Research on studies of feed additive Tasco, consisting of 96% dried seaweeds, influence on the amount and composition of milk in microelements and in iodine specification as well as reproductive characteristics performed by high-yielding cows are carried out. It is established that the studied product inclusion into cows’ rations by 40 and 60 gr a day per head allowed increase day yields from 29,5 kg to 31,7 and 32,8 kg (by 7,5 and 11,2%) in the first lactation period. The tendency of positive Tasco influence on cows’ reproduction is determined as service-period duration is decreased.