| The present study was about the connection between nutrients metabolize of the broilers and the levels xylan in the diet of xylanase. It was carried out to evaluate the effects of different levels xylan in the diet of xylanase on the metabolic rate of the DM (dry matter), energy, calcium, phosphorus and nitrogen, and founded the mathematics model of metabolic rate of nutrients, relationship of xylan levels of diets.Experiment 1: The D-xylose as the standard material, the orcinol?HCl as the display reagent, we had established a method to mensurate the content of the xylan in the feed raw materials by a dual-wave length spectrophotometry . In the response solution the D-xylose density is 0～100μg/ml, the change of the absorbency was accordant to Lambert-Beer law, the standard curve regression equation was y = 0.0039*x-0.0151(x was the double wave length extinction interpolation, r = 0.9972).The results indicated that this method was simple in operation, high in returns-ratio, well in the reproduction quality, small in the relative error. 10 kind of feed raw materials were mensurated in this method, the results showed that the content of the xylan in wheat, rice bran, corn, Soybean meal, barley, durra, bran, wheat-middlings, Cotton seed meal, vegetable seed meal were 6.88%, 15.06%, 4.54%, 5.81%, 6.70%, 2.69%, 16.78%, 9.09%, 12.64%, 8.21%, respectively.Experiment 2: This experiment was carried out to evaluate the digestion and metabolism method of hunger– feeding in short time training in broilers to mensurate metabolic rate of nutrients. 100 30-day-old commercial generation AA broilers which had the closely weight were randomly divided into two treatments (A and B), and each treatment contained 10 replicates. The treatment A broilers were given the hunger training in 5d through shorten the feeding time, then the broilers were given the hunger training through feeding 60min one day; the treatment B broilers were given the hunger training through feeding 60min one day.The results indicated that broilers could take the amount of diets which general metabolism experiment required, through appropriate hunger– feeding in short time training (the duration time was 5 days ago).Experiment 3 A simple factor design, 50 commercial generation AA broilers which had the closely weight and after the hunger training were randomly divided into ten treatments, and each treatment contained 5 replicates. The broiler of treatments 1-5 were feed five kinds basic diets which content of xylan (2.00%, 3.50%, 5.00%, 6.50% and 8.00%, respectively); the broilers of treatments 6-10 were feed on five kinds basic diets supplemented with xylanase.Results:(1)Diets which supplemented with xylanase could improve the metabolic rate of the DM, calcium, and phosphorus, the metabolic rate of the energy and nitrogen were no significantly different between control treatments and experiment groups, when the level of xylan which content in diets was lower than 5.00%. When the level of xylan was 2.00%, addition xylanase in diets could improve the apparent metabolic rate of the DM, calcium, and phosphorus were 9.09%(P<0.01), 15.02%(P<0.05), and 18.52%(P<0.01), respectively; and improve the true metabolic rate of the DM, calcium, and phosphorus were 3.76%(P<0.05), 16.32%(P<0.01) and 21.82%(P<0.01). When the level of xylan was 3.50%, addition xylanase in diets could improve the true metabolic rate of the DM and nitrogen were 4.42%(P<0.05) and 31.85%(P<0.01), respectively; and improve the apparent metabolic rate of the calcium and phosphorus were 19.53%(P<0.01) and 14.44%(P<0.05), respectively; the metabolic rate of every nutrients were no significantly affected by adding xylanase in diets, when the level of xylan higher than 5.00%.(2) The ture metabolic rate of the DM, phosphorus and energy had a negative linear correlation with the xylan levels of the diets, when level of xylan was 2.00～8.00%, the apparent metabolic rate decreases with the increase of the level of xylan, the regression equations: y=-119.4000x+90.0580 (R2=0.8841, P=0.0174), y=-237.0000x+68.4160 (R2=0.8138, P=0.0362) and y=-159.1333x+92.6567 (R2=0.9934, P=0.0002). A strong linear correlation was observed between the level of xylan and the ture metabolic rate of the DM, and phosphorus, the regression equations: y=-195.0667x+95.1793 (R2=0.8833, P=0.0176), and y=-547.3333x+90.9787 (R2=0.7991, P=0.0408), these regression equations could use when the level of xylan was 2.00～5.00%, because that supplemented with xylanase in the diets has no significantly effect on the metabolic rate of nutrients, but the ture metabolic rate of nutrients had no significantly improving by supplemented with xylanase in the diets.
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