1. Abecia, J., Sosa, C., Forcada, F., Meiklie, A., 2006. The effect of undernutrition on the establishment of pregnancy in the ewe. Reproduction, Nutrition, Development, 46, 367-378. doi: 10.1051/rnd:2006018
2. Abegaz, S., Guguma, G., Negussie, E., Gelmesa,U., Terefe, F., Rege, J., 2002. Factors affecting reproductive performance and estimates of genetic parameters of litter size in Horro sheep. The Journal of Agricultural Science, 139, 79-85. doi: 10.1017/S0021859602002265
3. Afshari, G., Hasanpoor, A., Hagpanah, H., Amoughli-Tabrizi, B., 2008. Seasonal variation of vitamin A and Beta-carotene levels in Ghezel sheep. The Turkish Journal of Veterinary and Animal Sciences, 32, 127-129.
4. Al-Haboby, A.H., Abdulkareem, T.A., Katab, G.K., 1995. Effect of vitamin A on the reproductive performance of Awassi sheep. Regional Symposium on integrated crop livestock system in the dry area of West Asia and North Africa, 6-8 November, Amman, Jordan, pp. 300.
5. Al-Haboby, A.H., Salman, A.D., Abdulkareem, T.A., 1999. Influence of protein supplementation on reproductive traits of Awassi sheep grazing cereal stubble. Small Ruminant Research, 34, 33-40. doi: 10.1016/S0921-4488(99)00041-3