19171 



ANIMAL PEODUOTION. 



677 



Digestion experiments with pigs, with special reference to the influence 

 of one feed upon another, and to the individuality of pigs, H. S. Gbindltt, 

 W. J. Cabmichael, and 0. I. Newlin (Illinois Sta. Bui. 200 {1911), pp. 55-9k, 

 figs. 4)- — The objects of the experiments reported in this bulletin were (1) to 

 determine the influence of one feed upon the digestibility of the nutrients of 

 another feed, (2) to study the individuality of pigs as to the thoroughness with 

 which they digest their feed, and (3) to determine the coefficients of digesti- 

 bility of the nutrients of the following rations : Wheat middlings, ground corn, 

 ground barley, wheat middlings and ground corn (1:1), ground barley and 

 ground corn (1:1), and tankage and ground corn (1:7.5). The feeding stalls 

 used in these experiments were large enough to allow the pigs to turn around 

 freely and were raised some 3 ft. from the floor to enable an easy collection 

 of the urine. The feces were collected in rubber-lined canvas bags held In 

 place by specially constructed harness. Illustrations are given of the digestion 

 harness and of the feeding stalls. 



Each of the rations was fed for two 10-day periods. Each test period was 

 preceded by a preliminary period of from 25 to 32 days during which the pigs 

 were accustomed to the test rations and to the stalls and harness. Four 7- 

 months-old pigs were used in each of the series, those in 1913-14 being cross- 

 bred Berkshire-Chester Whites, all from the same litter, and those in 1914-15 

 cross-bred Duroc Jersey-Poland Chinas, all from the same litter. Analyses are 

 given of the feeds and feces. 



The following table gives the average coefficients of digestibility of the rations 

 fed in these experiments: 



Digestion coefficients of rations when fed to sicine. 



nation. 



Number 



of e.xperi- 



ments. 



Dry sub- 

 stance. 



Protein. 



Ether 

 extract. 



Nitrogen- 



fre« 

 extract. 



Cruda 

 fiber. 



Wheat midd 1 ings 



Ground corn 



Ground barley 



Wheat middlings and ground com (1:1). 



Ground barley and ground corn (1:1) 



Tankage and ground com (1: 7.5) 



Per cent. 

 74.4 

 87.1 

 70.8 

 79.1 

 80.9 

 86.0 



Per cent. 

 80.0 

 74.5 

 54.0 

 77.3 

 66.5 

 74.8 



Per cent. 

 85.4 

 68.3 

 33.0 

 83.4 

 6/. 8 



Per cent. 

 81.2 

 92.1 

 81.2 

 85.9 

 88.9 

 92.2 



Per cent. 

 21.0 

 34.8 

 14.1 

 13.1 

 15.0 

 £1.3 



Discussing the influence of one feed upon the digestibility of another feed 

 as indicated by results obtained in these exi)eriments, the authors conclude, 

 " first, that the coefficients of digestibility of feeds calculated indirectly by sub- 

 tracting the weights of the digestible nutrients of one feed as directly deter- 

 mined in other periods from the corresponding values for two feeds combined may 

 be, and probably often are, decidedly inaccurate, and, second, that the weights 

 of the digestible nutrients of a mixed ration calculated by the use of the 

 coefficients of digestibility of the nutrients obtained directly for the individual 

 feeds when fed alone may be decidedly inaccurate. It, therefore, seems evident 

 from these considerations that, in order to obtain accurate results for the 

 cofficients of digestibility of mixed rations, digestion experiments should be 

 made directly upon the mixed rations as fed. In other words, in the future, 

 coefficients of digestibility of the nutrients for mixed rations should be obtained 

 and reported, rather than merely those for the individual feeds composing the 

 rations." 



