An experiment was conducted to determine the effect a newborn calf would have on initial success rate, lactation performance, infertility and progesterone levels during mammogenesis and lactogenesis in dairy cows undergoing hormonal inducement to lactate. Fourteen Holstein, Brown Swiss and Jersey infertile, non-lactating cows, loaned by Pacific Northwest dairymen, were...
Fourteen multiparous Holstein cows were paired by stage of
lactation and previous years milk yield and 14 Holstein first-calf
heifers were paired by stage of lactation. One member of each pair
was assigned to a 24L:OD or a 18L:6D photoperiod for 16 wk during
winter 1981 (Experiment 1). A similar...