Antimicrobial susceptibility of udder pathogens isolated from dairy herds in the west littoral region of Uruguay

A total of 522 strains belonging to streptococci, enterococci and staphylococci isolated from sub-clinical and clinical cases of bovine mastitis from the west littoral region of Uruguay were analysed for their susceptibility to several antimicrobial agents. The susceptibility patterns were studied by agar disk diffusion methods (ADDM) and broth micro-dilution to determine the minimum inhibitory concentration (MIC). The concentration that inhibits 90% (MIC90) of the analysed strains reported in micrograms per millilitre, for Staphylococcus aureus were > 8, 8, < or = 0.5, < or = 4, < or = 1, < or = 0.5, > 64, < or = 0.25, 0.5, < or = 1 and < or = 1 to penicillin, ampicillin, oxacillin, cephalotin, gentamicin, erythromycin, oxitetracycline, enrofloxacin, trimethoprim/sulfamethoxazole, neomycin, and clindamycin, respectively. Coagulase-negative staphylococci (CNS) had different values for penicillin (4) and ampicillin (2), while the other antimicrobial agents had the same MIC90 values as reported for S. aureus. The MIC90 values for streptococci were 0.12, 0.25, < or = 4, 16, < or = 0.25, 0.5, 0.25 for penicillin, ampicillin, cephalotin, gentamicin, erythromycin, oxytetracycline and trimethoprim-sulfamethoxazole, whereas MIC90 for enterococci were 4, 4, 4, < or = 0.5, 2, > 8 for penicillin, ampicillin, gentamicin, erythromycin, oxytetracycline and trimethoprim-sulfamethoxazole, respectively. Of 336 strains of S. aureus, 160 (47.6%) were resistant to penicillin. For 41 CNS strains, 10 (27%) presented penicillin-resistance. All the streptococcal strains were susceptible to penicillin, while 3 (7%) of the 43 enteroccocal strains were resistant. Non significant statistical differences were found between the results obtained by ADDM and broth micro-dilution for classifying bacterial isolates as susceptible or resistant according to the National Committee of Clinical Laboratory Standards.     

Oxidative response of neutrophils to platelet-activating factor is altered during acute ruminal acidosis induced by oligofructose in heifers

Reactive oxygen species (ROS) production is one of the main mechanisms used to kill microbes during innate immune response. D-lactic acid, which is augmented during acute ruminal acidosis, reduces platelet activating factor (PAF)-induced ROS production and L-selectin shedding in bovine neutrophils in vitro. This study was conducted to investigate whether acute ruminal acidosis induced by acute oligofructose overload in heifers interferes with ROS production and L-selectin shedding in blood neutrophils. Blood neutrophils and plasma were obtained by jugular venipuncture, while ruminal samples were collected using rumenocentesis. Lactic acid from plasma and ruminal samples was measured by HPLC. PAF-induced ROS production and L-selectin shedding were measured in vitro in bovine neutrophils by a luminol chemiluminescence assay and flow cytometry, respectively. A significant increase in ruminal and plasma lactic acid was recorded in these animals. Specifically, a decrease in PAF-induced ROS production was observed 8 h after oligofructose overload, and this was sustained until 48 h post oligofructose overload. A reduction in PAF-induced L-selectin shedding was observed at 16 h and 32 h post oligofructose overload. Overall, the results indicated that neutrophil PAF responses were altered in heifers with ruminal acidosis, suggesting a potential dysfunction of the innate immune response.     

