Contents lists available at ScienceDirect Animal Reproduction Science journal homepage: www.elsevier.com/locate/anireprosci Melatonin treatment in winter and spring and reproductive recovery in Sarda breed sheep Maria Consuelo Mura a , Sebastiano Luridiana a , Federico Farci a , Maria Veronica Di Stefano a , Cinzia Daga a , Luisa Pulinas a , Jože Starič b , Vincenzo Carcangiu a, ⁎ a Dipartimento di Medicina Veterinaria, Università di Sassari, Via Vienna 2, 07100, Sassari, Italy b Clinic for Reproduction and Large Animals – Section for Ruminants, Veterinary Faculty, University of Ljubljana, Cesta v Mestni log 47, 1000 Ljubljana, Slovenia ARTICLE INFO Keywords: Sarda sheep Seasonal reproduction Melatonin implant Fertility ABSTRACT This study aimed to evaluate the effect of melatonin treatment carried out between late winter and early spring on reproductive response in Sarda breed sheep and whether the photo-re- fractoriness can influence this reproductive response. The study was conducted on 3200 adult ewes, aged 3–6 years old, with body condition score (BCS) 2.5–4.0, from 16 commercial sheep farms in Northern Sardinia. In each farm 200 animals were enrolled and subdivided into 2 groups (n = 100 each): Group M (treated with one 18 mg melatonin implant), and group C (untreated). The melatonin treatments were performed on 10th February; 10th March; 10th April and on 10th May each time in 4 different randomly selected farms. Adult males, treated with 3 melatonin implants 1 week before females, were introduced in each flock 35 days after ewes’ treatment, and removed after 45 days of cohabitation with females. Pregnancy was determined by transab- dominal ultrasonography examination between 45th and 90th day after ram introduction. Data showed that melatonin treatment increased the fertility rate significantly (P < 0.05), with the higher fertility rate in the ewes treated in April and May. The average time in days from male introduction to lambing was shorter in treated than in control ewes (P < 0.05). Further, at the 160th and 170th day after male introduction the group M showed a higher number of lambed ewes compared to C (P < 0.01). This effect was observed at 180th and 190th days after ram introduction, also, but with lower significance (P < 0.05). In conclusion, melatonin treatment improved reproductive efficiency and advanced breeding season in Sarda sheep, especially when ewes were treated in spring. 1. Introduction Reproductive seasonality of dairy sheep at the Mediterranean basin latitudes is a major constraint for production (Chemineau et al., 2007). Furthermore, these areas have a mild climate during winter and autumn, rainfall mainly concentrated in spring and a very dry summer. Thus, the sheep production cycle is closely linked to pasture growth which occurs predominantly in autumn and spring (Carcangiu et al., 2011). Therefore, to increase the length of lactation (6–7 months), it is necessary to mate sheep in spring to obtain lambing in autumn. The timing of reproductive seasonality in many small ruminant species is controlled by the shortening of http://dx.doi.org/10.1016/j.anireprosci.2017.08.009 Received 23 March 2017; Received in revised form 4 August 2017; Accepted 9 August 2017 ⁎ Corresponding author. E-mail address: endvet@uniss.it (V. Carcangiu). Animal Reproduction Science xxx (xxxx) xxx–xxx 0378-4320/ © 2017 Elsevier B.V. All rights reserved. Please cite this article as: Mura, M.C., Animal Reproduction Science (2017), http://dx.doi.org/10.1016/j.anireprosci.2017.08.009