Production of N2 and N2O from nitrate ingested by sheep

Supplementing ruminants with nitrate reduces their enteric methane (CH₄) emissions; however, the greenhouse gas (GHG) mitigation achieved can be partially offset by small emissions of nitrous oxide (N₂O), a more potent GHG. Sheep were dosed intraruminally with ¹⁵ to investigate whether dietary is a precursor of N₂O and/or di‐nitrogen gas (N₂), and to quantify the amounts of recovered as N₂O and N₂ in gas emissions from sheep adapted or not adapted to dietary . Ruminally cannulated sheep were adapted to a hay diet supplemented with (n = 3; 10 g /kg DM) or urea (n = 3; 5.3 g urea/kg DM). On the day of the experiment all sheep were dosed intraruminally with ¹⁵ and quickly moved into gas‐tight chambers to enable recovery of ¹⁵N in N₂O and N₂ to be measured. Measurements of gases accumulating in the chambers were made over 10 successive 50 min periods; this enabled the amount of N₂O produced, and the recovery of ¹⁵‐N in N₂O and N₂ to be determined over a total of 10 hr. Only 0.04% of labelled ‐N was recovered as N₂O, and this was not dependent (p > .05) on whether or not the animals had been adapted to dietary . Approximatively 3% of ¹⁵‐N was recovered as ¹⁵N₂, which was also not dependent (p > .05) on whether sheep had been adapted to . Because the kinetics of rumen ammonia (NH₃) were uncertain, the recovery of ¹⁵N from in rumen NH₃ could not accurately be quantified, but our results suggest that approximately 76% of dietary was converted to NH₃ in the rumen. We conclude that the small amount of recovered in N₂ was evidence of denitrification, previously thought not to occur in the rumen.     

The future of radiotherapy in small animals – should the fractions be coarse or fine?

Radiation therapy has been used to treat animal cancers for more than 100 years. Clinical experiences and experimental results have been widely published and provide a basis for the recognition of radiation therapy as an integral component of multimodal cancer management in veterinary oncology. As the expectations of pet owners and the demand for treatment of companion animals with cancer have increased, veterinary oncology itself has undergone dramatic advances in the past several decades both in terms of improved diagnostics and treatments, including increased accessibility of radiation therapy. Synchronous with development of the specialism of veterinary radiation oncology, confusion and controversy have arisen with regard to distinguishing between different types of radiotherapy and methods of treatment delivery. Importantly, the confusion extends beyond semantics, and includes opinionated debate about defining which forms of therapy (if any at all) are optimal for a given patient. This exemplifies how, despite marks of maturity including age and a robust publication history, the field of veterinary radiation oncology is in some ways still in its infancy. The purpose of this article is to review the evidence base for daily (fine) fractionation versus weekly (coarse) hypofractionation in veterinary oncology, using selected tumour types as examples.     

A statewide,cross-sectional evaluation of the knowledge and level of concern of rabies among South Carolina residents

Animal rabies cases have increased steadily in South Carolina (SC) for the past decade. An understanding of the population's awareness and understanding of the disease is needed to tailor public health interventions. A marketing list-serv of SC residents' email addresses was used to recruit anonymous respondents for a Knowledge Attitudes and Practices (KAP) electronic survey. A total 516 South Carolinians completed the 31-question survey. Quantile regression and a Pearson's correlation evaluated potential associations between respondent's rabies knowledge and their attitudes and practices. Knowledge was assessed on topics of rabies biology, state animal case counts and rabies pet-related laws. Level of concern and level of knowledge were positively correlated. Additionally, statewide hotspot analysis revealed geographic areas warranting targeted public health interventions; counties with low public concern juxtapositioned with high animal rabies case counts. This study demonstrates the utility of statewide KAPs to gauge populations rabies perception and related preventative actions to tailor appropriate educational programs to limit human-animal rabies exposures.     

