The effect of oral and injection iodine supplements on milk yield,fat milk and some blood metabolities of dairy cows in isfahan province

In order to evaluate the effect of different iodine supplementations on milk production and total iodine concentration in blood serum this experiment was conducted with 180 Holstein lactating cows in 6 farms of Isfahan country side. The cows were in 70±35 days after parturition.The treatments were consisted of control (the diet without any iodine supplementation), oral iodine supplemented (OIS) that received 1.3 mg pure iodine per cow per day in form of potassium iodate and iodine injected groups (IIG) that injected intramuscularly iodized oil; 4.8 mg pure iodine per cows once time).Every 5-6 cows was allocated to one of three treatment groups. Milk yield and its fat were measured by the farm manager. The total iodine content of serum and thyroxine (T4) and triiodothyronine (T3) concentrations of serums were determined every month and calf weights were recorded at calving time. Results indicated that total iodine concentrations of serums in all groups were about 38.2µg/l in the start of trial. This parameter in IIG reached 67.24 µg/l in during that was significantly (p0.05) higher experiment period than other treatments. Milk yield and its fat in all treatments did not have any difference. The serum total iodine concentrations of calves at calving time in control, OIS and IIG groups were 61.89, 71.07 and 87.81 µg/l, respectively, that IIG was numerically(p0.05) higher than other treatments. Also, serum T3 and T4 concentrations were not different between treatments.The fertility in control, OIS and IIG groups were 3.35, 2.75 and 2.15, respectively, that in IIG group it was significantly (p0.05) lower than other treatments. The results of this experiment showed that IIG increased significantly (p0.05) total iodine of serum after 1 month that this trend was continued until six months later. In IIG treatment, the fertility was significantly (p0.05) higher than other treatments however milk yield did not show any difference between treatments.