Effect of increasing taurine and methionine supplementation on urinary taurine excretion in a model insectivore, the giant anteater (Myrmecophaga tridactyla)

Abstract

SummaryThe giant anteater (Mymercophaga tridactyla) is a highly specialized insectivore for which nutrient requirements are not clearly established, making diet formulation challenging for this species. Multiple clinical reports suggest anteaters have an obligate dietary taurine (TAU) requirement. Sulphur amino acid (SAA) metabolism in adult anteaters was evaluated using noninvasive methods to measure TAU synthesis potential from dietary methionine (MET) and a basal diet containing on a dry matter (DM) basis 1.7 mg TAU/kg DM and 6.9 g MET/kg DM. Urinary equilibrium times for TAU excretion were determined by feeding the basal diet with or without 1.5 g/kg DM supplemental TAU (crossover design; n = 4). Effects of supplemental dietary TAU (1.7, 2.0, 2.4, 2.7, 3.0, 3.3 g/kg DM) or MET (6.9, 9.0, 11.2 g/kg DM) on urinary TAU were evaluated (randomized block trials; n = 5 or 4 respectively). All urinary values (TAU, MET, unbound inorganic sulphate) were normalized to creatinine (CRT). Results indicate urinary TAU equilibrium in anteaters requires at least 2 weeks of feeding. Urinary ratio of TAU to CRT (TAU:CRT) increased as dietary TAU content increased from 1.7 to 3.0 g/kg DM, consistent with renal homoeostatic modulation of TAU excretion. Our data indicate that TAU needs were met by TAU in the basal diet or by de novo synthesis. Supplemental MET resulted in ~five-to eightfold increases in urinary TAU:CRT excretion, further supporting existence of mechanisms for TAU synthesis from dietary SAA in anteaters. Adult anteaters appear able to synthesize TAU when diets contain adequate SAA, but dietary TAU may be critical if protein intakes are low or of poor quality. This study may provide guidance on choice of domestic canids vs. felids as suitable physiologic models for improved nutrition in giant anteaters, and also outlines a noninvasive method for assessing TAU status/metabolism that may be useful across (Van Vleet & Ferrans, 1986).Vitamin E and TAU deficiencies as causal factors in the development of cardiomyopathy have been reported for several species. In a case of cardiomyopathy in flying foxes (Pteropus spp.) under human care, plasma vitamin E levels were reported to be unmeasurable in bats clinically diagnosed with cardiomyopathy, and critically low to unmeasurable in bats in the same group without a cardiomyopathy diagnosis (Heard, Buergelt, Snyder, Voges, & Dierenfeld, 1996). In this case, TAU plasma levels were reported as above 20 nmol/ml, concentrations not commonly associated with TAU-deficiency cardiomyopathy in domes- Although in many species TAU is a byproduct of cysteine degradation, cats, some dogs, foxes and some primate species may lack the capacity to synthesize sufficient amounts of TAU to maintain adequate levels (reviewed in Schaffer, Ito, & Azuma, 2014). The reported effects of TAU deficiency include tapetal and retinal degeneration, immune deficiency, muscle atrophy, premature ageing, impaired reproduction and cardiac dysfunction (Schaffer et al., 2014). Domestic cats appear to have low enz...

Feeding Asian pangolins: An assessment of current diets fed in institutions worldwide

“…Individuals at both of these sites have either bred and reared their own pups, or arrived pregnant and reared their own pups successfully on these insect only low taurine diets. This supports the suggestions of Nofs et al (; in press). Insects can be a good source of methionine [mean value of 3.16 ± 1.15 g/kg of insects as is] and of cysteine (1.35 ± 0.32 g/kg of insects as is; Finke, , ) which we can assume meets the requirements of the Sunda pangolins to endogenously produce sufficient amounts of taurine (Nofs et al, , , in press (2017)).…”

“…The most studied related species successfully kept in captivity is the giant anteater whose nutritional requirements have been modelled after those of the domestic dog (Nofs, Dierenfeld, & Backus, ; Nofs et al in press). This was suggested due to the anteater's capability of producing the amino acid taurine from Sulphur amino acids, a metabolic pathway also available to dogs.…”