Regulation Of New Heat-resistant Phytase On Growth Performance, Bone Development And Immune Function Of Weaned Piglets

The study was conducted to explore the new heat-resistant phytase（NHP）regulationof piglet on growth performance, bone development and immune function. The resultswould provide a theoretical basis for the applications of NHP in the piglet feed.Experiment I: Effect of NHP on growth performance serum biochemistryindexes and serum biochemistry indexes, and small intestinal mucosa morphologydevelopment of weaned pigletsThis experiment was conducted to study the effects of NHP on growth performance,Serum Biochemistry Indexes, and small intestinal mucosa morphology development of weanedpiglets by replacing part of calcium hydro phosphate by NHP in low phosphors diet. Atotal of256piglets weaned at30d of age (8.37±0.97kg of BW) were randomly allottedto4treatments with4replicates of16piglets using a randomized complete-block design,based on initial BW and sex. They were fed basal diet, low-phosphorus diet,low-phosphorus diet+500U/kg NHP, low-phosphorus diet+1000U/kg NHP,respectively.Results indicated that:1) Compared with low-phosphorus diet, supplementation of500U/kg or1000U/kg NHP improved average daily gain (ADG), but no difference amongeach treatment (P>0.05).2) There was no difference in the concentration of serum BUN,TP and ALB of treatment group (P>0.05).3) Compared with the low-phosphorus dietgroup, ileum villus length in control group and500,1000U/kg NHP group were increasedsignificantly(P <0.05). In conclusion, using NPH to replace part of phosphors in weanedpiglets’ diet almost do not affect growth performance, but could promote mucosal structureof small intestine in piglets on some degree. In addition,1000U/kg NPH is the mostappropriate option to replace phosphorus in diet.Experiment II: Effect of NHP on calcium and phosphorus metabolism andapparent nutrient digestibility of weaned pigletsThis experiment was conducted to study the effects of NHP on metabolism of calciumand phosphorus and apparent nutrient digestibility in weaned piglets by replacing part ofcalcium hydro phosphate by NHP in low phosphors diet. Grouping and diets are as same asExperiment I. The results as follows:1) Compared with low-phosphorus diet,supplementation of500U/kg or1000U/kg NHP improved Ca and P concentration, and coffin bone ash ratio, but there was no difference between them (P>0.05).2) There was nosignificant difference on serum Ca, P, and ALP concentration between each treatment (P>0.05).3) The phalanx section of piglets fed the diets supplemented NHP appeared thickercompact bone substance and higher cancellous substance density than those of controlgroups.4）The apparent digestibility of Ca, total phosphorus (TP), and dry matter (DM) ofbasal diet group,500U/kg NHP group and1000U/kg NHP group were greater than thoseof low-phosphorus diet group (P <0.05). In conclusion, by using NPH to replace part ofphosphors in diets could improve metabolism of calcium and phosphorus in piglets as wellas apparent nutrient digestibility. In addition,1000U/kg NHP is an appropriate choice toreplace phosphorus in diet.Experiment III: Effect of NHP on immune function and antioxidant capacity ofweaned pigletsThis experiment was conducted to study the effects of new NHP on immune functionand antioxidant capacity in weaned piglets by replacing part of calcium hydro phosphateby NHP in low phosphors diet. Grouping and diets are as same as Experiment I. The resultsshow that:1) Compared with the other groups, Morbidity rate in low-phosphorus diet groupis higher (P <0.05).2) The concentration of serum ALT, AST, IgG, IgA and IgM oftreatment group did not differ significantly (P>0.05).3) Antioxidant superoxidedismutase indicators(SOD), catalase(CAT), glutathione peroxidase (GSH-PX), glutathionereductase (GR) and malondialdehyde (MDA) had no significant differences in eachtreatment (P>0.05).(Conclusion) In conclusion, supplementation of NHP replace part ofinorganic phosphorus could not improve weaned piglets immunity and antioxidant capacity.So taking immunity and antioxidant capacity into consideration, the best dosage for PHYis1000U/kg.