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Abstract
SUMMARY
Infertility in cows is a multifactorial disorder that attracts attention of many researchers in recent years to study. The main objective of the present study was to reveal the role of oxidative stress in relation to ovarian activity during the peripartum period as well as anestrous associated with various reproductive disorders.
The present study was carried out on 96 native cows (2-6 years). Animals in this study were categorized into two groups. The first group (Experimental cows n =16) these cows were sampled with 10 days interval starting 20 days before parturition till the first PP behavioral estrus associated with ovulation. Six cows from this group were selected for ultrasonographic examination to follow up the ovarian changes till the first PP behavioral estrus associated with ovulation. The second group (Field cows n=80) which includes cows with history of infertility problems. This group also classified according to field history of reproductive status, according to age, parity and open days (months).
Heparinized blood samples were collected from all cows in all groups, plasma separated, stored at -20° C till the time of biochemical analyst was clear from the ultrasonographic examination to six cows in the first group that three cows of these cows haven’t CL and the rest had short lived CL (transient) with a life span of 7.3±0.58 day, presence of that CL resulting in prolongation of the post partum anoestrus period. In all cows follicular growth was detected 4-5 days postpartum and dominant follicle of the first follicular wave reached its maximum diameter (10.42 ± 0.34 mm) at 9.3±0.06 days postpartum. Moreover the first postpartum behavioral estrus observed at 35-47 days in all six cows. Three or four waves were noticed during this period, and the duration of second follicular wave was the longest period 18 days. The average diameters of the dominant follicle were increasing gradually till ovulation 10.95 ± 0.51, 13 ± 0.95, 15 ± 0.11 mm. Positive correlation was present between the diameter of follicles, vitamin E, and a negative correlation was present with vitamin C and NO production.
Concerning the first group (Experimental cows n =16), marked decrease in levels of β-carotene, vitamin A and E was noticed at the day of parturition. On the other hand vitamin C and NO decreased gradually till reached the minimal concentration at the day of estrus.
In the second group (Field cows n=80), significant decrease plasma level of β-carotene, vitamin A and E was noticed in anestrous cows with history of different reproductive disorders. Marked increase in NO in aged cows more than 4 years, significant reduction of β-carotene and vitamin E in young cows less than 4 years. Cows with more than three parities have significantly higher levels of NO than cows with one or two parities