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2. Force‐feeding significantly increased the weight and area of the crop, the weight of the proventriculus, the length and area of the jejunum and ileum, but decreased the weight of the gizzard and the thickness of its caudodorsal thick muscle. Feeding a barley‐based diet also decreased the thickness of caudodorsal thick muscle of gizzard.
3. Force‐feeding enhanced the absorption rates (μmol/cm2) of glucose and L‐methionine in both jejunum and ileum. Ducks fed on a maize‐based diet showed a slightly higher absorption rate of glucose compared to those fed on a barley‐based diet.
4. Force‐feeding caused a significant increase of endogenous non‐protein nitrogen (μg/cm2/h) in both jejunum and ileum and a slight increase of endogenous protein nitrogen in the jejunum. 相似文献
2. Within the first 24‐h‐fasting, villi of the duodenum showed a remarkable reduction in height and those of the jejunum revealed a gradual decrease; such a significant reduction of the villus height was not obtained in the ileum. After 36‐h‐fasting, villus height in each part gradually decreased with days of fasting.
3. All intestinal villus heights increased after only 1‐d‐refeeding of various kinds of diets following 3‐, 10‐, or 20‐d‐fasting. The duodenum especially rapidly recovered even after long‐term fasting of 20 d but the ileum showed very slow recovery, suggesting that the ileum seems to be inactive in absorptive function.
4. These variable alterations of villus height in the proximal intestine suggest that the higher intestinal absorptive ability is under the normal feeding, the more rapidly villus height is influenced by nutritional conditions.
5. Cell area and cell mitosis decreased after fasting, the latter showing a marked reduction. However, in spite of a remarkable decrease of cell mitosis in the proximal intestine after fasting, refeeding activated cell renewal and it soon reached control levels, demonstrating that the villus height mainly varied with the numbers of epithelial cells.
6. In the epithelial cells of the proximal intestine in chickens fasted for 20 d, large lysosomal autophagous vacuoles including mitochondria and dense bodies were observed. These were reduced in size by refeeding for only one day, suggesting that fasting may cause intracellular digestion through lysosomal autophagy.
7. These results lead to the conclusion that long‐term fasting for force moulting is possible, that a high protein and high energy diet can be fed immediately after fasting and that a cell undergoing lysosomal autophagy in normal chickens indicates undernutrition. 相似文献