ANDROSTENONE, ANDROSTENOL AND ODOR INTENSITY IN BACKFAT OF 100- AND 130-KG BOARS AND GILTS

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Abstract
Forty-nine boars and 13 gilts were fed ad libitum from 20 to 100 kg body weight. Fifteen boars and four gilts were slaughtered at 100 kg and the remaining animals were fed ad libitum or at 70% of ad libitum feed intake from 100 kg liveweight until they were slaughtered at 130 kg. Backfat samples were collected from the lumbar region of all pig carcasses at both slaughter weights, vacuum packaged and stored at −20 °C. Fat samples (10 g) were saponified and extracted with hexane and ether. Extracts were evaporated under nitrogen, and androstenol (5α-androst-16-en-3α-ol; 5α-androst-16-en-3β-ol) and androstenone (5α-androst-16-en-3-one; 5β-androst-16-en-3-one) were quantified by gas chromatography using 5α-androstane-3, 17-dione as internal standard. A trained panel of eight women scored the odor intensity of each fat sample on a scale of 1 (no odor) to 6 (strong odor). Androstenone was detected in backfat from all boars and concentrations ranged from 0.06 to 3.42 μg g−1 of fat with a mean value of 0.76 (±0.10, SEM) μg g−1. Five boars had no detectable backfat androstenol while the highest concentration recorded was 1.8 μg g−1 fat. Neither steroid was detected in gilt backfat. Odor intensity of fat samples heated by soldering iron or in sealed vials was greater (P < 0.01) for boars than for gilts. Boars weighing 100 kg had lower (P < 0.05) backfat odor intensity score and androstenone concentration than 130-kg boars. Androstenol concentration and odor intensity of fat were significantly correlated (r = 0.42; P < 0.05) with age of ad libitum fed boars. There was a significant quadratic response of odor intensity determined by vial test to increasing androstenol concentration in fat (R2 = 50%) but the relationship between odor score and steroid content was otherwise linear. The concentration of androstenol in boar backfat was only one-half of the androstenone concentration but it explained some variation in odor score over and above (7–16%) that which was explained by androstenone. Key words: Boar, odor, androstenone, androstenol, backfat