24 MASS. EXPERIMENT STATION BULLETIN 355 



A bulletin dealing with all phases of the subject of legume and grass silage will 

 be available for distribution before silo-filling time next June. 



The Value of Dried Citrus Pulp for Dairy Cows. (J. G. Archibald.) The dev- 

 elopment of the canned citrus fruit and citrus juice industry in the United States 

 during the past few years has resulted in the production of a new by-product feed 

 known as dried citrus pulp. This material consists of the dried and processed 

 cannery residues, chiefly rinds, seeds, and "rag" (the technical name for the white 

 network inside the rind and between the sections of the fruit), together with such 

 cull whole fruit as is unmarketable or unsuitable for human food. Depending on 

 its point of origin, it may come chiefly or entirely from oranges or grapefruit, or 

 may be a mixture of both. 



Although both the unprocessed "green" pulp and the dried commercial product 

 have been fed to various classes of livestock in California, Florida, Georgia, and 

 Texas for several years, the dried pulp made its first appearance in New England 

 feed markets early in 1938. It has come into this region chiefly as a competitor 

 of dried beet pulp in the ration of milking cows. Analyses show it to be strictly 

 a carbohydrate feed. 



Information on its value for milk production is limited. Favorable results are 

 reported from California and Florida, but in both cases the number of cows used 

 was small. No evidence is available concerning its value under New England 

 conditions of feeding and management. It was therefore decided, when it first 

 reached our markets a few months ago, to conduct an extensive feeding trial of 

 its merits with a large number of cows. Through the courtesy of officials in the 

 State Department of Mental Health it has been possible to conduct such a trial 

 in the herd at the Belchertown State School. 



Thirty-eight purebred Holstein cows were divided into two groups and were 

 fed dried citrus pulp and dried beet pulp by the double reversal method over a 

 period of 86 days (60 days actual trial; 26 days preliminary). Some difficulty was 

 experienced in getting the cows to eat the citrus pulp, although it was moistened 

 and some molasses added to it. 



Comparative effect of the two rations was noted on general condition of the 

 cows, gains in live weight, and milk production. In all these respects there was a 

 slight difference in favor of the beet pulp, but it was significant only for gain in 

 weight and then only barely so. 



It would seem that, with the exercise of some care and patience in getting cows 

 accustomed to the citrus pulp, it should prove a satisfactory substitute for beet 

 pulp in their rations. Because of its carbohydrate nature, if much of it is fed, the 

 protein content of the grain ration should be higher than otherwise. Citrus pulp 

 is heavier than the type of beet pulp ordinarily fed in New England and soaks 

 up less water. Anyone unaccustomed to feeding it should rely on weights rather 

 than on measures at first. 



DEPARTMENT OF BACTERIOLOGY 



Leon A. Bradley in Charge 



The research work of the department is divided between two general topics: 

 one being the bacteria of water, and the other intestinal bacteria important in 

 nutrition. The research program on the bacteriology of drinking water was 

 outlined in the annual report for 1937 (Mass. Agr. Expt. Sta. Bui. 347:26, 1938). 

 Some new work has been undertaken in the bacteriology of swimming pool 

 water, including a study of the influence of swimming load on the numbers of 



