Prevalence of iodine, selenium, copper and cobalt deficiencies on Irish cattle farms

Combined blood trace element deficiencies are common in Irish cattle herds, particularly iodine with selenium. The iodine (I₂) content of Irish soils ranged from 1 to 90mg/kg DM and was unrelated to iodine content of herbage; almost 100% of herbage samples were deficient in I₂; low or very low blood I₂ status was found in 57% of herds sampled in 1993. Soil selenium (Se) total content ranged from 0.2 to 6.0mg/kg DM; over 90% of herbage samples were deficient in Se; low or very low blood Se status was found in 36% of herds sampled in 1993. Soil extractable copper (Cu) varied between 0.7 and 44.4mg/kg DM, while molybdenum (Mo) content varied between 0.03 and 6.5mg/kg DM; 65% of herbage samples were low in Cu, 40% of grass samples had excess Mo; 4% of herds sampled in 1993 had low blood Cu status. Soil cobalt (Co) content varied between 0.2 and 18mg/kg DM; herbage had marginal to normal Co content; low or very low blood vitamin B₁₂ status was found in 55% of herds sampled in 1993.