differences in sero-prevalences among farm classes. In Lake Alaotra, the observed high density of palmipeds and widespread rice paddies were associated with high sero-prevalences for both viruses, and a homogeneous risk of virus transmission between the different farm classes. In Grand Antananarivo, farm visits by collectors or animal health workers, and farm contacts with several markets were identified as potential risk factors for NDV transmission. Further studies are needed to identify the circulating virus genotypes, model their transmission risk, and provide adapted control measures.     

Identification of risk factors associated with highly pathogenic avian influenza H5N1 virus infection in poultry farms, in Nigeria during the epidemic of 2006-2007

We conducted a matched case-control study to evaluate risk factors for infection with highly pathogenic avian influenza (HPAI) H5N1 virus in poultry farms during the epidemic of 2006-2007 in Nigeria. Epidemiologic data were collected through the use of a questionnaire from 32 case farms and 83 control farms. The frequency of investigated exposure factors was compared between case and control farms by using conditional logistic regression analysis. In the multivariable analysis, the variables for (i) receiving visitors on farm premises (odds ratio [OR]=8.32; 95% confidence interval [CI]=1.87, 36.97; P<0.01), (ii) purchased live poultry/products (OR=11.91; 95% CI=3.11-45.59; P<0.01), and (iii) farm workers live outside the premises (OR=8.98; 95% CI=1.97, 40.77; P<0.01) were identified as risk factors for HPAI in poultry farms. Improving farm hygiene and biosecurity should help reduce the risk for influenza (H5N1) infection in poultry farms in Nigeria.     

Use of an enzyme-linked immunosorbent assay in bulk milk to estimate the prevalence of Neospora caninum on dairy farms in Prince Edward Island, Canada

This study evaluated the use of bulk milk as a diagnostic tool for estimation of herd-level Neospora caninum exposure in Atlantic Canada; it was used to estimate the prevalence of dairy farms with a within-herd N. caninum-seroprevalence > or = 15% in Prince Edward Island (PEI). The variation over time of N. caninum antibodies in bulk milk is also reported. Skimmed bulk milk and individual serum samples were analyzed for N. caninum antibodies by using an enzyme-linked immunosorbent assay (ELISA). Bulk milk samples were collected in May 2004 (n = 235), May 2005 (n = 189), and June 2005 (n = 235). The prevalence of dairy farms with a within-herd seroprevalence > or = 15% on PEI was 6.4% in May 2004. In May and June 2005, respectively, 10.1% and 10.2% of farms had a > or = 15% within-herd seroprevalence. In 11 farms that were considered positive based on bulk milk samples, blood samples were collected from all adult cows in September 2005, in conjunction with a 4th bulk milk sample on the same day. The correlation coefficient between serology and bulk milk ELISA was 0.87. The results of this study demonstrate that the prevalence of N. caninum in dairy farms can be estimated by using a bulk milk ELISA.     

Husbandry practices, badger sett density and habitat composition as risk factors for transient and persistent bovine tuberculosis on UK cattle farms

Bovine tuberculosis (bTB) is a persistent problem in cattle herds in Great Britain and Ireland. Farm management and cattle husbandry practices can influence the risk of transmission of bTB and hence the likelihood of bTB breakdown (>or=1 reactor to the tuberculin skin test). Biological differences are expected in the transmission dynamics, and hence risk factors for bTB breakdown, on farms where infection persists in the herd compared to farms where infection is more sporadic or short-lived. Comparative case-control studies were performed to test farm management practices as potential risk factors for transient (under breakdown restrictions for 6 months) bTB breakdown over 5 years (1995-1999) on 179 and 171 UK cattle farms, respectively. Farms were characterised for badger sett density and farm habitat composition by ground survey, farmers were questioned retrospectively on management practices, and cases and controls were identified from national tuberculin test records. Controlling for routine tuberculin testing interval, log-transformed herd size, regional location, badger sett density and farm habitat complexity, multivariable logistic regression identified increased odds of both transient and persistent breakdown on farms that bought-in cows (odds ratio (OR)>or=4.9; 95% confidence interval (CI)>or=1.1;22.8). In addition, the purchase of >50 head of cattle (OR=4.0, 95% CI=1.0;16.0) and the storage of manure for >or/=6 months (OR=4.4; 95% CI=1.3;15.4) were risk factors for transient breakdown, whereas the use of silage clamps (OR=9.1; 95% CI=2.0;40.8) increased the risk of persistent breakdown. Decreased odds of both transient and persistent breakdown were associated with higher stocking densities (>3cattle/ha) (OR相似文献   

