Gliotoxinogenic Aspergillus fumigatus in the dairy herd environment.

The potential association between hygienic conditions in the environment of lactating cows and the presence of gliotoxinogenic Aspergillus fumigatus strains was studied. Milk samples (individual cow's milk [ICM], bulk tank milk [BTM]) from 44 dairy farms were sampled. In ICM samples, eight different species of Aspergillus were identified. A. flavus and A. fumigatus were predominant, with 37.8% and 26.1% relative densities, respectively. A. fumigatus strains were isolated from 61.4% of the BTM samples, and 34% of these strains were able to produce gliotoxin. Principal component analysis was used to associate the presence of A. fumigatus with some hygienic and sanitary practices. A significant and positive correlation was observed between dry cow therapy and forestripping. The presence of A. fumigatus gliotoxin producers in milk was associated with high somatic cells count (SCC) samples. Good hygienic and sanitary practices were associated with absence of A. fumigatus and relatively low SCCs of <250,000 cells/ml. In general, a high percentage of dairy farms were positive for A. fumigatus in BTM samples. This is the first work that indicates the positive effects of adequate hygienic and sanitary practices in dairy herds on the control of A. fumigatus and related species. By reducing the frequency of Aspergillus spp. in the dairy environment, the risk of farm handlers' exposure and the risk of intramammary fungal infections would also be reduced.

Naturally occurring aflatoxin M(1) in raw bulk milk from farm cooling tanks in Argentina.

The aim was to carry out a survey of aflatoxin M(1) (AFM(1)) in raw whole milk from bulk tanks. The sample collection was performed in farms located in one the most important milk-production zones in the centre of Argentina. A total of 94 samples of milk from 47 dairy farms were analysed. AFM(1) analysis involved the use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) with prior purification of the extracts using immunoaffinity columns. AFM(1) incidence in raw milk was high as 63.8% and levels were between not detected to 0.07 microg l(-1). Several contaminated samples (39%) were over the European Commission limit for infant milk (0.025 microg l(-1)), although none of samples were above Argentine legislation. Estimates of AFM(1) intake were assessed for different age populations. The average AFM(1) estimated daily intakes were 1.6, 0.5, 0.17 ng kg(-1) body weight day(-1) for 4-year-old babies, young children, and adults, respectively. All tested farms used pastures and silages at similar composition. Even though some farms (13) employed high-risk supplementary feeds, such as peanut pod and/or cotton seed, no statistically significant differences were observed between groups. Information from AFM(1) levels in milk in Argentina is limited. A systematic AFM(1) monitoring programme must be performed by means of accurate and reliable analytical techniques as a strategy for protecting milk consumers.

Pig characteristics associated with mortality and light exit weight for the nursery phase.

One thousand and ten weaned pigs that were reared in 1 nursery in Iowa from weaning (17 +/- 2 days ) until 10 weeks of age were evaluated. A weaning weight threshold of 3.6 kg maximized the sensitivity and specificity to correctly predict the likelihood of dying or being light in weight at exit from the nursery (< or = 14.5 kg). Weaning weight < or = 3.6 kg (OR = 2.92), barrow (OR = 1.75), and sow unit (A versus B, OR = 2.14) were significant predictors of mortality in the nursery. Birth weight < or = 1.0 kg (OR = 2.66), weaning weight < or = 3.6 kg (OR = 8.75), gilt (OR = 1.4), sow unit (OR = 2.38), and gilt as nursing sow at weaning (OR = 1.66) were significant predictors of being lightweight at nursery exit. Eighteen per cent of the nursery deaths and almost half of lightweight nursery pigs could be prevented if there were no lightweight pigs at weaning.

Mixed models applied to the study of variation of grower-finisher mortality and culling rates of a large swine production system.

Large scale production systems for swine are frequently organized in a hierarchical structure. Consequently, important production parameters, such as mortality and culling, can be analyzed at different levels. The major aims of this study were to assess variance components (VC) of mortality and culling rates attributed to sites and to barns within a site, and subsequently to investigate the impact of average entry weight, days on feed (length of the production turn), and season on the magnitude of the VC. Then, data from a large farm with 3 sites were collected during 5 y. In total, 1720040 pigs distributed in 1502 all-in/all-out grower-finisher groups were included. Linear mixed models were fitted for mortality and culling rates. The barn was modeled as the residual component (barn-to-barn variations) with production turn and site nested within production turn as random intercept variance components. Barn-to-barn pig group variation was the largest VC for mortality (63.08%), when no predictors were included in the models. Predictors, such as pigs placed on quarters 2 and 3, low average entry weight, and shorter production turn length, were associated together with higher mortality. The explained proportion of variance due to these predictors was about 12.05% and the VC for barn, site, and production turn were 67.6%, 17.6%, and 14.8%, respectively. Barn-to-barn variation was also the largest VC for culling rate (46.2%), but the same predictor mentioned above explained only about 1.4% of the variation. The VC for barn, site, and production turn were 46.8%, 21.3%, and 31.8%, respectively. Since the variability among barns far exceeded the variability among sites, the barn should be used as experimental unit in studies with grower-finisher mortality, culling rate, or both, as outcome variables.