Quality of life is reduced in obese dogs but improves after successful weight loss

Obesity is thought to affect quality of life, but limited objective data exist to support this supposition. The current study aim was to use a questionnaire to determine health-related quality of life (HRQOL) both before and after weight loss, in obese client-owned dogs. Fifty obese dogs were included, and represented a variety of breeds and genders. Prior to weight loss, owners were asked to complete a validated standardised questionnaire to determine HRQOL. Thirty of the dogs successfully completed their weight loss programme and reached target, and owners then completed a follow-up questionnaire. The completed questionnaire responses were transformed to scores corresponding to each of four factors (vitality, emotional disturbance, anxiety and pain), and scored on a scale of 0-6. Changes in the scores were used to explore the sensitivity of the questionnaire, and scores were correlated with responses to direct questions about quality of life and pain, as well as weight loss. Dogs that failed to complete their weight loss programme had lower vitality and higher emotional disturbance scores than those successfully losing weight (P=0.03 for both). In the 30 dogs that completed, weight loss led to an increased vitality score (P<0.001), and decreased scores for both emotional disturbance (P<0.001) and pain (P<0.001). However, there was no change in anxiety (P=0.09). The change in vitality score was positively associated with percentage weight loss (r(P)=0.43, P=0.02) and percentage body fat loss (r(P)=0.39, P=0.03). These results indicate demonstrable improvement in HRQOL for obese dogs that successfully lose weight.     

Farm management factors associated with bulk tank total bacterial count in Irish dairy herds during 2006/07

Research has shown that total bacterial count (TBC), which is the bacterial growth per ml of milk over a fixed period of time, can be decreased by good hygiene and farm management practices. The objective of the current study was to quantify the associations between herd management factors and bulk tank TBC in Irish spring calving, grass-based dairy herds. The relationship between bulk tank TBC and farm management and infrastructure was examined using data from 400 randomly selected Irish dairy farms where the basal diet was grazed grass. Herd management factors associated with bulk tank TBC were identified using linear models with herd annual total bacterial score (i.e., arithmetic mean of the natural logarithm of bulk tank TBC) included as the dependent variable. All herd management factors were individually analysed in a separate regression model, that included an adjustment for geographical location of the farm. A multiple stepwise regression model was subsequently developed. Median bulk tank TBC for the sample herds was 18,483 cells/ml ranging from 10,441 to 130,458 cells/ml. Results from the multivariate analysis indicated that the following management practices were associated with low TBC; use of heated water in the milking parlour; participation in a milk recording scheme; and tail clipping of cows at a frequency greater than once per year. Increased level of hygiene of the parlour and cubicles were also associated with lower TBC. Herd management factors associated with bulk tank TBC in Irish grazing herds were generally in agreement with most previous studies from confinement systems of milk production.     

Carry-over effects of dietary yeast RNA as a source of nucleotides on lymphoid organs and immune responses in Leghorn-type chickens

1. The carry-over effects of supplementing Leghorn-type chickens with yeast RNA as a dietary source of nucleotides for 4 weeks on growth, lymphoid organ weights and immune responses were assessed in a 12-week study. 2. A commercial starter feed supplemented with 0 (control), 5 (LR) or 10 (HR) g yeast RNA/kg was offered to 1-d-old male ISA Brown chicks for 4 weeks, and then all birds were given a commercial pullet grower feed for another 8 weeks. Growth performance, antibody responses to sheep red blood cells (SRBC) and cutaneous reactivity of toe webs to phytohaemagglutinin (PHA)-M were measured at 4-week intervals. 3. Growth rates, feed intake and feed efficiency were not affected by dietary yeast RNA during the supplementary period, but birds previously offered the HR diet grew faster than control birds during weeks 4 to 8.4. LR-fed birds had a higher spleen weight relative to body weight (BW) than control birds at week 4, but this effect was not detected at other times. 5. Serum primary antibody levels against SRBC were not affected by dietary yeast RNA at any time. 6. The toe-web PHA response was significantly higher at week 8 in control birds than in birds previously given the LR diet, although no difference among dietary treatments was observed at other times. 7. It is concluded that the addition of yeast RNA as a source of nucleotides to a commercial diet selectively stimulated the development of the spleen in young birds, but this effect did not persist into a later stage of the bird's life.     

