894 FOOD AND FEEDING. 



that the numbers assigned by different authorities are 42, 57, and 

 108 ; and M. Perranlt, Tom direct experiment, found the equivalent 

 number of colza-cake t* be 36, analysis giving 23 as the theoretical 

 number. On the whole it may be said, that in practice, the results, 

 although sufficiently different, still agree in ascribing to oil-cake a 

 nutritive value inferior to that indicated by theory. 



I have thought it important to insist upon the discrepancy which 

 is here so conspicuous between the inferences from chemical analy- 

 sis and those arrived at by experience, because it appears to me to 

 depend upon a particular circumstance which frequently intervenes 

 in the feeding of cattle, and which it is very important to be aware 

 of; I allude to the influence of the bulk of the allowance of food. 



Vegetable food of every description has nearly the same specific 

 gravity ; it is but little above that of water ; the bulk of the allow- 

 ance therefore depends upon its weight. Every one will conceive 

 that a ration of highly nutritious food, which for this reason would 

 occupy but little space, would be open to many objections. A cart- 

 horse, of the ordinary size, from what I have myself repeatedly 

 observed, requires from 26 to 33 lbs. of solid food, and about the 

 same quantity of water in the twenty-four hours. The bulk of this 

 allowance, when masticated and brought to the state in which it is 

 swallowed, will be upwards of 9^ cubic feet. Now, if for the ordi- 

 nary forage, one that is five times more nutritious were substituted, 

 oil-cake, for example, the dry ration, according to the rule of equiv- 

 alents, would be reduced to 6.6, or a Mttle more than 4^ lbs., and its 

 bulk would not surpass 5^ cubic feet. The animal would not feel 

 satisfied with this allowance, it would still feel hungry, or the food 

 given in such a concentrated shape would disagree with it. If, on 

 the contrary, a forage that is very little nutritious were substituted, 

 such as wheat-straw, the equivalent of which is 500, the ration 

 would then become too bulky to be eaten in the course of a day, it 

 would amount to as many as 165 lbs. It is therefore absolutely ne- 

 cessary to take into consideration the bulk of the food allowed : the 

 belly must of necessity be filled ; whatever the nutritive value of 

 any article, it must be given in a certain quantity ; and in the case 

 of such a substance as oil-cake, the consumption to fill the stomach 

 would cease to be in any kind of proportion to the nutritive equiv- 

 alent. 



It is extremely difficult to appreciate the precise limits beyond 

 which an article of forage or a given ration ceases to be nutritious. 

 When any addition is made to an allowance known and admitted to 

 be sufficient, the effect of the extra quantity is scarcely perceptible ; 

 so that, in practice, we are apt to fall into the error of estimating at 

 too low a rate the nutritious powers of food given in too large quan- 

 tities. I have had proof of this in a series of experiments on the 

 maintenance of a number of milch-kine. To a cow which was 

 receiving the equivalent of 33 lbs. of meadow-hay in dry fodder and 

 Jerusalem potatoes, an addition was made of 6| lbs. of oil-cake, by 

 which the allowance of nourishment was doubled theoretically ; the 

 4oiraal (Mily ate the half of the cake, howfever : still, the quality of 



