272 MASS. EXPERIMENT STATION BULLETIN 271 



of natural skim milk or diluted skim milk powder until four months old. 

 It is believed that very young calves should be given a vigorous start by 

 feeding some form of milk as a part of the ration until they are at least 

 four months of age. (See Bulletin 253 of this Station). They should not 

 be converted into cud chewers too early. 



Mineral Requirements for the Growth of Dairy Heifers. (J. B. Lindsey 

 and J. G. Archibald). A study of the calcium requirements has been 

 completed, using eight high-grade Holstein heifers. They were divided 

 into two groups; one was fed a ration high in calcium while the ration 

 for the other group was low in calcium. The average age of the heifers 

 was 140 days at the beginning and 858 days at the end of the experiment, 

 or time of calving. The ration for the high-calcium group consisted large- 

 ly of alfalfa hay, together with dried beet pulp and a grain ration made up 

 mostly of corn meal; for the low-calcium group hay of mixed grasses 

 (with 30 per cent alfalfa during the first period), dried apple pomace, 

 and corn and linseed meals. Seventy-six satisfactoi'y metabolism balance 

 trials were completed. The detailed data and discussion of results have 

 been prepared for publication and sent to the Journal of Agricultural Re- 

 search. 



The results, as a whole, point to accumulation of a considerable reserve 

 of all elements by the high-calcium group during the first year and a 

 lowering of retention later on. The low-calcium group, on the other hand, 

 not having accumulated such a large reserve in the earlier stages, must 

 have felt the need of more calcium and made the effort to utilize it to a 

 greater degree in the third year. 



BALAXCE RECORD OF RETENTION FOR EACH GROVP DURING THE ENTIRE EXPERIMENT 



Daily retention per Retention percentage 



The establishment of approximately a 2 to 1 ratio between the amounts 

 of calcium and phosphorus retained, irrespective of the ratio in the intake, 

 was very uniform in both groups and at all ages. 



The records of weight and height at withers did not show that one group 

 made any better growth than the other, in spite of the larger assimilation 

 of the elements by the high-calcium group. On the basis of the results 

 secured, it would seem to be a reasonable conclusion that heifers can make 

 satisfactory growth on rations supplying approximately 4.5 grams of cal- 

 cium daily during the first year of life, 3 grams daily during the second 

 year, and 2.5 grams daily during the third year, for each 100 pounds of 

 live weight. A good quality of Iiay with 30 per cent of legume hay or 

 rowen during the first year will supply these amounts, while legume hay 

 for roughage will be necessary to supply such amounts as were retained 

 by the high-calcium group. 



