Comparison of long-term progestin-based estrus synchronization protocols in beef heifers

Journal of Animal Science
D A MalloryD J Patterson

Abstract

Two experiments evaluated long-term progestin-based estrus-synchronization programs on the basis of potential for use in facilitating fixed-time AI in estrous cycling and prepubertal beef heifers. In Exp. 1, heifers were assigned to 1 of 2 treatments by age, BW, and estrous cyclicity status. Heifers assigned to the melengestrol acetate-PGF(2α) protocol (MGA-PG; n = 50) received MGA (0.5 mg·animal(-1)·d(-1)) in a 1.0-kg carrier from d 0 to 13 and were administered PGF(2α) (25 mg, intramuscularly) 19 d after MGA withdrawal (d 32). Heifers assigned to the Show-Me-Synch protocol (n = 49) received a controlled internal drug release (CIDR) insert (1.38 g of progesterone) from d 2 to 16 followed by PGF(2α) administration 16 d after CIDR removal (d 32). All heifers were fitted with HeatWatch estrus-detection transmitters at the time of progestin removal for continuous estrus detection through the synchronized period after PGF(2α). In Exp. 2, heifers (n = 396) were assigned to the same 2 treatments described in Exp. 1 by age, BW, and reproductive tract score. Heifers in Exp. 2, however, were fitted with HeatWatch estrus-detection transmitters at PGF(2α) to characterize estrus-distribution patterns during the synchronized period after PG...Continue Reading

References

Jun 1, 1975·Journal of Animal Science·E Gonzalez-PadillaJ N Wiltbank
Dec 1, 1987·Journal of Animal Science·D J ByerleyR E Short
Apr 1, 1966·Journal of Reproduction and Fertility·R G Zimbelman, L W Smith
Dec 2, 2008·Animal Reproduction Science·N R LeitmanD J Patterson

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Citations

Nov 5, 2013·The Veterinary Clinics of North America. Food Animal Practice·David J PattersonMichael F Smith
Jun 22, 2018·Animal : an International Journal of Animal Bioscience·P L P FontesG C Lamb
Oct 6, 2012·Journal of Animal Science·M A MirandoD J Patterson
May 8, 2014·Journal of Animal Science·G A BridgesG A Perry

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