1. Abecia JA, Chemineau P, Gómez A, Palacios C, Keller M and Delgadillo JA (2017) Exposure to photoperiod-melatonin-induced, sexually-activated rams after weaning advances the resumption of sexual activity in post-partum Mediterranean ewes lambing in January. Veterinary Sciences, 4(1), 4. doi:10.3390/vetsci4010004
2. Akers R M and denbow D M (2008) Anatomy and physiology of domestic animals. Blackwell publishing.
3. Alecozay AA, Selcer KW, Clark JR, Burns JM, Norman RC, Niswender GD and Leavitt WW (1988) Pattern of ovarian progesterone secretion during the luteal phase of the ovine estrous cycle. Biol. Reprod, 39: 287-294.
4. Arroyo J, Sánchez-Hernández NJ, Ávila- Serrano NY, Camacho-Escobar MA and Rodríguez-De-La-Torre M (2016) Reproductive seasonality in creole hair sheep in the tropic. Tropical Animal Health and Production, 48(1): 219–222. https://doi.org/10.1007/s11250-015-0927-z
5. Bathaei S (1996) Breeding season and oestrous activity of Iranian fat-tailed Mehraban ewes and ewe lambs. Small Ruminant Research. 22: 13-23
6. Canché JET, Monforte JGM and Correa JCS (2016) Environmental effects on productive and reproductive performance of Pelibuey ewes in Southeastern México. Journal of Applied Animal Research, 44(1): 508-512.
7. Čebulj-Kadunc N, Škibin A, Jenko Z (2017) Annual reproductive activity of ewes from Jezersko-Solchava, Bovec and Istrian breeds under variable field conditions. Small Ruminant Research, 149: 196-201
8. D’Occhio MJ, Gifford DR, Hoskinson RM, Weatherly T and Setchell BP (1988) Gonadotropin secretion and ovarian responses in prepubertal heifers immunized against androstenedione and oestradiol-17β. Journal of Reproduction and Fertility, 83: 159-168.
9. Ferasati C. (2011) Use of progesterone and eCG to enhance reproductive efficiency in the sheep herds of the province. Final report of the research-extension project. Kermanshah Province Agricultural Extension Coordination Management. (In Persion)
10. 10- Ferreira-Silva JC, Burnett TA, Souto PFMP, Pereira L C, Araujo MV, Moura MT and Oliveira MAL (2017) Progesterone (P4), luteinizing hormone (LH) levels and ovarian activity in postpartum Santa Inês ewes subject to a male effect. Archives Animal Breeding, 60(2): 95-100. doi:10.5194/aab-60-95-2017
11. Folch J and Alabart JL (2000) Características reproductivas de la oveja Rasa Aragonesa. Ovis, 68: 27-36.
12. Forcada F and Abecia JA (2006) The effect of nutrition on the seasonality of reproduction in ewes. Reproduction Nutrition and Development,
46: 355-365.
13. Forcada F, Abecia JA and Sierra I (1992) Seasonal changes in oestrous activity and ovulation rate in Rasa Aragonesa ewes maintained at two different body conditions levels. Small Ruminant Research, 8: 313-324.
14. Gómez-Brunet A, Santiago-Moreno J, Toledano-Diaz A and López-Sebastián A (2012) Reproductive seasonality and its control in Spanish sheep and goats. Tropical and Subtropical Agroecosystems, 15(1).
15. Gómez-Brunet A, López-Sebastian A, Muñiz- Herrando E and Cabellos B (1992) Función luteal y secreción de LH durante el anoestro post-parto en ovejas Manchegas: Influencia de la época del parto y tipo de destete. Investigación Agraria. Producción y Sanidad Animales, 7(3): 169-183.
16. Habibizad J, Karami-Shabankareh H and Chogha-Mirza K (2008) Follicular population and progesterone concentration changes during estrous cycle in Sanjabi ewes. Proceedings of the 3rd Iranian Congress of Animal Science. Ferdowsi University of Mashhad. (In Persion)
17. Hafez ESE (1993) Reproduction in farm animals. 6th ed. lea & febiger. philadelphia.
18. Hashemi MA, Safdarian MA and Kafib M (2006) Estrous response to synchronization of estrus using different progesterone treatments outside the natural breeding season in ewes. Small Ruminant Research, 65: 279-283.
