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Early resynchronization of non-pregnant beef cows based in corpus luteum blood flow evaluation 21 days after Timed-AI.
Palhão, M P; Ribeiro, A C; Martins, A B; Guimarães, C R B; Alvarez, R D; Seber, M F; Fernandes, C A C; Neves, J P; Viana, J H M.
Afiliación
  • Palhão MP; University José do Rosário Vellano - UNIFENAS, Alfenas, MG, 37130-000, Brazil. Electronic address: miller.palhao@unifenas.br.
  • Ribeiro AC; University José do Rosário Vellano - UNIFENAS, Alfenas, MG, 37130-000, Brazil.
  • Martins AB; University José do Rosário Vellano - UNIFENAS, Alfenas, MG, 37130-000, Brazil.
  • Guimarães CRB; University José do Rosário Vellano - UNIFENAS, Alfenas, MG, 37130-000, Brazil.
  • Alvarez RD; Veterinary Practitioner, Porto Esperidião, MT, 78240-000, Brazil.
  • Seber MF; University José do Rosário Vellano - UNIFENAS, Alfenas, MG, 37130-000, Brazil.
  • Fernandes CAC; University José do Rosário Vellano - UNIFENAS, Alfenas, MG, 37130-000, Brazil.
  • Neves JP; University José do Rosário Vellano - UNIFENAS, Alfenas, MG, 37130-000, Brazil.
  • Viana JHM; University José do Rosário Vellano - UNIFENAS, Alfenas, MG, 37130-000, Brazil; Embrapa Recursos Genéticos e Biotecnologia, Brasília, DF, 70770-917, Brazil.
Theriogenology ; 146: 26-30, 2020 Apr 01.
Article en En | MEDLINE | ID: mdl-32036057
The study aimed to verify whether a hormone protocol started at Day 13 (D13) after Timed Artificial Insemination (TAI) influences the conception rate. Nelore cows (primiparous and multiparous) from two commercial beef farms (n = 1,431) were first TAI (D0). Timed AI was performed in lots (TAI Lots) ranging from 187 to 346 cows. On D13, regarding the TAI lot, cows were assigned for either receiving (Resynch group, n = 1,002) or not (Control group, a subset of approximately 30%, n = 429) another hormone protocol for resynchronization. The same hormone protocol was used for the first TAI and for the resynchronization, except for 1 mg instead of 2 mg of estradiol benzoate (EB) at the begging of the protocol. Eight days later (D21), the Resynch group was checked for corpus luteum blood flow by color Doppler ultrasonography, and in those detected as non-pregnant, the protocol was completed and a 2nd TAI was performed at D23. Pregnancy diagnosis was later (D30) performed by B-mode ultrasonography in the control group and confirmed in the presumptive pregnant cows from the 1st TAI of the Resynch group. The remaining cows were checked for pregnancy 30 days after the 2nd TAI (experimental Day 53). The statistical model to explain conception rate considered the effects of Group (Control or Resynch), Farm, Parity (primiparous or multiparous), Sire, Technician (who perform AI), TAI Lot and pertinent interactions (Group*Parity, Group*Farm and Group*TAI Lot). The statistical analyses of the model were performed using the Proc Glimmix (SAS virtual University Edition). The conception rate for the 1st TAI was similar (P > 0.4) between Control (50.3%, 216/429) and Resynch group (52.6%, 527/1002). The positive predictive diagnostic on D21 showed high relation with PD30 (90.7%, 527/581). In Resynch group, non-pregnant cows (n = 421, 1002 minus 581) were re-inseminated. The conception rate of the 2nd TAI (42.8%, 180/421) was affected (P < 0.002) by side effects of the Farm (48.5 vs. 33.1%) and Parity (51.2 vs. 40.3%, for multiparous vs. primiparous, p < 0.001). Nevertheless, after the 2 TAIs of the Resynch group, the cumulative conception rate was 70.5% (707/1002). In conclusion, the early resynchronization of cows with a low (1 mg) EB dose and progesterone device at D13 after TAI can be used as a strategy to reduce conception interval in beef cattle, and thus to increase the number of pregnant cows from artificial insemination after the breeding season.
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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Bovinos / Cloprostenol / Cuerpo Lúteo / Estradiol / Sincronización del Estro / Hormona Folículo Estimulante Tipo de estudio: Guideline / Prognostic_studies Límite: Animals / Pregnancy Idioma: En Revista: Theriogenology Año: 2020 Tipo del documento: Article Pais de publicación: Estados Unidos

Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Bovinos / Cloprostenol / Cuerpo Lúteo / Estradiol / Sincronización del Estro / Hormona Folículo Estimulante Tipo de estudio: Guideline / Prognostic_studies Límite: Animals / Pregnancy Idioma: En Revista: Theriogenology Año: 2020 Tipo del documento: Article Pais de publicación: Estados Unidos