Risk factors for seropositivity to H5 avian influenza virus in ostrich farms in the Western Cape Province, South Africa

In a 2005 serological survey, carried out in response to an outbreak of H5N2 avian influenza (AI) in ostriches in the Eastern Cape Province, 16.3% of ostrich farms in the Western Cape Province of South Africa were found to be seropositive to H5 AI virus. We subsequently carried out a questionnaire-based census survey on all available registered Western Cape ostrich farms that still existed at the end of 2005 (367 farms, of which 82 were seropositive), in order to identify risk factors associated with farm-level seropositivity. A farm was classified as seropositive for H5 AI virus if one or more birds had tested positive (haemagglutination inhibition titre >1:16) in the 2005 survey, which had been designed to detect a minimum within-group seroprevalence of 10%. For each farm, risk factor information was collected using a questionnaire administered during a face-to-face interview with each farm owner or manager. Information was obtained on the ostrich population, movements of birds, environmental factors, management practices, and frequency of contact between ostriches and various wild bird species. Multiple logistic regression models were developed for the whole Western Cape Province and also for the two largest ostrich farming regions, "Klein Karoo" and "Southern Cape". Seroprevalence differed between regions, being highest in the Klein Karoo (31.6%). In all three models, increased risk of farm-level H5 AI virus seropositivity was associated with increasing numbers of ostriches, excluding chicks, present on the farm. Increased risk of seropositivity was associated with reduced frequency of cleaning of feed troughs (<1x/week vs. >1x/week), both overall (odds ratio (OR)=4.5; 95% confidence interval (CI): 1.5, 13.3) and in the Southern Cape (OR=53.6; 95% CI: 3.3, 864), and with failure to clean and disinfect transport vehicles, both overall (OR=2.3; 95% CI: 1.1, 4.8) and in the Klein Karoo (OR=2.6; 95% CI: 1.1, 6.5). Increased risk of seropositivity was also associated with increasing frequency of contact of ostriches with certain wild bird species: overall with white storks (Ciconia ciconia), in the Southern Cape with gulls (Larus spp.), and in the Klein Karoo with Egyptian geese (Alopochen aegyptiaca).     

Risk factors for clinical Salmonella enterica subsp. enterica serovar Typhimurium infection on Dutch dairy farms

Risk factors for outbreaks in 1999 of clinical Salmonella enterica subsp. enterica serovar Typhimurium infection on dairy farms were studied in a matched case-control study with 47 case farms and 47 control farms. All 47 case farms experienced a clinical outbreak of salmonellosis which was confirmed with a positive bacteriologic culture for serovar Typhimurium in one or more samples. Serovar Typhimurium phage type 401 and 506 (definitive type 104, DT104) were the most frequently isolated phage types (13 isolates). On most farms (66%), clinical signs were seen only among adult cows. The most frequently reported clinical signs were diarrhoea (in 92% of the farms) and depression (in 79% of the farms).Control farms were matched on region and had no history of salmonellosis. A questionnaire was used to collect data on case and control farms. The relationship between serovar Typhimurium status of the farm and possible risk factors was tested using conditional logistic regression. Significant factors in the final model were presence of cats on the farm (OR=0.06), purchase of manure (OR=21.5), feeding colostrum only from own dam (OR=0.08), a non-seasonal calving pattern (OR=25), unrestricted grazing of lactating cows (OR=0.07), and a high mean mowing percentage of pasture (OR=1.02).     

Risk factors for milk off-flavours in dairy herds from Prince Edward Island, Canada

