J. A. Cherry

Eating, drinking and temperature response of chicks to brain catecholamine injections

Abstract The effects of dopamine, norepinephrine and epinephrine on feed intake, water intake, water consumption and rectal body temperature (T R ) were investigated using broiler cockerels. Chicks were maintained in a thermoneutral environment with feed and water available ad lib. Solutions of dopamine, l-norepinephrine and l-epinephrine were prepared in concentrations of 33, 67 and 100 μg/10 μl in artificial cerebrospinal fluid and injected into the lateral ventricles. Dopamine and norepinephrine caused no effect on feed consumption while epinephrine caused a significant increase. Although norepinephrine had no effect on feed intake, it did precipitate a narcoleptic response which may have masked a stimulation of feed intake. Epinephrine and norepinephrine significantly decreased T R while dopamine had no effect. Water consumption was not affected by any of the catecholamines. These results suggest that epinephrine and possibly norepinephrine are involved in neural control of feed intake, but not water consumption in chickens.

Genetic selection for growth rate alters hypothalamic satiety mechanisms in chickens

The relationship between genetic and hypothalamic obesity was investigated by comparing the response to electrolytic lesioning of the ventromedial hypothalamus in chickens from lines developed through divergent selection for high and low body weight. The high-weight line exhibits obesity, while the low-weight line is relatively lean. Lesioned adult chickens from the low-weight line exhibited the expected obesity syndrome, while lesioned high-weight-line chickens exhibited neither increased feed consumption nor increased body weight. The results suggested that artificial selection for increased body weight resulted in a diminution of hypothalamic satiety mechanisms.

Age, body weight and body composition requirements for the onset of sexual maturity of dwarf and normal chickens

Comparisons of age, food intake, body weight and body composition at the onset of sexual maturity were made between dwarf and normal chickens from lines selected for high or low juvenile body weight. At the same age birds which had started to lay were significantly heavier and contained significantly more abdominal and carcass fat than those which were not laying. Differences between normal and dwarf pullets within lines varied with genetic background, indicating differences between lines in meeting a body weight or a body composition requirement, or both, for the onset of sexual maturity.

Quantitative analysis of the feeding behavior of four populations of chickens.

Abstract Comparisons were made among male chickens from four populations for traits associated with feeding behavior during the period from 21 to 71 days of age. The populations were obtained from two lines of chickens, divergently selected for juvenile body weight, into which the sex-linked gene for dwarfism was introduced. Differences among populations in body weight paralleled those for feed consumption, which appeared to be related to meal number rather than meal size. Males from the high-weight line, while spending significantly less time in feeding activity, consumed more feed than those from the low-weight line. Normal chicks exhibited a more pronounced periodicity in feeding rhythms than did the dwarf chicks. Positive correlations of meal size with premeal and with postmeal intervals support the hypothesis that both meal activation and termination mechanisms contribute to appetite control. Differences in the cross-correlation function of meal size with meal intervals between normal and dwarf birds suggested that meal termination mechanisms were of greater importance to appetite control in normal than in dwarf chickens.

Anorexia and sexual maturity in female white rock chickens. I. Increasing the feed intake

Long-term selection for low juvenile body weight has resulted in a line of chickens where sexual maturity is retarded or prevented because of anorexia.Ad libitum-fed pullets which had not commenced egg production by 240 days of age were randomly assigned to be force-fed or fedad libitum. Increasing food intake via force-feeding caused a significantly greater proportion of females to commence egg production than was noted forad libitum-fed controls. Moreover, of those pullets that commenced lay, age at onset was significantly earlier in those force-fed than in those fedad libitum.

Genetic analyses of gustation in the fowl

Preferences towards quinine sulfate (QS) and dextrose (DEX) were tested in purelines and reciprocal crosses of two lines of chickens that had undergone 22 generations of selection for high and low juvenile body weight. Parental line-F1 comparisons provided evidence for non-additive genetic variation for hedonic sensitivity towards QS and DEX, though in opposite directions. Additive genetic variation appeared to influence the preference ratios for both stimuli at super-threshold concentrations. These results are discussed with regard to their evolutionary implications.

Lipocyte hyperplasia and sexual maturation of Japanese quail (Coturnix coturnix japonica)

1. Hyperplastic growth of adipose tissue in Japanese quail (Coturnix coturnix japonica) was examined in relation to sexual maturity to determine whether fat cell number is fixed in mature individuals of this species. 2. Total DNA concentrations in the lipid (lipocyte) and non-lipid (stroma) fractions of collagenase (EC 3.4.24.3)-digested abdominal (retroperitoneal) fat depots were determined on a chronological-age basis from 28 to 240 d of age. The in vivo incorporation of [methyl-3H]thymidine into DNA of both the lipocyte and stroma fractions of abdominal fat from both ad lib. and restricted-fed (75% of ad lib.) females was also examined at ages before and subsequent to sexual maturity. 3. In both males and females, significant increases in abdominal fat weights at ages beyond sexual maturity were associated with increased lipocyte DNA. Regardless of the feeding regimen and stage of maturity, substantial radioactivity was recovered from both the stromal and lipocyte fractions of abdominal fat when female quail were examined 24 h after the administration of tritiated thymidine. When examined 5 d post-injection, the majority of the radioactivity was contained in the lipid fraction of collagenase-digested adipose tissue. 4. Both the total DNA content of adipose tissue and the incorporation of tritiated thymidine into adipose tissue indicated that lipocyte hyperplasia contributes to postmaturational increases in fat deposition.