Postpartum ovarian activity in Friesian cows under subtropical condition

الملخص EN

This investigation aimed to study cyclic and acyclic patterns of ovarian function in Friesian cattle.

Twenty one pregnant Friesian cows were taken randomly from a herd located at Sakha Experimental Station Animal Production Research Institute, Ministry of Agriculture, Egypt.

Cows were taken 15-20 days before the expected all mean length of regular normal progesterone cycles was 22.36 days with average progesterone peak concentration of 6.37 ng/ml.

calving day till two months of pregnancy.

Blood samples were withdrawn twice a week at 3-4 days intervals.

Plasma progesterone was determined using radioimmunoassay.

Heat detection was performed twice a day in all cows preconception.

Results revealed that the overall mean of postpartum anestrus period was 80.4 days.

During this period plasma progesterone was recorded at basal level (< 0.5 ng/ml), postpartum anestrus period was prolonged in the highly milk producing cows (91.88 vs 61.23 days).

The difference between low and high lactating cows in this respect was statistically insignificant.

Overall average length of postpartum to first ovulation interval was 116.3 days.

Postpartum to the first estrus interval averaged 127.0 days, while days open average 186.1 days.

Milk production had a significant (p < 0.01) effect on the postpartum to first ovulation and to first estrus intervals.

Number of ovulations and inseminations/conception were 3.9 and 2.35, respectively with insignificant effect of milk production on both traits.

The percentage of quiet ovulation was 41.7%.

This percentage was 71.4 , 42.1 and 27.3 % in the first, second and third postpartum ovulation, respectively.

Forty one percent of the short low peak progesterone cycles was 9.97 days in length with an average progesterone peak of 2.2 ng/ml.

Over all mean length of regular normal progesterone cycles was 22.36 days with average progesterone peak concentration of 6.37 ng/ml.