INTESTINE FULLNESS INFLUENCES FEEDING-BEHAVIOR AND CROP FILLING IN THE DOMESTIC TURKEY

Image-intensification radiology showed that artificial introduction of food slurry into the intestines of 6-12 wk-old turkey hens significan tly increased the proportion of boli entering the crop during an eveni ng meal, hence decreasing the proportion of boli travelling directly t o the gizzard. Since bolus movement is directed by esophageal motility , esophageal motility may be partially mediated by stretch or chemorec eptors in the distal duodenum. Increased crop filling during afternoon meals lends support to the widely held belief that the crop increases gut storage capacity and helps ''tide birds over'' the nightly fast. Artificial filling of the distal duodenum paradoxically increased food intake in birds observed by radiology while eating a single meal (mor ning and evening), and in birds observed by eye over a 3 h period in t he morning. This phenomenon is similar to that previously reported for rabbits and domestic chicken. Conversely, duodenal filling reduced fo od intake over a full day (11 h), more than compensating for the intro duced food. Rapid filling of the small intestine (within 25 min. of th e start of the meal) suggests a modification of the function of the do mestic turkey duodenum to serve as a ''mixing chamber,'' possibly enha ncing digestive efficiency. The ways in which this modification affect s digestion and absorption in the duodenum warrant investigation.