Limited genetic diversity of Aerococcus viridans strains isolated from clinical and subclinical cases of bovine mastitis in Slovakia

The Aerococcus viridans isolates from bovine mastitis in Slovakia were isolated and characterized by classical microbiological and biochemical, and molecular techniques including IGS-PCR and rep-PCR, ARDRA and 16S rDNA gene sequencing. The substantial variability of antibiotic resistance patterns was observed. The majority of strains were resistant to beta-lactam antibiotics, the resistance to tetracycline was observed in 3 tested strains, resistance to lincomycin was found in 4 strains and practically all tested strains were sensitive to neomycin and ciprofloxacin. While variable at a phenotypic level, no significant genetic variability among A. viridans isolates was detected by molecular DNA based methods. The data obtained suggest that a few A. viridans strains spread among cow's population in Slovak farms.     

Subolesin/akirin orthologs from Ornithodoros spp. soft ticks: cloning, RNAi gene silencing and protective effect of the recombinant proteins

Subolesin/akirin is a well characterized protective antigen highly conserved across vector species and thus potentially useful for the development of a broad-spectrum vaccine for the control of arthropod infestations including hard ticks, mosquitoes, sand flies and the poultry red mite Dermanyssus gallinae. Soft ticks could be also targeted by this vaccine if proved that the soft tick subolesin orthologs are conserved and induce protective immune responses too. However, to date no soft tick subolesin orthologs have been fully characterized nor tested as recombinant antigens in vaccination trials. The objectives of the present work were to clone and characterize the subolesin orthologs from two important vector species of soft ticks as Ornithodoros erraticus and O. moubata, to evaluate the effect of subolesin gene silencing by RNAi, and to test the protective value of the recombinant antigens in vaccination trials. The obtained results demonstrate that both soft tick subolesins are highly conserved showing more than 69% and 74% identity with those of hard ticks in their nucleotide and amino acid sequences, respectively. Additionally, we demonstrate that both soft ticks possess fully operative RNAi machinery, and that subolesin gene silencing by dsRNA injection inhibits oviposition indicating the involvement of subolesin in tick reproduction. Finally, vaccination with the recombinant soft tick subolesins induced a partial protective effect resulting in the reduction of the oviposition rate. These preliminary results encourage further studies on the use of recombinant subolesins as vaccines for the control of soft tick infestations, either alone or in combination with other specific molecules.     

A cohort study of preweaning piglet mortality and farrowing accommodation on 112 commercial pig farms in England

A cohort study was carried out on 112 breeding pig farms in England to investigate the impact of type of farrowing accommodation on preweaning mortality in piglets. Four types of farrowing accommodation were studied; farrowing crates, indoor loose pens, crate/loose systems (where the sow was restrained in a crate during birth and the first days of lactation before being moved to a loose pen) and outdoor farrowing in arcs in paddocks. Four estimates of preweaning mortality were collected: an oral estimate from the farmer before the visit, an estimate from the 6-month rolling average from computer records, records from 20 litters observed when the farm was visited and prospective records collected from 20 farrowings after the visit. These four estimates were significantly correlated. The prospective records also included a farmer reported date and cause of death. From the prospective data there were 25,031 piglets from 2143 litters from 112 farms, 6.5% of piglets were stillborn while live born preweaning mortality was 12%. Mixed effect discrete time survival, binomial and competing risk, models were used to investigate the association between preweaning mortality and farrowing accommodation, controlling for sow parity, litter size and number of piglets stillborn and fostered. There was a reduced risk of stillbirths in outdoor farrowing systems compared with crated systems. Farmers reported that crushing of healthy piglets was the most frequent cause of death accounting for 55% of live born preweaning mortality. There was no significant difference in mortality in live born piglets by farrowing system. There was a significantly higher risk of farmer reported crushing of healthy live born piglets in outdoor arcs compared with piglets reared with sows in farrowing crates and a significantly reduced risk of death from causes other than crushing in piglets reared outdoors or in crate/loose systems compared with piglets reared in crated systems. We conclude that, in the farms in this study, farrowing crates reduced the risk of preweaning live born mortality attributable to crushing but piglets in this system were at increased risk of death from other causes. Consequently crates had no significant effect on overall preweaning mortality percentage. In all four commercial production systems; outdoor, farrowing crates, crate/loose farrowing systems and indoor loose housed systems, there were similar levels of mortality.     

