title: Effects of summer heat stress on physiological variables, ovulation and progesterone secretion in Pelibuey ewes under natural outdoor conditions in an arid region.
abstract: Ten non-lactating multiparous Pelibuey breed ewes were housed in a corral to evaluate the effects of summer thermal stress on physiologic variables, estrous behavior, ovulation and corpus luteum functionality under natural conditions of an arid region. In summer and autumn, daily estrous detection with a ram fitted with an apron and blood sample collections were performed during two natural estrous cycles. An environment of heat stress was detected in summer and thermoneutral in autumn. Rectal temperature and respiratory frequency were greater (P < 0.01) in summer than in autumn during the morning and afternoon. Season did not affect (P > 0.05) live weight, body condition, length of estrous cycle or percentage of ewes in estrous and ovulating. Compared with autumn, serum progesterone concentrations in summer decreased (P < 0.05) between days 8 and 14 of the estrous cycle. It is concluded that under outdoor conditions of arid regions, while estrous and ovulatory activities of Pelibuey ewes were not affected by summer thermal stress, the corpus luteum functionality was decreased.
authors: Instituto de Ciencias Agrícolas, Universidad Autónoma de Baja California, Valle de Mexicali, México.
authors: Ulises
authors: U
authors: Macías-Cruz
authors: Instituto de Ciencias Agrícolas, Universidad Autónoma de Baja California, Valle de Mexicali, México.
authors: Miguel A
authors: MA
authors: Gastélum
authors: Instituto de Ciencias Agrícolas, Universidad Autónoma de Baja California, Valle de Mexicali, México.
authors: Francisco D
authors: FD
authors: Álvarez
authors: Instituto de Ciencias Agrícolas, Universidad Autónoma de Baja California, Valle de Mexicali, México.
authors: Abelardo
authors: A
authors: Correa
authors: Facultad de Medicina, Universidad Autónoma de Baja California, Mexicali, B.C., México.
authors: Raúl
authors: R
authors: Díaz
authors: Unidad Regional Universitaria de Zonas Áridas, Universidad Autónoma Chapingo, Bermejillo, Durango, México.
authors: César A
authors: CA
authors: Meza-Herrera
authors: Departamento de Nutrición Animal, Universidad Autónoma Agraria "Antonio Narro", Saltillo, Coahuila, México.
authors: Miguel
authors: M
authors: Mellado
authors: Instituto de Ciencias Agrícolas, Universidad Autónoma de Baja California, Valle de Mexicali, México.
authors: Leonel
authors: L
authors: Avendaño-Reyes
mesh_terms: D000818:Animals; D001831:Body Temperature; D003338:Corpus Luteum / Q000502:physiology; D030762:Estrous Cycle; D005260:Female; D006358:Hot Temperature; D010060:Ovulation; D011374:Progesterone / Q000378:metabolism*; D012621:Seasons; D012756:Sheep / Q000502:physiology*; D013312:Stress, Physiological / Q000502:physiology*
chemical_list: D011374:Progesterone
keywords: hair breed; ovulatory activity; sheep; thermal stress