788 
Journal of Agricultural Research 
Vol. XXXI, No. 8 
In respect to the interval of time elapsing after calving before 
reappearance of oestrum, the average number of days throughout 
the course of the experiment has been : 
Days 
Mineral group_39. 5 
Nonmineral group_38. 6 
These data show that both groups were quite similar in their 
behavior in these respects; in fairness, however, it must be stated 
that as the experiment has progressed the mineral group of cows has 
tended to come in heat sooner after calving, while the reverse has been 
true of the nonmineral group. 
(2) Difficulties in getting cows bred. Considerable trouble has 
been experienced in getting the cows with calf, some of them having 
to be served'four or five times before they would hold. The trouble 
has become somewhat more prevalent as the experiment has pro¬ 
gressed, but has been quite evenly divided between the two groups, 
as shown by the accompany figures: 
Group 
Average number of times 
bred 
1922 
1923 
1924 
Mineral....___-___ 
1.60 
1.67 
2.25 
2.67 
2.50 
2.25 
Nonmineral___ 
(3) Other abnormalities. There have been three cases of abortion 
and one premature birth in the herd since the commeilcement of the 
experiment. Two of the abortions were in the mineral group; the 
other one and the premature birth were in the nonmineral group. 
Two of the abortions are known to have been traumatic, and the 
others probably can not be attributed to the effect of the experiment. 
There have been two cases of retained placenta, both in the non- 
mineral group; but one of them was in the case of a cow which had 
had the same trouble previous to commencement of the experiment. 
(4) Condition of the calves at birth and subsequently. All calves 
dropped during the course of the experiment have either been raised 
to maturity or kept a sufficiently long time to enable an accurate 
opinion to be formed as to their constitutional vigor. Table VI 
summarizes the records. 
Table VI .—Condition of calves 
Mineral: 
1922.. 
1923- 
1924- 
Total. 
Nonmineral: 
1922 . 
1923 . 
1924 _ 
Group 
Vigorous 
Good 
F^ir 
Delicate 
Died at 
birth 
Abor¬ 
tions 
Total 
