title: Superovulatory response and embryo development in ewes treated with two doses of bovine somatotropin.
abstract: This study evaluated whether the administration of 50 and 100mg bovine somatotropin (bST) at the start of synchronization and at the time of natural mating in ewes improves the ovulation rate, embryonic development and pregnancy rate of transferred embryos. Forty-eight donors were assigned to three treatments: the bST-100 treatment (n=15) received 100mg bST at the start of synchronization and at natural mating, the bST-50 treatment (n=15) received 50mg bST on the same schedule as the previous group, and the control (n=18) did not receive any bST. Two embryos were transferred to each recipient (n=121): 35 received embryos from bST-100; 50 received embryos from bST-50, and 36 received embryos from the control. The superovulatory rate, percentage of recovered structures, cleavage rate, percentage of transferable embryos, embryo quality and development and pregnancy rate were analyzed using the GENMOD procedure of SAS. The number of corpora lutea and the cell number were analyzed using the GLM procedure of SAS. The insulin and IGF-1 concentrations were analyzed with ANOVA for repeated measures. The bST application did not affect the superovulatory rate, number of corpora lutea and recovered structures (P>0.05). The numbers of transferable embryos and embryos reaching the blastocyst were higher (P≤0.01) in the bST-50 (96.4±3.6% and 69.0±7.8%) than the bST-100 (93.0±4.5% and 27.2±38.9%) and control (87.7±5.4% and 50.4±6.4%) groups. The insulin and IGF-1 concentrations were higher (P<0.05) in the bST-treated groups, but the insulin concentration was higher (P<0.05) in the bST-100 group than in the bST-50 group. The pregnancy rate was similar (P=0.21) in ewes receiving embryos from the two treatments [bST-50, (70.0%); bST-100, (62.5%), and control, (56.6%)]. The administration of 50mg bST at the start of synchronization and at natural mating in superovulated ewes was concluded to enhance the proportion and development of transferable embryos. However, bST did not affect the pregnancy rate of transferred embryos.
authors.affiliation: Unidad Académica de Medicina Veterinaria y Zootecnia, Universidad Autónoma de Zacatecas, Carretera Panamericana Zacatecas-Fresnillo Km 31.5, 98500 El Cordovel Enrique Estrada, Zacatecas, Mexico. Electronic address: jose.carrera@uacj.mx.
authors.forename: J M
authors.initials: JM
authors.lastname: Carrera-Chávez
authors.affiliation: Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Av. Universidad 3000, 04510 México, DF, Mexico.
authors.forename: J
authors.initials: J
authors.lastname: Hernández-Cerón
authors.affiliation: Unidad Académica de Medicina Veterinaria y Zootecnia, Universidad Autónoma de Zacatecas, Carretera Panamericana Zacatecas-Fresnillo Km 31.5, 98500 El Cordovel Enrique Estrada, Zacatecas, Mexico.
authors.forename: M A
authors.initials: MA
authors.lastname: López-Carlos
authors.affiliation: Unidad Académica de Medicina Veterinaria y Zootecnia, Universidad Autónoma de Zacatecas, Carretera Panamericana Zacatecas-Fresnillo Km 31.5, 98500 El Cordovel Enrique Estrada, Zacatecas, Mexico.
authors.forename: R R
authors.initials: RR
authors.lastname: Lozano-Domínguez
authors.affiliation: United States Department of Agriculture, 11940 Don Haskins Dr. Suite E-3, El Paso, TX 79936, USA; Departamento de Ciencias Veterinarias, Universidad Autónoma de Ciudad Juárez, Henry Dunant s/n Zona Pronaf, 32315 Ciudad Juárez, Chihuahua, Mexico.
authors.forename: F
authors.initials: F
authors.lastname: Molinar
authors.affiliation: Unidad Académica de Medicina Veterinaria y Zootecnia, Universidad Autónoma de Zacatecas, Carretera Panamericana Zacatecas-Fresnillo Km 31.5, 98500 El Cordovel Enrique Estrada, Zacatecas, Mexico.
authors.forename: F G
authors.initials: FG
authors.lastname: Echavarría-Cháirez
authors.affiliation: Unidad Académica de Medicina Veterinaria y Zootecnia, Universidad Autónoma de Zacatecas, Carretera Panamericana Zacatecas-Fresnillo Km 31.5, 98500 El Cordovel Enrique Estrada, Zacatecas, Mexico.
authors.forename: R
authors.initials: R
authors.lastname: Bañuelos-Valenzuela
authors.affiliation: Unidad Académica de Medicina Veterinaria y Zootecnia, Universidad Autónoma de Zacatecas, Carretera Panamericana Zacatecas-Fresnillo Km 31.5, 98500 El Cordovel Enrique Estrada, Zacatecas, Mexico. Electronic address: arechiga@uaz.edu.mx.
authors.forename: C F
authors.initials: CF
authors.lastname: Aréchiga-Flores
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000166:cytology; D002417:Cattle; D002452:Cell Count; D004305:Dose-Response Relationship, Drug; D004624:Embryo Transfer / Q000662:veterinary; D047108:Embryonic Development / Q000187:drug effects*; D004973:Estrus Synchronization / Q000097:blood; D005260:Female; D013006:Growth Hormone / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D011247:Pregnancy; D018873:Pregnancy Rate; D034561:Sheep, Domestic / Q000196:embryology / Q000502:physiology; D013480:Superovulation / Q000097:blood / Q000187:drug effects*
chemical_list: C073294:growth hormone, bovine; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone
keywords: Embryo transfer; Ewe; IGF-1; Insulin; Somatotropin