Injectable progesterone in timed artificial insemination programs in beef cows.

Fábio Morotti,Gustavo Martins Gomes Dos Santos,Paula Alvares Lunardelli,Thales Ricardo Rigo Barreiros,Marcelo Marcondes Seneda,Camila Bortoliero Costa,Larissa Zamparone Bergamo,Jefferson Tadeu De Campos

doi:10.21451/1984-3143-2017-ar928

Abstract

The aims of this study were I) to compare the follicular diameter, corpus luteum diameter and serum progesterone (P4) concentrations in cows treated with conventional protocol vs. injectable P4 protocol; II) to determine the serum P4 profile in ovariectomized heifers; and III) to compare pregnancy rate between protocols. In experiment I, multiparous cows received a protocol for ovulation synchronization with an intravaginal P4 device (n = 38; device + EB day 0; device removal + PGF2α + eCG + EC day 8) or injectable P4 (n = 38; injection + EB day 0; PGF2α + eCG + EC day 8). In experiment II, ovariectomized heifers (n = 8) were treated with injectable P4 and blood samples were collected to determine the serum P4 profile. In experiment III, multiparous cows were timed AI with two different P4 approaches, intravaginal P4 device (n = 48) or injectable P4 (n = 47). In the first experiment, cows treated with P4 device had higher (P < 0.05) diameter of dominant follicle after ovulation induction (11.6 ± 1.8 vs.10.3 ± 1.8 mm) and ovulation rate (97%, 37/38 vs. 47.3%, 18/38) than cows treated with injectable P4. But, the follicular growth daily was higher (P < 0.05) in cows treated with injectable P4 than intravaginal device (1.3 ± 0.4 vs. 1.0 ± 0.3 mm/day, respectively). In experiment II, the P4 concentration peak occurred within 48 hours (6.54 ng/mL) and decreased after 96 hours (P < 0.05) after P4 injection. In experiment III, cows with P4 device had higher (P < 0.05) pregnancy rate than the injectable P4 group (60.4 vs. 34.0%, respectively). These results demonstrate that although the intravaginal P4 devices showed a higher pregnancy rate, a protocol with injectable P4 represents an easier method and a promising alternative for TAI in cattle.

Highlights

The timed artificial insemination (TAI) programs have been considered one of the largest biotechnological achievements for breeding cattle
In experiment I, the diameter of the dominant follicle 48 hours after ovulation induction and ovulation rate were higher (P < 0.05) in cows who received a conventional protocol for synchronization with an intravaginal P4 device than an injectable P4 solution (Table 1)
Cows treated with injectable P4 presented higher (P < 0.05) follicular growth per day and different time of ovulation to in comparison with cows treated with intravaginal device

Summary

Introduction

The timed artificial insemination (TAI) programs have been considered one of the largest biotechnological achievements for breeding cattle This is related to the fact that TAI allows all females receiving hormonal treatment to be inseminated without the need for estrus detection (Baruselli et al, 2004; Lamb et al, 2010). In this context, the synchronic control of wave emergence, dominant follicle growth and ovulation are. It is possible avoiding ovulation, but keeping the growth and maturation of the dominant follicle (Savio et al, 1993a; Stock and Fortune, 1993; Rhodes et al, 2002)

Objectives

Methods

Results

Conclusion