io the Rearhuj and Feeding of Cattle. 
2G1 
so, I ronteiul that thcoiy is completely on my side, and I trust 
practical men will not refuse me their aid in puttmg it to the test 
of practice. 
'J^he liver is the next or^^an to which I would attach peculiar 
importance in the aptitude of an animal to fatten. The bile is a 
fluid secreted by this or<ian. I have explained to you in my last 
lecture, that the bile is destined for supporting the heat of the 
animal liody. Liebig considers that bile may be produced by the 
liver itself from unazotized food received directly from the intes- 
tinal canal, together with azotized substances derived from the 
blood. An ox secretes about 37 lbs. of fresh bile every day, 
which is equivalent to 59 oz. of dry bile, the rest being water. 
In the normal state in which an animal is placed, little of this 
bile passes out along with the excrements, for the greatest part is 
taken into the blood, and its unazotized part consumed in the sup- 
port of respiration and consequent heat of the animal ; while the 
kidneys sejjarate in the urine the parts containing nitrogen. But 
if there be more bile formed than the air sufSces to consume, the 
excess is separated by means of the excrements. Tallow (fat) is 
probably produced from the excess of food which the liver has 
been unable to form into bile. Now suppose that we put up an 
ox which possesses a large, sound, and active liver, to be fed in the 
stall — we decrease the number of its respirations, and consequently 
the amount of oxygen which enters the body. Less bile, in this 
case, will be consumed ; but as it is still formed as before, though 
not quite so rapidly, a greater proportion will now pass out with 
the excrements. Let us suppose that the liver of this anlm.al 
secretes 37 lbs. of bile daily — 37 lbs. of bile contain about 40 oz. 
of carbon — and that the amount of food given to it is 60 lbs. of 
mangold-wurzel. Let us have in the same place another ox, re- 
ceiving exactly the same quantity of food, but whose liver, being 
smaller, only secretes 30 lbs. of bile daily. Now as bile is formed 
principally from substances which, if not so employed, would pro- 
duce tallow and also a certain quantity of flesh, the latter on secreting 
30 lbs. of bile daily must fatten more rapidly on the same food 
than the former ox, from whose liver 37 lbs. of bile are secreted ; 
because having 7 lbs. of bile less to form, all the food necessary 
for producing this must become tallow. An animal with a small 
liver will also produce more flesh (muscle) than an animal with 
a large sound liver, which produces much bile. Nitrogen is an 
essential constituent of the bile. The bile of animals permitted 
to roam in their natural state, receives this element from the 
transformed tissues of the body. It is known that albumen 
suffers no change in passing through the liver and kidneys, and 
hence the nitrogen of the bile must be received from the trans- 
formed tissues : but if the bile did not require this nitrogen, it 
