Changes in plasma levels of prolactin and estradiol, nutrient intake, and time spent nesting during the incubation phase of broodiness in the Chabo hen (Japanese bantam).
The plasma concentrations of prolactin (PRL) and estradiol, time spent nesting, consumption of feed and water, body weight, and hematocrit were measured during egg laying, incubating, and brooding of the chicks in a Japanese strain of dwarf bantam hen, Chabo. Plasma levels of PRL increased before incubation, were maintained at high levels during incubation, and decreased rapidly at the onset of hatching the young. The concentration of estradiol decreased before incubation and was maintained at low levels when circulating levels of PRL were high. During incubation, hens spent greater than 95% of the day on the nest, reduced their daily intake of feed and water by 63 and 78%, respectively, and decreased their body weight by 19% by the end of incubation. Thus, Chabo hens show a mode of incubation behavior similar to that reported in larger chickens. The temporal changes between nutrient intake and plasma levels of PRL at the start and end of incubation behavior suggested that changes in nutrient intake may not cause changes in the concentration of PRL, whereas the association between increased levels of PRL and decreased levels of estradiol suggested that they may be causally associated. Plasma levels of PRL also appeared to be associated with time spent on the nest.
Zadworny
D
D
Department of Animal Physiology, Faculty of Agriculture, Nagoya University, Japan.
Shimada
K
K
Ishida
H
H
Sumi
C
C
Sato
K
K
D000818:Animals; D001835:Body Weight; D002645:Chickens / Q000097:blood / Q000502:physiology*; D004327:Drinking Behavior / Q000502:physiology; D004958:Estradiol / Q000097:blood*; D005247:Feeding Behavior / Q000502:physiology*; D005260:Female; D008297:Male; D009425:Nesting Behavior / Q000502:physiology*; D011388:Prolactin / Q000097:blood*
D004958:Estradiol; D011388:Prolactin