40 MAINE AGRICULTURAL EXPERIMENT STATION. 



two and one-fourth times as much as the carbohydrates for that 

 purpose. Second, they are used as material for making fat. 



For convenience in stating the relation of protein to carbo- 

 hydrate material the term nutritive ratio is used. By nutritive 

 ratio is meant the relative amount of digestible fat and carbohy- 

 drates compared with the digestible protein. That is, if a food 

 is said to have a nutritive ratio of I to 6, that means that for 

 every pound of digestible protein it contains six pounds of 

 digestible carbohydrate material. To find the nutritive ratio, 

 the digestible fat is multiplied by 2j4 and the product added 

 to the carbohydrates. This sum divided by the number of 

 pounds of digestible protein, gives the number of pounds of 

 carbohydrate material to one pound of protein. 



It has been ascertained, by accurate experiment, that the 

 amount of food required to keep an animal from losing weight is 

 not materially different for different animals of the same size and 

 species. All the food that they will profitably eat above that 

 amount depends on their individual digestive and producing 

 capacities. It is therefore evident, that a ration which would be 

 profitable for one animal would not be for another, and no hard 

 and fast rules can be made. For this reason the accuracy of 

 feeding standards has been questioned by some feeders, but they 

 certainly must be considered a vast improvement over the com- 

 monly practiced, haphazard feeding of any materials at hand. 

 The successful and progressive feeder can, by studying his herd, 

 learn the capacity of each animal and vary its ration from the 

 standard to suit the individual. 



The German feeding standards recommended by Wolff are 

 the ones generally employed in this country when any standards 

 are made use of. A so-called American standard for dairy 

 cows, which was obtained by Woll, by means of extended cor- 

 respondence with dairymen in all parts of the country and the 

 use of averages for composition and digestibility of foods, gives 

 a somewhat wider ration with a nutritive ratio of 1 : 6.9 and only 

 2.13 pounds digestible protein per day. This ration can hardly 

 be said to be based on scientific data, and is probably too wide to 

 give the best results in most cases. In fact some of our best 

 dairymen in this State claim to derive the most profit from a 

 ration having a nutritive ratio of about 1 : 4 which is much nar- 



