| Two experiments were conducted with German-American crossbred growing rex-rabbits, to investigate the effects of supplementing lower phosphorus diet with either phytase,vitamin D3 (VD3),or their combination, on the performance and nutritive avlability by Rex-rabbits.In experiment 1,50 healthy rex-rabbits of three-month old approximate weight were assigned randomly into 5 group for a 6-week trial.The basical diet was composed of low-phosphorus.containing no phytase or dicalcium phosphate(CaHPO4), I, II, III, IV, V group was fed with basical diets adding 0, 400, 600, 800U/Kg phytase and 1.8 % CaHPO4 respectively. The main results obtained were showed as follows: (1) Dietary phytase had promoted the average daily gain but had no obvious effect on the average daily feed intake and the feed-meat ratio of rabbits(p>0.05).In comparison to I group , the average daily gain of group II, III, IV, V increased by 1.65%(p>0. 05), 5. 77%(p>0. 05), 11. 48%(p<0. 05) and 5. 57%(p>0. 05), among all the groups, III, IV group had no significant difference compared with V group(p>0.05).(2) Dietary phytase remarkably reduced the excretion of phosphorus :Compared with V group.the excretion of total phosphorus(TP) of I , II, III, IV groups decreased by 28.24%(P'<0.01), 30.59%(P<0.01), 42.35%(P<0.01), 47.00%(P<0.01) respectively and it was shown obvious difference bewteen group I and IV (P<0.05); the excretion of phytate phosphorus(PP) decreased by 11.1% (P>0.05), 19.4% (P>0.05), 25% (P<0.05), 33.3% (P<0.01) ,respectively,the fourth group was much lower than other three groups (P<0.01); the calcium(Ca) excretion of I, II,III, IV groups were in the downward trend.the fourth group was the lowest,reduced by 19.08% compared with group V (.P<0.05), however other groups had no significant difference compared withV group(p>0.05); The increasing level of dietary phytase decreased the excretion of Zinc(Zn), Manganese(Mn)and increased the excretion of Copper(Cu),but the difference among all the groups was not significant (P>0.05); (3)Supplemental phytase remarkably increased the utilization of phosphorus: Compared with I group.the apparent digestibilities of TP of group IK III, IV increased by 17.33% (P>0.05) ,39.90% (P<0.05),47.67%(P<0.01), but the differences between III, IV, V were not obviously (P>0.05) ; the apparent digestibilities of PP increased by 31.58% (P<0.05), 52.81 % (P<0.01), 65.92% (P<0.01), the PP apparent digestibilities of these groups increased by 23.21% (P>0.05) , 43.09% (P<0.05) , 55.36% (P<0.01) compared with group V; With the increasing level of dietary phytase and with adding inorganic sources in the diets,the apparent digestibilities of Ca,CP increased slightly also (P>0.05) .(4)The tibial ash content of II. III, IV groups were improved remarkably compared with I group, the fourth group was the highest,but it had no obvious difference compared with V group(p>0.05); With the increasing level of dietary phytase,the tibia Cu content of II, III, IV groups were in the down trend, the tibia Cu content of IV groups was much lower than that of V group (pO.05),but had no significant difference compared with the other groups(p>0.05); Among all the groups, there were no significant difference in the tibial Ca,P,Zn,Mn content and the tibial strength as well as the liver Cu,iron(Fe),Zn,Mn content (p>0.05). (5) Phytase Supplementation had no obvious effect on the level of serum calcium and serum phosphorus, the activities of alkaline phosphatase in the serum ,slaughting performance and the carcass qualities (P>0.05) .In experiment 2, 40 healthy rex-rabbits of three-month old approximate weight were assigned randomly into 4 group for a 6-week trial .This experiments was arranged as a 2 X 2 factorial to determine the effects of phytase and VDa.alone and in combination ,on performance and nutrient avalability by growing Rex Rabbits. The basical diet was composed of low-phosphorus,containing no phytase and VDs.The control group was fed with basical diet,the others were fed with basical diets adding 600U/Kg phytase, 1800IU/Kg VD... |
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