Irradiation of diets fed to captive exotic felids: microbial destruction, consumption, and fecal consistency.

Two frozen, raw horse meat-based diets fed to captive exotic felids at Brookfield Zoo were irradiated to determine the extent of microbial destruction and whether radiation treatment would affect consumption and/or fecal consistency in exotic cats. Fifteen cats, two African lions (Panthera leo), two Amur tigers (Panthera tigris altaica), one Amur leopard (Panthera pardus orientalis), two clouded leopards (Neofelis nebulosa), two caracals (Felis caracal), one bobcat (Felis rufus), and five fishing cats (Felis viverrinus), housed at Brookfield Zoo were fed nonirradiated and irradiated raw diets containing horse meat with cereal products and fortified with nutrients: Nebraska Brand Feline and/or Canine Diet (Animal Spectrum, North Platte, Nebraska 69103, USA). Baseline data were obtained during a 2-wk control period (nonirradiated diets), which was followed by a 4-wk period of feeding comparable irradiated diets. Feed intake and fecal consistency data were collected. An estimated radiation dose range of 0.5-3.9 kilograys reduced most microbial populations, depending on specific diet and microbe type. Irradiation had no overall effect on either feed consumption or fecal consistency in captive exotic cats, regardless of species, age, sex, or body mass. Data indicate that irradiation of frozen horse meat-based diets (packaged in 2.2-kg portions) result in microbial destruction in these products but that product storage time between irradiation and sampling may also affect microbial reduction. However, irradiation would be an appropriate method for reducing potentially pathologic bacteria in raw meat fed to exotic cats.

Hepatic iron accumulation over time in European starlings (Sturnus vulgaris) fed two levels of iron.

European starlings (Sturnus vulgaris) were used as a passerine bird model to examine the effect of dietary iron on the level of hepatic iron in birds. Nestling and fledgling starlings (n = 56) were raised on a controlled-iron diet. When birds maintained constant body weight, they were assigned in pairs to cages, and baseline sampling was performed. Pairs were then assigned to one of two diets: the controlled-iron diet (168 ppm, dry basis) or a high-iron diet (3,035 ppm, dry basis). Dry-matter intake and iron consumption were recorded. Dry-matter intake did not differ between the dietary treatment groups and was stable during treatment periods. Iron intake was higher in the high-iron group (P < 0.05). Birds were euthanized at baseline, 8 wk, and 16 wk. Body, liver, and spleen weights were measured. Hepatic iron and copper concentrations were determined. Body weight did not differ between the two treatment groups or among individuals for the study duration. Liver iron concentration differed over time and between treatment groups. Birds receiving both treatments had similar liver iron content at week 8 (3,107 +/- 228.6 ppm and 3,122 +/- 306.2 ppm high and controlled iron, respectively; P > 0.05), but by week 16, birds consuming the high-iron diet had greater hepatic iron levels than those consuming the controlled-iron diet (5,929 +/- 937.2 ppm and 3,683 +/- 229.5 ppm high and controlled iron, respectively; P < 0.05). Birds on the controlled-iron diet also had higher hepatic iron at 16 wk than at 8 wk. Liver copper decreased over time in all birds regardless of treatment. Results show that both dietary iron level and duration of time influenced hepatic iron storage. The controlled-iron diets still allowed accumulation of hepatic iron in an 8-wk period.

Whole body cholesterol, fat, and fatty acid concentrations of mice (Mus domesticus) used as a food source.

The concentrations of dry matter, cholesterol, saturated fat, monounsaturated fat, and 29 fatty acids were measured in four size categories of whole mice (Mus domesticus) that are commonly fed to zoo animals. Dry matter increased with age/size of mice, whereas cholesterol decreased with age/size. Significant differences in fatty acid content were found among mice categories with capric, lauric, and myristic acids. Mice categories had similar levels of palmitic, palmitoleic, heptadecenoic, stearic, oleic, linoleic, gamma linolenic, alpha linolenic, eicosenoic, eicosadienoic, arachidonic, docosahexaenoic, and lignoceric acids. Analyzed lipid content of mice exceeded domestic carnivorous animal requirements for linoleic and arachidonic acids. The fatty acid levels in mice were high, falling between published values in beef and fish. Generally, mice contained higher levels of polyunsaturated fatty acids, including the omega-3 fatty acids, and lower levels of saturated fatty acids than beef. Although fatty acid levels met or exceeded some dietary requirements for carnivores and omnivores, a possibility of excessive levels exists that could lead to eye and tissue abnormalities. Furthermore, as the intake of dietary polyunsaturated fatty acids increases, the dietary requirement for vitamin E increases. Thus, it is important that lipid profiles of feeder mice be known and considered when examining captive animal diets.

