Rural School Leaflet 869 



the body forms the bones and furnishes the mineral matter that is present 

 in all the tissues. The protein makes up the muscle tissues of the body 

 and any nitrogenous matter in the other tissues. The carbohydrates are 

 used to furnish the energy for the muscles. Any excess of carbohydrates 

 may be transformed into fat and stored as reserve material. Fats in the 

 body are used to give energy to the cells, or they may be stored as body fat. 



A cow or other animal has three uses for the food it takes into its body : 

 (i) to furnish energy for the mechanical work of the body; (2) to repair 

 any loss of material in the make-up of the body itself; (3) to store as fat 

 any food material in excess of these needs. Fat and carbohydrates and 

 excess protein over the protein requirements of the body, are used for energy 

 and fat production. Some protein and ash are used for the repair work and 

 for the new material added to the body in the case of the growing animal. 



A ration is the amount of food that is fed to an animal in twenty-four 

 hours for the above needs. The needs as to digestible protein, digestible 

 carbohydrates, and digestible fat for our animals have been carefully 

 calculated. Estimating the amount of food to meet these needs is called 

 computing a balanced ration. 



It has been found that there is a certain relation between the necessary 

 amount of protein and of carbohydrates and fat in a ration. This relation 

 has been called the nutritive ratio. The ratio is expressed between one 

 pound of digestible protein and the necessary number of pounds of digesti- 

 ble carbohydrates and digestible fat. When the first term of the ratio is 

 expressed as one, the second term is found by multiplying the fat by 2j, 

 adding to it the carbohydrates, and dividing this amount by the protein. 

 The digestible fat is multiplied by 2I because fat is considered to yield 

 to the body 2I times as much energy as carbohydrates. 



For dairy cows, it has been found that a nutritive ratio between 1 15 

 and 1 :6 seems to give the best results in milk flow. 



To conclude: When we wish to compute a ration for a dairy cow 

 weighing about 1,000 pounds, we try to furnish suitable food in sufficient 

 quantity to yield about twenty-four pounds of dry matter, in which the 

 relation of the protein to the carbohydrates plus 25 times the fat is as 

 I :S or 1 :6. 



7. The breeds of cows are mentioned in some detail in the article in 

 this number of the leaflet on the colors of cows. In order of richness of 

 milk, the dairy breeds rank as follows: Guernsey, Jersey, Ayrshire, and 

 Holstein. The milk of the Guernsey and the Jersey tests 5 per cent to 6 

 per cent of butter fat. The products of the Guernsey are a golden yellow; 

 the products of the Jersey a somewhat lighter yellow, or cream color. 

 The milk of the Ayrshire will average about 4 per cent of butter fat, while 

 the Holstein gives milk testing on the average about 3 . 5 per cent butter fat. 



