FEEDING ANIMALS 



323 



pharynx- 



--tongue 



lower mandible 

 of beak 



simple digestive tracts. The cow, the sheep, and the deer, 

 known as ruminants, have a complicated set of four stomachs, 

 by means of which they are able to digest large quantities of 

 coarse and comparatively unnutritious feed. The animals, such 

 as the ruminants, which have subsisted for centuries upon coarse 

 foods have a longer 

 digestive tract than 

 do those which have 

 lived upon a more 

 concentrated diet 

 (Fig. 162). The di- 

 gestive tract of cat- 

 tle is about twenty 

 times as long as the 

 body ; of sheep and 

 goats it is about 

 twenty-seven times ; 

 of the hog about 

 fourteen times ; and 

 of the horse only 

 about eleven times. 

 The ruminants, with 

 their large stom- 

 achs, can utilize 

 much coarse mate- 

 rial which would 



proventriculus, or 

 glandular stomach 



entrance of 

 urinary duct 



rectum 



anus... 



cloaca 



otherwise be wasted. 



The digestive tract FIG. 161. The digestive tract of a chicken. (Diagram 

 b m from Iowa State College) 



of the chicken is 



very different from that of the other animals described. The 

 chicken has no means of chewing its food, therefore the food 

 is swallowed whole and goes directly into the crop, where it 

 is moistened and softened; thence it goes through the true 

 stomach into the gizzard, where it is ground by the gritty 

 material present. The craving of chickens for gritty materials 

 is therefore easily understood. 