19. Hassani SR, Jafari-Ahengary Y, Moslemi-Pour F, and Samiei R (2010) Determination of the transition time from the reproductive season to the estrus in Dalagh ewes using progesterone. Proceedings of the 4th Iranian Congress of Animal Sciences. Tehran University. (In Persion)
20. Ijabo HM, Jatfa JW, Oyedipe EO, Bawa EK and Dawuda PM (2014) Serum progesterone profiles during the estrous cycle, pregnancy and postpartum periods in Yankasa ewes. Nigerian Veterinary Journal, 35(1): 921-927
21. López-Sebastián A, Palacio M, Gómez-Brunet A (1991) Techniques for the improvement of fertility and prolificacy of anoestrus ewes in Spain. FAO/IAEA. Isotope Aided Studies on Sheep and Goat Production, 1: 157-164.
22. Manvi Y (2014) Studies on estrus synchronization and fertility in ewes. Thesis submitted to partial fulfillment of therequirements for the award of the degree of Master of Veterinary Science in Veterinary
Gynaecology and Obsterics. University, Bidar. Bangalore, India.
23. O'Callaghan D, Karsch F J, Boland M P, Hanrahan J P and Roche J F (1992) Variation in the timing of the reproductive season among breeds of sheep in relation to differences in photoperiodic synchronization of an endogenous rhythm. Journal of Reproduction and Fertility, 96: 443-452.
24. Ortavant R, Pelletier J, Ravault JP, Thimonier J, Volland-Nail P (1985) Photoperiod: main proximal and distal factor of the circannual cycle of reproduction in farm mammals. Oxford Review of Reproductive Biology, 7: 306-345.
25. Pineda MH and Dooley MP (2003) McDonald veterinary Endocrinology and Reproduction. Iowa state press.
26. Santiago-Moreno J, Gonzalez-Bulnes A, Gómez- Brunet A and López-Sebastían A (2000) Effect of season on the resumption of postpartum cyclic ovarian activity in Mouflon (Ovis gmelini musimon) and Manchega sheep (Ovis aries). Small Ruminant Research, 36: 69-74.
27. Sasa A, Rodrigues PA, Nonaka KO, Balieiro JCC and Coelho L A (2016) Plasma melatonin and progesterone profiles of Suffolk and Romney Marsh ewes implanted with melatonin during anoestrus season at lower latitudes in southern hemisphere. Acta Scientiae Veterinariae, 44: 1-8.
28. Statistical Center of Iran (2017) Detailed results of country livestock farming census. Planning and Budget Organization. Available at https://www.amar.org.ir/Portals/0/News/1396/adams96.
pdf
29. Thimonier, J., Mauléon, P. 1969. Variations saisonnières du comportement d´oestrus et des activités ovariennes et hypophysaires chez les ovins. Annales de Biologie Animale Biochimie, Biophysique, 9: 233-250.
30. Thimonier J, Terqui M and Chemineau P (1986) Conduite de la reproduction des petits ruminants dans les différents parties du monde. In: Proceedings of an International Symposium on the Use of Nuclear Techniques in Studies of Animal Production and Health in Different Environments, International Atomic Energy Agency, Vienna, pp 135-147.
31. Valls Ortiz M (1983) Frequent lambing of sheep flocks in Spain: Productivity and management consequences. Livestook Production Science, 10: 49-58.
32. Wheeler AG and Land RB (1977) Seasonal variation in oestrus and ovarian activity of Finnish-Landrace Tasmanian-Merino and Scottish-Blackface ewes. Animal Production, 24: 363-376.
33. Zarkawi M and Soukouti A (2012) Ovarian status in fat-tailed Syrian Awassi ewes during different reproductive stages and hormonal treatments monitored by laparoscopy and progesterone concentrations, Journal of Applied Animal Research, 40(1): 20-25. DOI: 10.1080/09712119.2011.620256
34. Zarkawi M (1997) Monitoring the reproductive performance in Awassi Ewes using progesterone radioimmunoassay. Small Ruminant Research, 26: 291-294.