Study On Changes And Correlation Between Nutritional Status And Antioxidant Performance In Dairy Cows At Different Lactation Stages

The study selected the cows in different lactation stages as experimental animals to research the influence of lactation stage and milk production on nutritional status indicators and antioxidant indexs,and to analyse the correlation among them.All of these results can provide basis for scientific evaluation of the nutritional status and reasonable ration formulation with dairy cows.The paper consists of two parts.Experiment 1 was carried out to research the influence of different lactation stage and yield on nutritional status indicators and antioxidant indexes. Two factors completely randomized experimental design was adoped. One of the factors was stage of lactation (pre-perinal, postnatal, early lactation, mid-lactation and late lactation). The second factor was milk production, including high-yielding and low-yielding.Nutritonal status indicators consist of AKP, BUN, NEFA, GLU, VA, VE etal. Antioxidant indexs are composed by MDA, CAT, T-SOD, T-AOC, TrxR, GSH-PX.Experiment 2 was conducted to analyse the correlationship between nutritional status indicators and antioxidant indexes. Including two parts:the correlation ship between serum concentration of minerals and antioxidant indexes;the correlationship between vitamin A, E, free fatty acids (NEFA), β-hydroxybutyric acid, AKP, BUN, or GLU and the antioxidant indexes.The main conclusions were included as follows:The econtents of BUN, NEFA, P-hydroxybutyric acid in serum of high-yielding dairy cows were significantly or tend to significantly higher than that those of low-yielding dairy cows (P<0.05,0.05<P<0.10).AKP activity and the contents of BUN were higher in serum of dairy cows in the middle lactation period and it was lower in dairy cows in the post-perinatal period. The content of NEFA was higher in dairy cows in the post-perinatal and the later lactation period, it was lowest in pre-perinatal period; β-hydroxybutyric acid content was higher in post-perinatal period, and it was lower in other period.The lactation stage and milk vielding production have significantly interaction effects on the concentration of NEFA and β-hydroxybutyric acid in serumof dairy cows (P=0.05, P=0.005). The content of NEFA was higher in serum of low-and high-yielding dairy cows in the post-perinatal period. For low-yielding dairy cows which it was lower in the pre-perinatal period. The content of β-hydroxybutyric acid was higher in high- yielding dairy cows in post-perinatal period, in low-yielding dairy cows which it was also lower in pre-perinatal period.The serum antioxidant index has significantly differences in dairy cows in different lactation stages. The activity of CAT was higher in dairy cows in post-perinatal period and lower in middle lactation stage; the content of MDA in serum of dairy cows in pre-perinatal stage was lowest, it was higher in later lactation and early lactation period. The activity of T-AOC in serum of dairy cows in early lactation stage was highest, and lower in post-perinatal period. The activity of T-SOD was highest in the later lactation period, it was lower in post-perinatal and middle lactation period. The activity of GSH-PX was lowest in the middle lactation period and highest in pre-perinatal stage. TrxR activity in serum was highest in later lactation period, and lowest in the pre-perinatal period.The lactation stage and milk yielding production have significantly interaction effects on the activity of CAT, GSH-PX, TrxR and the content of MDA in serum of dairy cows (P<0.05)The content of Ca was highest in later lactation period, while lower in early lactation and post-perinatal period; The level of P was higher in the middle lactation period and lower in later lactation and post-perinatal period; The concentration of K was higher in pre-perinatal period and lower in early stage; The content of Mg was higher in early and middle lactation period.The content of Cd was higher in serum of dairy cows in the middle lactation period, which was lower in post-perinatal period; the content of Co was lower in serum of dairy cows in post-perinatal period, which was and higher in pre-perinatal period; the content of Cr was higher in early lactation period, lower in pre-perinatal period; the contents of Mo, Pb, Cu, Fe, Mn, Se was higher in serum of dairy cows in later lactation period, and Mo, Cu content were lower in pre-perinatal period, the contents of Pb, Se were lower in the early lactation period, the content of Fe was lower in the middle lactation period, Mn content was lower in the post-perinatal period; the content of Zn was lower in the pre-perinatal period and higher in the middle lactation period.The contents of VA and VE were lower in serum of dairy cows in the post-perinatal period, the content of VA in serum of high-yielding dairy cows was significantly higher than that of the low-yielding dairy cows.The content of Cu and Se in serum had a positive association with CAT, TrxR, T-SOD activity; There was a positive correlation between Zn, Mn content and TrxR, T-AOC, T-SOD, GSH-PX activity; Fe content had a positive association with CAT and T-AOC in low- and high- yielding dairy cows; Negative correlations were found for Co content and CAT, T-AOC, T-SOD activity as well as MDA content in dairy cows.The content of VA was positively or tended to positively correlate with T-AOC and T-SOD; There was a positive correlation between VE content and TrxR activity; The content of NEFA was positively or tended to positively correlate with MDA, CAT, TrxR and T-SOD; The concentration of β-hydroxybutyric acid had a negatively correlation with T-SOD, TrxR and T-AOC; The content of AKP was tended to positively or positively correlate with TrxR and T-SOD activity; The content for BUN was negatively related to the activity of CAT,T-SOD and GSH-PX; The content for GLU in dairy cows was positively related to CAT, TrxR activity and MDA content.