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Summary The objective of the present study was to examine the effect of signalment, body size and diet on plasma taurine and whole blood taurine concentrations. A total of 131 normal dogs consuming commercially prepared dog food had blood drawn 3–5 h post-prandially to be analysed for plasma amino acids and whole blood taurine. Body weight and morphometric measurements of each dog were taken. Plasma and whole blood taurine concentrations were 77 ± 2.1 nmol/ml (mean ± SEM) and 266 ± 5.1 nmol/ml (mean ± SEM), respectively. No effect of age, sex, body weight, body size, or diet was seen on plasma and whole blood taurine concentrations. Mean whole blood taurine concentrations were lower in dogs fed diets containing whole grain rice, rice bran or barley. The lowest whole blood concentrations were seen in dogs fed lamb or lamb meal and rice diets. Plasma methionine and cysteine concentrations were lower in dogs fed diets with animal meals or turkey, and whole grain rice, rice bran or barley. Fifteen of 131 dogs had plasma taurine concentrations lower than, or equal, to the previously reported lowest mean food-deprived plasma taurine concentration in normal dogs of 49 ± 5 nmol/ml (mean ± SEM) (Elliott et al., 2000). These findings support the theory that taurine deficiency in dogs may be related to the consumption of certain dietary ingredients. Scientific and clinical evidence supports the hypothesis that dilated cardiomyopathy is associated with low blood taurine concentration in dogs; therefore, further work is indicated to determine the mechanism by which diet can affect taurine status in dogs. [ABSTRACT FROM AUTHOR]

The objective of the present study was to examine the interaction between graded levels of leucine and dietary crude protein. Dose–response curves were generated using four 3 × 3 Latin squares (two dogs/square). Each square represented one of two concentrations of crude protein (140 or 280 g/kg diet) and one of two combinations of three concentrations of leucine (5.0, 7.0 and 9.0 g/kg diet or 9.0, 11 and 13 g/kg diet). An additional experiment was performed by feeding crude protein at 210 g/kg diet with either 7.0 or 11 g leucine/kg diet. Weight gain, food intake, nitrogen retention, plasma albumin and plasma amino acids were measured. The requirement was determined to be the minimum leucine concentration required to maximize weight gain and nitrogen retention. For 8–14-week-old male Beagle dogs, 140 g crude protein/kg diet in a diet containing 18 kJ metabolizable energy/g does not appear to support maximal growth. The leucine requirement was not affected by doubling the dietary crude protein level from 140 to 280 g/kg diet. From these results, the leucine requirement of 8–14-week-old Beagle dogs appears to be 11 g leucine/kg diet independent of the level of dietary crude protein, whereas dogs over 14 weeks require only 7 g leucine/kg diet for maximal nitrogen retention. [ABSTRACT FROM AUTHOR]