Safety and efficacy of a novel iron chelator (HBED; (N,N'-Di(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid)) in equine (Equus caballus) as a model for black rhinoceros (Diceros bicornis).

While iron overload disorder (IOD) and related disease states are not considered a common occurrence in domestic equids, these issues appear prevalent in black rhinoceroses under human care. In addressing IOD in black rhinos, altering dietary iron absorption and excretion may be the most globally practical approach. A main option for treatment used across other species such as humans, is chelation therapy using iron-specific synthetic compounds. As horses may serve as an appropriate digestive model for the endangered rhinoceros, we evaluated the potential use of the oral iron chelator N,N-bis(2-hydroxybenzyl)ethylenediamine-N,N-diacetic acid (HBED) in horses for safety and efficacy prior to testing in black rhinoceros. Health and iron digestibility and dynamics were assessed in horses (n = 6) before, and after treatment with HBED (50 mg/kg body weight) for 8 days using a crossover design with serum, faecal and urine collection. A preliminary pharmacokinetic trial was also performed but no trace of HBED was found in serially sampled plasma through 8 h post-oral dosing. HBED increased urinary iron output in horses compared to control by 0.7% of total iron intake (p < 0.01), for an average of 27 mg urinary iron/day, similar to human chelation goals. Blood chemistry, blood cell counts and overall wellness were not affected by treatment. As healthy horses are able to regulate iron absorption, the lack of change in iron balance is unsurprising. Short-term HBED administration appeared to be safely tolerated by horses, therefore it was anticipated it would also be safe to administer to black rhinos for the management of iron overload.

Challenges with effective nutrient supplementation for amphibians: A review of cricket studies.

Over the last 25 years, numerous studies have investigated the impact of insect supplementation on insect nutrient content. In light of recent nutrition related challenges with regards to zoo amphibians fed an insect based diet, this review attempts to comprehensively compile both anecdotal and published data in the context of practical application on this topic. Insects, primarily crickets, used for amphibian diets historically demonstrate low concentrations of key nutrients including calcium and vitamin A. Commonly used practices for supplementation involving powder dusting or gut loading have been shown to improve delivery of calcium and vitamin A, though often not reaching desired nutrient concentrations. The large variety of factors influencing insect nutrient content are difficult to control, making study design, and results often inconsistent. Formulation and availability of more effective gut loading diets, combined with a standardized protocol for insect husbandry and dietary management may be the most effective way to supplement insects for use in amphibian feeding programs. Ideally, the nutritional improvement of feeder insects would begin at the breeder level; however, until this becomes a viable choice, we confirm that supplementation of crickets through both gut-loading and dusting appear necessary to support the nutritional health of amphibians and other insectivores in managed collections.