Effects Of Grinding Particle Sizes Of Soybean Meal On The Nutrition Utilization Of Diet In Broilers

The effect of grinding particles sizes of soybean meal on the nutrient utilization of corn-soybean meal diets in broilers was studied by in vitro and in vivo methods.The grinding particle sizes and nutrition utilization of soybean meal were measured in vitro digestion trial. The particle sizes of soybean meal ungrinded and filtrated through 3.0mm, 2.0mm, 1.2mm and 0.8mm mesh sizes were determined by the fifteenth-sieve method, obtaining corresponding particle sizes of 2565μm, 529μm, 449μm, 334μm and 210μm. The average geometric particle sizes were significantly positive correlated with the grinding mesh sizes of hammer mill. Simulating the temperature and pH of the digestive tract in broiler, the five sizes soybean meals were digested in vitro adopting pepsin-trypsin method. The results showed: under the condition of 40℃, optimum pepsin concentration (75mg/ml) and trypsin thickness (110mg/ml), the digestibility of nutrition of soybean meal increased with the reducing of grinding particle sizes. The digestibility of crude protein, essential amino acids and dry matter of 449μm and below 449μm groups were significant higher than 2565μm, 529μm treatments (p<0.05).656 0-day-old AA broilers were randomly in vivo allotted to 4 dietary groups and replicated 4 times, which had 41 broilers, to carry out a 42-day feeding trial. At 42 days, one broiler was selected out from each duplicate of all treatments to study the effects of grinding particle sizes of the dietary soybean meal on the performance and digestion function of broilers by means of collection full excrements analysis method. The results showed: (l)In the starter phase there was no effect of soybean meal's particle sizes on the broilers performance (p>0.05). In the finishing phase and whole feeding period, the broilers performance of groups with 449μm and below 449μm were slightly superior to other treatments (p<0.05). (2)The digestibility of nutrition in vivo of different particle sizes soybean meal had more significant difference, the metabolizability of energy, the digestibilities of crude protein, dry matter and essential amino acids of 449μm dietary group were higher than 529μm and 210μm significantly (p<0.05), but didn't have difference to 334μm. (3)There were no effects of grinding particle sizes on the weight of proventriculus, the relative weight and length of duodenum, jejunum and ileum of42-day-old broilers (p>0.05). The gizzard relative weight of 210μm was higher than other groups, and was significantly differred with 334μm treatment (p<0.05). (4)Compared with 529μm, 334μm and 210μm treatments, the total protease activities in the jejunal contents of broilers of 449μm group was increased by 6.72%, 6.26% and 10.68%, respectively (p<0.05).