RT Journal T1 FERTILITY OF LACTATING JERSEY X HOLSTEIN-FRIESIAN COWS IN SUBTROPICAL REGION SUBMITTED TO A DOUBLE-OVSYNCH VERSUS OVSYNCH PROTOCOL FOR TIMED ARTIFICIAL INSEMINATION A1 A. A. Channa A1 M. Aleem A1 M. A. Jabbar A1 H. Monir A1 N. Ahmad1 JF Journal of Animal and Plant Sciences JO JAPS SN 1018-7081 VO 30 IS 1 SP 255 OP 258 YR 2020 FD 2020/01/02 DO DOI https://doi.org/10.36899/JAPS.2020.1.0030 AB

Pre-synchronization prior to Ovsynch protocol is an efficient method to improve ovulation and pregnancy rate in dairy cows. The objective of this study was to define the effect of Double-Ovsynch (DOS; GnRH, PGF2α 7 d later and GnRH 2 d later followed by the OVS protocol with interval of 7 d; timed AI 16 to 24 h after the last GnRH of OVS) and Ovsynch (OVS; GnRH, PGF2α 7 d later and GnRH 2 d later; timed AI 16- 24 h after the last GnRH) protocols on ovulation and pregnancy rate in crossbred dairy cows. The ovulation rate (day 7 post TAI, DOS n = 20 vs. OVS n = 21) and pregnancy rate (day 35 post TAI, DOS n = 125 vs. OVS n = 148) were determined using ultrasonography. Serum concentrations of progesterone on d 7 after the last GnRH of each protocol was determined in the subset of randomly selected cows (DOS n = 10) and (OVS n =10) protocol. The Ovulation rate (OR) was higher (P < 0.05) in DOS as compared to OVS (90% vs. 47%) protocols. Likewise, pregnancies per AI (P/AI) significantly (P<0.05) increased in DOS as compared to OVS (62 % vs. 30%). Mean serum concentrations of progesterone on d 7 remained similar (P > 0.05) between DOS and OVS (8.68 ± 0.78 ng/mL: 8.19 ± 1.85 ng/mL)protocols. It is concluded that DOS compared to OVS yields better ovulation and pregnancy rate in crossbred dairy cows.

K1 Ovsynch; Double-Ovsynch; Ovulation; Pregnancy; Crossbred cows PB Pakistan Agricultural Scientists Forum LK https://thejaps.org.pk/AbstractView.aspx?mid=AS-18-0055