(1) The kinds of audience investigated included the mate, unfamiliar females, other females and males with which subjects had had prior visual and auditory contact, and broody hens with and without young.
(2) Plasma concentrations of prolactin and corticosterone were determined in hourly samples collected over a 25-hr period from unrestrained turkey hens exhibiting incubation (broody) behavior.
(3) Under resting conditions thoracic skin temperature (Tths) and metabolic heat production (M) were significantly higher in broody than in non-broody hens, indicating a permanently increased conductance of the brood patch.
(4) The relation between metabolic rate and total peripheral resistance indicated more intense vasodilation for broody hens at the relatively low metabolic rates during moderate cooling, and more intense vasoconstriction for the broody hens at the high metabolic rates during stronger cooling.
(5) Body temperatures, metabolic rate, haemostatic parameters, and cardiovascular reactions to thoracic skin cooling were compared between incubating (broody) and non-broody Bantam hens.
(6) In broody hens, these coolings induced a large, immediate increase in M, no constriction of brood patch vasculature, and a decrease in colonic temperature (Tc).
(7) A higher thoracic skin temperature (Tths) for broody hens compared to non-broody hens suggests that brood patches are the probable site of this increased flow through arteriovenous anastomoses (AVAs).
(8) This treatment did not reduce broody behavior or have any beneficial effect on egg production.
(9) Under resting conditions, without thoracic skin cooling, cardiac output of broody hens was twice that of non-broody hens.
(10) Improved egg production was achieved both through an increase in the rate of egg production and through a reduction in broodiness.
(11) Hens also produced more (P less than .05) eggs when maintained under cyclic temperature conditions, although this observation was tempered by the fact that fewer hens were broody.
(12) Genetic changes in average clutch length, total days lost from broodiness, fertility, and response to cold stress did not have a major influence on semen production in the turkey.
(13) In addition, egg quality, broodiness, floor egg production, and poult weight data were obtained in Experiment 2.
(14) During moderate cooling, vasoconstriction in the feet and wattles of broody hens (but not of non-broody hens) freed non-nutrient blood flow for redistribution to the brood patches.
(15) Synthesis and release rates of prolactin and growth hormone (GH) in the anterior pituitary of laying and incubating broody chickens (Nagoya breed) were determined by a disc electrophoretic technique after in vitro incubation of anterior pituitaries with a labeled amino acid.
(16) In these hens, broodiness was disrupted on day 6 and feeding activity subsequently increased to levels of photorefractory hens.
(17) The RBC1 turkeys had linear increases in the percentage of broody hens during the first 84 and 180 days of production, the average length of the broody period, and the total number of days lost to broodiness during the 180-day period.
(18) When expressed as a deviation from RBC1, positive quadratic curvilinear changes were observed for E turkeys for number of clutches and broody periods, and days lost to broodiness during the first 180 days of production.
(19) Thoracic skin cooling from 35 to 25 degrees C decreased Tths less in broody than in non-broody hens.
(20) An assessment was made of the possible role of hypothalamic 5-hydroxytryptamine (5-HT) in the regulation of prolactin secretion in broody bantam hens.