Effect Of Dietary Crude Fiber Levels On Growth And Development Digestive Physiology And Cecal Microflora Colonization Law In Gushi Chicken

This paper studied the crude fiber level Gushi chicken could tolerate in diet and probed into the mechanism of Gushi chicken high level crude fiber tolerance capacity, this research would be of great significance to make full use of natural resources, resolve the demand conflict on the grain between human and livestocks, keep the competition advantages in market for the poultry industry, meet the consumers' need for healthful and good quality poultry product, and the breed protect and exploitation of Gushi chicken. It includes two parts, in experiment I the differences between total fecal collection method and indicator method in the digestibility determination of crude fiber were studied in Gushi chicken, and the replacement feasibility of total fecal collection method with indicator method in the nutrient digestibility determination for high level crude fiber diet in Gushi chicken was discussed. Effect of dietary crude fiber levels on body weight, body measurements, development of internal organs and immune organs, intestinal morphology and structure, serum biochemical parameters, caecum cellulase activity, and caecum microflora colonization law by PCR-DGGE were researched in Gushi chicken aged from 0 to 8 weeks in experiment II. The experimental results were as follows:Part I : Twenty six 24-wk-old healthy Gushi cocks with almost same body weight were selected and were fed on the diet supplemented with 9% pine leaf powder (crude fiber content was measured as 4.7%), crude fiber digestibility of which were determined by total fecal collection method, exogenous indicator (TiO₂) method and endogenous indicator (4N-AIA, acid insoluble ash) method respectively, and the differences among three methods were compared. The results indicated that there were difference between either of the two methods,but there were no significant difference between either of the two methods (P>0.05). Fecal recovery of TiO₂ averaged 97.2%, whereas that of 4N-AIA averaged 102.7% based on total fecal collections. Correlation analysis indicated that there were significant correlation between the crude fiber digestibility determined by total fecal collection method, exogenous indicator and endogenous indicator methods (P < 0.01) , the coefficient were 0.968, 0.971 and 0.971 respectively. Total fecal collection method could be replaced by indicator method in the determination of crude fiber digestibility for Gushi chicken.Part II: One thousand one hundred and fifty two 1-day-old Gushi chickens were selected and were randomly assigned to 6 groups, which consists of 4 replicates with half male and half female chickens. Six groups were fed to 8 weeks of age with crude fiber content 2.51% (control group),3.47% (group I ),4.58% (group II ),5.57%(group III),6.68% (group IV ),7.79% (group V) in diets respectively. Effect of dietary crude fiber levels on body weight, body measurements, development of internal organs and immune organs, intestinal morphology and structure, serum biochemical parameters, caecum cellulase activity, and caecum microflora colonization law by PCR-DGGE were researched in Gushi chicken aged from 0 to 8 weeks. Results indicated that (1) There were no significant differences on Gushi chicken body weight between control group and experimental groups at 2, 4, 6, 8 weeks of age (P > 0.05) . (2) There were no significant differences on Gushi chicken shank length between control group and experimental groups at 2, 4, 6, 8 weeks of age (P > 0.05) ; there were no significant differences on Gushi chicken shank girth, breast width, breast depth, body length, keel length, pelvis width, breast angle between control group and experimental groups at 6, 8 weeks of age (P > 0.05) . (3) There were no significant differences on the development of Gushi chicken duodenum, jejunum, ileum, cecum and most internal organs between control group and experimental groups at 2,4, 6, 8 weeks of age (P > 0.05). There were hyperplasia on Gushi chicken gizzard, proventriculus, liver and pancreas in experimental group compared to control group, but there were no significant difference on their weight (P> 0.05) ;there were no significant effect of crude fiber level on intestinal length, and there were no hyperplasia on Gushi chicken intestine in experimental group compared to control group. (4) With the increase of dietary crude fiber level, villus height of Gushi chicken duodenum, jejunum, ileum, cecum increased, while crypt depth decreased at 4 and 8 weeks of age. Crude fiber promoted the growth of intestinal villus. The intestinal villus were located in order observed under scanning electron microscopes, crude fiber level had no significant effect on the intestinal morphology in Gushi chicken. ( 5 ) The cecum cellulase activity of Gushi chicken were significantly increased with the dietary crude fiber level increased at 2, 4, 6, 8 weeks of age, except that the cecum cellulase activity of experimental group IV was lower than that of experimental group III at 6 weeks of age. And with the increase of weeks of age, the cecum cellulase activity of experimental group and control group were increased. (6) Dietary crude fiber level had no significant difference on activity of serum glutamate-oxalacetate transaminase and glucose concentration between experimental group and control group except experimental group II, there were significant difference on serum low density lipoprotein between experimental group and control group experimental groups (P< 0.05) ;while there were no significant difference on serum total protein, albumin, urea nitrogen, alkaline Phosphatase, triglyceride, cholesterol, high density lipoprotein between experimental group and control group experimental groups at 4 weeks of age in Gushi chicken (P > 0.05). At 8 weeks of age, there were no significant difference on activity of serum glutamate-oxalacetate transaminase between experimental groups and control group except experimental group III, and there were no significant difference on serum total protein, albumin, urea nitrogen, glucose concentration, alkaline Phosphatase, triglyceride, cholesterol, high density lipoprotein between experimental groups and control group (P > 0.05). (7) There were no significant difference on the development of spleen, thymus, bursal of Gushi chicken between experimental groups and control group at 2, 4, 6, 8 weeks of age (P > 0.05), except that there were significant difference on the development of thymus at 4 weeks of age, the development of bursal at 6 weeks of age and the development of spleen at 8 weeks of age between experimental group II and control group (P < 0.05). (8) With the increase of dietary crude fiber level, the band numbers of DGGE profiles of the V₃ region gene amplication of 16S rDNA of caecum microflora increased, it meant the significant increase or increase tendency of cecum microflora quantity and diversity at 2, 4, 6, 8 weeks of age, and the dietary crude fiber promoted the reduplication of bacterial connected with crude fiber decomposition, while there were no significant difference between 8 weeks of age and 2, 4, 6 weeks of age in the same group, although increased with increasing in their ages. The complex and stable microflora in cecum had been established in Gushi chicken at 2 weeks of age.The results of this research indicated that Gushi chicken could tolerate high level crude fiber in diet and obtain the necessary nutrient from it, to maintain certain level nutrition in, and there were no significant effect on their body weight and body development without significant hyperplasia in digestive organs. Probably Gushi chicken acclimatized themselves to high level crude fiber in diets for a long time that adjustable variances had taken place in digestive system, that it could fully digest and absorb the nutrient from low quality diets to meet their requirements. It meant that high level crude fiber could be added into the Gushi chicken diets to decrease the product cost, the threshold of crude fiber Gushi chicken could tolerate in diet would be detected in further study.