The influence of the odoriferous androstene steroids upon the response and courtship behaviour of gilts has been studied. These steroids are normally present in the submaxillary salivary glands of the boar, and have been shown previously to be an aid in the artificial insemination of gilts. Glands were excised from young boars after weaning, and at 6 months of age the ability of the boars to elicit a standing response from oestrous gilts was compared with that of littermate controls. In addition, a detailed record was made of behavioural activities performed by both gilts and boars, under a standard test procedure.
Analysis of the data showed that the presence of the glands was essential for normal behavioural patterns in both the females and the males. When confronted with a treated boar, the gilts were affected in three ways: approaching oestrus, they did not respond as early as they did to the controls; the intensity of their response was reduced; and it was held for a shorter period. The demeanour of the treated males was passive and unconcerned, i n contrast to the easily-aroused aggressive nature of the controls. The characteristic viscous salivary secretion was absent, and the scrotal sac was less pronounced and supported closer to the body.
These results suggest that elimination of the white, frothy saliva normally containing and dispersing the androstene steroids not only reduces the boar's ability to command and elicit a full sexual response from oestrous gilts, but it also reduces his own libido. In conjunction with previous work, these studies provide evidence for the pheromonal properties of androstenone and androstenol.