| Autor: |
Morales-Cruz JL; Departamento de Ciencias Veterinarias, Universidad Autónoma Agraria Antonio Narro-Unidad Laguna, Torreón 25315, Mexico., Calderon-Leyva G; Departamento de Ciencias Veterinarias, Universidad Autónoma Agraria Antonio Narro-Unidad Laguna, Torreón 25315, Mexico., Angel-García O; Departamento de Ciencias Veterinarias, Universidad Autónoma Agraria Antonio Narro-Unidad Laguna, Torreón 25315, Mexico., Guillen-Muñoz JM; Departamento de Ciencias Veterinarias, Universidad Autónoma Agraria Antonio Narro-Unidad Laguna, Torreón 25315, Mexico., Santos-Jimenez Z; Departamento de Ciencias Veterinarias, Universidad Autónoma Agraria Antonio Narro-Unidad Laguna, Torreón 25315, Mexico., Mellado M; Departamento de Nutrición Animal, Universidad Autónoma Agraria Antonio Narro, Saltillo 25315, Mexico., Pessoa LG; Independent Researcher, Torreón 25315, Mexico., Guerrero-Gallego HZ; Departamento de Ciencias Veterinarias, Universidad Autónoma Agraria Antonio Narro-Unidad Laguna, Torreón 25315, Mexico. |
| Abstrakt: |
The aim of this study was to evaluate the effect of the month of oocyte harvesting and the temperature-humidity index on oocyte number and quality harvested from Holstein cows and heifers, oocyte developmental competence, and total embryos produced in an area of intense ambient temperature for most of the year. A total of 5064 multiparous lactating cows and 2988 nulliparous heifers were used as oocyte donors and distributed across the months of the year. Overall, total oocytes per collection did not differ ( p > 0.05) between cows (16.6 ± 2.7) and heifers (15.1 ± 1.8), but oocyte developmental competence was lower ( p < 0.05) in cows (21.3 ± 5.4) than heifers (25.5 ± 4.0). For cows, the total number of oocytes harvested was two-fold higher ( p < 0.05) in November than in May. For heifers, the total number of oocytes harvested was highest in April (17.19 ± 0.53) and lowest in May (10.94 ± 0.32; p < 0.05). For cows, total embryos were highest in November (2.58 ± 0.42) and lowest in August (1.28 ± 0.10; p < 0.05). Thus, taken together, these results indicate that severe heat stress impaired the number and quality of oocytes harvested from donor Holstein multiparous cows and heifers, oocyte developmental competence, and total embryos produced in this area of intense ambient temperature for most of the year. |
