Heifer ovariectomy using the Willis spay instrument: Technique, morbidity and mortality.

Two field trials were conducted to determine the morbidity and mortality rates in heifers ovariectomized with a Willis spay instrument.Trial A used 384 Hereford and Hereford cross, auction source, heifers, weighing an average of 230 kg. In trial B, 138 auction and ranch source heifers of mixed breeding and weighing an average of 285 kg were used. All heifers were ovariectomized per vaginam, with the ovaries left in the abdomen. Prophylactic antibiotics were administered and heifers were observed at pasture for the next 150 days.The morbidity and mortality rates for heifers in trial A were 0.5% and 0.26%, respectively. In trial B, there was no morbidity or mortality.These trials indicate that the technique described is a low risk, expedient method of ovariectomizing heifers.