Antibody responses to recombinant bovine somatotropin in dairy cattle

Abstract Antibody responses to recombinant bovine somatotropin were followed over three lactations in Jersey, Meuse‐Rhine‐Issel and Friesian cows. Randomized blocks of animals were observed during a pretreatment period and were given 320, 640‐or 960 mg of recombinant somatotropin (somidobove) at 28 day intervals through the lactation period or left untreated. All treated animals developed a detectable antibody response to somidobove. These responses peaked at 45‐50 relative μg/ml as compared to pretreatment levels of 10‐25 relative μg/ml. A normal antibody response level is 1000‐4000 μg/ml. The antibody level returned to baseline values when treatment was discontinued and remained at baseline until treatment was resumed during the next lactation. Treated cows did not develop an anamnestic response during the second and third lactations when the antibody responses peaked at 38 and 27 relative μg/ml respectively. Antibody responses to somidobove were analyzed in calves born of cows that received somidobove ...