Dietary fat and carbohydrate have different effects on body weight, energy expenditure, glucose homeostasis and behaviour in adult cats fed to energy requirement

Identifying the target population and preventive strategies to combat feline obesity

Feline obesity continues to be a priority health and welfare issue. Most research surrounding obesity currently focuses on obesity treatment. However, treatment for feline obesity is slow, often unsuccessful and not without consequences. Identifying high-risk populations for obesity onset is crucial for developing and implementing preventive strategies. This review identifies post-gonadectomy kittens aged 5-12 months as the primary target population for obesity prevention in domestic cats and highlights dietary and feeding management strategies to be implemented for obesity prevention.

Comparison of methods for the effective evaluation of the energy content of poultry byproduct meal for beagles

The objectives of this study were to compare the energy values of poultry byproduct meal (PBM) as feed for adult beagle dogs using the direct, difference, and regression methods to examine dogs' nitrogen metabolism, energy utilization, gaseous metabolism, and body health. Five groups of six 12 mo old female beagles with an average body weight of 9.67 ± 0.52 kg were tested in a 5 × 6 incomplete Latin square design, with six repetitions in each group. Five experimental diets were tested consisting of 100% PBM; three substitution diets containing either 15%, 30%, or 45% PBM (termed 15PBM, 30PBM, and 45PBM, respectively); and a basal diet (included 6.90% PBM). Each experimental period lasted for 10 d, comprising 4 d of dietary acclimation followed by 6 d of testing (including 3 d feeding period and 3 d fasting period), during which the heat production (HP) was determined and feces and urine were collected. Results showed that, in the feeding state, the nitrogen intake, urinary nitrogen, apparent nitrogen digestibility, retained nitrogen, andHP increased significantly (P < 0.05) as the PBM level increased. The net protein utilization, biological value of protein, and total apparent digestibility of amino acids did not differ between the 30PBM and 45PBM diets (P > 0.05). The O2 consumption and CO2 production of beagles during the fasting period were not influenced by the PBM level (P > 0.05). The digestible energy and metabolizable energy values of the PBM estimated by the regression method were 20.16 and 18.18 MJ/kg dry matter (DM), respectively, and did not differ from those determined by the direct method (P > 0.05). The fecal DM percentages and fecal PBM scores were significantly higher in the PBM diet than in the difference method groups (P < 0.05). The direct method group had a significantly higher fecal score (4.63) than the other groups (P < 0.05), The fecal score of the 45PBM diet (3.50) was significantly higher than the 30PBM diet (2.90; P < 0.05). In summary, the direct and difference methods of determining the effective energy value of PBM for beagles, produce significantly different results. Under the conditions of this test, the best proportion of PBM in beagle feed for optimum energy provision is 30%.

Effect of raw and encapsulated policosanol on lipid profiles, blood biochemistry, activity, energy expenditure and macronutrient metabolism of adult cats

Objectives

The objective of this study was to verify the safety of policosanol supplementation for domestic cats. The effects of raw and encapsulated policosanol were compared with positive (L-carnitine) and negative (no supplementation) controls on outcomes of complete blood count, serum biochemistry, energy expenditure, respiratory quotient and physical activity in healthy young adult cats.

Methods

The study was a replicated 4 × 4 complete Latin square design. Eight cats (four castrated males, four spayed females; mean age 3.0 ± 1.0 years; mean weight 4.36 ± 1.08 kg; mean body condition score 5.4 ± 1.4) were blocked by sex and body weight then randomized to treatment groups: raw policosanol (10 mg/kg body weight), encapsulated policosanol (50 mg/kg body weight), L-carnitine (200 mg/kg body weight) or no supplementation. Treatments were supplemented to a basal diet for 28 days with a 1-week washout between periods. Food was distributed equally between two offerings to ensure complete supplement consumption (first offering) and measure consumption time (second offering). Blood collection (lipid profile, complete blood count, serum biochemistry) and indirect calorimetry (energy expenditure, respiratory quotient) were conducted at days 0, 14 and 28 of each period. Activity monitors were worn 7 days prior to indirect calorimetry and blood collection. Data were analyzed using a repeated measures mixed model (SAS, v.9.4).

Results

Food intake and body weight were similar among treatments. There was no effect of treatment on lipid profile, serum biochemistry, activity, energy expenditure or respiratory quotient (P >0.05); however, time to consume a second meal was greatest in cats fed raw policosanol (P <0.05).

Conclusions and relevance

These data suggest that policosanol is safe for feline consumption. Further studies with cats demonstrating cardiometabolic risk factors are warranted to confirm whether policosanol therapy is an efficacious treatment for hyperlipidemia and obesity.

