The effects of dietary nitrate on plasma glucose and insulin sensitivity in sheep

Nitrate (NO₃^¯) is an effective non‐protein nitrogen source for gut microbes and reduces enteric methane (CH₄) production in ruminants. Nitrate is reduced to ammonia by rumen bacteria with nitrite (NO₂^¯) produced as an intermediate. The absorption of NO₂^¯ can cause methaemoglobinaemia in ruminants. Metabolism of NO₃^¯ and NO₂^¯ in blood and animal tissues forms nitric oxide (NO) which has profound physiological effects in ruminants and has been shown to increase glucose uptake and insulin secretion in rodents and humans. We hypothesized that absorption of small quantities of NO₂^¯ resulting from a low‐risk dose of dietary NO₃^¯ will increase insulin sensitivity (S_I) and glucose uptake in sheep. We evaluated the effect of feeding sheep with a diet supplemented with 18 g NO₃^¯/kg DM or urea (Ur) isonitrogenously to NO₃^¯, on insulin and glucose dynamics. A glucose tolerance test using an intravenous bolus of 1 ml/kg LW of 24% (w/v) glucose was conducted in twenty sheep, with 10 sheep receiving 1.8% supplementary NO₃^¯ and 10 receiving supplementary urea isonitrogenously to NO₃^¯. The MINMOD model used plasma glucose and insulin concentrations to estimate basal plasma insulin (I_b) and basal glucose concentration (G_b), insulin sensitivity (S_I), glucose effectiveness (S_G), acute insulin response (AIRg) and disposition index (DI). Nitrate supplementation had no effect on I_b (p > .05). The decrease in blood glucose occurred at the same rate in both dietary treatments (S_G; p = .60), and there was no effect of NO₃^¯ on either G_b, S_I, AIRg or DI. This experiment found that the insulin dynamics assessed using the MINMOD model were not affected by NO₃^¯ administered to fasted sheep at a low dose of 1.8% NO₃^¯ in the diet.     

Computed tomographic description of the highly variable imaging features of equine oromaxillary sinus and oronasal fistulae

Oronasal and oromaxillary sinus fistulae are well‐documented complications following removal or loss of a maxillary cheek tooth. Diagnosis is currently based on a combination of oral examination, videoendoscopy, radiography, and computed tomography (CT). The objective of this retrospective, case series study was to describe the CT characteristics of confirmed oronasal and oromaxillary sinus fistulae in a group of horses. Inclusion criteria were a head CT acquired at the authors’ hospital during the period of 2012–2017, a CT diagnosis of oronasal or oromaxillary sinus fistulae, and a confirmed diagnosis based on a method other than CT. Signalment, clinical findings, oral examination findings, presence of a confirmed fistula, and method for confirmation of the diagnosis were recorded. A veterinary radiologist reviewed CT studies for all included horses and recorded characteristics of the fistulae. Seventeen horses were sampled. Fourteen oromaxillary sinus fistulae and three oronasal fistulae were identified. All fistulae appeared as variably sized focal defects in the alveolar bone. Defects frequently contained a linear tract of heterogeneous material interspersed with gas bubbles, considered consistent with food. Computed tomographic attenuation of the material (Hounsfield units, HU) varied widely within and between cases. In 16 of 17 cases, there was evidence of concurrent dental disease in addition to the fistulae. Although the gold standard diagnostic test remains identification of feed material within the sinus or nasal passages, findings from the current study support the use of CT as an adjunctive diagnostic test for assessing the extent of involvement and presurgical planning.     

Influence of soil type and pH on the colonisation of sugar beet seedlings by antagonistic Pseudomonas and Bacillus strains,and on their control of Pythium damping-off

In five different soils originating from Scotland (Craibstone and Cruden Bay), Germany (Magdeburg and Uelzen) and Greece (Tymbaki), Pseudomonas fluorescens B5 reached higher population sizes (4.7–5.7logCFU/plant) on 12-day-old sugar beet seedlings than Bacillus subtilis MBI 600 (4.1–4.8logCFU/plant). Total population size per plant was not affected by soil type. In all five soils, the antagonists reached highest population densities in the hypocotyl and the upper 2cm root section (P. fluorescensB5: 5.2–6.8log₁₀CFU/g plant fresh weight, Bacillus subtilisMBI 600: 5.2–6.1log₁₀CFU/g plant fresh weight) and declined to 0–3log₁₀CFU below 4cm root depth. Colonisation by P. fluorescens B5 down the root was slightly increased in the soils from Craibstone, Magdeburg, and Uelzen compared to the sandy clay loam from Tymbaki. In lux-marked P. fluorescens B5, population density was positively correlated with light emission in all soils; the light emission indicated physiological activity of the strains. However, P. fluorescens B5 reduced Pythium damping-off (measurement after 14 days plant growth) only in three of the five soils (Craibstone, Cruden Bay and Magdeburg). Co-inoculation of B. subtilis MBI 600 increased downward colonisation of the root by P. fluorescens B5, but not the total population ofP. fluorescens B5 per plant. Bacillus subtilisMBI 600 did not reduce Pythium damping-off in any of the soils nor did it influence the efficiency of co-inoculated P. fluorescens B5; its population consisted mainly of physiologically inactive spores. In Craibstone soil, pH did not affect population density, distribution along the root or biocontrol activity against P. ultimum of P. fluorescens B5 or B. subtilis MBI 600.