Intake, digestibility, and passage of a commercially designed diet by two Propithecus species.

The digestibility and passage of an experimental diet was used to compare the digestive physiology of two Propithecus species: P. verreauxi and P. tattersalli. Though both animals have a similar feeding ecology, the captive status of P. verreauxi is considered more stable than that of P. tattersalli. The test diet included a local tree species, Rhus copallina, at 15% of dry matter intake (DMI) and Mazuri Leafeater Primate Diet at 85% of DMI. The chemical composition of the diet (dry matter basis) was 25% crude protein, 34% neutral detergent fiber (NDF), and 22% acid detergent fiber (ADF) with a gross energy of 4.52 kcal/g. After a 6 week acclimation to the experimental diet, animals were placed in research caging. After a 7 day adjustment period, animals were dosed with chromium mordant and Co-EDTA as markers for digesta passage and all feed refusals and feces were collected at timed intervals for 7 days. Digestibility values, similar for both species, were approximately 65% for dry matter, crude protein, and energy, and 40% and 35% respectively, for NDF and ADF. Transit times (17-18.5 hr) and mean retention times (31-34 hr) were not significantly different between species, and there was no difference between the chromium mordant and Co-EDTA. Serum values for glucose, urea, and non-esterified fatty acids (NEFA) were obtained during four different time periods to monitor nutritional status. While there was no change in serum glucose, serum urea increased over time. The NEFAs increased across all four time periods for P. verreauxi and increased for the first three periods then decreased in the last period for P. tattersalli. Results obtained indicate no difference in digestibility nor digesta passage between species, and that both Propithecus species were similar to other post-gastric folivores.

A survey of serum and dietary carotenoids in captive wild animals.

Accumulation of carotenoids varies greatly among animal species and is not fully characterized. Circulating carotenoid concentration data in captive wild animals are limited and may be useful for their management. Serum carotenoid concentrations and dietary intakes were surveyed and the extent of accumulation categorized for 76 species of captive wild animals at Brookfield Zoo. Blood samples were obtained opportunistically from 275 individual animals immobilized for a variety of reasons; serum was analyzed for alpha- and beta-carotene, lutein + zeaxanthin, lycopene, beta-cryptoxanthin and canthaxanthin. Total carotenoid content of diets was calculated from tables and chemical analyses of commonly consumed dietary components. Diets were categorized as low, moderate or high in carotenoid content as were total serum carotenoid concentrations. Animals were classified as unknown, high, moderate or low (non-) accumulators of dietary cartenoids. Nonaccumulators had total serum carotenoid concentrations of 0-101 nmol/L, whereas accumulators had concentrations that ranged widely, from 225 to 35,351 nmol/L. Primates were uniquely distinguished by the widest range of type and concentration of carotenoids in their sera. Most were classified as high to moderate accumulators. Felids had high accumulation of beta-carotene regardless of dietary intake, whereas a wide range of exotic birds accumulated only the xanthophylls, lutein + zeaxanthin, canthaxanthin or cryptoxanthin. The exotic ungulates, with the exception of the bovids, had negligible or nondetectable carotenoid serum concentrations despite moderate intakes. Bovids accumulated only beta-carotene despite moderately high lutein + zeaxanthin intakes. Wild captive species demonstrated a wide variety of carotenoid accumulation patterns, which could be exploited to answer remaining questions concerning carotenoid metabolism and function.

Serum alpha- and gamma-tocopherols, retinol, retinyl palmitate, and carotenoid concentrations in captive and free-ranging bottlenose dolphins (Tursiops truncatus).

Concentrations of retinol, retinyl palmitate, beta-carotene, alpha-carotene, cryptoxanthin, lutein, lycopene, alpha-tocopherol, and gamma-tocopherol were measured in blood samples collected from 15 captive and 55 free-ranging bottlenose dolphins (Tursiops truncatus). From June 1991 to June 1994, blood samples were collected from captive animals residing at two locations; at Seven Seas (Brookfield Zoo, Brookfield, IL) and Hawk's Cay (Marathon Key, FL). Blood samples were collected from free-ranging animals from June 1991 to June 1996. Retinol levels were not significantly different between captive dolphin groups. However, Seven Seas animals had higher (P < 0.01) serum retinol concentrations compared to free-ranging animals (0.061 vs 0.041 microgram/ml). Retinyl palmitate was not detected in the serum of captive or free-ranging dolphins. Alpha-tocopherol levels were significantly (P < 0.05) higher for Seven Seas dolphins (16.4 micrograms/ml) than for Hawk's Cay (13.0 micrograms/ml) and free-ranging dolphins (12.5 micrograms/ml). Gamma-tocopherol concentrations were similar among captive and free-ranging dolphins. Free-ranging dolphins showed levels of circulating carotenoids (lutein and beta-carotene) while the captive animals did not. Additional carotenoids (lycopene, alpha-carotene and cryptoxanthin) were analyzed but not detected in any samples. Serum vitamin differences between captive and free-ranging dolphins may reflect the natural diet or indicate some potential biological or nutritional status significance.