Understanding the Nutritional Needs of Healthy Cats and Those with Diet-Sensitive Conditions

Diets for cats must provide complete nutrition and meet the needs of the individual patient. There is no single diet that is perfect for all cats, and veterinarians must consider the needs of the cat as well as the preferences of the owners when making dietary recommendations. This article focuses on the interface between animal factors and nutritional needs in cats and is divided into 3 sections. Section 1 addresses the dietary needs of healthy cats, including differences among life stages. Section 2 addresses common myths regarding feline nutrition. Section 3 addresses common nutrient-sensitive conditions in cats, including sarcopenia of aging.

Modelling net energy of commercial cat diets

Net energy accounts for the proportion of energy expenditure attributed to the digestion, metabolism, and absorption of ingested food. Currently, there are no models available to predict net energy density of food for domestic cats. Therefore, the objectives of this study were to measure the heat increment of feeding in cats, and to model the net energy of commercial diets. Metabolizable energy and calorimetry data from two previous studies was reanalyzed to create net energy models in the present study. Energy expenditure was calculated using measurements of CO₂ production and O₂ consumption. Net energy was determined as the metabolizable energy of the diets minus the heat increment of feeding. The heat increment of feeding was determined as the area under the energy expenditure curve above the resting fed metabolic rate. Eight net energy models were developed using metabolizable energy, 1 of 4 dietary parameters (crude protein, fat, fiber, and starch), and heat increment of feeding values from 0–2 h or 0–21 h. Two hours postprandial, and over the full calorimetry period, the heat increment of feeding amounted for 1.74, and 20.9% of the metabolizable energy, respectively. Of the models tested, the models using crude protein in combination with metabolizable energy as dietary parameters best fit the observed data, thus providing a more accurate estimate of dietary energy availability for cats.

Carbohydrate level and source have minimal effects on feline energy and macronutrient metabolism

The carnivorous nature of the domestic cat makes feline metabolism of carbohydrates unique. The cats' glycemic response has been previously studied, with variable outcomes in response to carbohydrate level and source, but is an important response to understand how to control glycemia. The objectives of this study were to determine the glucose and insulin responses of cats fed 3 commercial diets differing in carbohydrate content and source, and to investigate the effects of diet on RQ, energy expenditure (EE), and glycemic response. Domestic shorthair cats (=19, 10 males, 9 females) of similar age (4.3 ± 0.48 yr, mean ± SD) and of ideal body condition score were used. Cats were fed, once a day, 1 of 3 commercial diets that differed in their perceived glycemic response (PGR; 36.8%, 30.7%, and 23.6% starch for high, medium, and low PGR, respectively) with cats cycling through all diets in 3 periods in 6 complete and 1 incomplete 3 × 3 Latin square. Each period consisted of 8 d of adaptation to the diet, followed by 21-h calorimetry measurements, and real-time interstitial glucose measurements on day 9. On day 10, sequential blood sampling was completed to determine blood glucose and insulin. BW and ME intake did not differ among treatments. EE in the fasted state did not differ among treatments (P = 0.160), whereas postprandial EE was highest for the high PGR diet compared with the medium PGR and low PGR diets (P < 0.001). In conclusion, cats revealed a prolonged postprandial glucose and insulin response compared with other monogastric animals, yet diet effects were minimal. Overall, interstitial glucose measures were less variable than serum glucose measurements and followed a parallel pattern to RQ. Therefore, going forward, calorimetry and continuous interstitial glucose monitoring should be considered as less invasive alternatives to repeated blood sampling.

Digestibility Is Similar between Commercial Diets That Provide Ingredients with Different Perceived Glycemic Responses and the Inaccuracy of Using the Modified Atwater Calculation to Calculate Metabolizable Energy

Dietary starch is required for a dry, extruded kibble; the most common diet type for domesticated felines in North America. However, the amount and source of dietary starch may affect digestibility and metabolism of other macronutrients. The objectives of this study were to evaluate the effects of 3 commercial cat diets on in vivo and in vitro energy and macronutrient digestibility, and to analyze the accuracy of the modified Atwater equation. Dietary treatments differed in their perceived glycemic response (PGR) based on ingredient composition and carbohydrate content (34.1, 29.5, and 23.6% nitrogen-free extract for High, Medium, and LowPGR, respectively). A replicated 3 × 3 Latin square design was used, with 3 diets and 3 periods. In vivo apparent protein, fat, and organic matter digestibility differed among diets, while apparent dry matter digestibility did not. Cats were able to efficiently digest and absorb macronutrients from all diets. Furthermore, the modified Atwater equation underestimated measured metabolizable energy by approximately 12%. Thus, the modified Atwater equation does not accurately determine the metabolizable energy of high quality feline diets. Further research should focus on understanding carbohydrate metabolism in cats, and establishing an equation that accurately predicts the metabolizable energy of feline diets.