The Research Of Improvements Of The Zinc Nutritional Status Of Growing Pigs By Adding Phytase

This experiment includes two parts, simulating experiment and feeding experiment. gastric fluid digestion in vitro is used in the simulating experiment, and the spectrophotometer is used to determine the free zinc content in the gastric fluid. Experiment feed 1 is the pure corn-soybean meal diet, zinc oxide are added in the experiment feed 2 based on the feed 1. The content of free zinc in the gastric fluid is determined under the condition with and without phytase, thus the release quality of zinc level released by phytase can be measured. In the feeding expeiment, to explore the effects of the different levels of zinc on the growth performance, serum biochemical indicators and zinc deposition in serum and back hair of growing pigs, and to explore the effects of phytase on the the improvement of zinc nutrient level of growing pigs in production prictise, supplement with different levels of phytase (OFYT/kg,2000FYT/kg) and zinc (50mg/kg,80mg/kg, 110mg/kg) is added in feed of 85-day-old growing pigs. In this experiment,60 DurocxLandrace×Yorkshire three-breed cross growing pigs of 85±2 days old are selected from the Shenyang Xinmin Borui Agriculture and Animal Husbandry Science and Technology Co.,Ltd., the pigs are random grouped in 6 groups by the body weight, and the group size is 10 pigs. Growing pigs in Group I are fed low phytase (OFYT/kg) and low zinc (50mg/kg) level feed; Group II are fed low phytase (OFYT/kg) and medium zinc (80mg/kg) feed; Group III are fed low phytase (OFYT/kg) and high zinc (110mg/kg) level feed; Group IV are fed high phytase (2000FYT/kg) and low zinc (50mg/kg) level feed; Group V are fed high phytase (2000FYT/kg) and medium zinc (80mg/kg) feed; Group VI are fed high phytase (2000FYT/kg) and high zinc (110mg/kg) level feed. The experiment lasts one month. The body weight and feed intake of each pig are measured and recorded by the performance test station automatically.3 pigs are random selected in each group to collect precaval vein blood at the day before the experiment starts and the end of the day in the experiment, the enzyme activity of ALP, GSH-PX, LDH, CuZn-SOD and GSH-PX and the content of zinc and IgG level in the serum are detected, the white blood cell count in the whole blood are measured. At the same time, the back hair of each group are selected to detect the zinc deposition.The results show that:(1) The simulating experiment:The free zinc content in gastric fluid after not adding phyates and adding phyatse based on the experiment feed 1 are 2.21±0.02mg/kg and 39.20±0.13mg/kg. The free zinc content in gastric fluid after not adding phyates and adding phyatse based on the experiment feed 2 are 3.02±0.13mg/kg and 139.25±0.24mg/kg.(2) There are no significant effects of the different zinc levels on the growth performance of growing pigs.(3) The the activities of ALP and LDH results show that, the enzyme activities of the enzymes contain zinc are significantly increased with the increasing of zinc level, the level of AKP and LDH Ⅵ group compared with group Ⅳ increased by 35% and 45%(P<0.05),the level of AKP Ⅲ group compared with group Ⅰ increased by 74%(P<0.05).(4) The the activities of CuZn-SOD and GSH-PX results show that,the enzyme activities of antioxidant enzymes are significantly increased with the increasing of zinc level,the level of GSH-PX Ⅲ group compared with group Ⅰ increased by 95%(P<0.05),the level of GSH-PX Ⅵ group compared with groupⅣincreased by32%(P<0.05).(5) The IgG and the white blood cell counts results show that, there are no significant effects of the zinc level on the immune level of growing pigs.(6) The zinc content in the back hair and serum results show that, there are significant effects of zinc level on the zinc content in back hair, and the zinc content in back hair is significant increased with the increasing of zinc level in feed, but there are no significant effects of zinc level on the zinc content in serum.(7) The determination of nutrient substances in feed and feces results show that, there are no significant effects of zinc level on the digestbility of growing pigs.(8) According to results of the simulating experiment in vitro and the enzyme activities of enzymes contain zinc and antioxidant enzymes, phytase addition of 2000FYT/kg can replace the zinc supplement amount of 40mg/kg in the growing pig feed.To sum up, a high level of zinc can improve the enzyme activities of the enzymes contain zinc and the antioxidant enzymes, and it can increase the zinc deposition in back hair of growing pigs. Phytase addition of 2000FYT/kg can replace the zinc supplement amount of 40mg/kg in the growing pig feed.