Influence of dietary vitamins A and E on serum alpha- and gamma-tocopherols, retinol, retinyl palmitate and carotenoid concentrations in Humboldt penguins (Spheniscus humboldti).

Serum retinol, retinyl palmitate, beta-carotene, cryptoxanthin, lutein, alpha-tocopherol and gamma-tocopherol were measured in 18 captive Humboldt penguins (Spheniscus humboldti) prior to and following the removal of Columbia River (CR) smelt (Thaleichthys pacificus) from the diet. Dietary vitamin A was reduced from 59.8 to 13.5 IU g-1 (dry matter basis) when CR smelt was removed from the diet. Minimal changes were noted in dietary vitamin E. Serum samples Without-CR smelt had significantly lower circulating retinol (1.19 +/- 0.09 vs. 1.94 +/- 0.08 micrograms ml-1) and retinyl palmitate (0.033 +/- 0.012 vs. 0.105 +/- 0.004 microgram ml-1) compared to samples With-CR. The Without-CR smelt diet resulted in increased serum alpha-tocopherol from 26.4 +/- 0.94 to 39.1 +/- 3.72 micrograms ml-1. More serum samples taken Without-CR smelt had detectable levels of gamma-tocopherol than those With-CR smelt. Serum lutein was higher for the samples taken Without versus With-CR smelt. Serum cryptoxanthin did not differ. beta-Carotene was not detected. Data indicate that high levels of dietary vitamin A can affect circulating levels of retinol, retinyl palmitate and vitamin E. Thus, dietary vitamin A and the interrelationship between vitamins A and E should be considered when assessing captive penguins.

Use of a raw meat-based diet or a dry kibble diet for sand cats (Felis margarita).

Limited information is available on the utilization of different types of diets by captive exotic felid species. Utilization of diets by small exotic felids may differ depending on the diet fed. Eight sand cats (Felis margarita), which are small, 2- to 4-kg cats, were used to examine the digestibility of two types of diets: a raw meat-based diet and a dry kibble diet. Dry matter, crude protein and energy intakes and digestibilities were evaluated. Digestibilities for dry matter, energy, and crude protein were 83.5 +/- 4.8, 89.6 +/- 5.2, 92.4 +/- 5.3% for the raw meat-based diet and 72.7 +/- 12.3, 76.8 +/- 14.5, and 77.9 +/- 13.5% for the kibble diet. Physiological variables also were examined and included plasma taurine, vitamin A, retinyl palmitate, beta-carotene, calcium, and phosphorus. Plasma taurine means were 91.4 +/- 8.4 mumol/L in cats consuming the raw meat-based diet and 248.0 +/- 23.2 mumol/L in cats consuming the kibble diet. Plasma phosphorus was 5.2 +/- .1 and 4.5 +/- .1 mg/dL, respectively, in cats consuming raw meat-based and kibble diets. beta-Carotene was 25.2 +/- 2.9 and 2.9 +/- .3 micrograms/dL, respectively, for cats consuming the raw meat-based and kibble diets. These results indicate that diets formulated for small captive exotic felid species should be evaluated with respect to diet type and nutrient utilization.

Comparison of the sensitivities of growth and digestibility studies using intact, cecectomized, and cannulated roosters.

The sensitivity of several bioassays was determined using soybean meal and two autoclaved soybean meals. Chick growth study results revealed that a four percent difference in weight gain was sufficient to show statistical significance (P less than .05) between the diets. Lysine quantities and digestibility values were compared using excreta obtained from intact (excreta collected on mats or in bags), cecectomized. and ileal-cannulated roosters. A 30% difference in lysine quantity in the excreta (collected on mats) was required to detect statistically significant effects of different diets fed to intact birds. Using intact birds (excreta collected in bags), cecectomized, and cannulated birds, differences in lysine quantity of 41, 42, and 67% were required to show statistically significant effects. Results showed that altering birds did not significantly change lysine values obtained nor reduce variability among birds (P greater than .05).