314 POULTRY PRODUCTION 



The Gizzard. — The gizzard is oval in form, having two 

 oi)enings on its upper side, one communicating with the 

 proventriculus and the other with the saiall intestine. It is 

 depressed on each side, being situated behind the liver 

 and partly covered by the lateral lobes of that gland. It 

 is composed of two thick, red, powerful muscles covered 

 internally with a thick, horny epithelium. 



The gizzard is a very efficient crusher. It has been stated 

 that iron tubes capable of supporting a weight of 535 pounds 

 have been completely flattened out by passing through the 

 gizzard of a turkey. This crushing process is absolutely 

 necessary for the digestion of grains, and is most efficient 

 only when aided by the presence of grit and gravel taken in 

 through the mouth and always present in a normal bird. 

 The gastric juice is inca|)ablc (if digesting the cellulose walls 

 of the grains and does not act until the grains are reduced 

 by the gizzard to a more or less homogeneous ])ulp. The 

 constant action of the gizzard nuiy be noticed l)y holding a 

 little chick that has been sup]>lied with grit to the ear. '' The 

 gizzard does not ])ossess digestive gla.nils."' 



From the gizzard, the partially digested material passes 

 into the small intestine. Up to this point there has been no 

 digestion of fats, a limited digestion of carbohydrates and 

 protein, and a dissolving of mineral elements. 



Pa7icreas. — Immediately after its attachment to the 

 gizzard the intestine is folded in a long loop called the duode- 

 num, the sides of which are parallel and inclose the pancreas. 

 The pancreas, though it does not come in contact with the 

 food material, plays a very important part in the work 

 of digestion, and is relatively longer in birds than in animals. 

 It secretes a fluid known as the pancreatic juice, which 

 contahis "proteolytic, amylolytic, and lii)olytic ferments, "- 

 which help prepare protein, starch, and fat respectively for 

 digestion, acting in a slightly alkaline medium. This juice 

 emptied into the duodenum by one duct at each end. 



In 1856 Bernard, as reported by Brown,' "first pointed 



' Shaw, Jour. Am. Assu, lust, and Invest in Poul. Hush , vol. i, No. 2. 

 ' Shaw, American Journal of Physiology, vol. xx, No. 7. 

 3 Bureau of Animal Industrj-, Bulletin No. .5lj. 



