Effects of diet on the bacterial and eukaryotic microbiota across the gastrointestinal tract of healthy rabbits (Oryctolagus cuniculus).

OBJECTIVE: This study aimed to characterize the bacterial and eukaryotic microbiota of the gastrointestinal (GI) tract in domestic rabbits and to evaluate the effect of different diet characteristics, such as pelleting, extrusion, and hay supplementation. ANIMALS: 30 New Zealand White rabbits (15 male and 15 female; 6 to 7 months old) were fed 1 of 6 diets (5 rabbits per diet) for 30 days after an initial acclimation period. At the end of the trial, samples were collected from the stomach, small intestine, cecum, large intestine, and hard feces. METHODS: The samples were analyzed using 16S rRNA and internal transcribed spacer 1 region-targeted amplicon sequencing. RESULTS: The bacterial microbiota was distinct between the foregut and hindgut. The most abundant bacterial genera included an unclassified genus in the Bacteroidales order and Alistipes. Candida was the most abundant genus in the eukaryotic dataset. In the bacterial dataset, diet No Hay/Pellet E was shown to have lower diversity (Shannon diversity, P < .05) compared to all diet groups except for No Hay/Pellet M. Few significant differences in alpha-diversity indexes between diet groups were detected in the eukaryotic dataset. CLINICAL RELEVANCE: Our findings demonstrated that feeding hay had a significant effect on the beta diversity of the bacterial microbiota. Given the prevalence of gastrointestinal disease in the domestic rabbit population, furthering our understanding of what constitutes a healthy rabbit microbiota and the effects of different diets on the microbial community can help veterinarians implement better intervention strategies and allow pet owners to provide the best level of care.

Nutrient intake and influence on markers of oxidative stress in zoo-managed male snow leopards (Uncia uncia).

Oxidative stress (OS) results from the overproduction of reactive species. Nutrient intake can contribute positively or negatively to OS, and the lack of established nutrient requirements for most of the exotic species managed in zoos exacerbates the possibilities for nutrient imbalances that potentially could lead to reactive species production. The objective of this study was to evaluate the influence of nutrient intake and nutritional husbandry on markers of OS in male snow leopards (n = 14) maintained in U.S. facilities (n = 12). Diet samples and husbandry information were obtained and snow leopards were immobilized once for collection of blood. Samples were analyzed for chemical composition (diet and blood), antioxidant capacity (blood), and markers of OS (blood). Correlations between weekly nutrient intakes and markers of OS were analyzed by linear regression. Analyzed markers of OS included antioxidant enzymes (superoxide dismutase [SOD] and glutathione peroxidase [GPx]) and ferric reducing antioxidant potential that are protective against OS, and protein carbonyls, thiobarbituric acid reactive substances, and DNA/RNA damage that are indicative of oxidative damage. Weekly copper intake (10.1 to 80.2 mg) was negatively correlated with DNA/RNA damage (R 2 = 0.44; P = 0.01). Weekly sodium intake (4.4 to 12.7 g) was positively correlated with GPx activity (R 2 = 0.43; P = 0.04). More frequent feeding of whole prey (0.3 to 3 times/wk) was correlated with increased blood SOD activity (R 2 = 0.55; P < 0.01). In conclusion, greater dietary copper intake and more frequent feeding of whole prey may reduce OS in snow leopards. Dietary sodium intake and relationship with GPx activity should be further evaluated to determine benefit or detriment. No cause and effect can be inferred from our results, but our data suggest altering dietary form and nutrient concentrations may influence OS in snow leopards.

Factors affecting reproductive traits in male snow leopards (Unciauncia).

