Resynchronization of ovulation with new and reused intravaginal progesterone‐releasing devices without previous pregnancy diagnosis in Bos taurus indicus cows subjected to timed‐artificial insemination

Abstract

Contents The study aimed to evaluate pregnancy per artificial insemination (P/AI) of cows subjected to synchronization and resynchronization in ovulation protocols using intravaginal progesterone‐releasing insert (P4) before pregnancy diagnosis (PD) and the relationship of PR with the diameter of preovulatory follicles (ØPOF) before TAI. Cows (n = 378) were distributed into two groups: a resynchronization group with new devices (GRN; n = 185) and resynchronization group with used devices (GRU; n = 193). On Day 0, both groups received a new P4 and estradiol benzoate (EB). On D8, P4 removal + D‐cloprostenol + eCG + estradiol cypionate (EC) was done. On d10, TAI was conducted. On d32, cows were resynchronized and divided into two groups, GRN (n = 185) and GRU (n = 193). The GRN group received a new P4 + EB, and the GRU group received a used P4 + EB. On d40, the P4 was removed + PD. The non‐pregnant cows received D‐cloprostenol + eCG + EC. US was done again on d42 to determine ØPOF before the second TAI. The P/AI of the GRN and GRU groups after synchronization were 56.2% and 57.0% (p = 0.87), respectively, and those after resynchronization were 58.0% and 37.3% (p < 0.008), respectively. The P/AI of the GRN and GRU groups observed after TAI (synchronization + resynchronization) were 81.6% and 73.1%, respectively (p = 0.047). No difference (p = 0.067) in ØPOF between the pregnant and non‐pregnant cows in the GRN was found, whereas the GRU group showed a significant difference (p = 0.003). Resynchronization protocols optimized the P/AI in both groups. New intravaginal devices resulted in greater P/AI and P/AI accumulation in resynchronization as compared with the GRU; the ØPOF was related with P/AI.

Effect of oestrous resynchronization on the reproductive efficiency of zebu cows

“…In our experimental conditions, a cumulative pregnancy rate of 75.5% was obtained, thereby increasing the proportion of pregnant animals in the breeding season. These results are in agreement with Bó et al, () that observed a cumulative pregnancy rate of 78.5%, are similar to the results of Campos et al, () who reported a cumulative pregnancy rate of 76.6%, but are slightly less than the 81.6% conception rate reported by Oliveira et al, () who used new progesterone‐releasing devices.…”

Strategic re-use of intravaginal progesterone devices increases conception rate in primiparous Nellore cows

“…However, they present a considerable financial impact. Based on this observation, several studies have investigated the possibility of re-using P4 devices as viable and economically attractive alternatives (Pereira et al, 2018;Oliveira et al, 2019). In addition, the re-use of P4 devices can help reduce waste production during assisted animal breeding (Cavalieri et al, 2019).…”

Inseminación artificial a tiempo fijo y reinseminación de vacas para carne tratadas con y sin gonadotropina coriónica equina

“…losEn un estudio(de Oliveira et al, 2015) evaluaron las tasas de gestación en un programa de resincronización de ganado Nelore, los animales se sincronizaron utilizando un protocolo convencional de IATF basado en estradiol / progesterona; 30 días después, las hembras que no se gestaron en la primera IATF fueron resincronizadas con el mismo protocolo hormonal. De manera similar a lo observado en el presente estudio, de Oliveira et al (2015) y deOliveira et al (2019) subrayaron que la tasa de concepción promedio acumulada fue del 80.5 % y 81.6 %, respectivamente; sin embargo, ellos reportan un porcentaje promedio de gestación de 54 % y 56 % en la primera IATF, ligeramente inferior al observado en este estudio. En otros experimentos(Sá Filho et al, 2014;Faleiro et al, 2019) lograron tasas de gestación acumuladas del 75 %, ligeramente inferiores a los datos descritos en el presente estudio.…”