Diet preference and breeding success in captive-bred Greater rheas (Rhea americana): a preliminary study


Abstract: We conducted 2 consecutive experiments to verify whether adult captive Greater rheas (Rhea americana) could select diets differing in nutritional and energetic content, and to evaluate the effect of those diets on egg production and hatchability. From August to January, animals were offered four diets: processed feed for rheas (diet 1), diet 1 + soybean (diet 2), processed feed for chicken (diet 3), and diet 3 + soybean (diet 4). Rheas preferred the diets containing feed for chicken (diets 3 and 4, 179,67 ± 12.12 [S.E.] g/ind./day). Diet 2 was more consumed (95.67 ± 16.70 g/ind./day) than diet 1 (60.09 ± 11.31 g/ind./day), whereas preferences for feed for chicken did not vary with supplementation. Diet 1 and soybean-supplemented diets were consumed by males (113 ± 13.66 and 163.57 ± 13.33 g/ind./day, respectively) in a greater amount than by females (42.27 ± 8.61 and 96.72 ± 16.52 g/ind./day, respectively). Diet type did not affect egg production (43-63 eggs), but hatchability was 13% higher in eggs from females fed soybean-supplemented feed (diets 2 and 4), and those fed diet 2 produced more chicks. While diets 3 and 4 were apparently of lower nutrient quality, they provided more energy than those formulated with processed feed for rheas. Conversely, diet 2 seemed to be the most favourable for females during the reproductive season. The quality of diets provided to females would largely influence breeding success in captive Greater rheas.

Keywords: Greater rheas, breeding success, diet preference

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