Influence of level of barley supplementation on plasma carotenoid content and fat spectrocolorimetric characteristics in lambs fed a carotenoid-rich diet

• Plasma carotenoid content decreased when barley supplementation increased.
• Yellowness of perirenal fat decreased when barley supplementation increased.
• Treatment had no effect on the absolute value of the mean integral (AVMI).
• Yellowness of subcutaneous fat decreased with initial liveweight.

This study investigated changes in plasma carotenoid concentration and fat reflectance spectrum characteristics and color in lambs fed a carotenoid-rich diet with low-level (L, 100 g/lamb/day) or high-level (H, 400 g/lamb/day) of barley supplementation for 75 days before slaughter. Each treatment used 24 Romane male lambs that were individually penned indoors. Plasma carotenoid concentration at slaughter was 16% lower in H lambs than in L lambs. H lambs had heavier and fatter carcasses than L lambs. Yellowness and redness of perirenal fat were slightly lower in H lambs than in L lambs. The absolute value of the mean integral (AVMI) calculated from the reflectance spectrum of the fat in the 450–510 nm band was not affected by the treatment. Yellowness, chroma and AVMI of subcutaneous fat were not affected by the treatment but decreased with initial animal's liveweight.