Risk factors for mortality in grow-finishing pigs in Belgium.

The present study investigated risk factors for mortality in grow-finishing pigs of 137 pig herds belonging to one integration company during a period of 2.5 years. Mortality data, expressed as the number of dead pigs divided by the number of pigs placed in the fattening unit were investigated retrospectively. The following potential risk factors were evaluated: type of pig herd, season and year of placement in the fattening unit, pig density in the municipality, management practices (density of the pigs in the barn, origin of the pigs), housing conditions and feeding practices. The overall average mortality percentage was 4.70%. Three variables in a multivariable regression model were significantly associated with mortality: season of placement in the fattening unit, origin of the piglets and duration of the fattening period. Pigs placed in October, November and December, were at higher risk than pigs placed in other months. Herds that purchased pigs from a merchant, used pigs from other herds with an excess of piglets for filling their fattening units or herds that purchased pigs from more than five origin herds also suffered higher mortality. The mortality also increased in case of longer duration of the fattening period. This study documented for the first time that in addition to seasonal effects and a longer duration of the fattening period, purchasing feeder pigs from one or a limited number of herds is of crucial importance to achieve low mortality in the grow-finishing pigs.

Field trials of a vaccine against bovine mastitis. 1. Evaluation in heifers.

A vaccine was developed against bovine mastitis based on inactivated, highly encapsulated Staphylococcus aureus cells; a crude extract of Staph. aureus exopolysaccharides; and inactivated, unencapsulated Staph, aureus and Streptococcus spp. cells. This vaccine was tested on 30 heifers during a 7-mo period. The 30 heifers were randomly assigned to three groups of 10 heifers each. The prepartum group received two injections of the vaccine at 8 and 4 wk before calving, and the postpartum group received two injections at 1 and 5 wk after calving. The control group received two injections of a placebo at 8 and 4 wk before calving. The vaccine or the placebo was administered subcutaneously in the brachiocephalicus muscle of the neck. The frequencies of intramammary infections caused by Staph. aureus were reduced from 18.8% for heifers in the control group to 6.7 and 6.0% for heifers in the prepartum and postpartum groups, respectively. This protective effect was maintained for at least 6 mo. The relative risk of mastitis caused by Staph. aureus was 0.31 and 0.28 for heifers in the prepartum and postpartum groups, respectively, compared with that for heifers in the control group. The results of the trial indicated the effectiveness of the vaccine in decreasing the incidence of intrammammary infections caused by Staph. aureus. A slight but nonsignificant increase occurred in fat production in the milk of vaccinated cows. The vaccine had no observable effect on somatic cell count or streptococcal infections.

Field trials of a vaccine against bovine mastitis. 2. Evaluation in two commercial dairy herds.

A vaccine against bovine mastitis was developed. The vaccine was based on inactivated, highly encapsulated Staphylococcus aureus cells; a crude extract of Staph. aureus exopolysaccharides; and inactivated unencapsulated Staph. aureus and Streptococcus spp. cells. In this study, the vaccine was evaluated in 164 cows from two commercial dairies (A and B) during a 4-mo period. Two doses of the vaccine were administered subcutaneously to 82 cows in the brachiocephalicus muscle of the neck within a 4-wk interval. The results of this trial revealed significantly fewer intramammary infections caused by Staph. aureus at various levels of severity (clinical, subclinical, and latent) in cows that were vaccinated. The odds ratios of all types of intrammammary infections caused by Staph. aureus for dairies A and B, which were determined by a logistic model, were 1.84 and 1.89, respectively, for quarters of vaccinated cows and quarters of control cows. The colony counts for Staph. aureus in milk from infected quarters of vaccinated cows were significantly lower than those in milk from infected quarters of control cows. Also, the somatic cell counts per milliliter in milk from vaccinated cows were significantly decreased when the initial somatic cell count was < 500,000 cells/ml at the start of the trial. The vaccine had no observable effect on fat production in milk or on streptococcal infections.