Measurements of the median diameter of all teats were recorded within 2 days of calving on 892 cows from eight breeding lines. Teats with a median diameter of ≥35 mm were classed as bottle teats. Their incidence varied from zero in a Hereford line to 0-55 in a Sahiwal crossbred line. In all lines, except the Hereford line, bottle teats were the most important single cause of mortality, up to 2 months of age, of calves that were born alive. However, mortalities became disproportionately high only when all four teats were classed as bottle teats.

Of calves that survived to weaning, those born to cows with at least one bottle teat had heavier live weights at weaning than those born to cows without bottle teats. Consequently, more calves were selected for high growth rate as potential sires from cows with bottle teats than from cows without bottle teats. This, combined with the observation that bottle teats occurred only after at least two calvings, is likely to reduce progress towards elimination of the defect through culling. However, indirect culling of the defect through any effect on calf performance is completely ineffective and uneconomic, and it is recommended that cows be culled directly for the defect in the year in which it first appears.