
gO STORRS AGRICULTURAL EXPERIMENT STATION. 
This is not the whole story, but it is practically all that is 
definitely known to-day, and much more than was known a few 
years ago. Physiologists know that food has very diverse 
functions. They believe that the protein compounds have 
other functions than those briefly stated above. It is thought 
that certain of the different substances which chemists group 
together under the general designation of protein, stimulate 
the bodily activities in various ways. Investigators are, indeed, 
able to demonstrate by actual experiments that different chem- 
ical compounds, which occur in foods and feeding stuffs, in- 
fluence in widely different ways the health and strength of the 
animal and its capacity for production. Practical feeders under- 
stand perfectly well that. success in the selection of feeding 
stuffs and the compounding of rations depends upon a great 
many other things than the proportions of nutrients as shown 
by the chemist’s analyses. At the same time it is very 
important that the proportions of nutrients be properly fitted 
to the animal’s needs, and here one most essential thing is the 
proportion of protein—the ratio of nitrogenous to carbonaceous 
nutrients. 
Nutritive Ratio.—The effectiveness of a ration, then, depends 
not only upon the amount of digestible nutrients it supplies, 
but also upon the ratio of the tissue-forming substances to the 
fuel ingredients. This relation of the amount of protein to 
the amount of the carbohydrates and fats is expressed by the 
nutritive ratio. ‘The fuel value of the fat is about two and one- 
fourth times that of the carbohydrates and protein. If the 
sum of the digestible carbohydrates and two and one-fourth 
times the digestible fat of the ration is divided by the amount 
of digestible protein, the quotient gives what is called the 
- nutritive ratio. 
Wide versus Narrow Rations.—In calculating the nutritive 
ratio the protein is taken as one; the carbohydrates and fat taken 
together may be four, six, eight, or otherwise, as the case may 
be. Where the proportion of fuel ingredients is large the ratio 
is said to be wide, where it is small the ratio is narrow. Some 
writers in estimating rations for milch cows consider a ratio 
above 1:6, z. é., with more than six parts of fuel ingredients 
to one of protein as wide, and one with less than six of fuel 