Phenotypic and genetic evaluation of elbow dysplasia in Dutch Labrador Retrievers, Golden Retrievers, and Bernese Mountain dogs

Canine elbow dysplasia encompasses four developmental diseases: ununited anconeal process, osteochondrosis of the medial part of the humeral condyle, fragmented medial coronoid process (FCP), and incongruity of the elbow joint. Four radiographic views per joint were used to evaluate 2693 Labrador Retrievers (LRs), 1213 Golden Retrievers (GRs), and 974 Bernese Mountain Dogs (BMDs) for the presence of elbow dysplasia between 2002 and 2009 in the Netherlands. The views were also graded for signs of osteoarthritis and sclerosis. FCP was diagnosed most frequently in LRs, GRs and BMDs, with an incidence of 6%, 5%, and 15%, and a heritability of 0.17, 0.24, and 0.06, respectively. Heritabilities were estimated using a sire model and all available ancestors. Sclerosis at the base of the medial coronoid process was the radiographic sign most strongly correlated with FCP (r=0.95, 0.92, and 0.95 in LRs, GRs and BMDs, respectively). The sex of the dog was significantly correlated with the presence of osteoarthritis in LRs, but not in GRs and BMDs. Male LRs were 1.7-fold more frequently, but not more severely, affected by osteoarthritis than female dogs. Age at radiographic examination was significantly associated with osteoarthritis in all three breeds. The heritability estimates in Retrievers were high enough to warrant including FCP findings in the breeding policy, but until the biomechanical and genetic background of elbow dysplasia are better understood, correct phenotyping with a sensitive technique is essential.     

First evidence and molecular characterization of Babesia vogeli in naturally infected dogs and Rhipicephalus sanguineus ticks in southern France

Babesiosis is an emerging tick-borne disease of animals and humans caused by intraerythrocytic protozoa of the genera Babesia and Theileria. In France canine babesiosis has a high prevalence with Babesia canis thought to be the main aetiological agent of the disease. Babesia vogeli has already been reported to occur in Europe and in other countries around the Mediterranean Sea. The tick Rhipicephalus sanguineus, the main known vector of B. vogeli, occurs in southern France. However, only one case of a B. vogeli infected dog has been reported to date in France. To gain further insight into the prevalence of Babesia and Theileria infections in dogs and ticks of the R. sanguineus complex, a study was conducted in a veterinary practice in the south of France from January to September 2010. Twelve bloods from dogs and 36 R. sanguineus ticks were analyzed using PCR and sequencing. For the analysis of ticks, a new primer was designed to specifically amplify the B. vogeli 18S rRNA gene. Four dogs (33.3%) and 8 ticks (22.2%) were found to be infected with B. vogeli. This approach has thus revealed for the first time a cluster of cases of canine babesiosis caused by B. vogeli in France and highlights the need to systematically screen for pathogens potentially responsible for canine babesiosis at the species level using suitable molecular tools.     

Newcastle disease virus outbreaks: Vaccine mismatch or inadequate application?

Newcastle disease (ND) is one of the most important diseases of poultry, and may cause devastating losses in the poultry industry worldwide. Its causative agent is Newcastle disease virus (NDV), also known as avian paramyxovirus type 1. Many countries maintain a stringent vaccination policy against ND, but there are indications that ND outbreaks can still occur despite intensive vaccination. It has been argued that this may be due to antigenic divergence between the vaccine strains and circulating field strains. Here we present the complete genome sequence of a highly virulent genotype VII virus (NL/93) obtained from vaccinated poultry during an outbreak of ND in the Netherlands in 1992-1993. Using this strain, we investigated whether the identified genetic evolution of NDV is accompanied by antigenic evolution. In this study we show that a live vaccine that is antigenically adapted to match the genotype VII NL/93 outbreak strain does not provide increased protection compared to a classic genotype II live vaccine. When challenged with the NL/93 strain, chickens vaccinated with a classic vaccine were completely protected against clinical disease and mortality and virus shedding was significantly reduced, even with a supposedly suboptimal vaccine dose. These results suggest that it is not antigenic variation but rather poor flock immunity due to inadequate vaccination practices that may be responsible for outbreaks and spreading of virulent NDV field strains.     

Glucose and insulin responses to different dietary energy sources in Thoroughbred broodmares grazing cool season pasture

The objectives of this study were to characterize the glycemic and insulinemic responses of Thoroughbred broodmares fed late spring pasture only or a mixture of pasture and a high starch or low starch feed and to test hypotheses about differences in the glycemic and insulinemic effects of these dietary regimes. A group of 15 mares were divided into three treatment groups; pasture and high starch feed (PHS), pasture and low starch feed (PLS), and pasture only (PO) and maintained in these groups for 4.5 months prior to this study. These groups were maintained on a single pasture that was temporarily divided into three sections. The study protocol was conducted over two days. On day 1 the mares were fed their respective treatments and on day 2 all mares were allowed access to pasture only. On both days plasma glucose and insulin were measured in samples taken over a 7.5 h period. Baseline measurements for glucose and insulin were not different between any of the treatment groups on either day (P > 0.05). The baseline insulin concentrations of these pasture-kept mares (26.7 ± 8.3 mIU/L) were high compared to those reported from stall-kept horses. Plasma glucose and insulin on day 1 were influenced by treatment group, sample time, and an interaction between treatment and time (P < 0.05). On day 2 there was no significant influence of treatment group (P > 0.05). Glucose and insulin rose to higher (P < 0.01) peak concentrations in the PHS group on day 1 when compared to the PLS and PO groups, with no difference (P > 0.05) detected between the PLS and PO groups. These results are reflected in greater areas under the concentration-time curves for glucose and insulin in the PHS group on day 1 (P < 0.05). On day 2 there were no differences in any of the glucose and insulin characteristics for any of the treatment groups (P > 0.05). These results indicate a clear difference in the glycemic and insulinemic effect of the PHS feed compared to the PLS and PO groups. Of further interest are the glucose and insulin characteristics of these pasture-kept mares that indicate a low insulin sensitivity and high insulin secretory response. This study provides further information on factors influencing glycemic and insulinemic responses in horses.     

