Effects of algal docosahexaenoic acid in an extruded cat diet on nutrient digestibility, fecal characteristics and metabolites, and blood coagulation parameters and fatty acid profiles of plasma and red blood cell membranes

Omega-3 polyunsaturated fatty acids (w3-PUFA), including docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), are critical nutrients in feline diets. These nutrients are utilized as a key source of energy, in the transport of fat-soluble vitamins, in the formation of eicosanoids in inflammatory responses, and in the development of neural, retinal, and auditory functions. These w3-PUFA most commonly are added to feline diets through marine sources, mainly fish. Sustainability has become a concern in recent years. Algae can be a sustainable alternative for dietary supplementation of w3-PUFA; however, there is limited information on the safety and bioavailability of w3-PUFA from algal sources in feline diets. Therefore, the objective of this study was to determine the effects of dietary supplementation of algal-DHA (aDHA) on plasma fatty acid profile, blood coagulation parameters, and apparent total tract nutrient digestibility (ATTD) by adult cats. Three diets were formulated to contain 10% poultry fat alone (control; CT) or 8% poultry fat with a 2% inclusion of fish oil (FO) or a 2% inclusion of aDHA. All diets met or exceeded AAFCO nutrient profiles for adult cats. Thirty female and male adult cats (mean age: 1.8 ± 0.03 yr, mean BW: 4.5 ± 0.8 kg) were used in a completely randomized design and fed assigned diets for 90 d. Fasted blood samples were collected on 0, 30, 60, and 90 d and analyzed for serum metabolites, complete blood count, coagulation parameters, and plasma and red blood cell fatty acid profiles. A 4-d total fecal collection was performed at the end of the experimental period for determination of ATTD of macronutrients and fecal score. All diets were well-accepted by the cats and there were no differences (P > 0.05) in food intake among treatments. Similarly, fecal output and scores did not differ (P > 0.05) among dietary treatments, with scores being in the ideal range (score 2-3). All diets were highly digestible, and ATTD of dry matter, organic matter, crude protein, fat, and fiber did not differ (P > 0.05) among diets. Dietary supplementation of fish oil or aDHA did not affect (P > 0.05) plasma prothrombin time (PT), partial thromboplastin time (PTT), or fibrinogen parameters. All cats remained healthy throughout the study. Serum triglyceride concentrations were within reference range, but were higher (P 0.05). Fecal phenols and indoles and phenols alone were higher (P > 0.05) for the cats fed the aDHA treatment compared to both those fed the CT and FO treatments. Results indicate a 2% inclusion of DHA-enriched algal meal in a nutritionally complete adult cat food was a safe, bioavailable, and a sustainable alternative to FO in feline diets.U of I OnlyAuthor requested U of Illinois access only (OA after 2yrs) in Vireo ETD syste