Carnivores: Feed commercially prepared diets
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 5
Background information and definitions
Nutritional requirements of many exotic species are often unknown and therefore are commonly based on the nearest domestic relative. However, felids and canids typically eat many different parts of carcasses in the wild. Therefore, feeding a commercial diet may reduce the health risks to keepers and animals compared to handling raw meat but may not meet the nutritional needs of the animal. Identifying the digestibility and faecal or blood nutrient content may indicate the appropriateness of the diet in reference to the digestive health of the animal.
Supporting evidence from individual studies
A study in 1988 of cheetahs Acinonyx jubatus in 13 institutions in the USA found that when fed commercial food (supplemented minced meat products) or whole chicken carcasses, plasma a-tocopherol, retinol and taurine concentrations were within ranges recommended for domestic cats. Seven of 13 facilities maintained one fasting day per week, one had two fasting days per week and the others fed cheetahs daily. Thirteen facilities within the USA were surveyed for diet quantity, feeding schedule, dietary changes during lactation and body mass/condition. This was in conjunction with chemical analysis of 19 diet samples fed as well as blood analysis of 88 cheetahs across the facilities.Study and other actions tested
A replicated, before-and-after study in 1990–1991 of maned wolves Chrysocyon brachyurus in a research facility in the USA found that when fed a diet containing commercial pellets, dry matter feed intake and digestibility were similar compared to a high meat and fruit-based diet despite a lower protein content. Dry matter intake was similar on the commercial diet compared to the high fruit and meat diet (584 vs 389 g per 30 kg of body mass per day) as was digestibility (73 vs 77%) whereas the metabolisable energy derived from protein was lower (28.6 vs 36.4%). Excess dietary protein is associated with the renal disorder cystinuria in maned wolves. Feed intake was monitored for three days in two individually housed wolves and one breeding pair housed together but fed separately, for the high meat and fruit diet and for two breeding pairs, where feed intake was combined, for the commercial diet. The high meat and fruit diet consisted of whole rats (575 g per 30 kg of body mass per day) fed in the morning and a mixed feed of frozen meat mix, bread, rice, oatmeal and fruit fed in the afternoon. For the commercial diet, rats were reduced (50 g) and the afternoon mixed feed consisted of frozen meat mix, rice and dry commercial pellets for dogs. Three other diets were also studied but without digestibility being measured. Faecal samples were collected daily and dried for analysis.Study and other actions tested
A replicated, randomized study in 2013 of African wildcats Felis silvestris lybica in a zoo in the USA found that when fed a high protein commercial extruded diet, crude protein digestibility was lower and food intake and faecal output were higher compared to feeding a raw meat diet. Crude protein digestibility was lower when consuming a commercial diet (84%) compared to a raw meat diet (92%). Food intake and faecal output were higher on a dry matter basis when fed the commercial extruded diet (61.8 and 12.9 g/day respectively) compared to a raw meat diet (43.7 and 6.7 g/day respectively). There were no differences in faecal scores, ammonia or fatty acid concentrations between diets and no differences in the apparent digestibility of other nutrients, most blood metabolite levels or nitrogen retention. If commercial diets are nutritionally similar to raw meat diets then they may be preferred to reduce the risk of pathogens. Five adult wildcats were fed a raw meat or a high-protein dry commercial extruded diet and then switched to the other diet. Food offered and refused was weighed daily. Urine and faeces were collected in metabolism cages. Blood samples were collected from anaesthetised wildcats and serum metabolite was determined.Study and other actions tested
A replicated, controlled study in 2012 of cheetahs Acinonyx jubatus in a wildlife centre in South Africa, found that cheetahs fed commercial dry feline food had a similar likelihood of developing gastritis compared to cheetahs fed horsemeat and bone with supplement. Cheetahs on the commercial diet had a daily hazard of developing gastritis 2.2 times higher than cheetahs on the meat-based diet (gastritis grade 3 or above), although this difference was not significant. Serum urea levels were lower (14.76 vs 19.15 mmol/litre) and creatine levels higher (256.9 vs 249.1 umol/litre) on the commercial compared to the meat-based diet. Serum urea and creatine are expected to increase with renal disease. Forty-eight cheetahs which had a gastritis grade of less than 3 and whose blood protein creatine levels were below 300 umol/litre were studied. They were fed either 4 kg of horsemeat and bone, 5 g of vitamin/mineral supplement and 20 ml of fish-oil supplement (n=26) or 500 g of commercial adult feline food (n=22) daily, both diets included one whole eviscerated chicken twice a week. A concurrent study comparing a meat-based diet with a commercial food formulated for renal disease in cheetahs diagnosed with gastritis and/or renal disease was inconclusive. Gastritis was graded 0-9 based on biopsies, with 9 being most inflamed.Study and other actions tested
A small, randomized study in 2013 of African wildcats Felis silvestris lybica in a zoo in the USA found that canned, dry extruded and whole one to three day old chicken diets had lower organic matter digestibility compared to a ground-chicken diet. Organic matter digestibility was lower when fed canned (87%), extruded (86%) or whole chicks (85%) compared to a ground chicken diet (94%). Canned and extruded diets met macronutrient and mineral recommendations for domestic cat foods and tested negative for all microbes whereas whole one to three day old chicken and ground chicken diets met macronutrient requirements for domestic cats but were below recommendations for some minerals and tested positive for potentially pathogenic microorganisms. If commercial diets are nutritionally similar to raw meat diets then they may be preferred to reduce the risk of pathogens. Four wildcats were each fed four chicken-based diets: whole one to three day old chickens, ground chicken, canned commercial diet and extruded commercial diet. Wildcats were fed daily on each diet for 16 days. Each diet was analysed and apparent total tract macronutrient digestibility was measured daily using food intake and faecal output.Study and other actions tested
Referenced paperKerr K.R., Morris C.L., Burke S.L. & Swanson K.S. (2013) Apparent total tract macronutrient and energy digestibility of 1‐to‐3‐day‐old whole chicks, adult ground chicken, and extruded and canned chicken‐based diets in African wildcats (Felis silvestris lybica). Zoo Biology, 32, 510-517.