D. L. Cunningham

Dominance rank and cage density effects on performance traits, feeding activity and plasma corticosterone levels of laying hens (Gallus domesticus)

Abstract The effects of dominance rank and cage density on egg production rate, feeding activity, body weight gain, egg weight, shell strength and plasma corticosterone levels were determined for adult laying chickens in battery cages. White Leghorn layers were housed 5, 6 and 7 per cage, which provided 430, 358 and 307 cm 2 of floor area per bird (low-, moderate- and high-density cage environments, respectively). The chickens were maintained on a controlled lighting program of 8L:10D:2L:4D during the production cycle with the 8-h light segment beginning at 08.00 h. Dominance rank and cage density had significant effects on egg production rate and feeding activity. Moderate- and high-density treatments generally resulted in reduced egg production performances and feeding activities. Low dominance rank was associated with reduced egg production rates and feeding activities for the moderate- and high-density environments. However, the relationship of dominance rank with egg production and feeding activity varied with the density. Effects of dominance rank on body weight gain, egg weight, shell strength and plasma corticosterone level were not significant. Blood samples for corticosterone determination were obtained at 49 and 51 weeks of age from 06.00 to 07.00 h and from 19.00 to 20.00 h. Plasma corticosterone levels tended to increase with increasing density, but were not correlated with individual dominance status. Plasma corticosterone analysis failed to indicate a physiological stress response even though individual egg production rates demonstrated reduced well-being for low-ranking individuals. The results show that individual egg production rates may be used as an indicator of well-being for chickens in different cage environments.

Relationship between production factors and dominance in White Leghorn hens in a study on social rank and cage design

Abstract The effects of social rank and cage shape on feeding frequency, weight gain, production rate, egg size, shell strength and overt aggressive activity were determined for White Leghorn layers housed six per cage in deep and shallow cages. Social rank significantly affected feeding frequency, production rate, egg size, and aggressive activity for birds in both cage designs. Birds ranking high in the social order fed more frequently, had higher production rates, larger eggs and delivered more aggressive head pecks than birds low in the peck order. The effect for production rate was manifested only at the sixth bird level. Significant social rank effects on weight gain, final body weight and shell strength were not observed. Birds in shallow cages fed more frequently, gained more weight and were involved in more aggressive acts with cage mates than those in deep cages.

Behavioral effects of intraventricular dibutyryl cyclic AMP in domestic fowl

Intraventricular administration of dibutyryl cyclic AMP (dbcAMP) to domestic fowl induced behaviors within 60 seconds which persisted for 7-120 minutes. Stereotyped head movements and increases in preening were observed at the lowest dose (50 nmol), while at higher doses (150 and 225 nmol) head movements were interspersed with escape behavior, increases in locomotor activity, salivation and a loss of coordination. Administration also elicited vocalizations, mainly laying and type 1 warning calls. These calls contained many abnormal elements, possibly caused by relaxation of the syringeal musculature. The rate of calling was influenced by testosterone, being greater in hens and capons than in roosters or capons implanted with testosterone propionate. Caponization also intensified escape behavior. No behaviors were induced by administration of the hydrolysis product of dbcAMP, butyric acid. These behavioral effects of dbcAMP are similar to those reported to occur during electrical stimulation of loci in the avian brain.