| In this thesis,five bulk feed ingredients,corn,wheat,soybean meal,wheat bran and rapeseed meal,were used to determine the correlation between the state characteristics of the ingredients and the nutritional level by measuring the basic characteristics and rheological properties of the ingredients;the rheological parameters were obtained by fitting each ingredient to the Bingham fluid model.The correlation between feed state characteristics and nutritional level was further investigated by using the above-mentioned bulk ingredients to obtain compound feeds.After the establishment of the method for the determination of the digestive tract cereal state characteristics of broilers,the effects of different wheat contents in the diet on the growth performance,intestinal performance and cereal state characteristics of yellow-feathered broilers were investigated.Experiment 1.Study on state characteristics of 5 kinds of feed ingredientsAnalysis of the state characteristics and nutrient composition of the five raw materials showed that the pH values of corn,rapeseed meal and soybean meal were high and the pH values of wheat and wheat bran were low;the bulk and specific gravity were wheat > corn >soybean meal > rapeseed meal > wheat bran,and there were significant differences(P < 0.05)between the bulk of each raw material,while there were no significant differences(P > 0.05)between wheat and corn,corn and soybean meal,soybean meal and rapeseed meal.(P > 0.05);as the particle size of each raw ingredient gradually became smaller after crushing,the resting angle of each feed ingredient increased significantly(P < 0.05)and the stacking performance was enhanced;the viscosity of different ingredients differed,with the apparent viscosity of wheat being significantly higher than the other four ingredients(P < 0.05),and the viscosity of ingredients with particle sizes of 0.15 mm were significantly higher compared with the rest of the ingredients(P < 0.05);the resting angle of ingredients showed a significant positive correlation with its crude starch content,with a correlation coefficient of 0.72(P < 0.05),and a significant negative correlation with its crude protein content(P < 0.05),and the correlation coefficient varied less with particle size.Experiment 2.Study on state characteristics of 15 different formulations of broiler compound feedsThe analysis of the state characteristics and nutrients of 15 broiler diets showed that the resting angle of wheat-based diets was significantly higher than that of wheat-free diets(P <0.05);in the wheat-free diets,the content of soybean meal had a great influence on the change of resting angle,and the resting angle became smaller as the content of soybean meal increased(P < 0.05).There was a significant negative correlation(P < 0.05)between feed viscosity and crude ash,with a correlation coefficient of-0.55;a significant positive correlation(P < 0.05)between crude fiber content and both feed viscosity and angle of repose,with correlation coefficients of 0.59 and 0.63,respectively;and a significant positive correlation(P < 0.05)between feed viscosity and angle of repose,with a correlation coefficient of 0.85.Both corn and soybean meal showed negative correlations with the viscosity and resting angle of the compound feed,with corn showing stronger negative correlations(P < 0.05)with correlation coefficients of-0.95 and-0.77,and soybean meal showing a significant negative correlation with the resting angle with a correlation coefficient of-0.59.The correlations between wheat content and the viscosity and resting angle of the compound feed were both the correlation coefficients were as high as 0.97 and 0.87,with strong positive correlation.Experiment 3.Comparison of chyme status characteristics in different parts of digestive tract of broilersA method was developed to determine the state characteristics of broiler digestive tract surimi,showing that the size area of broiler musculo-gastric surimi particles as a percentage of the size over that area is consistent with the Rosin-Rammler model and can be used to determine the median surimi particle area and size distribution uniformity index;the DM content of chyme in each digestive tract of broilers was significantly different(P < 0.05);the pH of chyme in the ileum of broiler chickens was significantly lower than that in the duodenum and cecum(P < 0.05);the flow curve of chyme in the digestive tract of broiler chickens conformed to the Cross-Williamson model,and the zero-rate viscosity after fitting the equationα was cecum > ileum > jejunum > duodenum in descending order,with significant differences among all segments of the intestine(P < 0.05);the relaxation time of cecum chyme was significantly higher than the other three groups(P < 0.05).Experiment 4.Effects of different wheat content diets on growth performance,intestinal morphology and chyme status characteristics of yellow-feathered broilersIn yellow-feathered broilers fed different wheat-added diets,a significant increase in FCR(P < 0.05)and a significant decrease in ADG(P < 0.05)were found in each wheat diet group compared to the control group for the stages 1-21 d,22-42 d and the whole feeding period 1-42 d;cardiac index,spleen index and bursal index were significantly increased(P < 0.05);serum T-AOC,GSH-Px and T-SOD contents were significantly increased(P < 0.05);all groups of broilers showed a decrease in intestinal sex after the addition of wheat;with the increasing wheat content in the diet,the particle area of myogastric chyme in yellow-feathered broilers was significantly higher(P < 0.05),and the area distribution was more concentrated.the DM content and pH value were significantly lower(P < 0.05);the flow curve of the chyme was fitted to the Cross-Williamson model,which showed that the viscosity of the chyme increased significantly and the elasticity decreased significantly after the addition of wheat(P< 0.05). |
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