Addition of a dose of prostaglandin F2α to a fixed-time artificial insemination (FTAI) protocol in anestrous Nelore females.

Abstract

The current study aimed to assess the impact of an additional dose of PGF2α on the reproductive performance of multiparous, anestrous Nelore cows subjected to FTAI protocols. A total of 70 Nelore cows were included in the study. On Day 0 (D0), a 1g progesterone-releasing intravaginal device was inserted, and 2mg of estradiol benzoate was administered intramuscularly (IM). On D7, the animals were randomly assigned to two experimental groups: Control Group (CG; n=32)- received a single dose of PGF2α on D9. PGF Group (PGFG; n=38)- received two doses of PGF2α (D7 and D9). On D9, the P4 devices were removed, and all cows received IM injections of 500µg PGF2α , 0.6mg E2 cypionate, and 300IU of eCG. On D11, follicular characteristics of 32 cows (CG=14; PGFG=18) were assessed using B-mode and color Doppler ultrasonography. Parameters measured included follicle diameter (DFOL), follicle area (AFOL), follicle vascularization (VFOL), and follicle vascularization percentage (%VFOL). Pregnancy diagnosis was conducted on D45. The CG (n=14) exhibited mean values for DFOL, AFOL, VFOL, and %VFOL of 1.05±0.15 cm, 0.51±0.08 cm², 0.26±0.06 cm², and 51.91±11.25%, respectively. The PGFG (n=18) demonstrated mean values of 1.08±0.22 cm, 0.46±0.18 cm², 0.24±0.09 cm², and 56.33±18.91%. No statistically significant differences were observed between the groups (P>0.05). Regarding pregnancy rates, the CG achieved 34.4% (11/32), while the PGFG achieved 42.1% (16/38). Similarly, no significant differences were observed between the groups (P>0.05). It can be concluded that the inclusion of an additional dose of PGF2α in the synchronization protocol for FTAI in anestrous Nelore cows did not enhance follicular morphofunctional parameters, ovulation rates, or pregnancy rates in these animals. Implications. Therefore, the administration of an additional PGF dose should be carefully considered in FTAI protocols. This study demonstrated that administering an additional dose of PGF2α did not influence follicular morphofunctional parameters pregnancy rates.