A sudden increase in the incidence of milk off-flavours in bulk tank milk from Prince Edward Island (Canada) dairy farms in the late 1990s prompted an investigation of potential herd-level risk factors. A prospective case-control study was conducted from 2000 to 2002. Data on herd management were obtained by questionnaire and field investigation from all the 62 identified off-flavour positive farms (cases) and 62 loosely matched (for data-collection convenience) off-flavour negative farms (controls). Forty-three of the 62 cases (69%) of milk off-flavours identified during the study period were classified as “transmitted” (feed) off-flavours, and 9 (15%), 6 (10%), and 4 (6%) as “rancid”, “oxidized” and “malty” off-flavours, respectively. Given this evidence and the relatively low incidence of other flavour defects in milk, only transmitted-flavour cases were considered in the analyses of risk factors. Poor air quality in the lactating cows’ barn (OR = 40.8), using baled silage as the main forage (OR = 10.6), as well as feeding roughage before milking (OR = 253.3) or as a free choice (OR = 3.2) all were significantly (P < 0.05) associated with the incidence of transmitted flavours in bulk-tank milk. Clipping the hair on the cows’ udder (OR = 0.07) and changing the bedding material more than once a day (OR = 0.12) were protective. The finding about feeding baled silage before milking has raised hypotheses about silage composition (in particular the off-flavour compounds or their precursors) and also about the process of silage making itself.     

The potential of measuring serum amyloid A in individual ewe milk and in farm bulk milk for monitoring udder health on sheep dairy farms

The aim of the study was to determine the diagnostic value of measuring serum amyloid A (SAA) concentrations in milk of individual ewes and in farm bulk milk for monitoring udder health. Udder health was calculated by examining a randomly selected group of seven flocks at each farm visit by means of California mastitis test and bacteriological examination of 5749 milk samples. SAA was determined additionally in 267 randomly selected milk samples from six flocks. Thirty-one bulk milk samples from these farms were tested for SCC and SAA levels. Subclinical infections were detected in 29.5% of samples whereas no clinical infections were observed. Intramammary infected udder halves showed significantly elevated SAA concentrations (121.3+/-25.3 microg/ml) in milk compared to the levels of healthy udder halves (8.0+/-1.9 microg/ml; p<0.001). SAA was significantly elevated in sheep with elevated CMT scores and positive bacteriological results. Bulk milk SAA levels ranged from 18.6+/-6.7 to 37.4+/-14.1 microg/ml and showed a positive correlation with bSCC (r=0.38, p=0.018) but not with percent infected glands (r=0.022, p=0.453). This study demonstrated that SAA levels in milk can be used to detect subclinical mastitis in individual ewes whereas further investigations are needed to determine the value of measuring SAA in bulk milk for monitoring flock udder health.     

Indications of a relationship between buying-in policy and infectious diseases on dairy farms in Wales

During the period February to May 2008, bulk milk samples were collected from 57 dairy farms throughout Wales in the framework of a voluntary somatic cell count project. Bulk milk samples were tested for antibodies to bovine viral diarrhoea virus (BVDV), bovine herpesvirus type 1 (BHV-1) and Leptospira Hardjo, and samples were also tested for the presence of BVDV antigen by PCR. A questionnaire was used to determine whether the herd was open or closed, what the vaccination status was, and to obtain general farm information such as the herd size and average milk yield. Vaccination against BVD, infectious bovine rhinotracheitis and leptospirosis was practised on 37, 12 and 35 per cent of the farms, respectively. The presence of bulk milk antibodies on farms that did not use vaccination was 75 per cent for BVDV, 54 per cent for BHV-2 and 76 per cent for L Hardjo. Open herds had 10 times the odds (95 per cent confidence interval [CI] 1.7 to 59.4)of having bulk milk antibodies for BVDV and 16.7 times the odds (95 per cent CI 2.0 to 49.7) of having bulk milk antibodies to BHV-1 compared with closed herds. A farm with bulk milk antibodies to one disease had significantly higher odds of having bulk milk antibodies to a second disease (P<0.05).     

Toxoplasma gondii in sheep from the Campania region (Italy)

A cross-sectional serological survey was conducted in order to evaluate, irrespective of abortion, the Toxoplasma gondii infection in pastured sheep from the Campania region of southern Italy. A geographical information system was used in order to uniformly sample the ovine farms (n=117) throughout the entire region. Blood and milk samples were collected from 10 adult sheep (>18 months) on each farm (total number=1170 sheep). Serum samples were tested for the presence of IgG antibodies to T. gondii using a commercial indirect fluorescent antibody test. For each farm, the 10 milk samples collected were pooled in order to obtain a single milk sample per farm (total number=117 milk samples). The 77.8% (91/117) of the farms and the 28.5% (333/11,170) of the sheep resulted positive by serology. In addition, the presence of T. gondii DNA was detected by PCR in 4 milk samples out of the 117 examined (3.4%).     

