ORGANIC NUTRIENTS 151 



herbivora. There is more uniformity in this respect with regard to oil 

 cake and the grains. But the digested portions in this instance produce a 

 greater gain in swine than in ruminants. The difference, according to 

 Fingerling, amounts to 30 per cent if the nutrients are administered in 

 easily digestible form. 



According to Kellner, and contrary to general belief, age and breed 

 do not influence digestibility. Individual animals, however, may show 

 a difference of 3 or 4 per cent in this respect. 



The influence of exercise has at various times been the subject of study 

 and investigation. The results have shown that moderate exercise does 

 not affect digestion unfavorably (this does not take into detailed consid- 

 eration the effect of exercise upon the digestive processes in the different 

 portions of the digestive tract). Grandeau and Leclerc found, however, 

 that active work, in a walk or trot, has an unfavorable influence upon 

 protein digestion. 



Excessive additions of carbohydrates to the ration may, under certain 

 conditions, retard digestion. The same is true of the fats when admin- 

 istered in bulk but not when given in a finely divided state. Increase of 

 the proteids favors digestion. The relative proportions of the nutrients 

 to insure digestion of all feeding stuffs, should not exceed 1 to 10 per 

 cattle, nor 1 to 12 for swine. Cattle powders, milk powders, fattening 

 powders, appetizer powders, etc., have no favorable effect upon digestion 

 in otherwise healthy animals. 



2. Organic Nutrients 



The nutrient requirements vary according to species, breed, variety, 

 age, purpose, etc. The live weight of the animal should constitute the 

 basis of feed standardization and should be determined by frequently re- 

 peated weighings before feeding and always at the same hour of the day. 



In the first place all animals require a certain amount of digestible 

 albumen or protein. While albumen or protein may be substituted to a 

 certain extent for the fat and carbohydrates of a ration, it can not be re- 

 placed by the latter. The comparatively high price of protein is at the 

 bottom of the custom usually followed in preparing rations with the 

 minimum protein content. And yet agricultural interests in particular 

 have frequently pointed out that it is better to feed an excess of protein 

 than an excess of carbohydrates, on the economic ground that it results 

 in a richer manure ! 



After completed development of all the organs, the requirements for 

 proteids, in addition to the minimum for the support of life, are only 

 what is required for the complete digestion of the food. Muscular 

 energy and fat can be produced, or furnished, as a rule by the carbo- 

 hydrates and the fat. Accordingly the requirements for protein are not 

 high. In general, the need of mature animals is supplied by 1 pound of 

 digestible protein for every 8 or 10 pounds of digestible nitrogen-free 

 extract (carbohydrates plus fat X 2.2). 



