BRIEF SUMMARY AND CRITIQUE
ON
GENETIC CONTROL OF FOOD INTAKE IN CHICKENS

Feed consumption of chickens was poorly understood compared to other mammalian species. In previous studies, both factors of environment and genetic were found to influence the chickens' growth, yet 80-90 percent of the growth improvement were due to the genetic influence.

The major focuses of this article were:

• searching for the linkage between food intake and genetic aspects,
• exploring how genetic control affects the food intake.

To achieve the first idea, the author established four different populations -- 14L, 14H, 42L, and 42H, which can be distinguished by their growth rate, body weight, or carcass composition. The author also observed the food intake of these chickens and found that the genetic architecture of feed intake was positively proportional to body weight, except for the first few days post-hatch.

To approach the second idea, the author tried to analyze the genetic influence on the neurochemicals. By means of the heterosis as an indicator, six catecholamine-related compounds of the chickens were examined and the genetic background influence to the neurochemical disposition were found. Besides, by taking advantage of pharmacological agents, which can specifically lesion certain brain area or alter the function of specific neurochemical system, the author demonstrated that the MSG significantly influenced the growth by increasing 51% of fat pad size and by decreasing 7% of breast weight. From the observation of the experiments, since the MSG treatment was found to deplete the dopamine from the hypothalamus when chickens were forty-two days old, it was suggested that the depletion of catecholamine were involved in the development of obesity of chickens. Moreover, the aspartate changes resulted from the MSG treatment also provided another evidence that the genetic factors did influence the nervous system, which controls the food intake.

The overall structure of this paper is well-organized and its presentation is very good. The author outlined the major ideas proposed and reviewed some of their approaches. Because they didn't try to explain the technique in a detailed way, it makes this paper highly readable, but to implement their methods according to what this paper presented seems to be difficult. The authors demonstrated a lot of experimental results in which a variety of parameters were considered; therefore, their effective approaches are attractive.

The principal idea had been proposed in the author's other previous papers, and some techniques they used were previously well-developed and popularly used by other researches. So, the major contribution of this paper should be the author collected the related experimental results and took advantage of them as a genetic model to study chickens' food intake.

(Source: American Institute of Nutrition, 1994)
(Author: G. F. Barbato)
(Summary by: Chia-Yu Hsu)