INFLUENCE OF THE PLANE OF NUTRITION UPON MILK 73 
It is clear special care must be taken in studying factors 
influencing the properties of butter fat that the results are 
not vitiated by this factor of under-nutrition. A survey of 
the literature of the subject makes it clear that certain in- 
vestigators have made this error and the results they attrib- 
uted in some cases to certain feeds are really the results of 
under-nutrition. 
Application to cases of abnormal butter.—Cases of 
abnormal butter are not infrequently reported in the agri- 
cultural and chemical literature, for which no adequate ex- 
planation can be offered. Most of these cases are reported 
by food officials whose duty it is to detect adulterated butter, 
and accordingly have to do largely with the Reichert-Meissl 
number of the butter fat. Such cases are much more fre- 
quently reported by officials in European countries than in 
the United States. It will not be possible to take up all 
of the cases that have been reported. Several typical ones 
have been selected, however, and the applications of the re- 
sults of the underfeeding studies pointed out in explanation 
of the abnormalities found. 
Van der Zande® has reported a feeding experiment in which 
a decrease in volatile acids occurred while the cows were on 
pasture. ‘The change in the composition of the butter fat was 
attributed by the author to a period cf severe weather during 
the experiment. In view of the experiments pointed out 
above showing the ease with which cows may be underfed 
while on pasture it seems evident that this factor was re- 
sponsible for the change in the composition of butter fat 
found by Van der Zande. 
Reinsch® has reported a sample of abnormal butter fat from 
five Holstein cows, which showed a Reichert-Meissl number of 
19.7 and a saponification value of 213.9. The cows were in good 
health, and had been in milk but a few months. Their ration 
consisted of pasture grass ad libitum with the addition of six 
*K. H. M. Van der Zande, Verslag. Ver. Exploit. Proef. Hoorn, pp. 45— 
50, 1902. 
9A. Reinsch, Ein Fall von sogenannter “anormaler’ Butter in Z. Nahr, 
Genussm., 8, pp. 505-508, 19.04. 
