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Heat Production and Gaseous Metabolism of Young Male Chickens

Eight Figures

Animal Nutrition Division, Bureau of Animal Industry, United States Department of Agriculture, National Agricultural Research Center, Beltsville, Maryland

Thirty-five experiments, each of 72 hours duration, were made in which energy and gaseous metabolism of male Rhode Island Red chickens between the ages of 4 and 133 days was measured. The conditions prevailing in the calorimeter during each experiment were: temperature, 90°F.; relative humidity, 60%; O₂ content, 21%; and CO₂ content, not exceeding 1%. The oxygen consumed during periods of 2 hours and the carbon dioxide and heat produced during periods of 8 hours were determined. In some of the experiments either casein or gelatin was fed during the twenty-third hour in order to study the thermogenic effect of these two proteins.

Data on basal metabolism, maximum resting metabolism, R.Q.'s, CO₂ and O₂ thermal quotients and equivalents, total water elimination, diurnal rhythm, and the thermogenic effects of casein and gelatin are given. Curves are presented that show the course of the diurnal rhythm of oxygen consumption in the domestic fowl, and how the amplitude of this diurnal rhythm changes with age.

It is concluded that:

1. The basal energy metabolism per gram of live weight, after 66 hours of fasting, is greatest in the male Rhode Island Red chicken when it is about 15 days old or when the weight is about 70 gm. Thereafter the basal energy metabolism decreases at a rapid rate until it becomes relatively constant at an age of about 100 days, or an average weight of about 980 gm.

2. In the very young chick the maximum resting metabolism after the ingestion of feed is about 60% greater than the basal metabolism, whereas between the ages of 16 and 20 weeks it is only about 25% greater.

3. The basal R.Q. is very nearly the same for all ages between 4 and 133 days; it is 0.719±0.004.

4. The total water elimination per gram of live weight was fairly constant at all ages studied. It was 2.8±0.1 mg. per hour per gram when the chickens were at the basal level and 3.1±0.1 mg. per hour per gram during the 8-hour period between 2 P.M. and 10 P.M. of the first day of the experiment.

5. The thermal equivalent of oxygen in the chicken is 4.653±0.031 kg.-calories per liter about 10 hours after the last ingestion of feed; and 4.377±0.039 kg.-calories per liter when the fasting metabolism is at the basal level.

6. The maximum energy metabolism occurs at about 8 A.M. and the minimum at about 8 P.M.

7. The amplitude of the diurnal rhythm of the energy metabolism is greatest in the very young chick and decreases rapidly with age.

8. In the chicken the SDA of casein is about 9.7 kg.-calories per gram of nitrogen and that of gelatin is about 8.7 kg.-calories per gram of nitrogen. The difference is statistically significant.

9. The SDA of casein and gelatin in the growing chicken is apparently not affected by age but the duration of the SDA is longer in the older chickens than it is in the younger ones, and longer for gelatin than it is for casein.

10. The SDA of casein and gelatin in the chicken is not so great as it is in man or the dog.