THE MILK SUPPLY OF MASSACHUSETTS 129 



in. MILK PRODUCTION AND SHIPPED-IN FEED 



The output of milk from the farms of Massachusetts and the other New 

 England states is based only in part upon the product of the native soil. 

 To a very considerable extent it is based upon purchased feeds which are 

 the product of the farming of other regions. To a certain extent, also, 

 tl-ese purcliased feeds form the basis for improving the fertility of the 

 local soil and make a small contribution to the second-quality meat which 

 i, a by-product of the local dairy industry. It is the purpose of this paper 

 to make as close an estimate as the available data permit of the relation 

 of this purchased feed to the food production of the dairy industry. 



In one sense all of the milk output from the New England farms is 

 locally-produced food. In the form of milk it is strictly a local product 

 pnd the feeds brought in from the West would be of little or no value for 

 direct human consumption. Nevertheless, milk coming from a herd fed 

 largely on purchased hay and grain is not as completely the product of 

 local farming as is the milk coming from a pasture section where little 

 •or no feed is brought in from the outside. The payment for feed requires 

 a large deduction from the profits in the first case. The milk made by the 

 use of western grain is also partially based upon the product of the soil 

 In other sections of the country, and its flow would be diminished if the 

 supply of outside grain were stopped. Thus part of the local milk produc- 

 tion is merely the final stage in a series of operations in food production, 

 the earlier stages of which are conducted elsewhere. 



Method of Estimate 



Th fairest basis for estimating the proportion of milk production based 

 upon locally-produced feeds, as distinguished from that due to purchased 

 feeds, is the relative nutritive value contained in each of these classes of 

 feeds. Under practical conditions the dairy cow usually gets a fairly 

 T^ell-balanced ration, certainly a mixture of roughage and some form of 

 concentrates. The problem is to find the share which each class of feeds 

 contributes to production in mixed rations as they appear in practice. To 

 tiup end it is necessary, by some such ir.eans as reducing the nutritive value 

 of the. feeds to some common denominator and ascertaining the quantity 

 used of eacli, to determine the ability of each group of feeding stuifs to 

 pioduce milk. 



Several common denominators are used for comparing the nutritive 

 \alue of different feeds. Recent practice among nutritional chemists gives 

 a leading place to the measure known as the net thermal equivalent. This 

 is comparable to tlie calorie which is used in measuring the nutritive value 

 of human foods. It takes account, however, of the fact that much of the 

 fiber in animal feed, while having a thermal value, has little energy value 

 for utilization in the bodies of the animals. Only the part of the feed 

 which is actually utilized for production and maintenance is included in 

 the net thermal equivalent. 



The net thermal equivalent, accordingly, is used in determining the 

 nutritive value in all feeds whose use is measurable in terms of weight. 



