Factors to Assess for Re-breeding after Parturition in Milking Cows

The purpose of this study was to assess for re-breeding concentrate period in postpartum in milking cows. The 48 cows aged $3.5{\sim}5.5$ years and of $400{\sim}600\;kg$ body weight were examined every 3rd day from 15 to 36 day postpartum. Blood samples for progesterone and estradiol $17{\beta}$ hormone analyses were withdrawn from the coccygeal vein every third day until the end of the experiment. The ovarian follicular numbers were verified and measured using a multi frequency probe. The least squares means are presented for each day by GLM of SAS. The results showed that ovary lengths (right ovary; $1.64{\pm}0.62\;cm$, left ovary; $1.44{\pm}0.46\;cm$) were similar in right and left ovary activity level during estrous cycle of postpartum cows. We were judged completed uterus on day at $2.31{\pm}0.17\;cm$ level of cervix diameter. And we were monitoring started at $6.44{\pm}2.03\;cm$ from day 15 after postpartum. The results showed that mean plasma concentration of progesterone (3.28 ng/ml) in large follicle gradually increased days 30 in postpartum. And, monitoring of estradiol 176 (22.18 pg/ml) hormone during postpartum period would be useful to predict the ovarian and uterus activity for re-breeding in postpartum milking cows. From these results, we conclude that cervix diameter (mean: 2.31 cm) was very important for reproductive organ recovery standard level of postpartum milking cows, hormone secretion level ($P_4$: 3.28 ng/ml, $E_2$: 22.18 pg/ml) and body condition score ($2.5{\sim}2.75$) level about 30 days in postpartum period.