author(s)
Prabaharan Vaiyapuri, Palanisamy Mahakrishnan and Satheshkumar Soundarapandian

abstract
Supplementing exogenous Progesterone (P₄) during the early luteal phase shall increase the conception rate among the repeat-breeding cows. The present study was undertaken to compare the efficacy of the P₄ impregnated intra-vaginal sponge (PIVS) which were used fresh and after storage, on fertility in repeat breeding cows. A total of 40 repeat breeding cows were selected and divided in to four groups randomly. Group I (n=10): Freshly purchased PIVSs were used; Group II (n=10): PIVS were stored for 6 months after purchase and utilized; Group III (n=10): PIVS were stored for 12 months after purchase and utilized; Group IV (n=10): No P₄ supplementation(Control). The sponges were kept intravaginaly from Day 6-16 post insemination. Pregnancy diagnosis was performed 28-35 days after insemination. Blood samples were collected on Day 6 and Day 10 post insertion of the vaginal sponge for P₄ hormone estimation. There was a significant decrease (P<0.05) in P₄ concentration on day 16 in both the pregnant and non pregnant animals of Group III when compared to Group I. There was no significant increase in P₄ concentration in the control group in both pregnant and non-pregnant animals when compared between days 6 and 16. Even though higher fertility rates were observed in Group I, when compared to the other groups, it does not differ significantly at P<0.05 level. Based on the study, Progesterone impregnated intra-vaginal device may be used for increasing the conception rate in repeat breeding cows which are better to use within 6 months after production. Suitable adjuvant may be added to improve the keeping quality of the Progesterone impregnated intra-vaginal device for more than 6 months.