Effect of Slow-Release Pellets of Selenium and Iodine on Performance and Some Blood Metabolites of Pregnant Moghani Ewes and Their Lambs Akram Zarbalizadeh-Saed 1 & Jamal Seifdavati 1 & Hossein Abdi-Benemar 1 & Abdelfattah Z. M. Salem 2 & Alberto Barbabosa-Pliego 2 & Luis M. Camacho-Diaz 3 & Amir Fadayifar 4 & Reza Seyed-Sharifi 1 Received: 14 June 2019 /Accepted: 25 July 2019 # Springer Science+Business Media, LLC, part of Springer Nature 2019 Abstract The need for minerals during pregnancy in mammals increases by progress of gestation due to embryo development. Therefore, the supply of trace minerals for pregnant ewes in late pregnancy may be of vital importance. The present study was carried out to evaluate the effect of selenium and iodine release slowly on the performance and some blood parameters of pregnant ewes and their lambs. Experiments were performed on 40 pregnant ewes from 3 to 4 years old in the last month of pregnancy with a weighing average of 52 ± 5 kg and a factorial experiment (2 × 2) in a completely randomized design with 4 treatments and 10 replicates used for 120 days (30 days before and 90 days after parturition of ewes). Experimental treatments were containing the following: (1) control, (2) ewe receiving bolus containing iodine, (3) ewe receiving bolus containing iodine and selenium, and (4) ewe receiving bolus containing selenium. One month before the expected birth date, the pellets will be fed to each of the livestock by bolus gun. During the test period, ewes will not receive any other mineral supplements and will be kept in a group in a herd. Ewes were blood sampled at 10 days prepartum and 30 and 60 days postpartum. The results showed that body weight on birth and weaning of lambs and average daily gain of lambs were highest in bloused animals that were related to the slow-release selenium tablet lambs (P < 0.05). Lambs born to mothers receiving 0.3 mg day -1 of selenium per day had a keratin phosphoki- nase concentration of T 4 concentration and T 4 to T 3 lower than that of zero selenium (P < 0.05). Daily gain, glutathione peroxidase activity, and T 4 concentration at iodine 0.4 mg day -1 were significantly higher than iodine level (P < 0.05). The adding of slow- release pellets of iodine and selenium improved the immune system. Keywords Iodine . Pellet . Selenium . Slow-release Implications Nutritional status during pregnancy and the proper growth rate of lambs in early life are two essential factors in good sheep production systems. Traditionally, farmers do not use any mineral supplements for their animals. The need for minerals during pregnancy in ewe increases for embryo development and reaches its peak during the late pregnancy, including the supply of trace minerals for pregnant ewes to protect the fetus and improve the growth of lambs born. This study aimed to investigate the effect of slow-release pellets of iodine and sele- nium on the performance of pregnant ewes and their lambs. The adding of slow-release pellets of iodine and selenium improved the immune system. * Jamal Seifdavati jseifdavati@yahoo.com * Abdelfattah Z. M. Salem asalem70@yahoo.com 1 Animal Science Department, Faculty of Agriculture and Neutral Resources, University of Mohaghegh Ardabili , Ardabil, Iran 2 Facultad de Medicina Veterinaria y Zootecnia, Universidad Autónoma del Estado de México, Toluca, Estado de México, Mexico 3 Facultad de Medicina Veterinaria y Zootecnia, Universidad Autónoma de Guerrero, Cd. Altamirano, Guerrero, Mexico 4 Animal Science Department, University of Lorestan, Khorramabad, Iran Biological Trace Element Research https://doi.org/10.1007/s12011-019-01853-w