1
|
Cuadro F, García Pintos C, Núñez-Olivera R, Brochado C, Bó GA, Menchaca A. Equine chorionic gonadotropin (eCG) treatment in heifers: Double ovulation, twinning rate, and pregnancy losses in twin pregnancies. Theriogenology 2024; 226:213-218. [PMID: 38914033 DOI: 10.1016/j.theriogenology.2024.06.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Revised: 06/18/2024] [Accepted: 06/20/2024] [Indexed: 06/26/2024]
Abstract
This study aimed to evaluate the effects of different doses of equine chorionic gonadotropin (eCG; 200 and 300 IU) administered at the end of a fixed-time artificial insemination (FTAI) treatment protocol on ovulation, pregnancy, and twin rates in Bos taurus beef heifers. In addition, pregnancy losses in heifers with singleton and twin pregnancies were determined. A total of 2382 Angus heifers treated with a 6-day estradiol/progesterone-based protocol for FTAI (J-Synch protocol) were randomly allocated to two experimental groups to receive 200 or 300 IU of eCG administered intramuscularly at the time of intravaginal progesterone device removal; FTAI was performed from 60 to 72 h after device removal. The pregnancy rate did not differ (P = 0.89) between the 200 and 300 IU eCG groups. The number of corpus luteum induced by both eCG doses was determined by ultrasonographic examination 14 days after insemination and those treated with 300 IU of eCG had a greater double ovulation rate (P < 0.05). In addition, 300 IU eCG treated heifers had a higher twinning rate on day 30 of gestation (P < 0.05) and parturition (P < 0.05). Pregnancy losses from 30 days of gestation to calving did not differ between heifers treated with 200 and 300 IU of eCG (P = 0.70). However, regardless of the experimental group, heifers bearing twins had greater pregnancy losses than heifers with singletons (P < 0.05). In conclusion, reducing the dose of eCG from 300 to 200 IU under FTAI treatment protocol decreases double ovulation and twinning rates, maintaining a similar pregnancy rate in heifers. Nulliparous cows carrying two fetuses suffer greater pregnancy losses than cows with singletons.
Collapse
Affiliation(s)
- F Cuadro
- Instituto de Reproducción Animal Uruguay, Fundación IRAUy, Montevideo, Uruguay; Plataforma de Investigación en Salud Animal, Instituto Nacional de Investigación Agropecuaria (INIA), Montevideo, Uruguay
| | - C García Pintos
- Instituto de Reproducción Animal Uruguay, Fundación IRAUy, Montevideo, Uruguay; Plataforma de Investigación en Salud Animal, Instituto Nacional de Investigación Agropecuaria (INIA), Montevideo, Uruguay
| | - R Núñez-Olivera
- Instituto de Reproducción Animal Uruguay, Fundación IRAUy, Montevideo, Uruguay
| | - C Brochado
- Instituto de Reproducción Animal Uruguay, Fundación IRAUy, Montevideo, Uruguay
| | - G A Bó
- Instituto de Reproducción Animal Córdoba (IRAC), Córdoba, Argentina; Instituto A.P. de Ciencias Básicas y Aplicadas, Medicina Veterinaria, Universidad Nacional de Villa María, Villa del Rosario, Córdoba, Argentina
| | - A Menchaca
- Instituto de Reproducción Animal Uruguay, Fundación IRAUy, Montevideo, Uruguay; Plataforma de Investigación en Salud Animal, Instituto Nacional de Investigación Agropecuaria (INIA), Montevideo, Uruguay.
