| Three series of trails were conducted to estimate the phosphorus bioavailability in feedstuffs for pigs.the measurements were digestibility,dialyzability,absorptivity respectively, digestibility and dialyzability were compared with digestability,the relativity between the results and relevant digestibility were analyzed respectively,test the feasibility of everted gut sacs,then screen out a more appropriate in vitro method for phosphorus bioavailability of plant-origin ingredients.In Exp.1,digestibility of phosphorus in feedstuffs were measured by metabolic balance technique.Thirty-six crossbred pigs(Duroc×Landrace×orkshire) with an average initial weight of about 40kg were aUoted to four treatments randomly,each treatment has three replicates of three pigs.The treatments were designed in a 2×2 factorial arrangement,and were as follows:(1) wheat diet whiout additional phytase,(2) wheat with additional phytase(947FTU/kg in totally, substitute 0.7g/kg phytase,the same as below),(3) rough rice without additional phytase,(4) rough rice with additional phytase.The results showed that:(1) The ADG was not numerically different among the treatments(P>0.05),the ADFI of treatment 1 were the best among the treatments(P<0.05),the F/G of treatment 1 lower than treatment 2 and treatment 3 significantly(P<0.05).(2) the type of diet had no significant effect on the apparent digestibility of phosphorus(P>0.05),addition of phytase can increase the apparent digestibility of phosphorus in the same diet(P<0.05).In Exp.2,dialyzability of phosphorus in feedstuffs were measured by artificial membranes. 39 artificial membranes were allotted to 13 treatments,each treatment has three replicates.The treatments include 4 diets which demonstrated in experiment 1 and 9 plant-origin ingredients, they were corn,soybean meal,wheat middling and reddog,wheat bran,wheat,rough rice,cottonseed meal,rapeseed meal and rice bran respectively.The results showed:1) The dialyzability of 4 diets were 5.91%,10.58%,7.58%,11.13%,the dialyzability of 9 plant-origin ingredients were15.54%,9.55%,31.37%,20.09%,11.28%,13.92%,11.38%,14.70%,10.67%respectively;2) The type of diet had no significant effect on the dialyzability of phosphorus(P>0.05),addition of phytase can increase the dialyzability of phosphorus in the same diet(P<0.05);3) The dialyzability of phosphorus of 9 plant-origin ingredients has relativity with their apparent digestability and true digestability,the correlation coefficient are 0.608 and 0.644 respectively.In Exp.3,absorption of phosphorus in feedstuffs were measured by everted gut sac.The treatments were the same as experiment 2.The experiment were divided to two steps,step 1, confirm the optimum incubated time of everted gut sac,the incubation time of 5 treatments was 20,30,40,50 and 60min respectively.Step 2,Investigate the absorption of feedstuffs in pigs' intestine under the primest incubated time.The result showed:1) the absorption of phosphorus was arising in the former 40min,then started to decline.So,40min was chosen to be the incubated time of step two.2) absorption of phosphorus in 4 diets were 40.11%,51.02%,21.15%,48.74%respectively,which in 9 plant-origin ingredients were 42.28%,19.05%,36.65%,31.81%,48.04%,47.33%,32.23%,46.29%,32.31%respectively.3) In the situation of no phytase addition,the absorption of phosphorus in wheat diet higher than that in rice diet significantly(P<0.05),the addition of phytase can significantly increase the absorption phosphorus in diets.In a word,the experiment showed that,the correlation coefficient of dialyzability and absorptivity with true digestability were higher than that with apparent digestability,thereinto, the correlation coefficient between absorptivity and true digestability was the highest.Everted gut sac can measure the phosphorus bioavailability more accurately. |
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