MASSACHUSETTS ANIMAL INDUSTRY j^g 



Average Composition of tlie Milk 

 since Conunencement of the Mineral Experiment.* 



(Expressed as 'percentages of the liquid milk) 



"No Bone Meal" 

 Group. 

 12.67 

 4.16 

 8.51 

 0.725 

 0.117 

 0.098 



* These figures have been corrected for difi'erences in tlie relative number of Hol- 

 steins and Jerseys in each group, otherwise the much richer -Tersey millv might give the 

 figures a v/rong significance. In the case of total ash, calcium and phosphorus, they 

 have al.so been corrected for any influence that difference in stage of lactation of the 

 cows in the two uproups might have. It is well known that as a cow advances in lac- 

 tation her milk becomes richer. This correction has not been necessary for the total 

 solids and fat, as they liave lieni determined regularly every month for all cows. 



Effect on Reproduction 

 Recurrence of Heat. 



Regarding regularity, the records show the following: 

 Regularity 



Good 



Fair 



Poor 



The average length of time after calving before the first heat has been: 



"Bone Meal" group, 37 days 



'No Bone Meal"' group, 39 days 



The condensed data show that both groups were quite similar in their be- 

 havior in these respects. In fairness, however, it must be stated that as the 

 experiment has progressed, the cows that received the bone meal have tended 

 to come in heat sooner after calving, while the rever.se has been true of those 

 tliat did not receive bone meal. 



Difficulties in Getting Coics Bred. 



Considerable trouble has been experienced in getting the cows with calf, 

 some of them needing the attention of a veterinarian, and having to be served 

 four or five times before they would hold. Up until the past year or so the 

 trouble became somewhat more prevalent as the experiment progressed. Since 

 then, for some unaccountable reason, tiie cows have improved considerably in 

 this respect. The groups have been quite evenly divided with respect to it, 

 as the accompanying figures show. 