Innovative Traditional Italian Durum Wheat Breads: Influence of Yeast and Gluten on Performance of Sourdough Moddizzosu Breads

This research investigated the impact of semolina dough formulation (percentage of sourdough [SD] addition and presence of yeast [Y] or common wheat gluten [G]) added singly and in combination on the sensory and physicochemical profiles of fresh and stored sourdough‐started durum breads, particularly Moddizzosu type. Main distinctive features of breads were identified, and optimal amounts of SD addition in presence of either yeast or gluten were used to achieve high‐quality fresh and stored soured durum breads made with semolina and remilled semolina at a ratio of 80:20. Common features of durum breads included color parameters and crumb grain characteristics of either fresh or stored samples. Increasing SD significantly increased scores for overall acceptability. In yeasted costarted samples, a linear promotion of both aroma and taste intensity resulted from increasing amounts of SD, whereas the opposite trend was observed for unyeasted breads. Higher values for degree of acidification, specific volume, crumb cohesiveness, resilience, and springiness but lower pH, moisture content, crumb hardness, and chewiness in durum samples were achieved with increased SD. The presence of Y counteracted acidification, harmonized volume increase, hardness, cohesiveness, springiness, and resilience, minimizing the effects of the SD added. Y and G acting singly as crumb softeners when added together to soured durum breads started with SD at a dose >10% provided lower and slower crumb firming kinetics. Breads with especially slow retrogradation kinetics corresponded to yeasted started samples with or without added gluten, regardless the presence or absence of SD. In unyeasted soured breads, the dose of SD slightly decreased the rate and extent of amylopectin retrogradation, irrespective of gluten addition.     

Age-dependent presence of fetuin in bovine nasal secretion.

At least two age-dependent proteins were detected in nasal secretion (NS) of young calves by crossed immunoelectrophoresis. One of them was identified as fetuin. The other one was not identified. The concentration of fetuin in NS was found to increase in cases where a sample of NS had been obtained at birth and a second sample taken within 11 days. Thereafter a decrease was always found towards day 15 or 30.     

Size matters: West Nile Virus neutralizing antibodies in resident and migratory birds in Spain

The rapid range expansion of West Nile Virus has raised interest in understanding the population dynamics and dispersal patterns of emerging infectious diseases by wildlife. We analyzed different ecological and evolutionary factors related to West Nile Virus neutralizing antibody prevalence in 72 bird species sampled in southern Spain. Prevalence of antibodies reached its maximum during the autumn and winter in comparison to summer months. Prevalence of antibodies was directly related to body mass and migratory behaviour. The greater prevalence of antibodies observed in summer migrants can be explained, among other factors, by the diversity of localities involved in their life cycles or the geographic areas visited during their migrations. Greater prevalence in larger species was explained by their longevity because the relationship was already significant when analyzing only first year birds, and probably also involved a high attraction to vectors by larger hosts. Coloniality and winter gregarism were unrelated to the prevalence of antibodies against this highly host generalist pathogen. Evolutionary relationships between species were unrelated to differences in the prevalence of antibodies. Our results suggest larger species as good candidates for easy, faster and cheaper monitoring of local, seasonal and annual changes in WN virus serology.     

Adjuvant effect of ginseng extracts on the immune responses to immunisation against Staphylococcus aureus in dairy cattle

A crude ginseng extract (GS) and the purified ginsenoside R(b1) (R(b1)) were evaluated for their adjuvant effects in dairy cattle at immunisation with ovalbumin (OVA) and/or a Staphylococcus aureus bacterin used for prevention of bovine mastitis. To evaluate a suitable dose of GS as an adjuvant, 36 lactating cows were randomly divided into six groups. The cows were inoculated twice intramuscularly with a 2-week interval, with saline solution, OVA in saline, or OVA in combination with 4, 16 or 64 mg GS, or Al(OH)(3). The level of specific antibodies to OVA in serum and milk whey was measured before immunisations and 1-5 weeks after the second immunisation. The antibody response in serum was significantly higher in animals immunised with OVA and GS than in animals immunised with OVA alone. A significant increase in milk antibody titres compared with OVA only was only found 2 weeks after the second immunisation in the group immunised with OVA and 4 mg GS. In the second part of the study, 18 heifers were randomly divided into three groups and were immunised twice intramuscularly with a two week interval, with the S. aureus bacterin (control), or with the bacterin in combination with 4 mg GS or 1mg R(b1). The specific antibody response to S. aureus and the lymphocyte proliferation after stimulation with PWM, concanavalin A (Con A) or a specific S. aureus antigen was evaluated in blood samples taken before and after immunisations as specified above. Addition of R(b1) resulted both in significantly higher antibody production and lymphocyte proliferation in response to PWM, Con A and S. aureus antigens than in the control group. Addition of GS induced a significantly higher lymphocyte proliferation in response to PWM and Con A than the control, but had no additional effect on the antibody production. In conclusion, both GS and R(b1) were safe adjuvants, and R(b1) had the strongest adjuvant effects, when used for immunisation against S. aureus in dairy cattle. Field trials are warranted to test the ability of GS and R(b1) to enhance the efficacy of mastitis vaccines in protection against intramammary infections.     