Risk factors for hazard of release from salmonella-control restriction on Swedish cattle farms from 1993 to 2002

In Sweden, only a few cattle farms are infected with salmonella each year and this can be attributed to the Swedish salmonella control programme. All findings of salmonella in animals, feed and food of animal origin are notifiable and restrictions are always put on infected herds until they have been cleaned up from the infection. However, there has been concern about increasing costs for clean-up of salmonella-infected farms as well as increasing length of the restriction periods. Our aim was to investigate potential risk factors associated with the length of restriction periods on Swedish cattle farms between 1993 and late 2002. All 112 cattle farms that were notified to the Swedish Board of Agriculture as infected with salmonella during the study period, were included in this longitudinal and retrospective study. The putative risk factors were analysed using the proportional-hazards model. There was a lower hazard for release from salmonella control restrictions after the European Union (EU) accession in 1995, and/or change of testing from one to two negative herd tests for release of restrictions (hazard ratio (HR)=0.56, 95% confidence interval (CI)=0.38, 0.84), for every additional number of 100 cows (HR=0.83; CI=0.7, 0.97), if rodents and/or wild birds were abundant (HR=0.5, CI=0.27, 0.98) and if there was more than one farm site in the company (HR=0.47, CI=0.28, 0.81).     

Factors related to the incidence of clinical encephalomyocarditis virus (EMCV) infection on Belgian pig farms

We set up a matched case-control study of potential risk factors for clinical encephalomyocarditis virus (EMCV) in 58 pig farms in West Flanders (Belgium). In total, 29 farms experienced a clinical outbreak of EMCV confirmed by EMC virus isolation. Mortality was seen only among suckling piglets (18 case farms), in piglets and other age-groups (4 case farms), or only among fattening pigs (7 case farms). Five farms had reproductive problems among the sows. Control farms were matched geographically on farm size and farm type and were selected on the absence of clinical signs. A questionnaire on potential risk factors for EMCV was developed to collect data at both case and control farms. The exploration of the data used clusters of factors associated with clinical EMCV infection: (a) rodents, (b) general farm set up and (c) general hygiene. The multivariable relationships between clinical appearance of EMCV and potential risk factors were tested with conditional logistic regression. The final model on all farms contained presence of mice (OR=8.3) as a risk factor for clinical EMCV infection while the flow of manure up through the slatted floor (OR=0.11) and movement of manure between manure pits in the pig stable (OR=0.14) were protective.     

Prevalence of respiratory bacterial pathogens and associated management factors in dairy calves in Taiwan

This study aimed to investigate the prevalence at both farm-level and calf-level and to identify the risk factors of respiratory bacterial pathogens in dairy calves in Taiwan. The status of bovine respiratory disease (BRD) was evaluated by using the Wisconsin scoring system from a total of 400 pre-weaned calves from 32 different farms in Taiwan, then the nasopharyngeal swabs were collected. The prevalence of respiratory pathogens was 84.37% at farm-level and 45.50% at calf-level, and Pasteurella multocida (P. multocida) was the most prevalent pathogen. The presence of Mycoplasma bovis (M. bovis), P. multocida, Mannheimia haemolytica (M. haemolytica) and Histophilus somni (H. somni) were all higher in BRD positive calves than BRD negative calves, but only in H. somni was significant (P<0.001). Then nine farm management risk factors were analyzed by using multivariate logistic regression models to determine the risk factors of respiratory bacterial pathogens (farm and calf-level). In the result at farm-level, only unheated colostrum was significantly associated with pathogen positive farms (Odds Ratio (OR)=11.43). At calf-level, the predominant risk factor for each pathogen, M. bovis, P. multocida, M. haemolytica and H. somni, was late first colostrum feeding (OR=272.82), unheated colostrum (OR=3.41), waste milk feeding (OR=6.59) and high pneumonia treatment cost (OR=2.52), respectively. For effective preventive measures, farmer education on milk and colostrum feeding are urgently warranted.     

