BackgroundPet owners have many feeding options, some may be considered unconventional by veterinary practitioners. Provision of appropriate nutrition is a basic requirement, with adverse health outcomes possible when a pet diet is inadequate.ObjectiveTo capture dog and cat feeding practices, with a special focus on countries with large English-speaking populations, and to compare with data published over the previous 10 years.MethodsAn electronic questionnaire was provided for dog and cat owners online. Responses were analysed using descriptive statistics, and comparisons made with data from nine peer-reviewed articles published over the previous 10 years.ResultsResponses from 3673 English-speaking dog and cat owners in Australia, Canada, New Zealand, the UK and the USA were included. In previous publications, conventional (commercial, heat-processed) products were the predominant method of feeding. In recent publications, feeding unconventional (raw, homemade, vegetarian) diets appeared more prevalent. In the present study, most (79 per cent dogs, 90 per cent cats) pets were offered conventional food. However a few (13 per cent dogs, 32 per cent cats) pets were fed conventional foods exclusively. Many pets were offered homemade (64 per cent dogs, 46 per cent cats) and/or raw (66 per cent dogs, 53 per cent cats) foods. Different feeding practices were associated with geographical location.ConclusionAs an increased risk of nutrient insufficiency and associated conditions have been attributed to unconventional feeding practices, veterinarians must be aware of pet feeding trends and educate clients about the nutritional needs of companion animals.

The objective of this study was to determine the dose-response relationship between dietary choline intake and one-carbon cycle activity in overweight cats at maintenance energy requirements. This study was approved by the University of Guelph Animal Care Committee (AUP#4118). Overweight (body condition score:≥6/9) adult male neutered cats (n = 14) received each of five choline chloride doses individually for three weeks in a 5x5 latin square design. Doses were based on body weight (BW) and the daily recommended allowance (RA) for choline for adult cats (63 mg/kg BW0.67). Doses were: 2xRA (126 mg/kg BW0.67), 4xRA (252 mg/kg BW0.67), 6xRA (378 mg/kg BW0.67), 8xRA (504 mg/kg BW0.67), and control (no additional choline). Choline was administered onto the commercial extruded cat food (3620 mg choline/kg diet), given once a day at maintenance energy requirements (130 kcal/kg BW0.4). Fasted serum samples were analyzed for metabolomics through quantitative nuclear magnetic resonance (NMR) spectroscopy and direct infusion mass spectrometry (DI-MS) at the end of each period. Data was analyzed using proc GLIMMIX in SAS, with group and period as the random effects, and dose as the fixed effect. Statistical significance was considered at P < 0.05. Tukey’s post-hoc test was performed to assess multiple comparisons. Choline at 6x and 8x RA appears to increase transmethylation through the one-carbon cycle, as suggested by increased serum betaine, dimethylglycine (DMG) and methionine (P < 0.05). Carnitine, methylated by s-adenosylmethionine (SAM), increased (P < 0.05). Serine and threonine, precursors for the biosynthesis of homocysteine, appear to have been spared (P < 0.05). Supplemental dietary choline (6x and 8xRA) may be beneficial for overweight cats, as it may increase activity of the one-carbon cycle and methyl status; which are necessary for hepatic function. To better understand the impact of choline on methylation reactions, the quantification of specific proteins, gene expression and/or conversion rates is required.

Carbon oxidation methods have been used as rapid and sensitive methods to determine whole-body AA requirements in multiple species. The objectives of the current studies were to validate complete CO recovery, determine the bicarbonate retention factor, and estimate the Phe requirement, in the presence of excess Tyr, in adult dogs using the direct oxidation technique. In this series of studies, 2 oxidation chambers were constructed and calibrated to ensure accurate collection of breath CO. First, 104.6 ± 7.1% CO was recovered from chambers and suggests that the chambers were appropriately designed for complete and efficient CO recovery. Second, we determined bicarbonate retention in 5 dogs using repeated oral dosing of a bicarbonate tracer (NaHCO) with small meals. At isotopic and physiological steady state, 102.5 ± 2.6% of the delivered NaHCO was recovered in breath. Third, the Phe requirement, when Tyr was supplied in excess, was determined by the rate of appearance of CO in the breath (CO). Dogs ( = 5) were fed test diets with different concentrations of Phe ranging from deficient to excessive for 2 d prior to conducting the tracer studies. The mean Phe requirement (when Tyr was supplied in excess) was 0.535% of diet (upper 95% confidence interval = 0.645% diet) on an as-fed basis or 0.575% of diet (upper 95% confidence interval = 0.694% of diet) on a DM basis and was based on a calculated (modified Atwater calculation) dietary ME density of 3.73 Mcal/kg DM. These data support the use of carbon oxidation methods and oral dosing of isotope to measure whole-body requirements of indispensable AA in adult dogs and suggest the current recommendations may be low.

