Breed and maternal effects on the intake of tannin-rich browse by juvenile domestic goats (Capra hircus)
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Goat breeds differ in their consumption of tannin-rich browse, but the relative contributions of genetics and learning to these differences is unclear. The objective of this study was to differentiate between the effects of breed (nature) and rearing environment (nurture) on consumption of a tanniferous species by kid goats. We used Damascus and Mamber goat kids, and the browse species Pistacia lentiscus L. (tannin-rich) and Phillyrea latifolia L. (tannin-poor) to study the effects of breed and maternal attributes on: (i) propensity to consume these species when offered separately as a single food and (ii) preference when offered together. A cross-fostering experiment was conducted in which groups of Mamber and Damascus kids were reared indoors by biological mothers or by does of the reciprocal breed. To this design was added an artificially reared group of each breed that had been fed milk powder and had no adult role model. Propensity to consume and preference were tested prior to weaning when the "Nave" kids had no foraging experience, and after the "Experienced" kids had been weaned and allowed to forage, either together with their treatment does or alone in the case of the artificially reared groups, in an area containing both target species. For both Nave and Experienced kids, testing comprised nine 5-min exposures under controlled conditions. In the propensity test, Nave and Experienced kids of all treatment groups consumed both browse species readily. In the preference test, the rearing doe had a significant effect on the preference for P. lentiscus shown by Experienced but not by Nave, kids. This showed that that exposure to different role models while foraging induced differences in diet selection. Kid breed did not have a significant effect on preference for P. lentiscus. The preference for P. lentiscus shown by kids reared artificially (61%) or by Damascus does (55%) was significantly higher than that shown by kids reared by Mamber does (41%). This indicates avoidance learning rather than preference learning with respect to this plant species, and that kids may consume P. lentiscus readily in the absence of maternal influence. Learning appears to be far more dominant than genetics in determining goat kid preference/avoidance for tannin-rich browse. 2009 Elsevier B.V.