Seroprevalence of Babesia bigemina in smallholder dairy cattle in Tanzania and associated risk factors

Variations in the seroprevalence of antibody to Babesia bigemina infection by farm and animal level risk factors were investigated for 2 contrasting regions of Tanga and Iringa in Tanzania. Tanga is situated in the eastern part of the country and has typical tropical coast climate while Iringa is situated in the Southern Highlands and has a tropical highland climate. Two hundred farms from each region were selected using simple random sampling procedure and visited once between January 1999 and April 1999. Blood samples were collected from 1329 smallholder dairy animals on selected farms for harvesting serum which was subsequently used for serodiagnosis of B. bigemina using an indirect enzyme linked immuno-sorbent assay (ELISA). Of the 1329 sera samples screened, 34.9 % were positive for B. bigemina. The prevalence was higher in Iringa Region [43%, 95% confidence intervals (CI) = 39.5-47.3] than in Tanga Region (27%, CI = 23.6-30.5). Using a logistic binomial regression model as an analytical method for predicting the likelihood of animal seropositivity, we found (in both regions) that the risk of positive reaction varied with the animal's age, history of grazing and geographical location. Seroprevalence increased with age (beta = 0.01 and 0.01 per year of age, P < 0.005 in Tanga and Iringa, respectively). Animals located in Lushoto and Iringa urban district were associated with increased risk of seropositivity [Odds ratio (OR) = 4.24, P = 0.001, for Lushoto, and OR = 1.81, P = 0.040, for Iringa Urban, respectively). Animals grazed 3 months prior to sampling had higher odds for seropositivity than zero/semi-grazed, despite farmer-reported high frequency of tick control (OR = 2.71, P = 0.0087, for Tanga, and OR = 4.53, P = 0.001, for Iringa). Our study suggests that even though herd sizes are small, B. bigemina infection is widespread in many smallholder dairy farms and endemic stability with respect to this disease has not yet been attained, but the observed levels are sufficiently high to ensure that clinical disease would be a risk.     

Effect of previous antimicrobial treatment on fecal shedding of Salmonella enterica subsp. enterica serogroup B in New York dairy herds with recent clinical salmonellosis

The association of herd- and sample-level factors with the isolation of Salmonella group B from cattle fecal samples was analyzed. Study farms were 65 dairy herds with a recent history of laboratory-confirmed clinical salmonella infections. Herds were visited once per month for three months to collect data and samples for bacteriological culture. Herd size varied widely from 34 to 3700 total cattle on the farm (median=370). Salmonella serogroup B was isolated from 270 of 2726 samples tested. The predominant serotypes identified were S. Typhimurium and S. Typhimurium var. Copenhagen. Logistic regression was used to analyze the relationship between potential risk factors and isolating Salmonella serogroup B. The only herd-level factor which was significantly associated with fecal shedding was total herd size (hundreds of cattle OR=1.09; 95% confidence interval (CI): 1.05, 1.14). The probability of a positive sample decreased substantially for longer intervals between the initial clinical case and sampling (interval in months OR=0.5; 95% CI: 0.3, 0.6). The presence of diarrhea increased the risk of shedding (OR=2.1; 95% CI: 1.4, 3.0). The effect of recent treatment with antimicrobial agents depended on age group. For heifers and cows, recent antimicrobial treatment increased the probability of isolating Salmonella (heifers OR=11.8; 95% CI: 2.9, 48.8; cows OR=4.1; 95% CI: 2.0, 8.4), but this effect was not statistically significant for calves before weaning. Among animals without recent antimicrobial treatment, preweaned calves were more likely to have positive samples than cows (OR=3.5; 95% CI: 1.8, 6.9; heifers OR=4.7; 95% CI: 2.3, 9.6).     

Epidemiology of salmonella infections in pig units and antimicrobial susceptibility profiles of the strains of Salmonella species isolated

One hundred and thirteen finishing pig units and 74 sow units in Catalonia, Spain, were examined to determine the prevalence of salmonella infections and the factors that could be associated with them. Pooled faecal samples were taken from the finishing units, and samples of faeces were collected from individual sows. The Salmonella isolates were serotyped, phage typed and examined for their antimicrobial susceptibility to 18 common antimicrobial drugs. In addition, blood samples from pigs on 141 farms were analysed by ELISA. In both the bacteriological and serological surveys, a questionnaire with 84 questions was completed for each farm. Salmonella species were isolated from 20 per cent of the finishing units and 24 per cent of the sow units; 14 serotypes were detected in the finishing pigs and 11 in the sows. More than 30 per cent of the strains were resistant to tetracycline, sulphonamides, ampicillin or streptomycin, and 69 per cent of the strains were resistant to three or more agents up to 10 compounds. Seventy-seven per cent of the farms had at least one seropositive animal, and 26 per cent of these farms had an individual seroprevalence of 50 per cent or more. The factors associated (P<0.05) with the excretion of Salmonella species in the finishing units were the practice of raising livestock other than pigs (odds ratio [OR]=6.18), the herd size (OR=5.87), and a past history of clinical salmonellosis (OR=4.97). For the sows, the factors associated (P<0.05) with the excretion of Salmonella species were having open-flushed drainage of sewage (OR=34.48), a lack of rodent control measures (OR=0.05) and the number of sows in the unit (OR=9.26). Factors associated with seropositivity in the finishing units were a lack of bird-proof nets (OR=0.30) and the use of water from private wells (OR=3.64).     

