Comparative Efficacy of Progesterone-Based Ovulation Synchronization Protocols in Simmental Heifers

Relevance. Objective of this study was to synchronize oestrus in Simmental heifers of a specific age on a farm engaged in the sale of pregnant heifers by administering progesterone at various intervals — both in cyclic and acyclic animals — followed by an assessment of the effectiveness of the applied synchronization protocols.

Methodology. The study used one hundred Simmental heifers. From the total livestock, five equal groups were formed by random sampling. Control group (n = 20): monitoring of oestrus signs without any hormonal treatment and threefold insemination. Group 1 (n = 20): Day 0 — GnRH + progesterone implant; Day 5 — implant removal, PGF2α + progesterone administration; Day 8 — GnRH + insemination. Group 2 (n = 20): Day 0 — GnRH + progesterone implant; Day 5 — implant removal, PGF2α + progesterone; Day 8 — GnRH + first insemination and Day 9 — repeated insemination. Group 3 (n = 20): Day 0 — GnRH + progesterone implant; Day 8 — implant removal, PGF2α + progesterone; Day 11 — GnRH + insemination. Group 4 (n = 20): Day 0 — GnRH + progesterone implant; Day 8 — implant removal, PGF2α + progesterone; Day 11 — GnRH + first insemination and Day 12 — GnRH + repeated insemination.

Results. The pregnancy rates in the groups were 30%, 65%, 80%, 30%, and 15%, respectively. The highest rate was recorded in the second group. It has been established that this particular procedure should be recommended to all farms seeking to obtain pregnant heifers.

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