Selection by sheep and goats for perennial ryegrass and white clover offered over a range of sward height contrasts

The selection by sheep (six Coopworth ewe hoggets, 44·3 ± 4·6 kg live weight) and goats (six Saanen/Anglo‐Nubian yearling males, 38·1 ± 3·8 kg live weight) for perennial ryegrass (Lolium perenne) and white clover (Trifolium repens) and for sward height was measured in two experiments involving paired turves. Pairs of turves with herbage of differing height and of either the same or different plant species were offered. One sward (fixed height species, FHS) was always offered at 130 mm and the other (variable height species, VHS) at 130, 90 or 50 mm. Turves (450 mm × 220 mm) were cut to a soil depth of 100–150 mm from areas of perennial ryegrass and white clover regrown to the desired height after previously being cut to 30 mm. Each turf in a pair was weighed (±1 g) before and after grazing by penned animals maintained on a barley‐based pelleted diet. The number of prehending bites taken from each turf was recorded over a grazing period (128 ± 12 s). Bite mass, bite rate and intake rate were calculated. As the sward height of the VHS turf declined, an increasing proportion of the diet was selected from the 130 mm turf. When averaged over all height contrasts, both animal species selected a higher proportion (0·776 ± 0·026) of their diet from 130‐mm white clover than from 130‐mm perennial ryegrass (0·591 ± 0·018) turves. On average, goats selected a higher proportion (0·721 ± 0·022) of their dry‐matter (DM) intake from the 130‐mm turf than sheep (0·646 ± 0·019), but the effect was not consistent. In contrasts with perennial ryegrass as the VHS (and both perennial ryegrass and white clover as FHS), the proportion of the diet selected from the 130‐mm turf was very similar for both animal species. However, with white clover as the VHS (and both perennial ryegrass and white clover as FHS), goats selected a higher proportion of their intake from the 130‐mm turf to the extent that in the 130‐mm perennial ryegrass/50‐mm white clover contrast sheep showed as strong selection for 50‐mm white clover as goats did for 130‐mm perennial ryegrass. This lesser selection of goats for white clover as its height in a sward declines is likely to contribute to the higher white clover content observed in swards grazed by goats. Bite mass was greater on white clover (246 ± 5 mg DM bite^–1) than on perennial ryegrass (173 ± 5 mg DM bite^–1) and was greater for goats (255 ± 6 mg DM bite^–1) than for sheep (195 ± 5 mg DM bite^–1). Bite rate was greater on perennial ryegrass (45·9 ± 1·0 bites min^–1) than on white clover (39·9 ± 1·0 bites min^–1) and was greater for sheep (45·5 ± 1·1 bites min^–1) than for goats (42·5 ± 1·1 bites min^–1). Apparent intake rate by both sheep and goats was lower (mean, 5·0 ± 0·29 g DM min^–1) on 130 mm perennial ryegrass/white clover than on 130 mm perennial ryegrass/perennial ryegrass (7·0 ± 0·27 g DM min^–1), but was higher (9·62 ± 0·29 g DM min^–1) on 130‐mm white clover/perennial ryegrass than on 130‐mm white clover/white clover (8·2 ± 0·29 g DM min^–1) combinations.