Risk factors associated with the salmonella status of dairy farms in England and Wales

Between October 1999 and February 2001 the salmonella status of 449 dairy farms in England and Wales was determined by environmental sampling on up to four occasions. Data were collected through interview-based questionnaires, and multivariable analyses were used to identify risk factors associated with the farms either being Salmonella positive (prevalence data) or becoming Salmonella positive (incidence data). Region, herd size, month of visit and the lack of a clean visitor parking area were significantly associated with the prevalence of Salmonella species, and there was a significant trend towards an increased risk in late summer and autumn. The introduction of six- to 24-month-old cattle into a herd was associated with a reduced prevalence, but the introduction of adult cattle only, or calves with other cattle, was associated with an increased (but not significant) risk of farms being Salmonella positive. Month of visit, the lack of a clean visitor parking area, the use of part-time workers and not feeding calves whole milk, but not region or herd size, were associated with an increased incidence of salmonella.     

Assessment of Risk Factors in Milk Contamination with Staphylococcus aureus in Urban and Peri‐Urban Small‐Holder Dairy Farming in Central Ethiopia

Assessment of risk factors associated with milk production systems is central to ensuring quality and safety of milk and milk products. This study was aimed at identifying possible risk factors in milk contamination in urban and peri‐urban areas of the central high lands of Ethiopia. A total of 477 on‐farm pooled milk (n = 433) and combined bulk milk samples (n = 44) were collected and processed using standard microbiological techniques to isolate and characterize Staphylococcus aureus. In addition, 433 individual farm owners and 22 collection centre owners were interviewed using a structured and pre‐tested questionnaire. Multivariate logistic regression was used to determine risk factors. Of the total individual on‐farm pooled milk samples analysed (n = 433), it was found that 103 of the individual milk samples (24%) and 17 of the combined bulk milk (39%) were positive for S. aureus. This difference in prevalence was statistically significant. Even though there were a number of potential variables associated with the recovery of S. aureus in bovine milk, four variables including cleaning milk container with hot water and detergent [Adjusted OR: 0.342, 95% CI, (0.166, 0.701)], mastitis check [Adjusted OR: 3.019, 95% CI (1.542, 5.913)], travel time to collection centres [Adjusted OR: 4.932, 95% CI, (2.265, 10.739)] and amount of milk delivered by farmers to collection centres per day [Adjusted OR: 1.059 (1.032, 1.087 β = 0.057)] were found to be statistically significantly associated with isolation of S. aureus. We recommend a targeted educational intervention on defined risk factors to reduce the post‐harvest S. aureus contamination of raw milk in urban and peri‐urban milk shed areas of central Ethiopia.     

Farm management factors associated with bulk tank somatic cell count in Irish dairy herds

The relationship between bulk tank somatic cell count (SCC) and farm management and infrastructure was examined using data from 398 randomly selected, yet representative, Irish dairy farms where the basal diet is grazed grass. Median bulk tank SCC for the farms was 282,887 cells/ml ranging from 82,209 to 773,028 cells/ml. Two questionnaires were administered through face-to-face contact with each farmer. Herd-level factors associated with bulk tank SCC were determined using linear models with annual somatic cell score (i.e., arithmetic mean of the natural logarithm of bulk tank SCC) included as the dependent variable. All herd level factors were analysed individually in separate regression models, which included an adjustment for geographical location of the farm; a multiple regression model was subsequently developed. Management practices associated with low SCC included the use of dry cow therapy, participation in a milk recording scheme and the use of teat disinfection post-milking. There was an association between low SCC and an increased level of hygiene and frequency of cleaning of the holding yard, passageways and cubicles. Herd management factors associated with bulk tank SCC in Irish grazing herds are generally in agreement with most previous studies from confinement systems of milk production.