Observations on intramammary infection and somatic cell counts in cows treated with recombinant bovine somatotropin

Data were collected on udder health variables as part of a study of the effects of recombinant bovine somatotropin on production in lactating dairy cows. Milk samples, obtained at three intervals during the study, were assessed for their somatic cell count and bacteriological culture result. There was an increase in the prevalence of infection at mid-lactation in the 20.6 and 41.2 mg per day treatment groups as compared to the controls. There was no difference detected in the mean cell count between groups from the samples collected pretrial, mid-lactation, or late lactation. However, analysis of the individual cow Dairy Herd Improvement somatic cell count data showed a difference between groups which was most evident in mid-lactation.