Iodoform as an Anti-Methanogenic Feed Additive in Total Mixed Rations of Dairy Cows

This pilot study investigated whether reductions in enteric CH4 emissions could be obtained without affecting dry matter intake (DMI) when iodoform was mixed into total mixed rations (TMRs). The experiment consisted of four periods of 14 d with four rumen-cannulated Holstein dairy cows. In the pre-period, no iodoform was added to TMR, while either 8, 16, or 20 mg iodoform/kg DM was added to TMR in the remaining periods in a change-over design. However, the experiment was not balanced across treatments and periods due to unexpected animal responses in the second period. Dry matter intake and gas exchange were measured the last 3 d in each period using respiration chambers. Rumen grab samples were collected for microbial analyses on d 14. Dry matter intake was unaffected by the addition of iodoform to TMR at or below 20 mg/kg DMI. Methane and H2 yields (g/kg DMI) quadratically decreased (up to 46%) and increased (up to 1127%), respectively, with the increasing dose. This pilot study indicated that CH4 reductions can be obtained with an addition of up to 20 mg iodoform/kg DM in the diets of dairy cows without affecting DMI. However, high iodine concentration in iodoform limits its use in commercial herds within the EU.