ABSTRACT: The population of snow leopards (Unciauncia) maintained in US zoos is no longer sustainable due to poor reproductive success. Our objective was to assess reproductive traits in male snow leopards and identify factors (markers of oxidative stress in seminal fluid, surveys of husbandry practices, gonadal and adrenocortical activity, dietary intake of various nutrients, and genetics) that may affect ejaculate traits and subsequent fertility. Ejaculates (2.9 ± 0.2 mL) from 32 male snow leopards (9.8 ± 0.7 years; 38.6 ± 0.8 kg) housed at 27 institutions contained 119.2 + 26.0 x 106 spermatozoa, of which 75.1 ± 2.3% were motile and 28.6 ± 2.6% exhibited normal morphology. Overall, 34% of males produced <5 million spermatozoa and 27% of males produced spermatozoa with <20% normal morphology. Activity of superoxide dismutase (SOD) in the seminal fluid was negatively correlated (P < 0.05, r2 = 0.90) with normal sperm morphology. Husbandry practices, mean concentrations of fecal androgen metabolites (fAM), and baseline concentrations of fecal glucocorticoid metabolites (fGM), inbreeding coefficients, and generations each male was removed from the founders in their lineages were not correlated (P > 0.05) with the total number of spermatozoa or the proportion of spermatozoa with normal morphology. Total sperm count was positively correlated (P < 0.05, R2 = 0.86) with the weekly intake of polyunsaturated fatty acids (PUFA) and the proportion of spermatozoa with normal morphology tended (P < 0.10, R2 = 0.31) to be positively correlated with copper intake. Altering the nutrient composition of snow leopard diets could provide managers with a possible method of improving reproductive traits in this endangered species. LAY SUMMARY: The population of snow leopards (Uncia uncia) maintained in US zoos has been declining since 1993 due to poor breeding success. Our objective was to assess the reproductive traits of male snow leopards and identify factors (e.g. hormones, diet, genetics) that may be affecting the quality of semen produced and therefore subsequent fertility. Within a cohort of 32 male snow leopards maintained at 27 US zoos, we found that 34% produced less than 5 million sperm and 27% of males produced sperm where less than 20% looked normal. The quantity and quality of the recovered sperm was not correlated with husbandry practices, concentrations of hormones (androgens and glucocorticoids) in feces, or genetics. However, the number of sperm was positively correlated with polyunsaturated fatty acids in the diet. Altering the nutrient composition of snow leopard diets could provide managers with a possible method of improving reproductive traits in this endangered species.

Nutrient evaluation of a pork by-product and its use as environmental enrichment for managed large exotic cats.

North American zoological institutions typically feed ground raw meat diets to large exotic cats. These diets typically are nutritionally complete, but lack physical properties characteristic of whole prey. Lack of mastication and prey manipulation may contribute to behavioral and health challenges. Pork by-products may provide environmental enrichment to mitigate these challenges. The objectives of this study were to evaluate a pig head for nutritional composition and to determine if a pig head was biologically relevant environmental enrichment for managed large exotic cats. Pig heads consisted of: DM: 48.5%; OM: 60.7%; CP: 38.4%; fat: 22.0%; CF: 13.5%; TDF: 3.4%; GE: 4.1 kcal/g DM. Five individually housed exotic cats (Panthera tigris tigris, Panthera tigris altaica (n = 2), Panthera tigris jacksoni, Panthera leo) were observed in 2-h blocks, 24-h before pig head introduction (Baseline), at time of pig head introduction (Enrichment) and immediately after the pig head was removed (Post Enrichment) via instantaneous scan sampling for 4 consecutive weeks. Active behaviors were 55.7% higher on Enrichment compared to Baseline days, and 26.4% higher compared to Post Enrichment days (p<0.0001). Active behaviors were 39.8% higher on Post Enrichment compared to Baseline days (p<0.0001). Total active behaviors were highest (p<0.0001) in week 3 and lowest (p<0.0001) in week 4 with differences as high as 64.5% seen among weeks. In conclusion, pig heads have potential to provide nutrient dense enrichment to large exotic cats, and employing a pig head as environmental enrichment increased active behaviors and did not lose novelty.