An investigation of the metabolism of a number of Light Sussex cockerels has shown that there exists a rhythm in the metabolism during fasting amounting to about 9% as between morning and night observations, the former being the higher by the percentage stated.Two methods were adopted to exclude the effect of variation in the activity of the birds at different times of day. In the first, the birds were artificially stimulated during the normal period of repose in such manner as to give periods of approximately equal activity by day and by night. In the second, the movements of the birds were recorded by a system of “point scores”, and regression equations were deduced from a large number of such experiments so as to make it possible to reduce the metabolism observations to a basis of zero activity.The results obtained by these two methods of procedure were in good agreement with one another.The metabolism in the standing position is 40–45% above that in the sitting position, a figure considerably above that for the increase of metabolism as between the lying and standing positions usually found in quadrupeds, while at the moment of rising the heat output may occasionally be trebled, but averages about cent per cent above sitting. The former of these observations is of importance in estimating food requirements as our experiments show that generally speaking rather more than 12 out of each 24 hr. period is spent standing when the birds are kept in cages. It follows that the sitting metabolism must be increased to allow for this when the figure is being used for computation of rations. The large heat increase on rising to the standing posture is of such short duration as to exert little influence on the mean metabolism over a 24 hr. period.
The metabolism of a Berkshire and a Middle White pig has been investigated by means of the calorimeters at the School of Agriculture, Cambridge. The general routine and technique of the observations have been as heretofore.Measurements of the fasting katabolism of each of the two pigs have been obtained in a series extending from an early age to maturity, and the phenomena in general follow the lines of those originally discovered in the Large White; but the fasting katabolism of the Middle White was below that of the Large White earlier studied.The fall in body temperature and in metabolism during the fasts were found to be correlated, and the possible effect of skin colour in this matter is noted.The effect of environmental temperature is investigated and reasons are given for supposing that the critical temperature of the Middle White pig is very low.It is concluded that the existence of a maximum somewhere in the curve showing fasting katabolism per unit area at different ages is necessitated by the two physiological facts (a) that warm blooded animals have to be maintained at a temperature which varies only within very narrow limits, and (b) that the processes of growth are accompanied by waste of energy as heat.
The following paper is the first of a projected series on the results of work which has been in progress in the Animal Calorimetry Department of this Institute during the past five years. Subsequent papers will deal with body temperature variations, effects of environmental temperature, metabolism, energy expenditure, etc.
With Plates I and II and Three Text-figures.) INTRODUCTORY.THE present paper is the outcome of the discovery recently made, in attempting to work up data acquired on the metabolism of pigs by calorimetric methods, that the various formulae which have been proposed for the computation of the surface area of these animals lead to extraordinarily divergent results.This divergence is of such magnitude as to render any results which depend upon a surface area so computed of little absolute, though possibly of comparative, value. The divergence becomes on the whole greater the greater the weight of the animal in question, and there are individual differences and probably breed differences in this respect.The following example illustrates the sort of divergence which may be expected, and is normally found, in a pig of about 2001b. weight. The pig and the observation have been selected from a considerable number, in many of which greater divergencies were shown. It is felt that the publication of the full data available on this point would seriously disturb the balance of a paper already somewhat overweighted with tabular matter without affording information of commensurate usefulness :Essex Pig G. Age 348 days. Weight, fed 203f lb., fasted 183$ lb. Mean length from point of withers to root of tail 30| in.The surface area comes out as follows: By the two-thirds power formula of Meeh(i), using the constant proposed by Voit(2), viz. S dm.* = 9 " 02 v'PPlg.1-839 m. 2 fed; 1-772 m. 2 fasted.By the same formula but using the constant proposed a year later by Rubner(3) viz. = 8 ' 7 ^^t e i ' 7 7 3 m -2 fed > 1>662 m-2 f a s t e d -
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