The effect of dietary energy and protein levels on production in breeding female ostriches

Abstract

1. In a study spanning two breeding seasons, we assessed the effect of different dietary energy and protein levels on body mass, body condition, and egg production of female ostriches. 2. During the first breeding season, groups were given diets with energy concentrations of 8·5, 9·5 and 10·5 MJ/kg dry mass (DM) metabolisable energy (ME) and protein concentrations of 135, 150 and 165 g/kg. In the second breeding season, groups were given diets with ME of 7·5, 8·5 and 9·5 MJ/kg and protein contents of 105, 120 and 135 g/kg. 3. Body mass of birds on diets of 7·5 and 8·5 MJ/kg ME decreased significantly in the course of the breeding season compared with birds fed on diets with higher energy contents and body measurements decreased, suggesting a loss of body condition. 4. Females fed on diets containing only 7·5 MJ/kg ME produced significantly fewer eggs at significantly longer intervals, resulting in fewer chicks hatched. 5. There was no significant difference in egg mass, initial chick mass, chick survival to one month of age and body mass of chicks at one month. 6. Dietary protein concentrations had no effect on egg production, egg mass, hatchability, initial chick mass, chick survival or chick mass at one month old. 7. The female ostriches regained their original body mass during the 4-month rest period between breeding seasons, but significant differences in some parameters during the second breeding season suggest that they may not have fully recovered their body condition. 8. A dietary energy content of 7·5 MJ/kg proved to have an adverse effect on egg production by breeding female ostriches, and it may be concluded from this study that a diet containing 8·5 MJ ME/kg DM and 105 g/kg protein should be regarded as the minimum that can be used for breeding female ostriches without compromising egg production.