Sarah Depauw

Animal fibre: The forgotten nutrient in strict carnivores? First insights in the cheetah

As wild felids are obligate carnivores, it is likely that poorly enzymatically digestible animal tissues determine hindgut fermentation, instead of plant fibre. Therefore, faecal concentrations of short-chain fatty acids (SCFA, including branched-chain fatty acids, BCFA), indole and phenol were evaluated in 14 captive cheetahs, fed two different diets differing in proportion of poorly enzymatically digestible animal tissue. Using a cross-over design, the cheetahs were fed exclusively whole rabbit or supplemented beef for 1 month each. Feeding whole rabbit decreased faecal propionic (p < 0.001) and butyric (p = 0.013) acid concentrations, yet total SCFA was unaltered (p = 0.146). Also, a remarkably higher acetic acid to propionic acid ratio (p = 0.013) was present when fed whole rabbit. Total BCFA (p = 0.011) and putrefactive indole (p = 0.004) and phenol (p = 0.002) were lower when fed whole rabbit. Additionally, serum indoxyl sulphate, a toxic metabolite of indole, was analysed and showed a quadratic decrease (p = 0.050) when fed whole rabbit. The divergent SCFA ratios and the decrease in putrefaction when fed whole rabbit could be caused by the presence of undigested tissue, such as skin, bone and cartilage, that might have fibre-like functions. The concept of animal fibre is an unexplored area of interest relevant to gastrointestinal health of captive cheetahs and likely other felids.

Fermentation of animal components in strict carnivores: a comparative study with cheetah fecal inoculum

The natural diet of felids contains highly digestible animal tissues but also fractions resistant to small intestinal digestion, which enter the large intestine where they may be fermented by the resident microbial population. Little information exists on the microbial degradability of animal tissues in the large intestine of felids consuming a natural diet. This study aimed to rank animal substrates in their microbial degradability by means of an in vitro study using captive cheetahs fed a strict carnivorous diet as fecal donors. Fresh cheetah fecal samples were collected, pooled, and incubated with various raw animal substrates (chicken cartilage, collagen, glucosamine-chondroitin, glucosamine, rabbit bone, rabbit hair, and rabbit skin; 4 replicates per substrate) for cumulative gas production measurement in a batch culture technique. Negative (cellulose) and positive (casein and fructo-oligosaccharides; FOS) controls were incorporated in the study. Additionally, after 72 h of incubation, short-chain fatty acids (SCFA), including branched-chain fatty acids (BCFA), and ammonia concentrations were determined for each substrate. Glucosamine and glucosamine-chondroitin yielded the greatest organic matter cumulative gas volume (OMCV) among animal substrates (P < 0.05), whereas total SCFA production was greatest for collagen (P < 0.05). Collagen induced an acetate production comparable with FOS and a markedly high acetate-to-propionate ratio (8.41:1) compared with all other substrates (1.67:1 to 2.97:1). Chicken cartilage was rapidly fermentable, indicated by a greater maximal rate of gas production (R(max)) compared with all other substrates (P < 0.05). In general, animal substrates showed an earlier occurrence for maximal gas production rate compared with FOS. Rabbit hair, skin, and bone were poorly fermentable substrates, indicated by the least amount of OMCV and total SCFA among animal substrates (P < 0.05). The greatest amount of ammonia production among animal substrates was measured after incubation of collagen and rabbit bone (P < 0.05). This study provides the first insight into the potential of animal tissues to influence large intestinal fermentation in a strict carnivore, and indicates that animal tissues have potentially similar functions as soluble or insoluble plant fibers in vitro. Further research is warranted to assess the impact of fermentation of each type of animal tissue on gastro-intestinal function and health in the cheetah and other felid species.

Blood Values of Adult Captive Cheetahs (Acinonyx jubatus) Fed Either Supplemented Beef or Whole Rabbit Carcasses

