| Summary: | 碩士 === 國立中興大學 === 畜產學系 === 90 === The growth rate between broilers and Taiwan country chickens is different.The latter needs long feeding period to achieve the same body weight with broiler. Growth of chickens and metabolism of nutrient are correlative with gastrointestinal development. The purpose of this study was to investigate the intestinal growth and energy consumption in broilers and Taiwan country chickens at different growing periods. One hundred and forty one day old broliler chickens and Taiwan country chicks fed commercial diet were used. Body weight gain and nutrient availability were determined. At the prior, middle, last growing period, when the broilers were 2, 4, 6-weeks old and Taiwan country chickens were 5, 10, 16-weeks old, 16 chickens were fasted for 24 hours, injected with colchicine intraperitoneally at a dose of 3.5mg/ kg. At intervals of 0, 60, 120, 180 minutes after colchicine administration, chickens were sacrificed and gut tissues were collected to make slides stained by H.E. or Feulgen (Schiff’s reagent). Intestinal morphology and crypt cell proliferation rate (CCPR) were calculated using a light microscope image analysis system. DNA,RNA, and protein concentration of intestinal mucosa were determinated. Four additional chickens were sacrificed and gut tissues were collected to determine oxygen consumption at each growing period. The result showed that body weight of broiler chickens and Taiwan country chickens increase with ages. Relative weight of digest organs including proventriculus ,gizzard ,intestine, pancreas, liver and yolksac decreased with ages. The duodenal, jejunal and caecal crypt cell proliferation rate were fast at the prior and middle period than the finished period. The crypt cell proliferation rate of Taiwan country chickens were faster than broiler chickens posthatch, then decreased after the middle period. The crypt cell proliferation rate of the two strains declined in the middle period, and nearly stopped in the finishing period. From segment comparisons, the duodeunal proliferation rate of two strains was faster than the jejunal, but the caecal proliferation rate in two-week-old broilers was faster than the duodenal. There was an increase in villus height, villus perimeter and crypt depth with age in all intestinal regions of the two strains in the middle growing period. No differences were found between the middle and last growing periods besides the villus areas. The morphology of intestine villi developed from finger-like into plate-like into wave-like shapes with ages increased. Caecal mucous membrane becomed blubber. Intestinal mucosa protein concentration of the two strains were higher at 0 day, then decreasingly with age. Cell size(Protein/DNA) and tissue activity (RNA/DNA) of jejunal and ileal mucosa declined with age, and the quantity of protein synthesis (Protein/RNA) changed irregularly. The cell size of Taiwan country chickens was higher posthatch, then fluctuated after 5 weeks,the duodenal and jejunal protein synthesis rate declined with age, the tissue activity of jejunal and ileal mucosa declined with age. Oxygen consumption expressed per unit tissue of the duodenum increased with time in two strains. There were no significant differerces in different segments with age. Comparing total organ oxygen consumption of broiler chicks at different ages, which were higher at 2weeks and 4weeks than 0 week. However there were no difference between 2week and 4weeks, total organ oxygen consumption at 6weeks were higher than the two prior growth period. Total organ oxygen consumption increased with organ weight. That increased from 0 week to 10 weeks, no significant differences found after 10 weeks. Increasingly models of total organ oxygen consumption were in concert with that of intestine length or weight, all tended to become stable after 10 weeks, showed energy consumption were not raising with age.
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