June, 1940] AGRICULTURAL RESEARCH IN N. H. 25 



months. After seventy days, the basal metabolism of the darkened 

 cows remained essentially the same (increase 2 per cent), whereas 

 the animals with extra light showed an increase of about 10 per cent 

 in basal heat production. While the data so far suggest an increase 

 in metal:)olism as an effect of longer exposure to light, the results 

 can be regarded as only tentative, and it seems advisable that a se- 

 ries l)e carried out in which the extra lighting is applied as early as 

 October. 



A number of gas check tests have been carried t)ut with the mask 

 and apparatus designed to measure the energy expended by the horse 

 during work. The check tests with carbon dioxide gas show a re- 

 covery of 99.2 per cent. Twelve actual experiments in which this 

 mask and apparatus were used on a draft type horse (gelding) 

 weighing 650 kgs. have so far been carried out. First trials were 

 made with the horse quietly standing, and these were checked with 

 a metabolism measurement made under similar conditions in the res- 

 piration chamber. The results checked closely. 



A sequence of trials was carried out on a flat-surfaced road. The 

 results given as calories of energy expended per hour are shown in 

 the following table : 



Calories Calories Calories 



816.0 804.0 



2322.0 2717.0 1967.0 



3540.0 3841.0 3882.0 

 5565.0 4620.0 



This is. so far as we know, the first time on record in which the 

 energy expended by the horse at a gait faster than a walk has been 

 measured. The gratifying feature of these attempts is primarily the 

 fact that this mask and the technique involved have been demon- 

 strated to be dependable, thus opening an entirely untouched phase 

 in the study of energetics. 



A series of monthly experiments was carried out during the year 

 on five Chester White pigs to determine the basal metabolism during 

 growth. This work is being continued. (Purnell and Adams Funds 

 and Carnegie Institute of Washinqton. D. C .) 



Sheep Breeding 



While it is evident as has been previously shown^ that exceptional 

 lecundit}' as represented l^y constant twinning in sheep is a trait of 

 exceptional individuals and of a hereditary character, the effort to 

 develop this trait in the flock as a whole has presented some very 

 perplexing problems which still remain unanswered. One of these is 

 the fact that under apparently identical conditions of feeding and 

 general management some ewes are very irregular in twin produc- 

 tion from year to year. 



A lieginning was made this past year to determine whether chang- 

 es in nutritional condition as represented by factors other than suf- 



'N. H. Technical Bulletin No. 47, 1931. 



