6 MASS. EXPERIMENT STATION BULLETIN 334 



Table 8. — Milk production (corrected to 4 percent fat) 



On Soybean- On Dried 

 Cottonseed Blood 



Ration Ration 



(Pounds) (Pounds) 



First 30-day period 10,914.8 10,682.8 



Second 30-day period 10,118.3 9,887.6 



Third 30-day period 9,208 . 8,526 . 1 



Fourth 30-day period 7,839 . 4 7,868 . 5 



Total production 38,080 . 5 36,965 . 



Average daily production per cow i 28.9 28.0 



JObtained by dividing the total by 1320, the number of cow days on each ration. 



Milk Production 



This is summarized in Table 8. The figures given have been corrected to a 

 uniform fat basis of 4 percent by the usual formula (.4M -f- 15F) in whichfM 

 equals actual milk production and F equals calculated fat production based 

 on the fat test of the milk and the actual milk production. Due to the fact that 

 the average fat test of both groups was quite close to 4 percent, the corrected 

 values do not differ greatly from the actual milk production. 



The results show an apparent moderate difference in milk production in 

 favor of the standard ration, but calculation of the probable error of this differ- 

 ence shows that it is not significant. The fact that the cows did not decline 

 significantly in milk production when approximately half of the protein in 

 their grain came from the dried blood is a fair indication that this material 

 may be substituted for a similar amount of protein from ordinary protein 

 concentrates with good results insofar as milk production is concerned. 



Composition of the Milk 



Composite milk samples were taken from each group of cows about midway 

 of each feeding period. The sampling period was three days in length and 

 samples from individual cows in a group were pooled to make a group sample. 

 Table 9 shows that there was no significant difference between the rations in 

 this respect. 



Table 9. — Composition of the milk (percentages) 



On Soybean- On Dried 



cottonseed Blood 



Ration Ration 



Total solids 12.48 12.40 



Fat 3.83 3.79 



Ash .721 .723 



