The Effect of Iodine Levels Above of NRC Recommendations on Performance and Thyroidal Hormones in Holstein Dairy Cows

Document Type : Scientific - Research Articles


1 Ferdowsi University of Mashhad

2 Ferdwosi University of Mashhad


In order to survey of using iodine levels above of NRC recommendations on performance and thyroidal
hormones, sixteen Holstein dairy cows with the average live body weight and daily milk production of 652 ± 43
and 32.9 ± 2.4 kg respectively, allocated to 4 treatments in a complete randomized design. The dietary treatments
were 1) the basal diet (without Potassium Iodide) as control diet, 2, 3 and 4, the basal diet plus 2.5, 5 and 7.5
mg/kg DM Potassium Iodide respectively. The number of replications in each treatment was 4 cows. The dry
matter intake (DMI), milk yield and composition were compared between treatments. The iodine concentrations
in feed, water, urine and blood as well as thyroidal hormones (T3 and T4) were determined. There were no
significant differences between treatments for DMI, milk yield and compositions as well as diet efficiency.
Iodine contents in blood and urine were affected by iodine supplementation and increased significantly (P