Effect of immune modulators and lactation number on in vitro proliferation of lymphocytes from non-pregnant dairy heifers and cows

The proliferation of blood lymphocytes from non-pregnant, non-lactating heifers was comparable to that of non-pregnant cows in their first lactation. Both low and high levels of β-hydroxybutyrate and low levels of prolactin, but not isoproterenol, reduced the proliferative response of dairy heifers and cows in their first or second lactation.