title: Effect of time of progesterone supplementation on serum progesterone and the conception rate of cooled Holstein heifers during the summer.
abstract: To investigate the effects of progesterone supplementation at two different times on serum progesterone (P4 ) concentration, conception rate and resynchronization of cooled Holstein heifers in summer, 90 heifers were randomly assigned to two groups: (i) heifers subjected to TAI (timed artificial insemination) and progesterone supplementation from days 4 to 14 after TAI (S1; n = 45); and (ii) heifers under the same TAI protocol as S1 and progesterone supplementation from days 17 to 22 after TAI (S2 ; n = 45). The groups S1 and S2 were cooled 10 days before and 21 days after TAI. Respiratory rate, body surface temperature, vaginal temperature and rectal temperature recorded during the experiment were not different (P > 0.05) between S1 and S2 groups. Progesterone concentration was not different (P > 0.05) in S1 compared to S2 . The conception rates on days 30 and 55 were similar between groups (P > 0.05). Progesterone supplementation did not increase either conception rate or concentrations of P4 in heifers during the summer. Heifers not pregnant to first service in the group S2 were resynchronized (77.7%) for a second breeding.
authors: Instituto de Ciencias Agrícolas, Mexicali, B.C., México.
authors: Abelardo
authors: A
authors: Correa-Calderón
authors: Instituto de Ciencias Agrícolas, Mexicali, B.C., México.
authors: Rolando
authors: R
authors: Pérez-Velázquez
authors: Instituto de Ciencias Agrícolas, Mexicali, B.C., México.
authors: Leonel
authors: L
authors: Avendaño-Reyes
authors: Instituto de Ciencias Agrícolas, Mexicali, B.C., México.
authors: Ulises
authors: U
authors: Macias-Cruz
authors: Facultad de Medicina, Universidad Autónoma de Baja California, Mexicali, B.C., México.
authors: Raúl
authors: R
authors: Diaz-Molina
authors: Departamento de Ciencias Agronómicas y Veterinarias, Instituto Tecnológico de Sonora, Ciudad Obregón, Son, México.
authors: Fernando
authors: F
authors: Rivera-Acuña
mesh_terms: D000818:Animals; D001831:Body Temperature; D002417:Cattle / Q000097:blood* / Q000502:physiology*; D005260:Female; D005306:Fertilization / Q000187:drug effects; D006358:Hot Temperature; D007315:Insemination, Artificial; D011374:Progesterone / Q000008:administration & dosage* / Q000097:blood* / Q000494:pharmacology; D012007:Rectum / Q000502:physiology; D012119:Respiration; D012621:Seasons; D013997:Time Factors; D014621:Vagina / Q000502:physiology
chemical_list: D011374:Progesterone
keywords: cattle; cooling fertility; heat stress; progesterone