This study evaluated nutrient intake and relevant blood parameters of 14 captive cheetahs, randomly assigned to a meat-only diet (supplemented beef, SB) or a whole prey diet (whole rabbit, WR) for 4 weeks each. Despite a higher food intake, daily metabolizable energy intake was lower when fed WR (308 kJ BW(-1) ) compared with SB (347 kJ BW(-1) ) (P = 0.002). The ratio of protein to fat was markedly lower for WR (2.3:1) compared with SB (8.8:1), which was reflected in higher serum urea levels when fed SB (P = 0.033), and a tendency for elevated cholesterol levels when fed WR (P = 0.055). Taurine intake of cheetahs fed WR was low (0.06% on DM basis); however, analytical error during taurine analysis cannot be ruled out. Feeding WR resulted in a well-balanced mineral intake, in contrast to SB. The latter provided a low calcium:phosphorus ratio (1:2.3), thereby increasing the risk of metabolic bone disease. The high zinc content of SB (200 mg/kg DM), compared with WR (94 mg/kg DM), was reflected in higher serum zinc concentrations (P = 0.011). Feeding WR resulted in an increase in serum vitamin A (P = 0.011). Therefore, the risk of hypervitaminosis A in captive cheetahs when fed WR exclusively on a long-term basis should be evaluated. Our findings suggest that neither diet is likely to provide appropriate nutrition to captive cheetahs when fed exclusively.

Incubation of selected fermentable fibres with feline faecal inoculum: correlations between in vitro fermentation characteristics and end products

This study aimed to evaluate correlations between fermentation characteristics and end products of selected fermentable fibres (three types of fructans, citrus pectin, guar gum), incubated with faecal inocula from donor cats fed two diets, differing in fibre and protein sources and concentrations. Cumulative gas production was measured over 72 h, fermentation end products were analysed at 4, 8, 12, 24, 48 and 72 h post-incubation, and quantification of lactobacilli, bifidobacteria and bacteroides in fermentation liquids were performed at 4 and 48 h of incubation. Partial Pearson correlations, corrected for inoculum, were calculated to assess the interdependency of the fermentation characteristics of the soluble fibre substrates. Butyric and valeric acid concentrations increased with higher fermentation rates, whereas acetic acid declined. Concentrations of butyric acid (highest in fructans) and propionic acid were inversely correlated with protein fermentation end products at several time points, whereas concentrations of acetic acid (highest in citrus pectin) were positively correlated with these products at most time points. Remarkably, a lack of clear relationship between the counts of bacterial groups and their typically associated products after 4 h of incubation was observed. Data from this experiment suggest that differences in fibre fermentation rate in feline faecal inocula coincide with typical changes in the profile of bacterial fermentation products. The observed higher concentrations of propionic and butyric acid as a result of fibre fermentation could possibly have beneficial effects on intestinal health, and may be confounded with a concurrent decrease in the production of putrefactive compounds. In conclusion, supplementing guar gum or fructans to a feline diet might be more advantageous compared with citrus pectin. However, in vivo research is warranted to confirm these conclusions in domestic cats.

SERUM PROTEIN CAPILLARY ELECTROPHORESIS AND MEASUREMENT OF ACUTE PHASE PROTEINS IN A CAPTIVE CHEETAH (ACINONYX JUBATUS) POPULATION

Abstract: Renal and gastrointestinal pathologies are widespread in the captive cheetah (Acinonyx jubatus) population but are often diagnosed at a late stage, because diagnostic tools are limited to the evaluation of clinical signs or general blood examination. Presently, no data are available on serum proteins and acute-phase proteins in cheetahs during health or disease, although they might be important to improve health monitoring. This study aimed to quantify serum proteins by capillary electrophoresis in 80 serum samples from captive cheetahs, categorized according to health status and disease type. Moreover, serum amyloid A concentrations were measured via a turbidimetric immunoassay validated in domestic cats, whereas haptoglobin and C-reactive protein were determined by non–species-specific functional tests. Cheetahs classified as healthy had serum protein and acute phase protein concentrations within reference ranges for healthy domestic cats. In contrast, unhealthy cheetahs had higher (P < 0.001) serum amyloid A, α2-globulin, and haptoglobin concentrations compared with the healthy subgroup. Moreover, serum amyloid A (P = 0.020), α2-globulin (P < 0.001) and haptoglobin (P = 0.001) concentrations in cheetahs suffering from chronic kidney disease were significantly greater compared to the reportedly healthy cheetahs. Our study indicates that serum proteins in the cheetah can be analyzed by routine capillary electrophoresis, whereas acute-phase proteins can be measured using available immunoassays or non–species-specific techniques, which are also likely to be applicable in other exotic felids. Moreover, results suggest that serum amyloid A and haptoglobin are important acute-phase proteins in the diseased cheetah and highlight the need to evaluate their role as early-onset markers for disease.