Nutritional and physiological studies on the regulation of egg white protein synthesis in the chicken

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1. Protein synthesis in individual tissues of laying hens was measured in vivo. It was found that fractional rates of protein synthesis in liver and oviduct were faster than those in any other tissues tested, and that the observed differences in fractional synthesis rates almost entirely accounted for by changes in RNA:protein ratios.2. Protein synthesis measured with DL-methionine was found to be underestimated by 4 to 36% in comparison with that measured with the L-isomer.3. A mathematical model for predicting the growth of replacement pullets was constructed with special reference to seasonal variations in food intake. It was found that d delay of 5 - 6 weeks with respect to environmental temperature would be necessary for the prediction of food intake.4. Protein synthesis in tissues and in the whole body of laying hens was measured during the egg formation cycie. Protein synthesis in the liver and in the whole body was not changed. Magnum protein synthesis was at its highest value when an ovum stayed there. In other tissues, on the other hand, protein synthesis was lowest when an ovum stayed in the magnum.5. Stgeroid hormone treatment enhanced the growth of oviduct in immature young chicks. The effect was more evident by the combined administration of estrogen and testosterone than by the administration of estrogen alone.6. Strain difference in the responsiveness of oviduct to steroid treatment was examined in three types of immature chicks. The highest response was found in egg-type chicks, followed by dual-purpose-, and meat-type birds in the decreasing order. Further studies sre necessary to clarify the relationship between genetic factors and responsiveness to steroid treatment.