384 —BOARD -OF AGRICULTURE. [Pub. Doc. 



to ascertain the laws governing the production of flesh and 

 fat. Among tlie questions to ])e answered were these : (1) 

 What becomes of the digested portion in its rehition to the 

 production of lean meat and fat? and (2) Is there any way 

 to feed so that flesh and fat can be produced at will ? and 

 further, How shall animals be fed so as to get the greatest 

 returns for food consumed ? 



As early as 1858-GO the celebrated physiologists Bischofl' 

 and Voit had published the results of their investigations 

 relative to the movements of the nitrogenous compounds 

 on carnivorous animals (dogs and cats). They overthrew 

 the theory that nitrogen in any form was exhaled through 

 the lungs or skin, and proved conclusively that the only 

 nitrogen given off" 1iy the animal was to be found in that 

 undigested portion, the solid excrements, and in the end 

 product of nitrogenous decomposition, the urea of the urine. 

 By finding the diflerence between the amount of nitrogen in 

 the food consumed and the amount given out in the solid 

 and liquid excrements, it couhl be ascertained whether or 

 not the animal had put on or lost nitrogen, and hence put 

 on or lost flesh or lean meat. This discovery was confirmed 

 on steers and sheep at the Gottingen station. Here, then, 

 we have a method for determining the loss or gain in lean 

 meat; for 100 parts of dry flesh contain a])out 16 parts of 

 nitroofen, and 100 divided by 16 gives us the factor 6.25. 

 iSow, by multiplying the percentage of nitrogen gained or 

 lost by 6.25, we calculate it to dry flesh, and this can be 

 easily reduced to moist or natural flesh. 



To determine the production or non-production of fat, the 

 case was not so easy, but still a way was found. Professor 

 Pettenkofer of Munich invented the so-called Pettenkofer 

 respirations apparatus, by the use of which one is enabled 

 to estimate the amount of gaseous exhalations given off' by 

 animals. Living beings exhale, as a result of the decom- 

 position of food consumed, carbondioxide (CO^) and water 

 (H-C)) through the lungs, and many farm animals a con- 

 sidcral)le quantity (as high as ten per cent) of marsh gas 

 (CH^) through the skin and vent. If, now, the amount of 

 carl)on can be measured in these gases, it is possible to 

 obtain by calculations the amount of fat gained or lost in 



