Effects of Low Levels Zinc Polyaspartic Acid on Growth Performance,Blood Parameters,Tissue and Organ Zinc Accumulations and Zinc Emission of Growing Pigs

This experiment was conducted to study the effects of zinc polyaspartic acid (PASP) monohydrate on growth performance,nutrient apparent digestibility, serum indexes, tissue and organ zinc accumulations and zinc emission of growing pigs, and to determine the substitution effect of zinc polyaspartic acid for zinc sulfate. Ninety Duroc×Landrace×Large White growing pigs with the body weight of (31.73±3.50) kg were randomly assigned into 3 groups with 6 replicates per group and 5 pigs per replicate. The zinc level and source of the control group was 80 mg·kg^-1 zinc sulfate, while group Ⅰ and group Ⅱ were 60 and 40 mg·kg^-1 zinc polyaspartic acid monohydrate， respectively. Pre-trial period was 7 days, and formal experiment period was 30 days. The results showed as follows: 1) There was no significant difference in average daily gain, feed to weight ratio and diarrhea rate among control group and test groups (P>0.05). 2) The calcium (Ca) apparent digestibilities of test group I and test group Ⅱ were significantly higher than that of the control group (P<0.05); There was no significant difference among groups in apparent digestibility of crude protein (CP), crude fat (EE), crude fiber (CF), crude ash (Ash) and phosphorus (P) (P>0.05). The apparent digestibility of zinc in the test group Ⅰ was significantly higher than those of the control group and the test group Ⅱ (P<0.05). 3) Compared with the control group， the fecal zinc content in the test group Ⅰ and Ⅱ were decreased by 21.65% and 30.87%, respectively, and the difference was significant (P<0.01). 4)The glutamate transaminase (ALT) activity of control group was significantly higher than those of test group Ⅰ and Ⅱ(P<0.05), the globulin(GLB) level of test group Ⅰ was significantly higher than those of control group and test groupⅡ(P<0.05), the indexes of blood glucose (GLU), total protein (TP), albumin (ALB), total cholesterol (TC) and alkaline phosphatase (AKP) were not significantly different among groups (P>0.05). 5)There were no significant difference of the zinc accumulations in liver, kidney, spleen, pancreas, bone, hair, longgissimus dorsi among groups (P>0.05), the serum zinc concentrations of test group Ⅰ and Ⅱ were significantly higher than that of control group (P<0.05). In summary, under this experimental condition, 40 mg·kg^-1zinc polyaspartic acid monohydrate could satisfy the needs of growing pigs at this stage, the fecal zinc content was significantly reduced, thus proving the feasibility of adding polyaspartic zinc instead of high dose zinc sulfate in growing pigs’ feed, and the emission reduction of zinc.