Guerra M H, Cabrera M C, Abella D Fernández, Saadoun A, Burton A
Estación Experimental Facultad Agronomía Salto, Universidad de la República, Udelar, Uruguay.
Laboratorio Calidad de Alimentos & Productos, Departamento de Producción Animal & Pasturas, Facultad de Agronomía, Universidad de la República, Udelar, Uruguay.
Heliyon. 2019 Sep 20;5(9):e02486. doi: 10.1016/j.heliyon.2019.e02486. eCollection 2019 Sep.
Australian Merino ewes and lambs producing fine fibre wool for export are raised in the north-west of Uruguay in pasture-based systems. We studied the status of selenium and iodine in pregnant Merino ewes (10 per treatment) grazing in natural pasture, in natural pasture and supplemented with Se (0.1 mg Se/kg dry matter intake) and I (1 mg I/kg dry matter intake), or in natural pasture and supplemented with Se alone (0.1 mg Se/kg dry matter intake), during the last 30 days of gestation. Further, we evaluated the performance and wool quality of their offspring. Content of Se and I in natural pasture, in the sera of pregnant ewes, and in the wool of their offspring and levels of thyroidal hormones-TSH, T4, and free T3 (FT3)-in the sera of pregnant ewes were determined. The performance of lambs and the commercial parameters of fine fibre wool produced were measured. Results showed normal Se levels in serum (0.12-0.15 mg/l) in the ewes grazing in natural pasture (0.07-0.09 mg/kg DM) during late pregnancy. The observed increase in Se content in the pasture at lambing (0.11-0.16 mg/kg DM) improved serum Se levels (0.216 mg/l); however, the serum levels were not affected by the supplementation. I content in pasture showed adequate levels (0.50-0.60 mg/kg DM), which were reflected in the blood serum values 30 days prior to lambing (0.197-0.208 mg/l). However, at lambing, the I content in blood serum decreased (0.150 mg/l). Further, the supplementation did not modify the serum I levels (0.163-0.175 mg/l). An increase in FT3 levels in ewes at lambing could be associated with the increase in Se content in pasture and/or the adequate I content in pasture. No effect of supplementation was observed. Lambs showed good results regarding the quality of fine fibre wool and performance after supplementation with Se and I or Se alone and exhibited slightly improved Se and I content in wool. In conclusion, natural pasture provides adequate status in Se and I for the Merino ewes and their offspring without any additional beneficial effects of supplementation with Se and I or only Se.
乌拉圭西北部采用以牧场为基础的养殖系统，饲养用于出口的产优质羊毛的澳大利亚美利奴母羊和羔羊。我们研究了在妊娠最后30天，在天然牧场放牧的怀孕美利奴母羊（每组10只）、在天然牧场且补充硒（0.1毫克硒/千克干物质摄入量）和碘（1毫克碘/千克干物质摄入量）的母羊，以及在天然牧场且仅补充硒（0.1毫克硒/千克干物质摄入量）的母羊体内硒和碘的状况。此外，我们评估了它们后代的生长性能和羊毛质量。测定了天然牧场、怀孕母羊血清以及它们后代羊毛中的硒和碘含量，以及怀孕母羊血清中的甲状腺激素——促甲状腺激素（TSH）、甲状腺素（T4）和游离三碘甲状腺原氨酸（FT3）水平。测量了羔羊的生长性能以及所产优质羊毛的商业参数。结果显示，在妊娠后期，在天然牧场放牧的母羊血清中的硒水平正常（0.12 - 0.15毫克/升），此时天然牧场中的硒含量为（0.07 - 0.09毫克/千克干物质）。产羔时牧场中硒含量的增加（0.11 - 0.16毫克/千克干物质）使血清硒水平提高（0.216毫克/升）；然而，血清水平不受补充剂的影响。牧场中的碘含量显示处于充足水平（0.50 - 0.60毫克/千克干物质），这在产羔前30天的血清值中有所体现（0.197 - 0.208毫克/升）。然而，在产羔时，血清中的碘含量下降（0.150毫克/升）。此外，补充剂并未改变血清碘水平（0.163 - 0.175毫克/升）。产羔时母羊血清中FT3水平的升高可能与牧场中硒含量的增加和/或牧场中充足的碘含量有关。未观察到补充剂的影响。在补充硒和碘或仅补充硒后，羔羊在优质羊毛质量和生长性能方面表现良好，且羊毛中的硒和碘含量略有提高。总之，天然牧场为美利奴母羊及其后代提供了充足的硒和碘状态，补充硒和碘或仅补充硒没有任何额外的有益效果。