| |
Collapse
|
2
|
Cedeño AV, Cuervo R, Tríbulo A, Tríbulo R, Andrada S, Mapletoft R, Menchaca A, Bó GA. Effect of expression of estrus and treatment with GnRH on pregnancies per AI in beef cattle synchronized with an estradiol/progesterone-based protocol. Theriogenology 2020; 161:294-300. [PMID: 33370598 DOI: 10.1016/j.theriogenology.2020.12.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 12/07/2020] [Accepted: 12/10/2020] [Indexed: 10/22/2022]
Abstract
Three experiments evaluated the effects of expression of estrus and gonadotropin releasing hormone (GnRH) treatment on pregnancies per AI (P/AI) in beef cattle that were treated with an estradiol/progesterone (P4)-based protocol for fixed-time artificial insemination (FTAI). In Experiment 1, 20 non-lactating beef cows were treated with 2 mg estradiol benzoate (EB) and an intravaginal device containing 0.5 g of P4. Seven days later, P4 devices were removed and all cows received prostaglandin F2 alpha (PGF2α) and 0.5 mg estradiol cypionate (ECP). Estrus was detected using tail paint and cows that did not show estrus by 48 h after P4 device removal were randomized to receive GnRH or no treatment. Ovulation, as determined by ultrasonography, occurred earlier in cows that showed estrus (68.0 ± 2.5 h) than in cows that did not (82.0 ± 2.1 h, P < 0.05). Furthermore, cows that received GnRH ovulated earlier (78.0 ± 2.6 h) than those that did not (86.0 ± 2.0, P < 0.05). Experiment 2 determined whether expression of estrus and the administration of GnRH to animals that did not show estrus increased P/AI. Non-lactating beef cows and heifers (n = 1356) were treated as in Experiment 1 (P4 device removal, PGF2α and ECP administration on Day 7) or extended until Day 8. All animals in estrus by 48 h after P4 device removal were inseminated and those not showing estrus received GnRH or no treatment and were FTAI 8 h later (i.e., at 56 h). P/AI were greater (P < 0.01) in animals that were observed in estrus by 48 h (56.4%) than in those that did not show estrus (46.5%). Likewise, animals that did not show estrus but were treated with GnRH had greater P/AI (53.8%, P < 0.04) than those that did not receive GnRH (37.9%). Experiment 3 was designed to determine the effect of delaying GnRH treatment to the time of FTAI (at 56 h) in cows not showing estrus by 48 h after P4 device removal. Suckled beef cows (n = 969) were treated as in Experiment 1, except that all cows also received 400 IU of eCG at the time of P4 device removal on Day 7. Cows that showed estrus by 48 h or 56 h had greater P/AI (62.3%, P < 0.05) than those did not show estrus (51.5%). Furthermore, when cows that did not show estrus by 48 h were analyzed separately, P/AI were greater (P < 0.05) in those that received GnRH at 48 h and were FTAI by 56 h (64.9%) than in those that received GnRH concurrent with FTAI by 56 h after device removal (54.6%). In summary, expression of estrus was associated with earlier ovulations and resulted in greater P/AI in cows and heifers treated with an estradiol/P4-based protocol for FTAI. Furthermore, GnRH treatment in animals that did not show estrus hastened the time of ovulation and increased P/AI.
Collapse
Affiliation(s)
- Andrés V Cedeño
- Instituto de Reproducción Animal Córdoba (IRAC), Zona Rural General Paz, 5145, Córdoba, Argentina; Maestría en Reproducción Bovina, Facultad de Ciencias Agropecuarias, Universidad Nacional de Córdoba, Argentina; Laboratorio de Biotecnología de La Reproducción Animal, Medicina Veterinaria, Escuela Superior Politécnica Agropecuaria de Manabí Manuel Félix López (ESPAM-MFL) Bolívar, Manabí, Ecuador
| | - Rodrigo Cuervo
- Maestría en Reproducción Bovina, Facultad de Ciencias Agropecuarias, Universidad Nacional de Córdoba, Argentina; Instituto de Ciencias Básicas, Medicina Veterinaria, Universidad Nacional de Villa María, Villa Del Rosario, Córdoba, Argentina
| | - Andrés Tríbulo
- Instituto de Reproducción Animal Córdoba (IRAC), Zona Rural General Paz, 5145, Córdoba, Argentina
| | - Ricardo Tríbulo
- Instituto de Reproducción Animal Córdoba (IRAC), Zona Rural General Paz, 5145, Córdoba, Argentina
| | - Salvador Andrada
- Instituto de Reproducción Animal Córdoba (IRAC), Zona Rural General Paz, 5145, Córdoba, Argentina
| | - Reuben Mapletoft
- Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - Alejo Menchaca
- Instituto de Reproducción Animal de Uruguay, IRAUy, Montevideo, Uruguay
| | - Gabriel A Bó
- Instituto de Reproducción Animal Córdoba (IRAC), Zona Rural General Paz, 5145, Córdoba, Argentina; Maestría en Reproducción Bovina, Facultad de Ciencias Agropecuarias, Universidad Nacional de Córdoba, Argentina; Instituto de Ciencias Básicas, Medicina Veterinaria, Universidad Nacional de Villa María, Villa Del Rosario, Córdoba, Argentina.
| |
Collapse
|