Resumo

ESTRADA-CORTES, Eliab et al. Relationship between body development and reproductive response of heifers to estrus synchronization protocols in the small-scale dairy system. Rev. mex. de cienc. pecuarias [online]. 2024, vol.15, n.1, pp.115-129.  Epub 12-Abr-2024. ISSN 2448-6698.  https://doi.org/10.22319/rmcp.v15i1.5998.

The objectives were to determine the reproductive response of Holstein heifers in small-scale dairy herds to estrus synchronization protocols based on prostaglandins (PG), estradiol benzoate (EB), and progesterone (P4). Heifers at least 13 mo old (n= 138) were randomly included in one of two synchronization protocols: PG) administration of 500 (g cloprostenol i.m. at d 0 and d 14; and PGPE) similar to PG but with an additional application of 100 mg P4 + 2 mg EB on d 7. The estrus rate of the PG group was similar to that of the PGPE group (84.3 vs 79.4 %; P>0.1). Heifers in PGPE had a higher percentage of estrus between 37-84 h post-treatment vs the PG group (94.2 vs 82.5 %; P=0.05). The conception rate of the PGPE group was higher than that of the PG group (94.4 vs 83.1 %; P=0.05). In the PG group, body development at weaning was lower in heifers that did not show estrus vs those that did (P<0.05). Nonetheless, in the PGPE group, birth weight was lower in heifers that showed estrus than those that did not (P<0.05). In conclusion, heifers in the small-scale dairy system have a good reproductive response to prostaglandin-based estrus synchronization (cloprostenol). The inclusion of EB + P4 into the hormonal synchronization protocol with PG improves conception rate but has a minimal effect on the distribution of the beginning of estrus expression after treatment.

Palavras-chave : Estrus synchronization; Heifers; Small-scale dairy herds.

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