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The effect of arginine and glycine supplementation on reducing body protein losses and on enhancing wound healing after trauma was studied in two age groups. Mature (4 month) and aged (24 month) Fischer 344 male rats were fed a diet containing 25% casein and 0.4% methionine with or without supplementation with 2.4% arginine . HCl and 1.0% glycine for 7 days before and after laparotomy. Nitrogen (N) balance studies (N intake - urinary N) were carried out during the last three pretrauma days and seven posttrauma days. The supplemented rats retained significantly more N than the controls and the mature rats significantly more than the aged rats. Polyvinyl alcohol sponges, implanted during surgery and removed from the rats on day 3 or 7 after surgery, were analyzed for hydroxyproline content and for the ratios of type III/type I collagen synthesized. Sponges obtained from the supplemented and the mature rats had more hydroxyproline and higher ratios of type III/type I collagen than those from the control and the aged rats. The beneficial effect of arginine and glycine supplementation on improving N retention in traumatized rats appears to be due, at least in part, to increased collagen synthesis in wounds.

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The energetic costs of egg production are considered, as is the relationship between egg production and feed intake. Hens feed during the photophase with a peak in consumption prior to the scotophase. This pattern of intake, followed by nocturnal fast, would be expected to lead to an energy deficit at night. However, much of the energy requirement of the night is met by utilization of feed stored in the upper gastrointestinal tract. It is presumed that some nocturnal energy deficit occurs and is met by changes in metabolism and endocrine balance. The hormonal involvement in these changes in avian metabolism is discussed.

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Two groups of Single Comb White Leghorn pullets, 4 months of age, were fed 1·85 and 2·70% calcium in the diet, respectively, for twelve consecutive periods, each consisting of 4 weeks.Records of egg production and egg weight were kept throughout the entire experiment for each hen. Calcium balance and egg-shell quality studies were conducted with 16 pullets for 5 consecutive days out of each 28-day period.A highly significant difference between the lots favouring the high-calcium birds was found in egg production, shell weight, and calcium retention. There were no significant differences between the lots in percentage calcium retention, food consumption, and body weight. The high-calcium group was shown to retain more calcium from the feed and excrete more calcium through eggs. Calcium retention and percentage calcium retention increased upon commencement of egg production to reach a maximum at the second period of production. Both remained fairly constant thereafter.The hens went into negative balance early in production and returned to positive balance during the later part of the first laying year. The return to positive balance could be explained by an increase in calcium retention and a decrease in egg production. There was no reduction in shell weight, or shell weight per unit surface area during the period covered by this trial.