Abstract #M243
Section: Physiology and Endocrinology
Session: Physiology and Endocrinology: Estrous synchronization and detection of estrus in cattle
Format: Poster
Day/Time: Monday 7:30 AM–9:30 AM
Location: Gatlin Ballroom
Session: Physiology and Endocrinology: Estrous synchronization and detection of estrus in cattle
Format: Poster
Day/Time: Monday 7:30 AM–9:30 AM
Location: Gatlin Ballroom
# M243
Estradiol and GnRH on ovulation induction in crossbred cows estrus synchronized.
Fabrício Albani Oliveira1, Jurandy Mauro Penitente Filho1, Erly Luisana Triana Carrascal1, Carlos Thiago Oliveira1, Adriana Moreira Zolini1, Italo Augusto da Costa Soares1, Ciro Alexandre Alves Torres*1, 1Federal University of Viçosa, Viçosa, MG, Brazil.
Key Words: ovulation, crossbred cows, timed AI
Estradiol and GnRH on ovulation induction in crossbred cows estrus synchronized.
Fabrício Albani Oliveira1, Jurandy Mauro Penitente Filho1, Erly Luisana Triana Carrascal1, Carlos Thiago Oliveira1, Adriana Moreira Zolini1, Italo Augusto da Costa Soares1, Ciro Alexandre Alves Torres*1, 1Federal University of Viçosa, Viçosa, MG, Brazil.
Three different ovulation inductors, estradiol benzoate (EB), estradiol cypionate (EC) and gonadotropin releasing hormone (GnRH) were evaluated in timed artificial insemination (TAI) of lactating crossbred cows. Two hundred and 16 (216) cows were used in 2 experiments. In experiment I (n = 45), follicular dynamics and in the experiment II (n = 171) pregnancy per AI were evaluated. All cows were submitted to a synchronization protocol: d 0 (D0) insertion of a progesterone-release intravaginal device (PRID) plus IM injection of EB 2 mg; D8, PRID removal plus IM injection of PGF2a (0.150 mg) and eCG (400 IU). The cows were then randomly assigned into 1 of 3 groups: (1) EB9 (n = 61): IM injection of EB (1 mg) on D9, and AI 52 h after PRID removal; (2) EC (n = 58): IM injection of EC (1.0 mg) on D8 and AI 48 h after PRID removal and (3) GnRH (n = 52): IM injection of GnRH (100 µg) on D10 and AI 52 h after PRID removal. Ultrasonographic examinations of the ovaries were performed on d 0, 8, and on the day of TAI to determine follicular diameter and ovulation. Follicular data were analyzed using ANOVA and pregnancy per AI with Chi-squared test at 5% probability. No interaction was found between treatment and observation day on number of follicles or on the follicular classification (P > 0.05). The intervals from TAI to ovulation were 12.4, 12.8 and 14.8 for EB, EC and GnRH, respectively (P > 0.05). No interaction between treatment and day of observation was detected for diameter of the largest follicle (11.4, 11.0 and 10.7 mm for EB, EC and GnRH, respectively; P > 0.05). The rate of follicle growth was slower in the EC cows than the other treatments (EB = 1.5, EC = 0.7 and GnRH = 1.9 mm; P < 0.05). There were no effects (P > 0.05) of treatment on ovulation rate (EB = 100, EC = 93.3, GnRH = 93.3%) and pregnancy per AI (EB = 62.3, EC = 37.9, GnRH = 51.9%). Sample size might have limited the ability to detect statistical differences among treatments. The use of EB, EC, and GnRH as ovulation inductors in TAI protocols in crossbred cows resulted in no differences in ovulatory responses or pregnancy per AI.
Key Words: ovulation, crossbred cows, timed AI
