Do lambs differentiate the odor of their mother from that of an alien ewe? Focus on inguinal wax

Ewes bear scent glands located near the udder which smelly secretion is interesting to newly-born lambs searching a teat to suck on. This glands’ secretion – inguinal wax (IW) – was found to be reactogenic to lambs before they initiate suckling from the dam. The present study aimed to further assess whether IW odor affects two vital aspects of newborn lambs’ behaviour: orienting and engaging suckling. First, forty-six lambs were tested in two-choice odor tests contrasting i) own mother's Inguinal Wax (IW-M) vs. unfamiliar mother's Inguinal Wax (IW-nM), ii) IW-M vs. control and iii) IW-nM vs. control, to measure their differential orientation to maternal IW odor presented against either IW from another dam or a control. Second, a bottle-feeding test (n = 41 lambs) assessed lambs’ elicitation of suckling from IW-odorized vs. control bottles. Relative to the control, IW odor enhanced lambs' orientation during the two-choice odor test, but without differentiation of maternal IW from non-maternal IW. Otherwise, lambs did not engage more suckling on a bottle when odorized with maternal IW relative to a control bottle. Some aspects of lambs’ responses were differentiated by sex, but this effect was independent on odor condition. In sum, this preliminary study indicates that ovine IW is somehow inherently attractive to lambs before they associate it with suckling. • Inguinal wax odor is attractive to suckling-naïve lambs. • Lambs did not differentiate maternal from non-maternal inguinal wax. • No difference in lambs’ suckling behaviour was observed between inguinal wax and control odors. • Lambs’ behavioural responses to inguinal wax were not differentiated by sex.