The 'boar taint' steroid 5α-androst-16-en-3-one: an immunisation trial

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Abstract
Entire and castrated male pigs were actively immunized against the steroid 5.alpha.-androst-16-en-3-one (androsterone) conjugated to bovine thyroglobulin as its carrier protein. This immunogen was incorporated with either Freund''s complete adjuvant or a water-in-oil emulsion adjuvant; only the latter was found to be acceptable in the pig tissue. Levels of free and antibody-bound androstenone were measured in the plasma of immunized and control boars. In the controls, levels of free androstenone rose from 15 ng/ml at 13 wk old to 36 ng/ml at 27 wk. In the immunized boars, levels of free steroid fell from 16 ng/ml at 13 wk old to zero at 17 wk old while levels of antibody-bound androstenone rose from zero at 13 wk old to a mean level of 70 ng/ml at 27 wk. When immunized and control boars and non-immunized gilts were killed at 135 kg live wt, the levels of androstenone in their carcass fat were measured. Their meat was also subjected to organoleptic testing. Meat from animals whose fat contained significant levels of androstenone (0.4-1.6 .mu.g/g) was found to taste of boar taint while meat from control gilts with low fat levels of the steroid (0.1-0.2 .mu.g/g) tasted normal. The uptake of [3H]androstenone was compared in 12 separate body tissues of one immunized and one control boar. No significant differences were found. The presence of specific antibody in the immunized boar had not inhibited movement of steroid between plasma and body tissue. Some hypotheses raised by these findings are discussed and the likelihood of successfully using immunization against boar taint is examined and questioned.