FATTY ELEMENTS OF FOOD, AND ON FATTENING. 425 



nothing of new azotized principles which would be converted into 

 caseine. 



If we now, by an easy transition, pass to the phenomena of fatten- 

 ing, we still find that the principles which have been laid down can 

 be most satisfactorily applied. Setting out from the numbers ob- 

 tained from the experiments of Mr. Riedesel, which, in many points, 

 agree with all I have seen myself, we arrive at the following con- 

 clusions. 



An ox weighing 1320 lbs. avoird. will keep up his weight upon 

 about 22 lbs. of good hay per diem. Put up to fatten, the same ani- 

 mal would require about twice this quantity, say 44 lbs., upon which 

 he would gain at the rate of about 2 lbs. per day. 



Now, if we even take Mr. Riedesel's conclusions as a little too fa- 

 vorable, as giving at least the maximum nutritive value to the hay and 

 its equivalents, we may still admit, with him, that 22 lbs. of hay will 

 produce about 17 pints of milk, or about 2 lbs. avoird. of flesh, con- 

 taining 0.55 lbs., or rather more than | lb. of fat. Now, 22 lbs. of 

 hay contain nearly 12 oz. 12 dwts. of principles soluble in ether, 

 i. e. of fatty or waxy matter. 



The fatting ox, consequently, fixes a certain proportion of these 

 principles in the same way as the cow. There is only this differ- 

 ence, that the cow returns with the milk she yields a considerable 

 quantity of the fat she finds in her food. There consequently exists 

 an obvious relation between the formation of milk and fattening — a 

 position which would gain support, did it require any, from a note 

 which I owe to the politeness of M. Yvart, who, in summing up a 

 long array of facts, concludes with these words : " The secretion of 

 milk appears to alternate with that of fat. When a milch-cow fat- 

 tens, she loses her milk ;" and the converse of the proposition is no 

 less true ; when we would fatten a cow, we must let her go dry. 



The breeds of kine admitted to be the best milkers remain long 

 lean after the calving. In some of the short-horned English breeds, 

 the quantity of milk is often very considerable shortly after the 

 calving ; but the animals are much disposed to get fat, and getting 

 fat, the secretion of milk neither continues so long, nor is it so plen- 

 tiful, as in some of the other less improved kinds. English hogs, 

 which become much fatter than French hogs, appear not to be such 

 good nurses. Now, if we admit that there is this intimate relation 

 between the formation of milk and that of fat, we are obviously very 

 near the admission, that articles of food containing fatty substances 

 indispensable to the production of milk, are also indispensable to the 

 production of animal fat. And, then, has it ever yet happened that 

 animals have been fattened with food devoid of grease ? I have not, 

 for my own part, met with a single fact which countenances such a 

 proposition. I have referred to the distinguished agriculturist, who 

 attempted to fatten pigs upon potatoes, but who only succeeded by 

 adding a certain quantity of graves to the food — an article which, as 

 every one knows, conf ains a considerable proportion of fat in its com- 

 position. 



M. Payen has, in fine, made some experiments which appear alto 

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