title: Palatability, digestibility, and metabolizable energy of dietary glycerol in adult cats.
abstract: Glycerol is a humectant, which reduces water activity when added to the diet. This property seems to offer dietary benefits, specifically in high-moisture diets for cats, where some humectants cannot be used. According to the U.S. Food and Drug Administration, glycerol is generally recognized as sustenance safe (GRAS). It is suggested that cats are able to metabolize glycerol and use it as an energy source without compromising health. Three experiments were conducted to evaluate the following characteristics of glycerol in the diet for cats: 1) a preference test, 2) digestibility, ME, and fecal and urinary characteristics, and 3) postprandial plasma glycemia. Twelve healthy adult female cats were randomly distributed among 4 treatments consisting of a basal diet (4,090 kcal ME/kg DM, 32% CP, 11% fat, 2.3% crude fiber, and 7.0% ash) and 3 diets with varying percentages of glycerol, made by replacing the basal diet with 2.5, 5.0, and 10.0% purified glycerol (99.5%). The inclusion of glycerol proportionally reduced ( < 0.05) water activity in the diets. The preference test was conducted by observing the contrast between the basal diet and the 5.0% and 10% glycerol diets. Cats did not show a preference for any diet in particular ( > 0.05). The digestibility assays showed that increasing dietary glycerol levels did not affect food intake or the apparent total tract digestibility of macronutrients and energy ( > 0.05). The inclusion of glycerol in the diets did not alter the stool moisture, fecal score, or urine volume. However, glycerol was detected in urine when it was incorporated into the diet at 10%. Glycemia increased up to 900 min following the first meal after the fasting period with no difference between treatments, even when the means were adjusted for food intake. The blood glucose area under the curve also showed no significant difference between treatments ( > 0.05). Cats accepted glycerol under the conditions of the study, and its nutritional value was determined as it has been done for other species. The ME of glycerol for adult cats was estimated to be 3,185 kcal/kg DM. Supplementing the diets of the cats with 10% glycerol may exceed their capacity to metabolize glycerol, possibly leading to urinary excretions.
authors.forename: G S
authors.initials: GS
authors.lastname: Machado
authors.forename: J G
authors.initials: JG
authors.lastname: Pezzali
authors.forename: F R
authors.initials: FR
authors.lastname: Marx
authors.forename: A M
authors.initials: AM
authors.lastname: Kessler
authors.forename: L
authors.initials: L
authors.lastname: Trevizan
mesh_terms: D000821:Animal Feed / Q000032:analysis*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001786:Blood Glucose; D002415:Cats / Q000502:physiology*; D004032:Diet / Q000662:veterinary*; D019587:Dietary Supplements; D004063:Digestion / Q000502:physiology*; D004435:Eating; D004734:Energy Metabolism / Q000502:physiology*; D005243:Feces; D005247:Feeding Behavior; D005260:Female; D005990:Glycerol / Q000737:chemistry / Q000378:metabolism*; D009753:Nutritive Value; D019518:Postprandial Period
chemical_list: D001786:Blood Glucose; D005990:Glycerol