7 OESTRAL RESPONSE AND FERTILITY IN DAIRY COWS TREATED WITH PROGESTERONE FOR 6 DAYS PRIOR TO OESTRUS SYNCHRONIZATION WITH PROSTAGLANDIN F2α
M. Orozco A , C. G. Gutierrez A , R. Lopez A , C. Aguilar A , C. Roque A and J. Hernandez-Ceron AFacultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Avenida Universidad 3000, México
Reproduction, Fertility and Development 26(1) 118-118 https://doi.org/10.1071/RDv26n1Ab7
Published: 5 December 2013
Abstract
The present study tested whether the increase in serum progesterone concentrations for 6 days before oestrus synchronization with prostaglandin F2α (PGF2) increases oestral response, pregnancy rate, and reduces the incidence of twin births in dairy cattle. Seven hundred and eighty-three first-service dairy cows were synchronized with 2 injections of PGF2 14 days apart, starting on Day 35 postpartum. Six days before the second PGF2 injection, cows were assigned to 2 groups: P4 and control. The P4 group (n = 387) received a progesterone-releasing intravaginal device and an intramuscular injection of 500 mg of progesterone. The control group (n = 396) did not receive the progesterone-releasing intravaginal device or progesterone injection. Cows were inseminated 12 h after exhibiting oestrus. Pregnancy diagnosis was performed 40 and 45 days after insemination by rectal palpation and the cumulative pregnancy rate on Day 90 postpartum was determined retrospectively through the individual records. The response to the progesterone treatment varied according to the parity of the cows (P < 0.05). Thus, progesterone administration improved the percentage of cows detected in oestrus in multiparous [192/255 (75.2%) v. 161/267 (60.2%)] but not in primiparous [93/132 (70.4%) v. 90/129 (69.7%)] cows. Progesterone treatment increased pregnancy rate in multiparous [53/192 (27.6%) v. 27/161 (16.7%)] but not in primiparous cows [25/93 (26.8%) v. 29/90 (32.2%)]. Likewise, progesterone administration increased the cumulative percentage of pregnant cows on day 90 postpartum in multiparous [149/255 (58.4%) v. 129/267 (48.3%)] but not in primiparous cows [77/132 (58.3%) v. 82/129 (63.5%)]. The incidence of twin births was lower (P = 0.07) in cows treated with progesterone [1/74 (1%)] than in the control group [4/53 (7%)]. It is concluded that progesterone administration before oestrus synchronization with PGF2 in first service dairy cows improves oestral response, increases pregnancy rate, and percentage of pregnant animals on Day 90 postpartum in multiparous cows, but not in primiparous cows, and decreases the incidence of twin births.
This research was supported by PAPIIT-UNAM research grant (IN219811-3).
