Effects Of Supplemental Phytase On Performance And Nutrient Utilization Of Growing Pigs

The present study concentrated on the effects of phytase supplementation on the performance, nutrient utilization, serum metrits and phosphorus faecal excretion in corn-soybean meal-cottonseed meal diets for growing pigs. Meanwhile, in these experiments two levels available phosphorus (AP) (0.16%, 0.25%), two levels Ca (0.53%, 0.69%), two levels crude protein (CP) (15.2%, 16.9%) were designed so as to investigate the effects of these factorials on bioavailabilities of phytase.Experiment 1. 2×2 factorials rearing experiments were conducted. Thirty-two crossbred pigs with 25kg body weight (BW) were used to investigate the effects of phytase, P level and their interaction on growing performance. These pigs were randomly arranged to 4 groups with 8 replicates of 1 pig. There were 4 treatments with 2 dietary levels of AP (0.16%, 0.25%) and 2 levels of phytase supplementation (0, 500FTU/kg). The basic diet was formulated as recommended by National Research Council (1998). The results showed that phytase supplementation improved average daily weight gain by 0.765% and decreased ADFI, F/G and feed cost per kg of body gain (CPG) by 4.08%, 4.82% and 4.04% respectively. The decrease of dietary AP resulted in the reduction of ADG and ADFI by 21.83% (P<0.01) and 5.9%, increase of F/G, CPG by 20.0% and 19.9% respectively. Pigs fed with 0.25% AP diet had superior performance to pigs fed with 0.16% AP diet added with phytase.Experiment 2 and experiment 3. Two balance experiments using 48 pigs same with experiment 1 were carried out to study the effects of dietary Ca and dietary protein on bioavailabilities of phytase. Each experiment has 3 treatments 8 replicates of 1 pig. At the end, 3 trial male pigs were selected randomly from each group to conduct the metabolism experiment.What can be conclude from the results is as follows:1. Performance and nutrient utilization. Pigs fed with AP (0.16%) and Ca (0.53%) diet added with phytase (500FIU/kg) had the best performance and nutrient utilization. Especially, the digestion of energy was improved by 4.23% (P<0.05). P digestibility (PD) and P retention (PR) was improved significantly (54.4%, 56.5% respectively). Pigs fed with AP (0.16%) and CP (15.2%) diet added with phytase and Lysine AA had better performance, but little inferior nutrient utilization to pigs fed with 0.16% AP diet added with phytase.2. Plasma biochemical parameters: All of three experiments shows that biochemical parameters in serum were not significantly affected by phytase supplementation, although serum P, serum BUN and serum GLU concentration tended to increase, serum AKP activity tended to decrease of pigs fed with diet added phytase.3. Environmental protection. Phytase supplementation decreased P and Ca faecal excretion by 16.7% (P<0.01) and 7.9% (P<0.05).