| In order to study the variation characteristics and regularity of plasma leptin, glucose, calcium and phosphorus in prenatal and early lactation of Holstein cows, the effect of plasma leptin concentrations on other plasma indexes of Holstein cows, and the changes of plasma calcium in different storage conditions of Holstein cows. In this study, the author have been determined the concentrations of plasma leptin, glucose, calcium and phosphorus of 30 Holstein cows which in 2 to 4 parity and sampled every 7 days by jugular vein between one week before calving and 9 weeks postpartum. And determined 5 Holstein cows'plasma samples stored at room temperature,4℃and -20℃Storage 1 day,2 days,3 days,5 days,10 days,20 days,30 days and 50 days. The results shown that (ⅰ) the concentration of plasma leptin was lowest in the 1st week of postpartum (2.24±0.14 ng/mL), and began to increase at the 3rd week of lactation, peak at the 6th week (18.81±4.64 ng/mL), then gradually declined, and recovery to a lower level at the 8th week. The concentration of plasma glucose at the calving day was significantly higher than the other weeks (P<0.01). The lowest concentration of plasma calcium was at the first week of lactation, and then gradually recovered to normal, at the 6th week to reach the highest. The lowest concentration of plasma phosphorus was at one week before calving, (ⅱ) The higher leptin group (22) cows'maximum leptin concentrations during the experiment were higher than or equal to the value of 32.8 ng/mL, the lower leptin group (8) cows'leptin concentrations during the experiment were all lower than or equal to the value of 6.8 ng/mL. The concentration of plasma leptin in the higher leptin group was significantly higher than the lower leptin group at the 6th week of lactation (P< 0.05). (ⅲ) Overall experimental cows and the higher leptin group cows, plasma leptin were significantly correlated with plasma calcium. (ⅳ) it was probably that the abnormal increase of plasma Leptin concentration was relative to plasma glucose inhibition. (ⅴ) In the same conditions, the concentrations of plasma calcium are becoming lower with days past. And in the same time, the concentrations of plasma calcium are becoming lower with storage temperature increased. |
