SEX DIFFERENCES IN FEED INTAKE, BEHAVIOR AND WEIGHT GAINED BY GREATER RHEAS (RHEA AMERICANA) IN CAPTIVITY DURING THE PRE-REPRODUCTIVE SEASON

Abstract

The use of common rhea, Rhea americana, as breeding bird requires knowledge of nutritional physiology. It is important the analysis jointly of feed intake, behavior and weight gain. Our objective was to determine and analyze differences in the feed intake, weight gained and behavior of captive subadults and adults male and female rheas during autumn and winter in the Humid Pampas, Argentina. Neither males nor females showed significant seasonal differences in the weights with which they initiated the trials. Daily feed consumption didn't show significant differences neither between seasons nor between sexes. However, we observed differences in weight gain by males between seasons and during the autumn trial, the weight gain was higher for males. Rhea behavior also varied seasonally. Males and females spent more time preening and resting than walking and feeding during autumn, the opposite occurred in winter. The males had a higher tendency towards walking than to feeding, the females showed the opposite in autumn. Analyzing the feed intake, weight gained and the time spent on feeding we hypothesized that males are more efficient for feeding. This analysis allowed us to observe there are nutritional issues that can be explained from a behavioral point of view.