ANNUAL REPORT, 1947-48 17 



from the College Farm; three from cooperating farmers. In addition to regular 

 fodder analysis, sugar and carotene were determined in all samples. The chemical 

 changes which take place in the hay from cutting tiine to feeding time (often 3 

 to 6 months) were followed closely for all lots of hay from the College Farm and 

 for one lot from a farmer cooperator. Factors studied were exposure to prolonged 

 sunlight; exposure to rain; field curing and storing as loose hay; field curing and 

 storing as baled hay; barn drying of loose hay; and barn drying of baled hay. 

 One feeding trial with two milking cows was conducted over a four-month period. 



Action of either bright sunlight or rain for two days reduced carotene content 

 of field-cured haj' at loading time to about a third of its initial value. Sunlight, 

 although it caused some lowering of the sugar content, had a much less adverse 

 effect on sugar than on carotene. 



Barn drying of either loose or baled hay may have possessed some initial ad- 

 vantage over field curing in conservation of carotene; but by the time the hay 

 had been in storage several weeks, this advantage had largely disappeared, owing 

 apparently to adverse storage conditions (high mow temperatures). This was 

 also true to a lesser extent for sugar. Sugar content of some lots of hay was 

 markedly reduced in storage, regardless of method of curing; this is thought to 

 be due to the fact that the hay was stored too wet and/or to trouble with blower 

 installations. 



The advantages of baling and barn drying may be entirely offset by attempting 

 to barn-dry either baled or loose hay at too high moisture levels. Tentatively 40 

 to 45 percent of moisture is suggested as the upper limit for safe storage over a 

 barn dryer. 



From the standpoint of carotene and sugar conservation, present methods of 

 curing and storing hay need further study. There is some evidence to show that 

 where a blower is operated efficiently, sugar is quite well conserved; but if farmers 

 are interested in saving as much carotene as possible, good silage seems to be the 

 answer in the present state of our knowledge. 



The feeding trial was conducted with hay in which the sugar content had been 

 greatly reduced (from around 6 percent to about 2 percent) by adverse curing 

 conditions. When this hay was supplemented with sufficient crude glucose 

 syrup to bring the total sugar intake back to normal, the cows produced 1.1 

 pounds more milk (4% — F.C.M.) daily than when the supplemental sugar was 

 withheld. Shrinkage in milk flow from month to month was 1.6 percent when 

 the syrup was fed and 7.8 percent when it was withheld. Whether this favorable 

 result was a specific effect of the added sugar, or whether it simply represented a 

 response to increased intake of total digestible nutrients is not known. Further 

 light on the question will be sought this coming season by using a larger number 

 of cows in a comparison of two kinds of hay, similar in character, except that 

 one will have normal sugar content, while the other will be designedly low in 

 sugar. 



DEPARTMENT OF BACTERIOLOGY 

 Leon A. Bradley in Charge 



Survival of Escherichia coll from Sewage in Soil of a Septic Tank Disposal 

 Field. (James E. Fuller.) This study was prompted by the failure to recover 

 Escherichia coli from the soil of the disposal fields of an experimental septic 

 tank installation (Mass. Expt. Sta. Bui. 441, p. 17, 1947). In the present project 

 pure cultures of E. coli are being inoculated into soils, both sterilized and non- 



