268 Basal Metabolism of Swine 



As the observed curve is nearly a straight line below about 16" it 

 has been continued backwards in a straight line to 0°, the dotted line 

 being the part of the curve obtained by extrapolation. The values of 

 the metabolism in Table III are taken from this extended curve. 



It may be presumed that in so far as the extrapolated values are in 

 error, the error is on the side of their being too low since the observed 

 part of the cui-ve is concave upwards. The}' will however provide a 

 sufficient approximation for our present purpose. 



It will be seen that the maintenance ration at 0° is more than 

 double that at 22°, and both these temperatures are not unfrequontly 

 met with on farms in this countiy. 



Conclusions. 



The critical temperature of the hog under experiment was approxi- 

 mately 21" C. 



At this temperature his basal metabolism was a minimum and 

 amounted to 2,160 calories in 24 hours when he was 420 days old and 

 weighed 300 lbs. This corresponds to 904 calories per day per square 

 metre of body surface. 



As the temperature of his surrounding.s fell below 21° C, the basal 

 metabolism increased at the rate of about 4 per cent, per degree Centi- 

 grade, which corresponds to an increase of about 40 per cent, for a 

 temperature difference of 10°C. which is commonly found between 

 summer and winter conditions. 



Thus, if the same law holds in the case of a steer whose basal meta- 

 bolism at 18° C. or summer temperature is 6,000 calories, his basal 

 metabolism at 8° C. in an open yaid in winter would be 9,000 calories. 



The suggestion is that the increase of 3,000 cahjries is met b}' the 

 utilisation of the thermic energy of the coarse fodder included in his 

 ration. 



{Received June 2^th, 1922.) 



