C. f*ROWTHER AND H. E. WoODMAN 



53 



ration was then ample for the extra requirements of milk production 

 was evidenced by the consistent positive nitrogen- balances recorded. 

 Towards the end of the trial, when the daily yield of milk had fallen 

 below 20 lb. (containing about 48 gm. N) the amount of cake fed daily 

 was reduced to 5 lb. This resulted in the estabUshment of a decided 

 negative nitrogen-balance. 



Summary of nitrogen-balaii 

 Daily ration; 21-5 lb. seeds 



Table VI. 

 ces for Cow D during period of lactation. 



hay + linseed cake* (for amounts see Table). 



* 1 lb. cake contained 400 gm. dry matter and 21 gra. nitrogen (approx. average for 

 whole lactation period). 



t Amount of cake reduced to 9 lb. on day 068. 



t See note ([!) Table IV. 



§ Including N of calf and placenta (estimated at minimum of 1050 gm.). 



During this period of about 90 analytical days in the lactation period, 

 Cow D actually retained about 537 gm. of nitrogen and only lost 18 lb. 

 body-weight. For the whole trial of 546 experimental days, it will be 

 seen that this cow consumed about 96,000 gm. nitrogen and of this 

 retained 1040 gm. {i.e. slightly over 1 per cent.), this being roughly the 

 amount of nitrogen absorbed in foetal development and lost from the 

 body at parturition. 



It was originally intended to continue the experiment through the 

 whole period of lactation, but circumstances rendered this impracticable. 



It is of interest to compare in the case of Cow D for the peiiod sub- 

 sequent to calving (Tables V, VI) the consumption of nitrogen over and 

 above "equihbrium requirements" with the amount of nitrogen secreted 

 in the milk. For this purpose we may take the "equilibrium require- 