This study aimed to investigate changes in serum metabolites using direct infusion mass spectrometry (Di-MS) after 12 weeks with or without additional choline in growing, post-gonadectomy kittens. The present study was approved by the University of Guelph Animal Care Committee (AUP#4118). Intact, male kittens (3-months old; n = 15) were fed a base-diet to growth requirements (3310mg choline/kg DM) over an 11-week acclimation. Kittens were gonadectomized (week 1) and assigned to base-diet (n = 7) or base-diet with 300mg/kgBW0.75 additional choline (n = 8) and fed to mimic ad libitum food intake (3 meals totaling thrice daily requirements) for 12-weeks. Fasted serum samples were obtained and analyzed for 130 metabolites via Di-MS (week 0 and 12). The proc GLIMMIX procedure (SAS) was used to analyze differences between groups as a repeated measure. Additional choline resulted in higher serum concentrations of one-carbon metabolites such as methionine, serine, betaine, and sarcosine (P < 0.05). As expected, serum concentrations of phosphatidylcholines increased with additional choline, as did serum concentrations of lysophosphatidylcholines and sphingomyelins, compared to no additional choline (P < 0.05). There was minimal impact on acyl carnitines with a decrease in medium length acyl carnitines (P < 0.05). Additionally, there was an increase in serum concentrations of spermine, trans hydroxyproline, methionine sulfoxide, proline, and indole acetic acid, and a decrease in serum trimethylamine N-Oxide compared to control (P < 0.05). Effects of growth stage or gonadectomy may have resulted in increased serum amino acid concentrations such as asparagine, glutamine, glutamic acid, histidine, lysine, methionine, threonine, and tyrosine in both groups (P < 0.05). These results may indicate benefits for providing additional choline to post-gonadectomy kittens on one-carbon metabolism and fatty acid oxidation which could promote healthy weight and body condition. However, more research is warranted to further understand choline’s role in energy balance and its potential in prevention and treatment of feline obesity.

Phenylalanine (Phe) consumption may delay gastric emptying (GE) and feed intake. Two studies were conducted using a 2*2 latin square design with 12 healthy male cats to evaluate effects of 1) dietary Phe (PHE, 44mg/kg-BW) compared with an isonitrogenous amount of alanine (ALA, 23.7 mg/kg-BW) on feed intake, and 2) PHE and ALA on GE and GE rate (GER). In study 1, cats were given PHE or ALA 15 minutes before 120% of their daily food and intake was measured. Treatment, day, and their interaction were evaluated using PROC GLIMMIX in SAS. Treatment did not affect rate of food consumption (p >0.05). For study 2, cats were provided PHE or ALA 15 minutes before receiving 100% of their daily food intake for 3 days. On d4, cats received PHE or ALA and subsequently received [1-13C] octanoic acid (5mg/kg BW) on 10g of feed before being fed 50% of their daily food intake. Breath samples were collected to measure 13CO2 enrichment for 12 hours post-meal using indirect calorimetry. Data from cats that returned to baseline enrichment were evaluated for total AUC (GE) and time to peak enrichment (GER). The effect of treatment, body condition score (lean vs. overweight), and their interaction were evaluated using PROC GLIMMIX in SAS. Cats receiving PHE had later peaks (445±71 min) in 13CO2 enrichment (p< 0.05) than cats receiving ALA (244±71 min) but had similar total GE (p >0.10). Obese cats tended (P=0.09) to have greater total GE than lean cats, regardless of treatment. Lean cats on PHE had slower (p< 0.05) emptying rates than lean cats on ALA, but both were similar to obese cats (p >0.05). Overall, Phe did not reduce feed intake or total GE but did delay GE and thus reduced GER. A longer study is warranted to understand whether PHE can control food intake in cats.