Maternal interest in lambs smeared with polar and nonpolar substances

Abstract

Maternal interest in their own and alien lambs was examined in groups of 7-11 ewes before and after their lambs were coated with nonpolar substances (white soft paraffin or liquid paraffin), or more polar substances (polyethylene glycol, glycerol, silicone oil or diisooctylphthalate). Maternal interest in alien lambs was significantly increased by smearing lambs with the nonpolar material, but the effect was absent when lambs were washed before coating; more polar coatings had little or no effect. The coatings had little or no effect on the maternal interest in the ewe's own lambs. We suggest that coatings of polar materials, while dissolving polar components from the skin and wool, does not prevent the release of volatile nonpolar constituents which ewes employ to distinguish between lambs. We also suggest that nonpolar coatings dissolve and retard the release of lamb odour components of similar polarity, while permitting the release of other constituents which appear generally attractive to maternal ewes, and result in increased acceptance of alien lambs.