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Title:Effects of dietary macronutrient profile and feeding frequency on circulating metabolites, postprandial endocrine response, and voluntary physical activity of healthy adult cats
Author(s):Deng, Ping
Director of Research:Swanson, Kelly S.
Doctoral Committee Chair(s):Swanson, Kelly S.
Doctoral Committee Member(s):Fahey, George C.; Tappenden, Kelly A.; Graves, Thomas K.
Department / Program:Animal Sciences
Discipline:Animal Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Dietary macronutrients
Feeding strategies
Feeding frequency
Appetite-regulating hormones
Plasma metabolite profiles
Physical activity
Dietary water content
Abstract:For many years, the incidence of obesity has been one of the most common health issues in domestic cats. Obesity is a risk factor for the development of insulin resistance and type II diabetes mellitus. The prevalence of highly palatable commercial pet foods, a sedentary indoor lifestyle, and inappropriate feeding strategies largely contribute to obesity in cats. This dissertation focused on diet composition and feeding strategies to understand how dietary factors may affect appetite regulation, metabolism, and energy expenditure of cats and in the development of weight-loss programs. Herein, six studies were designed to address two major research objectives: 1) to evaluate how dietary macronutrient composition influences circulating metabolites and appetite-regulating hormones in healthy adult cats; and 2) to investigate whether different feeding strategies promote voluntary physical activity in healthy adult cats. Because very little is known regarding appetite-regulating hormone concentrations in feline plasma and their relationship with feeding frequency, Study 1 was designed to monitor daily fluctuations of circulating glucose, insulin, total ghrelin, and leptin concentrations in cats fed 2 or 4 meals per day. Results from this study suggested that cats fed 4 meals daily had greater leptin incremental area under the curve (AUC) 0-24h and less variable concentrations of glucose and insulin compared to cats fed 2 meals. Study 2 was a macronutrient bolus experiment, similar to a glucose tolerance test, to measure the acute response of a single macronutrient dose on postprandial glucose, insulin, total ghrelin, and leptin concentrations in healthy adult cats. Circulating hormone data were highly variable and indicated changes due to dietary macronutrients. We observed that a carbohydrate bolus increased glucose and insulin incremental AUC 0-6h, and tended to increase leptin net AUC 0-6h. Study 3 evaluated the effects of three isoenergetic diets rich in protein, fat, or carbohydrate (vs. a control diet with balanced macronutrients) on fasting and postprandial glucose, insulin, total ghrelin, and leptin concentrations in healthy adult cats. We reported that cats fed control and high-carbohydrate (HC) diets had greater glucose incremental AUC compared to those fed the high-fat (HF) and high-protein (HP) diets. Study 4 used a high-throughput metabolomics approach to characterize fasting blood metabolite profiles of cats fed various dietary macronutrient concentrations. Cats fed HP, HF, and HC diets formed distinct metabolite profiles and three potential biomarkers, gamma-glutamylleucine, 3-hydroxyisobutyrate, and 3-indoxyl sulfate were identified to distinguish cats fed the three macronutrient-rich diets. This study revealed that cats fed the HP diet had decreased metabolites associated with nucleotide catabolism, but increased metabolites associated with amino acid and fat metabolism for energy, as well as increased metabolites associated with gut microbial metabolism. Cats fed the HF diet had increased metabolites associated with lipid metabolism and oxidative status. Besides the diet, appropriate feeding strategies to promote physical activity have been suggested as a key contributing factor to manage body weight (BW), but research is lacking. Study 5 evaluated the effects of feeding frequency on voluntary physical activity in cats fed to maintain BW. Our data suggested that increased meal frequency promoted overall physical activity by increasing the food anticipatory activity (FAA). Study 6 evaluated the effect of increasing dietary water content without changing energy intake on voluntary physical activity in cats. Our results suggested that increased dietary water content also increased daily physical activity, but appeared to occur by increasing the physical activity level after meals. Manipulating dietary macronutrient composition and designing appropriate feeding strategies appear to impact physiological and physical outcome variables in the cat.
Issue Date:2014-01-16
Rights Information:Copyright 2013 Ping Deng
Date Available in IDEALS:2014-01-16
Date Deposited:2013-12

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