Dietary Iodine and Selenium Affected the mRNA Expression Levels of Skin Monodeiodinase (II, III) in Liaoning Cashmere Goats

Livestock are frequently provided nutrient-depleted diets, which can negatively impact animal health and productivity. In our previous trial, we found that iodine (I) supplementation (not selenium (Se)) could increase cashmere production. In order to explore the role of I and Se in cashmere growth, we investigated the effects of dietary I and Se supplementation in Liaoning cashmere goats. Serum thyroid hormone status and the mRNA expression levels of skin monodeiodinase (MDII, MDIII) were measured during the cashmere fiber growth period. Forty-eight 2.5-year-old Liaoning cashmere goats (38.6?±?2.65 kg BW) were divided into six equal groups, and their diets were supplemented with I (0, 2, or 4 mg/kg DM) and Se (0 or 1 mg/kg DM) in a 2?×?3 factorial treatment design. The six treatment groups were: I₀Se₀, I₂Se₀, I₄Se₀, I₀Se₁, I₂Se₁, and I₄Se₁. Concentrations of I and Se in the basal diet (group I₀Se₀) were 0.67 and 0.09 mg/kg DM, respectively. The trial started in September of 2009 and lasted 70 days. For every measured parameter, supplemental Se had no significant effect on thyroid hormones, but improved the mRNA expression levels of skin MDIII (P?<?0.01). However, supplemental I increased levels of thyroid hormones (thyroxine and triiodothyronine) and improved the mRNA expression levels of skin MDII (P?<?0.05). These results show that the addition of I to cashmere goat feedstock may be an effective means of increasing cashmere production through thyroid hormones regulating the mRNA expression of skin MDII.