Chapters in Books (Agricultural Economics)

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    Neonatal recognition in sheep
    (Springer New York, 2013) Burger, B. V.; Viviers, Marlize Z.; Le Roux, Niel J.; Morris, John; Bekker, Jan P. I.; Le Roux, Maritha
    The strong bond formed between ewe and lamb shortly after parturition is an important factor in lamb survival. Evidence exists that the ewe can distinguish her lamb by its unique smell, but the constituents of such a putative pheromone have not yet been identified. We have identified 133 volatile organic compounds in the cranial wool of Dohne Merino lambs that are presumably constituents of the neonatal recognition cue of this sheep race. Quantitative analysis and comparison of the odour profiles of the twins of 16 ewes of a flock of 165 twin-bearing ewes (9 .69% sample group) revealed that the wool volatiles of twins are qualitatively as well as quantitatively practically identical, but differ from those of other twins or non-twin lambs in the flock. The 88 constituents present in at least 20% of the analysed wool samples were considered as variables for multivariate analysis. A ?-value <0.0001 was calculated, indicating that the pairing of twins according to the qualitative and quantitative composition of the wool is statistically highly significant. Bioassays carried out during the lambing seasons of 2009 and 2010 confirmed the previously established role of the odour of lambs in ewe-lamb recognition. However, ewes rejected alien lambs dressed in jackets that were sprayed with mixtures formulated with synthetic analogues of the identified wool volatiles according to the qualitative and quantitative compositions of the experimental ewes' own lambs. This is probably due to the volatiles not being released into the atmosphere in quantitative ratios emulating the odour of the lambs accurately enough to satisfy the experimental ewes.