Fertility of two bulls with poor sperm morphology

The aim of this study was to determine the degree of subfertility of 2 Friesland bulls (Bulls 1 and 2) with poor sperm morphology. An Ayrshire (Bull 3) with good sperm morphology served as control. Bull 1 had a mean of 48% morphologically normal sperm, 36% sperm-head defects and 18% flagellar defects. Bull 2 had a mean of 28% normal sperm, 28% flagellar defects and 33% proximal cytoplasmic droplets. Bull 3 had a mean of 83% normal sperm. Each bull was exposed to 19 cyclic heifers. Heifers of Breeding Groups 1, 2 and 3 did not differ with respect to body mass, age and breed. Pregnancy was diagnosed by means of B-mode ultrasonography 25-50 d after service. Bulls 1, 2 and 3 served 13, 17 and 16 heifers, respectively, during one oestrous period each. Of these heifers 6 (46%), 2 (12%) and 12 (75%) respectively, conceived.