Exposure of growing and adult captive cheetahs (Acinonyx jubatus) to dietary isoflavones: twenty years later

Abstract

Dietary isoflavones are associated with oestrogenic and anti-oestrogenic effects, and have been linked to infertility in cheetahs. This study aimed to determine the isoflavone content of commercially prepared diets consumed by captive cheetahs. Sixteen international zoological facilities provided diets, and the isoflavone content of each diet was determined by acid hydrolysis and HPLC quantification. Proximate nutritional composition was also determined. Over half the diets analysed contained detectable concentrations of isoflavones, whereby total isoflavone content ranged from 1.75-183 mg/kg dry matter. The zoo-specific diets were calculated to deliver a median isoflavone dose of 0.07 mg/kg body weight (BW) and a maximum of 1.95 mg/kg BW to captive cheetahs. On a metabolic body weight basis this equates to a maximum of 4.90-5.43 mg/kg(0.75) . Some diets prepared for hand-rearing neonatal cheetahs could expose neonates to doses of up to 4.24 mg/kg BW (or 4.24-6.33 mg/kg(0.75) for cubs under 3 months of age). Only one of six zoo-specific diets was found to deliver isoflavones in doses shown to possess biological activity in other species. Therefore, on average, dietary isoflavones were not found in commercially prepared diets consumed by captive cheetahs in concentrations predicted to cause physiological changes. However, a small proportion of these diets, including hand-rearing formulas, contained elevated isoflavones concentrations which may influence cheetah fertility, behaviour or other physiological parameters.

Dietary Factors Associated with Faecal Consistency and Other Indicators of Gastrointestinal Health in the Captive Cheetah (Acinonyx jubatus)

“…Raw meat feeding was shown to be the most common practice in all regions. As shown previously [ 25 ], carcass-feeding was restricted to European facilities, and a smaller proportion fed in African facilities, whereas commercially prepared diets were only fed in North American facilities. The regional bias in the use of carcass-based or commercially prepared diets for cheetahs may be due to differences in availability, cultural views on the use of certain food items, concerns regarding hygiene or storage of carcasses, or varying husbandry recommendations.…”