Treatments to Optimize the Use of Artificial Insemination and Reproductive Efficiency in Beef Cattle under Tropical Environments

Table 5

Ovulation, conception, and pregnancy rates of Bos indicus pubertal heifers (Study 1) and nonlactating cows (Study 2) submitted to a synchronization of ovulation protocol using progesterone associated with estradiol having different strategies to improve fertility. Adapted from Peres et al. [53].

Item	Ovulation rate	Conception rate	Pregnancy rate
Study 1-CIDR uses and eCG^a
CIDR 1st use/0 IU eCG	84.3% (161/191)	49.1% (79/161)	41.4% (79/191)
CIDR 1st use/200 IU eCG	89.9% (169/188)	51.5% (87/169)	46.3% (87/188)
CIDR 1st use/300 IU eCG	94.6% (177/187)	52.0% (92/177)	49.2% (92/187)
CIDR 3rd use/0 IU eCG	83.4% (176/211)	49.4% (87/176)	41.2% (87/211)
CIDR 3rd use/200 IU eCG	87.2% (170/195)	54.7% (93/170)	47.7% (93/195)
CIDR 3rd use/300 IU eCG	93.9% (170/185)	47.1% (80/170)	44.2% (80/181)
Study 2-Time of PGF2𝛼 treatment and eCG^b
PGF2𝛼 d 7/0 IU eCG	80.3% (143/178)	59.4% (85/143)	47.7% (85/178)
PGF2𝛼 d 7/300 IU eCG	90.7% (156/172)	62.1% (97/156)	56.4% (97/172)
PGF2𝛼 d 9/0 IU eCG	64.4% (112/174)	42.0% (47/112)	27.0% (47/174)
PGF2𝛼 d 9/300 IU eCG	89.3% (159/178)	50.9% (81/159)	45.5% (81/178)

aPubertal heifers received a nonpreviously used CIDR (1st use) or a CIDR used previously for 18 d (3rd use) at initiation of a TAI protocol, and 0, 200, or 300 IU of eCG on d 9 relative to CIDR insertion, in a 2×3 factorial design. There were effects of eCG treatment on ovulation, conception, and pregnancy rates (𝑃<.05).
bNonlactating cows were treated with 12.5 mg of dinoprost tromethamine on d 7 (48 h before CIDR withdrawal; PGF2𝛼 d 7) or on d 9 (immediately after CIDR withdrawal; PGF2𝛼 d 9), and 0 IU of eCG or 300 IU of eCG on d 9 of an ovulation synchronization protocol. There were effects of time of PGF2𝛼 treatment on ovulation, conception, and pregnancy rates (𝑃<.05); eCG affected ovulation and pregnancy rates (𝑃<.05).