Animal Reproduction Science 107 (2008) 85–93 Prevention of suckling improves postpartum reproductive responses to hormone treatments in Pelibuey ewes Julio C´ esar Camacho Ronquillo a,b , Arturo Pr ´ o Mart´ ınez b , Carlos Miguel Becerril P´ erez b , Benjam´ ın Figueroa Sandoval c , Graeme B. Martin d , Javier Valencia e , Jaime Gallegos S´ anchez b,∗ a Benem´ erita Universidad Aut´ onoma de Puebla, 4 sur 104, C.P. 72000 Puebla, Mexico b Colegio de Postgraduados, Campus Montecillo, Programa de Ganader´ ıa, km 36.5, Carretera Federal M´ exico-Texcoco, C.P. 56230 Montecillo, Estado de M´ exico, Mexico c Programa de Edafolog´ ıa, km 36.5, Carretera Federal M´ exico-Texcoco, C.P. 56230 Montecillo, Estado de M´ exico, Mexico d Faculty of Natural and Agricultural Sciences, University of Western Australia, Crawley 6009, Australia e Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autonoma de M´ exico, Mexico Received 12 September 2006; received in revised form 12 May 2007; accepted 19 June 2007 Available online 23 June 2007 Abstract To determine the effects of suckling on postpartum (pp) reproductive efficiency in Pelibuey ewes, two experiments were performed. In Experiment 1, 112 ewes were randomly assigned to one of two groups at parturition: Without restriction of suckling (WRS) 24 h day -1 for 60 days (n = 56), and Weaned Ewes (WE), weaned at 40 days pp (n = 56). On Day 30 pp, all ewes were given Prostaglandin (PGF2) and one of four treatments (n = 14): T1, intravaginal progestagen (FGA; 40 mg) for 12 days from day 30 pp + equine chorionic gonadotropin (eCG; 300 UI) until 2 days before removing FGA; T2, FGA was applied for 12 days; T3, a second application of PGF2 was given on day 40 pp + eCG on the same day; T4, a second injection of PGF2 was applied on day 40 pp only. In all the analyzed characteristics, the best results were obtained in WE. Within the WE group, the best treatment (P < 0.05) was T1 with 85.7% of the ewes in oestrus, 71.4% pregnant and a prolificacy of 1.9. Within the WRS group the best results were observed in T1. In both groups, the lowest results (P < 0.05) were obtained in T4. In Experiment 2, 75 ewes were randomly assigned to one of three groups (n = 25) immediately after parturition: Group 1, Without restriction of suckling (WRS, as in Experiment 1); Group 2, with restriction of suckling (RS; suckling for 30 min day -1 ); Group 3, Early Weaning (EW: at 7 days pp). All ewes were given PGF2 at 30 days pp and the same ∗ Corresponding author. E-mail address: gallegos@colpos.mx (J. Gallegos S´ anchez). 0378-4320/$ – see front matter. Crown Copyright © 2007 Published by Elsevier B.V. All rights reserved. doi:10.1016/j.anireprosci.2007.06.021