The influence of separate-sex rearing on ostrich behaviour and skin damage

Abstract

Separate-sex rearing of slaughter ostriches was investigated as a management strategy to minimize skin damage. Day-old ostrich chicks were divided into three treatment groups; a group of mixed-gender and two single-sex groups, one male and one female. At three months of age, because of the large variation in live weights, the birds were sorted within treatment according to weight. Each gender treatment was represented by six replications and each weight class treatment was represented by nine replications. At slaughter, chest circumference, slaughter weight, carcass weight, skin weight, skin area and skin grading were recorded. The only slaughter trait that was affected by gender treatment was skin weight without fat, with all-male groups having significantly heavier skins than all-female groups. Behavioural observations, carried out at nine and 13 months of age, indicated that aggression was more prevalent in all-male groups compared to all-female and mixed-gender groups. The all-female groups had the lowest levels of aggression. Diurnal time-activity budgets were largely unaffected by the gender composition of the groups. Evaluation of the skins at slaughter showed that kick marks on the area outside of the crown were more prevalent in all-male groups, indicating that increased aggression was associated with increased kicking behaviour which led to skin damage. However, because of the location of the kick marks, skin grading was not influenced. Weight class treatment also affected the prevalence of kick marks. Aggression and kick marks on the skin were generally more pronounced in the groups comprising the heavier chicks, suggesting that body weight may have an important effect on hormone levels and aggressive behaviour. Because of the general lack of improvement in the skin grading of the ostriches due to the increased skin damage in all-male groups when separated, it is concluded that the practice of separate-sex rearing has no definite benefits for slaughter ostrich production and product quality.


Keywords: Separate-sex rearing, Ostrich behaviour, Gender, Skin damage, Aggression


South African Journal of Animal Science Vol.33(2) 2003: 95-104