Influence of fresh alfalfa supplementation on fat skatole and indole concentration and chop odour and flavour in lambs grazing a cocksfoot pasture

• We tested four levels of alfalfa supplementation in lambs grazing a cocksfoot sward.
• We measured perirenal fat skatole content and we evaluated chop odour and flavour.
• Perirenal fat skatole content was higher for lambs that consumed alfalfa.
• Intensity of ‘animal’ flavour increased from the lowest level of alfalfa onwards
• ‘Animal’ flavour plateaued when fat skatole content was in the range 0.16–0.24 μg/g.

We investigated the influence of the level of fresh alfalfa supplementation on fat skatole and indole concentration and chop sensory attributes in grazing lambs. Four groups of nine male Romane lambs grazing a cocksfoot pasture were supplemented with various levels of alfalfa for at least 60 days before slaughter. Perirenal fat skatole concentration was higher for lambs that consumed alfalfa than for those that consumed only cocksfoot. The intensity of ‘animal’ odour in the lean part of the chop and of ‘animal’ flavour in both the lean and fat parts of the chop, evaluated by a trained sensory panel, increased from the lowest level of alfalfa supplementation onwards and did not increase further with increasing levels of alfalfa supplementation. The outcome of this study therefore suggests that these sensory attributes may reach a plateau when perirenal fat skatole concentration is in the range 0.16–0.24 μg/g of liquid fat.