18 MASS. EXPERIMENT STATION BULLETIN 388 



Consequently the comparative value of the treatments for controlling damping-off 

 could not be determined. 



The treatments all gave some control of weeds. There were wide differences, 

 however, in the different treatments and also in different replications of the same 

 treatment, except in the case of steaming, which gave consistently good control 

 in all replications of either the fall or the spring treatments. Some replications 

 of the treatments with calcium cyanam.id, chlorpicrin, and double-strength formal- 

 dehyde solution applied in the fall gave fairly good control of weeds; but these 

 were largely offset by unsatisfactory control in other replications of the same 

 treatments. Steaming was the only treatment that gave entirely satisfactory 

 control of weeds. 



The experiment is being repeated. 



DEPARTMENT OF ANIMAL HUSBANDRY 



Victor A. Rice in Charge 



A Study of the Mineral Elements of Cow's Milk. (J. G. Archibald and C. H " 

 Parsons.) During the winter of 1940-41 the possibilit\- of increasing the man- 

 ganese content of milk by feeding supplemental manganese was investiga.ted. 

 Eight cows in the college herd were divided into two groups of four each, and fed 

 manganous sulfate (1 ounce daily) by the double reversal system. Monthly 

 sampling and analyses of the milk of the individual cows from November through 

 April, showed that, regardless of group or individual, the feeding of the manganese 

 supplement definitely increased the manganese content of the milk. On the 

 average the amount of manganese in the milk of cows receiving the supplement 

 was just about double that in the milk from cows not receiving it. (46.1 gammas 

 of Mn per liter of milk as contrasted with 23.5 gammas per liter). Advance 

 announcement of this finding has been published in Milk Plant Monthly, Vol. 

 30, No. 9, September, 1941. 



Investigation of the Merits of Legume and Grass Silage for Massachusetts 

 Agriculture. (J. G. Archibald and C. H. Parsons.) As a result of comparative 

 trials extending over three years with molasses and phosphoric acid as silage 

 preservatives, this station has discontinued the use of phosphoric acid as a pre- 

 servative. The reasons for this are: 



1. Molasses silage has been definitely more palatable to milking cows than 

 phosphoric acid silage. 



2. Molasses costs somewhat less, even when the much smaller amount of 

 phosphoric acid required is taken into consideration. 



Work this past year with grass silage has centered chiefly around its effect on 

 milk flavor in contrast with the effect of corn silage. Part of the herd was fed 

 grass silage and another part corn silage, and the schedule was reversed at mid- 

 season. Individual milk samples from all cows milking at the time have been 

 taken for a period of three days in each month from November through April 

 and judged for flavor. There are some discrepancies among the results, and the 

 differences are not very marked, but in general the grass silage has produced milk 

 with a higher flavor score and with less incidence and persistence of the common 

 off-flavors. Individual off-flavors most reduced when grass silage was fed were 

 malt, bitter, rancid, and oxidized in the order named. 



A Study of Urea as a Partial Substitute for Protein in the Rations of Dairy 

 Cows. (J. G. Archibald.) This project has been actively conducted throughout 

 the year. Results are available from two years of double reversal trials with eight 



