Effect Of Fertilizer Treatment To Alpine Meadow On Antioxidant System Function In Yaks

To assess the impact of nitrogen (N) fertilization on concentrations of mineral in herbage and antioxidant function in yaks, three experiments were conducted in the Huanghe Shouqu grassland pasture area. In the fertilizing experiment, pasture replicates (80ha;n=2/treatment) received the same fertilizer treatment, consisting of I) 90 kg N/ha from ammonium sulfate ((NH₄)₂SO₄), â…¡) 90 kg N/ha from ammonium nitrate (NH₄NO₃), â…¢) 90 kg N/ha from urea (CO(NH₂)), and â…£) control (no fertilizer ). (NH₄)₂SO₄ contains 24% sulfate (S), therefore, (NH₄)₂SO₄ fertilized pastures received 103kg S/ha. Forage and soil sampling for mineral analysis were conducted at 30d intervals in the whole experiments period of 150 days. In the grazing experiment, eighty yaks, 3 to 4 y old, with similar body weight, nutrition, and development condition, were selected for the study. They were randomly divided into 4 groups, each consisting 5 yaks and were grazed in the fertilized pasture (Group â… , â…¡, â…¢, and â…£ for fertilizer treatment â… , â…¡, â…¢, and â…£, respectively). To determine the effect of fertilizer treatment on liver mineral concentrations in grazing yaks, random liver tissue samples were collected at 30d intervals. To determine the effect of fertilizer treatment on blood mineral contents, hemoglobin (Hb) contents, and antioxidant function, blood samples were collected at 30d intervals in the whole studies period of 150d. In the supplementing mineral experiment, 20 yaks with the contents of Cu, Se, or both Cu and Se lower than normal were obtained from the fertilized pastures. They were randomly divided into 4 groups and were fed for 50d with herbage from (NH₄)₂SO₄ fertilized pasture. Group I was used as control and received no Cu and Se. Group â…¡ was injected with 0.2% Na₂SeO₃ solution, 8ml/yak, in 10day intervals. Group â…¢ was supplemented with CuSO₄, 5g/yak , at 10 day intervals. Group â…£ was the combination of both group â…¡ and â…¢. To determine the effect of fertilizer treatment on liver mineral concentrations in yaks, liver biopsy collections were performed by a trained technician at 10 day intervals. To determine the effect of fertilizer treatment on blood mineral contents, Hb, and antioxidant function in yaks, jugular blood was collected in heparinized at 10 day intervals.In the fertilizing experiment, the results showed that the Mn contents of soil ingroup I was significantly lower (P<0.05) than those in other groups. There were not significant differences among other groups. The mean N concentrations in forage from group I, II, and III, was significantly higher (PO.01) than that from group IV. The mean S concentration in forage from group I was significantly higher (PO.01) than those from group II, III, and IV. The mean content of Mn in forage from group I was significantly higher (P<0.05) than those in other groups. The Zn content of forage from group I was significantly higher than that from group IV. But, no significant difference were found among group I, II, and III. The mean concentrations of Cu in forage from group I, II, and III were significantly lower (P<0.05) than that from group IV. But, there were no significant differences among group I, II, and III. The Se content of forage from group I was significantly lower (P<0.01) than those from other groups. There were significant temporal dynamics of mineral contents in forage.In grazing experiment, The Mn content of blood from fertilized pasture with (NH4)2SC>4 was significantly higher (P<0.05) than those from group II, III, and IV. The Zn content of blood from group I was significantly higher (P<0.05) than that from group IV, but no difference was found among blood samples from group I, II, and III. The Cu content of blood from group I was significantly lower (P<0.05) than those from group II or III and was significantly lower (P<0.01) than that from group IV. The Se content of blood from group I was significantly lower (P<0.01) than those from other groups, but, no significant differences were found among group II, III, and IV. The mean content of Mn in liver from fertilized pasture with (NH^SC^ was significantly higher (P<0.05) than those from group II, III, and IV. The Zn content of liver from group I was significantly higher (PO.05) than that from group IV, but no difference was found among blood samples from group I, II, and III. The Cu content of liver from group I was significantly lower (P<0.05) than those from group II or III and was significantly lower (P<0.01) than that from group IV. The Se content of liver from group I was significantly lower (PO.01) than those from other groups, but, no significant differences were found among group II, III, and IV. Tere were significant temporal dynamics of mineral contents in blood and liver. The activities of SOD and CAT in serum from group I were significantly lower (PO.01) than those from group IV, and significantly lower (PO.05) than those from group II or III. The SOD andCAT activities of serum from group II and III were significantly lower (P<0.05) than those from group IV. The activity of GSH-Px in serum from group I was significantly lower (P<0.01) than those from other groups, The Cp content of serum from group I was significantly lower (P<0.01) than that from group IV and was significantly lower (P<0.05) than that from group II and III. The MDA content of serum from group I was significantly higher (P<0.01) than that from group IV, and was signicantly higher (P<0.05) than those from group II and III. The content of MDA in serum from group II and III was significantly higher (P<0.01) than that from group IV. Tere were significant temporal dynamics of SOD, CAT, GSH-Px, Cp and MDA in blood.When the experiment ended, hemoglobin (Hb), mean corpuscular hemoglobin (MCH), mean corpuscular volume (MCV), and packed cell (PCV) from group I, II, and III were significantly lower (P<0.01) than those from group IV. The red blood cell (RBC) from group I, II, and III were significantly higher (P<0.01) than those from group IV. This indicated that the yaks from fertilized pastures were affected by hypochromic and microcytic.In the supplementing mineral experiment, the Cu contents of blood from group III and IV were significantly higher (P<0.01) than those from group I and II. The concentrations of Se in blood from group II and IV were significantly higher (PO.01) than those from group I and III. The Cu content of liver from group III and IV were significantly higher (PO.01) than those from group I and II. The Se concentrations in liver from group II and IV were significantly higher (PO.01) than those from group I and III. The activities of SOD and CAT from group III and IV was significantly higher (PO.01) than those from group I and II. The activities of GSH-Px from group II and IV was significantly higher (P<0.01) than those from group I and III. The Cp contents in serum from group I and II were significantly lower (P<0.01) than those from group III and IV, The MDA contents of serum from group II, III and IV were significantly lower (P<0.01) than those from group I.