| Summary: | 碩士 === 國立中興大學 === 動物科學系所 === 97 === A study was conducted to determine the effects of antibiotic, probiotics and plant extracts supplement in diet on the growth and intestinal characteristics in the broilers. Five dietary treatments, consisting of the control (CON), enramycin 8 ppm (ANTI), plant extract-I 0.3 kg (PE I), plant extract-II 0.5 or 1 kg in starter and finisher diet ( PE II), respectively and probiotics 0.5 kg (PRO). Body weights, feed intake and feed to gain ratio were measured at 21 and 35 days of age. The results of the present study shown that there were no significant difference on the body weight, body weight gain and feed to gain ratio of broilers fed with both plant extracts and probiotics when compared with the control group. All of supplement treatments were significantly increased (P<0.05) the Lactobacillus population in the crop and jejunum-ileum of broilers at 21 days of age when compared with the control group, except in the jejunum-ileum of broilers fed with plant extract-I. At 21 days of age, the Lactobacillus : Coliform and Lactobacillus : Enterobacteria ratio of jejunum-ileum were significantly higher (P<0.05) than the control group when the broilers fed with plant extracts-II and probiotics. At 35 days of age, supplementing the diets with probiotics was significantly highest (P<0.05) on the Lactobacillus : Enterobacteria ratio of jejunum-ileum than the other group. From 0-21 days period, it was observed that supplementation of probiotics and plant extract-II were significantly decreased (P<0.05) on pH value in the crop and jejunum-ileum when compared with the control group. In addition, from 22-35 days period, the pH values in the crop and cecum of broilers supplemented with probiotics were significantly lower (P<0.05) than those in the control or the other supplement groups. There were no significant differences of VFA concentration in the jejunum-ileum and cecum in all of supplementation groups. At 21 day of age, the concentration of lactic acid in the jejunum-ileum was highest (P<0.05) in the broilers fed with probiotics, furthermore, all of supplementation groups were significantly lower (P<0.05) in the NH3 concentrations of jejunum-ileum and cecum than the control group. And there were no significant difference on the villus height, crypt depth and villus height/crypt depth ratio of the duodenum and jejunum among all of the supplemented groups. In conclusion, supplementation of the diets with probiotics was significantly highest on the Lactobacillus : Enterobacteria ratio of jejunum-ileum than the other groups. Therefore, supplementation of plant extract-I, plant extract-II and probiotics were significantly increased the populations of Lactobacillus as well as significant reduction in the pH values and concentrations of NH3 in the GI segments when compared with the control group. Moreover, the concentration of lactic acid in the jejunum-ileum of the broilers fed with probiotics was significantly highest than the other groups.
Key Words：Probiotics, Plant extracts, broilers
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