Vitamin D insufficiency is associated with various disease processes. We determined whether consumption of a diet supplemented with HyD®, a 25-hydroxycholecalciferol (25(OH)D3) source, would safely increase plasma 25(OH)D3 concentrations in Golden Retrievers with low vitamin D status. We hypothesised that dietary supplementation with HyD® would rapidly increase and sustain plasma 25(OH)D3 levels in healthy Golden Retrievers with low vitamin D status compared with supplementation with vitamin D3. Of fifty-seven privately owned dogs recruited with written owner consent, eighteen dogs with low vitamin D status were identified and sorted between two groups to have similar initial plasma 25(OH)D3 concentrations, sex distributions, ages and body weights. Dogs of each group were fed a dry dog food supplemented with either 16 μg/kg of 25(OH)D3 as HyD® (n 10) or 81 μg/kg of cholecalciferol (D3) (n 8) for 4 months. Plasma 25(OH)D3 concentrations were determined monthly. A significant time effect (P < 0⋅001) and time by group interaction (P = 0⋅0045) were found for monthly determined plasma 25(OH)D3 concentrations. Dogs fed the HyD®-supplemented diet experienced a 40⋅5 % rise in plasma 25(OH)D3 values after 1 month (P < 0⋅001) and no change thereafter. Plasma 25(OH)D3 values of dogs supplemented with vitamin D3 did not increase (P > 0⋅05) and were less than values of dogs supplemented with HyD® (P = 0⋅044). With few exceptions, average haematologic, biochemical and urinalyses results remained within the reference range for both groups. Dietary supplementation with HyD® is sufficient to safely increase and sustain plasma 25(OH)D3 levels in healthy dogs.

Mitochondrial respiration was assessed in sixteen 7-day-old broilers as a subset of a larger study assessing the effects of Cu and Zn supplementation above requirements with a coccidiosis challenge on gain/feed ratio. The birds were selected from four treatments (four birds/treatment): a control diet (Cu 15 mg/kg and Zn 60 mg/kg) + coccidiosis challenge (CC), a Cu diet with 245 mg/kg Cu from tribasic copper chloride (TBCC) + CC, a negative control diet (Cu 15 mg/kg and Zn 60 mg/kg) - CC and a Zn diet with 2000 mg/kg Zn from ZnO. The diets were composed of 49% corn, 40% soybean meal, 6.2% vegetable oil (diet dry matter = 90.62%, crude protein = 21.37%, fat = 7.7%, metabolizable energy = 12.1 MJ/day) and were fed for 14 days. Birds were dissected, and approximately one gram of liver tissue was used for mitochondrial oxygen consumption and proton leak kinetics assays. Respiratory control ratio and mitochondrial proton leak assessed by calculating rates of oxygen consumption at 175mV membrane potential were greater for the negative control group, but there were no differences in average gain/feed among treatments. In summary, broilers that did not undergo coccidiosis challenge had lower proton leak and higher respiratory control ratio. However, the impact of supplementation of Cu and Zn above requirements did not appear to prevent changes in respiratory control ratio and proton leak kinetics with coccidiosis challenge.

No abstract