FEEDING STANDARDS CALCULATING RATIONS 115 



It is often highly beneficial to add wheat bran or linseed meal to the 

 ration on account of their slightly laxative effect. (218, 254) On the 

 other hand, when animals are already receiving such laxative feeds as 

 silage, pasture grass, and legume hay, the use of large amounts of bran 

 or linseed meal may be unwise. 



160. Bulkiness of ration. We have already seen that at least with 

 the horse and with young ruminants the ration must contain some rough- 

 age to distend the digestive tract properly. (106-7) Futhermore, 

 for the best results the proportion of concentrates and roughages in the 

 ration should be regulated according to the kind and class of animal 

 to be fed and the results sought. Cattle, sheep, and horses can be 

 wintered satisfactorily on roughages alone, if of suitable quality. (80, 90) 

 Even brood sows may be maintained partly on legume hay, when not 

 suckling their young. In the rations for growing and fattening animals 

 and those at work or in milk, a considerable part of the ration should 

 consist of concentrates. 



The various feeding standards recognize these facts in the amount of 

 dry matter which they prescribe in the rations for the different classes 

 of animals. Obviously, when the requirement of digestible nutrients or 

 of net energy is high compared with the total amount of dry matter 

 advised, the proportion of concentrates in the ration must be large. On 

 the other hand, for the mere maintenance of animals the standards call 

 for a much smaller amount of digestible nutrients or of net energy, com- 

 pared with the amount of total dry matter. 



161. Mineral matter. In the various feeding standards no statement 

 is made as to the amount or kind of mineral matter required by the differ- 

 ent classes of animals, the supposition being that a ration which provides 

 the proper amount of protein and other nutrients will also furnish an 

 adequate supply of mineral matter, with the exception of common salt, 

 which should always be supplied to stock. (100) We have already 

 seen that in some cases, especially with the pig, the mineral supply may 

 be deficient in amount or unbalanced in character in rations which meet 

 the ordinary standards. (95-101, 119, 149) In computing rations the 

 special requirements of the various classes of animals, as set forth in the 

 various chapters of this book, should therefore be kept clearly in mind. 



The mineral constituents most apt to be deficient are calcium and 

 phosphorus. When calcium is lacking in rations it may be cheaply 

 supplied in such forms as precipitated calcium carbonate, finely ground 

 limestone, or chalk. Both calcium and phosphorus may be furnished by 

 feeding bone meal, bone flour, bone black, precipitated bone, or even 

 ground rock phosphate. 



162. Palatability.- As has already been pointed out (56), the palata- 

 bility of the ration is an important factor in stimulating digestion and 

 inducing the animals to consume heavy rations. The wise feeder will 

 utilize feeds of low palatability chiefly for such animals as are being 

 merely maintained, and will feed growing and fattening animals, milk 



