Usefulness of Urinary Creatinine/Urea Nitrogen Ratio as Indicator of Body Protein Catabolism in Dogs Fed Low Protein Diets

Replacement of Dietary Carbohydrate with Protein versus Fat Differentially Alters Postprandial Circulating Hormones and Macronutrient Metabolism in Dogs

The effect of dietary macronutrients on fasting and postprandial responses was examined. Thirty-six healthy dogs were fed a high-carbohydrate (HiCHO) food once daily for 5 weeks, followed by randomization to either a high-protein, low-carbohydrate (PROT_LoCHO) or high-fat, low-carbohydrate (FAT_LoCHO) food for 5 weeks, then crossed over to the other LoCHO food for 5 weeks. Plasma samples were obtained at the end of each feeding period at timepoints before (0 h) and 2 h post-feeding. Apparent total circulating energy availability was assessed as a summation of the energetic contributions of measured glucose, β-hydroxybutyrate, triglycerides (TGs), non-esterified fatty acids (NEFAs), and fatty acids not from TGs or NEFAs. In both the fed and fasted states, there were increases in circulating apparent total energy availability after feeding the FAT_LoCHO food compared with the HiCHO or PROT_LoCHO foods. Changes from the postabsorptive to postprandial points in catabolic, anabolic, and signaling lipids all exhibited food effects. Consumption of either LoCHO food led to lower leptin/ghrelin ratios in the fasted state relative to the HiCHO food. The FAT_LoCHO food led to the highest postprandial levels of the incretins gastric inhibitory peptide and glucagon-like peptide-1, yet the lowest increases in insulin relative to the other foods. These findings provide information on how macronutrients can influence dietary energy processing and metabolic health.

Efficacy of vitamin D2 in maintaining serum total vitamin D concentrations and bone mineralisation in adult dogs fed a plant-based (vegan) diet in a 3-month randomised trial

Dogs are considered omnivores based on their evolution consuming diets including animal tissue. Few feeding trials evaluating the nutritional suitability of exclusively plant-based (vegan) diets in dogs have been published, and the efficacy of vitamin D2 in maintaining canine serum vitamin D levels has not been clearly determined. A blinded dietary trial included sixty-one healthy desexed adult dogs: thirty-one fed an experimental extruded vegan diet (PLANT) and thirty fed a commercial extruded meat-based diet (MEAT) for 3 months. Dogs were screened via veterinary examination and routine laboratory analyses prior to enrolment, at baseline and exit timepoints. Body composition was measured by dual-energy X-ray absorptiometry and blood was collected for vitamin D profiling. All dogs maintained health parameters, body weight and composition throughout the study. Dogs maintained on PLANT demonstrated a significant reduction in platelet count, creatinine, blood urea nitrogen and cholesterol, though values remained within normal reference ranges. Dogs fed PLANT also demonstrated a shift from vitamin D3 to vitamin D2 metabolites, though total vitamin D analogue levels were unchanged, with the exception of 24,25-dihydroxyvitamin D. Bone mineral content and density did not differ from baseline values. Health status was maintained in dogs fed PLANT and vitamin D2 appeared efficacious in maintaining serum total vitamin D concentrations and bone mineralisation. Findings support the hypothesis that PLANT was comparable to MEAT for maintenance of healthy adult dogs for at least 3 months and identified areas where further research is warranted to elucidate the potential risks and benefits of plant-based (vegan) diets.

Mineral and glycerol concentrations in drinking water on body weight loss and acid-base balance in feed-deprived Holstein bulls

Situations in which cattle are feed-deprived over extensive periods of time are common in the context of transport and is an animal welfare concern which may also compromise growth and carcass yield grade. This study investigated how the main components of an oral rehydration solution would affect BW loss and blood parameters in feed-deprived bulls. Three dose-response experiments were performed with 24 bulls each (n = 6 per treatment) to study the effect of mineral concentration in Study I (0, 100, 200 and 300 mOsm/kg), the K⁺ to Na⁺ ratio in Study II (25:75, 40:60, 60:40 and 75:25), and glycerol concentration in Study III (0%, 1%, 2% and 4% of the final solution). The blocking factor was initial BW and treatments were randomly assigned within each block. Measurements included fluid intakes, BW, and blood parameters at 0, 24 and 48 h relative to the start of feed deprivation. In Study I, increasing mineral concentration in solution linearly decreased BW losses at 48 h. At 24 and 48 h, serum urea linearly decreased with increasing mineral concentration. At 48 h, blood K⁺ and Na⁺ linearly increased, resulting in increased blood osmolarity. Additionally, at 24 h feed deprivation, blood pH linearly increased with increasing osmolality. In Study II, BW losses decreased with increasing K⁺ to Na⁺ ratio at 24 h, but not at 48 h. No effect of the K⁺ to Na⁺ ratio was found on blood parameters, apart from a trend for a linear decrease of blood osmolarity at 48 h. In Study III, serum urea tended to linearly decrease with increasing glycerol inclusion at 24 h, while blood glucose linearly increased with glycerol inclusion at 24 and 48 h. These combined results indicated that a solution with an osmolality of 200 mOsm/kg and a high K⁺ to Na⁺ ratio would effectively mitigate BW losses and maintain blood acid-base balance, whereas high glycerol inclusion sustained blood glucose in feed-deprived bulls.