Effects of source of supplemental zinc on performance and humoral immunity in beef heifers

Two experiments were conducted to evaluate receiving-period performance, morbidity, and humoral immune response, as well as finishing performance and carcass characteristics of heifers fed different sources of supplemental Zn. In Exp. 1, 97 crossbred beef heifers (initial BW = 223.4 kg) were fed a 65% concentrate diet with no supplemental Zn (control) or 75 mg of supplemental Zn/kg of DM from Zn sulfate, Zn methionine, or Zn propionate. During a 35-d receiving period, heifers were monitored daily for signs of bovine respiratory disease. Serum samples were collected for Zn analysis on d 0, 14, and 28. After the receiving period, heifers were adapted to and fed a high-concentrate diet with no supplemental Zn for 42 d. Heifers were then assigned to finishing diet treatments, with the same concentrations and sources of supplemental Zn as during the receiving period and fed for an average of 168 d. Serum samples also were obtained on d 0 and 56 of the finishing period and at the end of the study. During the receiving period, control heifers had a greater (P < or = 0.05) BW and G:F on d 35 than heifers in the other treatments, but no differences were observed among treatments for morbidity or serum Zn concentrations (P > or = 0.50). For the finishing period, DMI and ADG did not differ among treatments; however, overall G:F tended (P = 0.06) to be less for control heifers than for heifers in the 3 supplemental Zn treatments. On d 56 of the finishing period, control heifers tended (P = 0.06) to have a lower serum Zn concentration than heifers in the 3 supplemental Zn treatments. In Exp. 2, 24 crossbred beef heifers (initial BW = 291.1 kg) were fed the same 4 treatments as in Exp. 1 for a 21-d period. The humoral immune response to treatments was determined by measuring specific antibody titers after s.c. injection of ovalbumin on d 0 and 14. Body weights and blood samples for serum Zn concentration and ovalbumin IgG titers were collected on d 0, 7, 14, and 21. Serum Zn concentration and specific ovalbumin IgG titers did not differ (P > 0.10) among the 4 treatments on any sampling day. Results from these 2 studies showed no major differences among the sources of supplemental Zn for receiving period morbidity, ADG, DMI, and humoral immune response of beef heifers; however, a lack of supplemental Zn during an extended finishing period tended to negatively affect G:F.     

Cattle selected for lower residual feed intake have reduced daily methane production

Seventy-six Angus steers chosen from breeding lines divergently selected for residual feed intake (RFI) were studied to quantify the relationship between RFI and the daily rate of methane production (MPR). A 70-d feeding test using a barley-based ration was conducted in which the voluntary DMI, feeding characteristics, and BW of steers were monitored. The estimated breeding value (EBV) for RFI (RFI(EBV)) for each steer had been calculated from 70-d RFI tests conducted on its parents. Methane production rate (g/d) was measured on each steer using SF(6) as a tracer gas in a series of 10-d measurement periods. Daily DMI of steers was lower during the methane measurement period than when methane was not being measured (11.18 vs. 11.88 kg; P = 0.001). A significant relationship existed between MPR and RFI when RFI (RFI(15d)) was estimated over the 15 d when steers were harnessed for methane collection (MPR = 13.3 x RFI(15d) + 179; r(2) = 0.12; P = 0.01). Animals expressing lower RFI had lower daily MPR. The relationship established between MPR and RFI(15d) was used to calculate a reduction in daily methane emission of 13.38 g accompanied a 1 kg/d reduction in RFI(EBV) in cattle consuming ad libitum a diet of 12.1 MJ of ME/kg. The magnitude of this emission reduction was between that predicted on the basis of intake reduction alone (18 g x d(-1) x kg of DMI(-1)) and that predicted by a model incorporating steer midtest BW and level of intake relative to maintenance (5 g x d(-1) x kg of DMI(-1)). Comparison of data from steers exhibiting the greatest (n = 10) and lowest (n = 10) RFI(15d) showed the low RFI(15d) group to not only have lower MPR (P = 0.017) but also reduced methane cost of growth (by 41.2 g of CH(4)/kg of ADG; P = 0.09). Although the opportunity to abate livestock MPR by selection against RFI seems great, RFI explained only a small proportion of the observed variation in MPR. A genotype x nutrition interaction can be anticipated, and the MPR:RFI(EBV) relationship will need to be defined over a range of diet types to account for this.