6 
Bulletin 110 . 
In the analyses given in the table it will be noticed that the great¬ 
est difference in the percentage of protein is 1.27 per cent and this is 
in favor of the sample taken when in full bloom over the one cut in 
half bloom. We are justified in assuming that the preceding analyses 
are thoroughly representative of the composition of alfalfa hay cut 
at these different periods, and we will neglect any error introduced 
by assuming that the whole of the nitrogen is present as proteid 
and consequently all of equal value. In the analyses given it 
appears that the hay cut when the plants were in full bloom con¬ 
tains the largest percentage of proteids. We have so many analyses 
showing this to be the case in our samples, that we believe that it is 
true for alfalfa hay grown under the average conditions obtaining in 
Northern Colorado. The difference is seldom so great as that shown by 
the hay cut in half bloom and full bloom in the analyses given. In 
the samples given each 100 pounds of the thoroughly dried hays 
would contain 16 . 5 , 15 . 7 , and 16.8 pounds respectively according to 
which, if the proteids alone be the standard of value, the hay cut in 
full bloom is the best, but pound for pound they are as I have before 
stated almost equal. While this series of analyses gives these results 
others will show the earlier cut hays to have slightly the advantage. 
But chemical composition is not the only consideration to be taken 
into account. The weight of hay cut off of an acre at full bloom i§~ 
considerably more than the same acre would yield if cut in early or 
half bloom, probably from 10 to 15 per cent more. Regarding the 
degestibility of the hays made at the different stages of growth, using 
the proteids as our criterion) because we assume them to be the most 
valuable constituent, experiments show them to be very nearly alike, 
with a slight difference in favor of the hay cut at full bloom. 
We found the coefficient of digestion of the proteids in hay cut at 
the period of half bloom, by artificial digestion, to be 79.30 and 79.60 
and by animal digestion 73 . 7 , 73.6 and 70 . 4 . Artificial digestion seems 
to be fairly reliable though a little too high. The error, however, is 
likely to be in the same direction in the case of both samples, if so the 
hay cut at full bloom is slightly preferable. 
As soon as alfalfa passes the stage of full bloom there is a decided 
fall in the amount of proteids present, the same is true of the nitrogen 
free extract.. The loss of proteids amounts to about 2.5 per cent 
of the weight of the hay and the proteids are according to the results 
obtained by artificial digestion less digestible than at either early,, 
half or full bloom. 
Effects of Differences in the Seasons.—That there are differences 
in the hay from season to season, within comparatively narrow limits 
of course, due to the distribution of rainfall and variations in temper¬ 
ature, is a fact generally recognized. In speaking of this subject in 
Bui. No. 39 I conclude from a series of samples taken over a period of 
three years and representing hay grown on four different soils, that, 
the composition of the first cutting is practically constant while that 
of the second and third cuttings is much less so, and in the latter we } 
probably find the maximum variation that can reasonably be attribu- 