Characterizing the APEC pathotype

The purpose of this study was to compare avian pathogenic Escherichia coli (APEC) isolates to fecal isolates of apparently healthy poultry (avian fecal E. coli or AFEC) by their possession of various traits in order to ascertain whether APEC and AFEC are distinct and if the APEC strains constitute a distinct pathotype. Four hundred and fifty-one APEC and one hundred and four AFEC isolates were examined for possession of traits associated with the virulence of human extraintestinal pathogenic E. coli (ExPEC) as well as APEC. Several of the genes occurred in the majority of APEC and only infrequently in AFEC, including cvaC, iroN, iss, iutA, sitA, tsh, fyuA, irp2, and ompT. Of these genes, several have been found on large plasmids in APEC. Other genes occurred in significantly more APEC than AFEC but did not occur in the majority of APEC. Isolates were also evaluated by serogroup, lactose utilization, and hemolytic reaction. Twenty-nine and a half percent of the APEC and forty-two and three tenths percent of the AFEC were not serogrouped because they were not typeable with standard antisera, typed to multiple serogroups, were rough, autoagglutinated, or were not done. Around 65% of the typeable APEC (205 isolates) and AFEC (41 isolates) were classified into shared serogroups, and about a third of both fell into APEC- (113 isolates) or AFEC- (19 isolates) unique serogroups. Most were able to use lactose. No isolate was hemolytic. Overall, the majority of the APEC isolates surveyed shared a common set of putative virulence genes, many of which have been localized to an APEC plasmid known as pTJ100. This common set of genes may prove useful in defining an APEC pathotype.     

Comparison of the type and number of microorganisms and concentration of endotoxin in the air of feedyards in the Southern High Plains

OBJECTIVES: To determine the bacterial, fungal, and endotoxin concentrations in aerosolized ambient air during the winter and summer in feedyards located in the Southern High Plains, identify aerosolized microbial pathogens, and determine the size of microbial and dust components. SAMPLE POPULATION: Aerosol samples were obtained from 7 feedyards. PROCEDURE: Aerosol samples were collected upwind, on-site, and downwind from each feedyard at a point 1 m above the ground by use of biological 2- and 6-stage cascade impactors. RESULTS: Significantly more microbes were cultured from on-site and downwind samples than upwind samples. There were significantly more microbes during the summer than during the winter. However, mean endotoxin concentration was significantly higher during the winter (8.37 ng/m3) than the summer (2.63 ng/m3). Among 7 feedyards, mean +/- SE number of mesophilic bacteria (1,441 +/- 195 colony-forming units [CFUs]/m3) was significantly higher than mean number of anaerobic bacteria (751 +/- 133 CFUs/m3) or thermophilic bacteria (54 +/- 10 CFUs/m3) in feedyard air. Feedyard aerosol samples contained more mesophilic fungi (78 +/- 7 CFUs/m3) than thermophilic fungi (2 +/- 0.2 CFUs/m3). Eighteen genera of bacteria were identified by use of an automated identification system. CONCLUSIONS AND CLINICAL RELEVANCE: It appeared that gram-negative enteric pathogens offered little risk to remote calves or humans via ambient aerosols and that gram-positive pathogens of the Bacillus, Corynebacterium, and Staphylococcus spp can be spread by aerosols in and around feedyards. It was common to detect concentrations of endotoxin in the ambient air of 7 feedyards.     

Virulence factors of Escherichia cofi from cellulitis or colisepticemia lesions in chickens

This study was designed to compare virulence factors of cellulitis-derived Escherichia coli to colisepticemic E. coli in order to clarify whether E. coli associated with cellulitis comprise a unique subset of pathogenic E. coli. Isolates were tested for serotype, capsule, aerobactin production, colicin production, the presence of the iss gene, and serum resistance. Untypable isolates made up the greatest percentage of each group. Serotypes O2 and O78 were the most commonly identified among both groups of isolates. No statistical differences in the distribution of aerobactin or colicin production, capsule, or iss gene were observed between groups. Cluster analysis showed that 90% of the E. coli isolates had greater than 42% livability in serum-resistance tests. No separation of colisepticemic vs. cellulitis E. coli isolates was observed on the basis of SR. Colicin production by E. coli was highly correlated with serum resistance (P = 0.0029). These data suggest that cellulitis E. coli have virulence traits similar to those of colisepticemic E. coli.