FEAR-RELATED BEHAVIOR IN JAPANESE-QUAIL DIVERGENTLY SELECTED FOR BODY-WEIGHT

The damaging effects of fear on a number of performance indicators in poultry and other farm animals are becoming increasingly recognised. M ore specifically, there is growing evidence for a negative association between growth and fearfulness (an underlying behavioural characteris tic). The present study examined this putative relationship in Japanes e quail from two genetic fines that had been selected over several gen erations for low (LBW) or high (HBW) body weight at 4 weeks of age and in those of a non-selected control (CON) line. HEW quail were substan tially heavier than LEW ones at 31 days of age (197 and 34 g, respecti vely), with CON birds occupying an intermediate (104 g) position. Bird s were observed individually and once only between 26 and 32 days of a ge in one of three putative tests of fear. Quail of the LEW line showe d greater avoidance of a conspicuous novel object placed near the home cage and longer tonic immobility fear reactions, and they vocalized a nd struggled later and less often during brief mechanical restraint th an did the HEW quail. Quail of the control line generally showed inter mediate responses. Plasma corticosterone concentrations following mech anical restraint were greater in LEW quail than in CON or HEW ones. Co nsideration of the intra-individual correlations between behavioural a nd adrenocortical responses to restraint suggested that the nature of the relationship was labile and that it was sensitive to the backgroun d genome. Collectively, the present findings demonstrated that underly ing fearfulness was greater in quail that had been genetically selecte d for low rather than high body Height. The present results thereby su pport the hypothesis that fearfulness and growth are negatively associ ated. (C) 1997 Elsevier Science B.V.