Studies On Bio-detoxification Of Cottonseed Meal And Its Application In Broiler Diets

The microbe which can degrade free gossypol(FG) in cotton seed meal(CSM) was screened in this study, and optimal fermentation parameters for bio-degradation of FG was studied.The result showed substrate:water (moisture)1:0.94, fermentation time62.33h, material adding 30.96g/150mL, inoculum size 10%, wheat bran 20% where the elimination rate of FG was maximized to 86%.Animal experiment was also conducted to study effects of fermented cottonseed meal(FCSM) in diets on broilers. It showed that growth performance, meat quality, immune organ indices, apparent protein and enegy digestibility were not affected(P>0.05) in FCSM groups compared to the control, and viable count of Lactobacillus was enriched and E.coli was reduced significantly when birds fed a diet containing 20% FCSM. In conclusion, the optimum added proportion of FCSM was 20%.Experiment 1. The Screening of Microbe for Detoxification of Free Gossypol in Cootonseed MealThis experiment was conducted to screen a microbe which can degrade FG in CSM.The liquid-state CSM culture without other carbon source was used to screen the microbe needed from 9 strains, 25~28℃, 250 r/min, and FG level was determined after 48h shaking culture, the result showed Candida utilis can degrade 70% FG in CSM, and no difference was observed in other 8 strains, then Candida utilis was used to ferment CSM in solid state substrate, 28℃, FG level was determined in fermented substrate after 48h static-culture. The result showed that elimination rate was around 65%~70%. The tested Candida utilis in this trial could largely degrade FG in CSM.Experiment 2. The Optimization for Bio-detoxification of Free Gossypol in Cottonseed MealThe optimal condition for biodegradation of FG was studied. Plackett-burman and response surface analysis method were applied to optimize fermentation parameters. The results indicated the elimination rate was mainly influenced by moisture, material adding,and fermentation time by Plackett-burman.In the second step, the levels of those three main factors were further optimized by using Box-Behnken design, the optimal levels of the variables were as follows: moisture 48% (water:substrate=0.94:1), material adding 30.96g, fermentation time 62.33h. Under the optimal conditions, the elimination rate was increased by almost 20%, up to 85.99%. At three fermentation batches under optimization, the experiment values were almost close to the predictive values. After fermentation, the crude protein level was not affected, and soluble protein was enhanced from 6.96% to 10.2%, some essential amino acids levels were also increased, but arginine was decreased. After optimization, FG was reduced largely, and the quality of cottonseed meal was improved remarkably.Experiment 3. Studies on Application of Fermented Cottonseed Meal in Broiler DietThis experiment was conducted to study the effects of fermented cottonseed meal (FCSM) in broiler diets on growth performance, meat quality, immune organ and digestibility of gross energy and crude protein.A total of one hundred and ninty-two day-old broiler chickens were alloted to 4 treatments with 6 replicates of 8 chickens each. The experiment lasted 6 weeks. The dietary treatments were: (1) 15% FCSM; (2) 20% FCSM;(3) 30% FCSM ; (4) the control (corn-soybean diet without FCSM) . The result showed no significant differences in growth performance were found between FCSM and the control group (P>0.05). Compared with the control, meat quality, immune organ and metabolism of gross energy and crude protein in broilers of FCSM groups were not affected (P>0.05). Taking economic cost into consideration, the optimum added amount of FCSM was 20%.Experiment 4. Effect of Fermented Cottonseed Meal on Intestinal Microbial Flora in BroilersThe effect of FCSM on intestinal microbial community in broilers was studied by traditional method and denaturing gradient gel electrophoresis (DGGE) analysis of 16S ribosomal RNA. A total of one hundred and ninty-two day-old broiler chickens were alloted into 4 treatments with 6 replicates of 8 chickens each.The experiment lasted 6 weeks. The dietary treatments were: (1) 15% FCSM; (2) 20% FCSM; (3) 30% FCSM ; (4) the control (corn-soybean diet without FCSM). At the end of the experiment, 24 randomly selected chickens from each replicate were sacrified to study microflora of caecum contents. The traditional method showed that compared with the control, FCSM groups did not affect Bifidobacterium enumeration (P>0.05), whereas, viable count of Lactobacillus was enriched and E. coli was reduced significantly when birds were fed diets containing 15% and 20% FCSM(P<0.05). DGGE analysis showed there were no abnormity of the microflora in the cecum. In conclusion, FCSM can improve intestinal micro-ecosystem, increased beneficial bacteria and reduced harmful bacteria.The optimum added amount of FCSM was 20%.