Pregnancy rate to FTAI in Braford heifers submitted to J-Synch protocol

PRINCIPI, S; REINERI, PS *; PUNTA PEREZ, R; CORIA, MS * (EQUAL CONTRIBUTION); PALMA, GA

MEDICINA VETERINARIA-RECIFE

UNIV FEDERAL RURAL PERNAMBUCO

Lugar: Pernambuco; Año: 2020 vol. 14 p. 328 - 333

1809-4678

The objective of the present work was to evaluate the effect of J-Synch protocol used in heifers on pregnancy rate (PR), after artificial insemination at detected estrus (IADE) and fixed-time (FTAI). Two hundred ninety-three Braford heifers were used. On day 0, all heifers received 2.0 mg of estradiol benzoate administered intramuscularly (IM) and an intravaginal progesterone-releasing device (DIB, 0.5g). Heifers were randomly assigned to the following group: 1) J-Synch: on day 6, DIB devices were removed and 500 µg of d-Cloprostenol sodium (d-CS) was administered IM and paint was applied on tail base (tail-paint). On day 9 (60 h after DIB removal), heifers with the tail-paint rubbed off (≥ 40%) were inseminated. Those not showing estrus by 72 h after DIB removal received 100 µg of GnRH at that time and were FTAI. 2) Conventional: on day 7, DIB devices were removed, and 500 µg of d-CS and 0.5 mg of estradiol cypionate were administered IM and tail-paint. At 48 h after DIB removal, heifers with the tail-paint rubbed off were IADE. Those not showing estrus by 54 h after DIB removal were FTAI. Pregnancy was diagnosed by ultrasonography 30 days after FTAI. Pregnancy rate not differ between protocols (44.28% and 42.48%, P = 0.673). However, a higher PR was observed in IADE heifers (P = 0.047). In conclusion, the combination of tail painting and FTAI can be successfully applied to inseminate heifers with the same efficiency, and these protocols could be used as a new alternative of reproductive schedule.