Impact of short-term feedlot finishing on carcass traits, colour stability, and sensory quality of Karoo lamb

The flavour-specific character of Karoo lamb meat as a geographic product is linked to region-specific fragrant shrubs grazed by sheep. During severe drought, lambs are often removed from veld pastures and finished in feedlots, which may dilute their distinctive sensory attributes and alter overall quality. This study investigated the effect of short-term feedlot finishing on Karoo lamb meat quality. Dorper ram lambs (30.14 ± 2.78 kg; 3–4 months) were subjected to cereal/lucerne-based diets for different durations: D0 (grazing; n = 8), D21 (21 days; n = 8), and D28 (28 days; n = 8). A randomised block design with three treatments and eight replications (n = 24) was used. Data were analysed with a linear mixed-effects model, with feeding duration as a fixed effect and animal, abattoir, slaughter day, tasting day, and session as random effects. For colour shelf life, a split-plot design was applied. Slaughter weight (P = 0.032), carcass weight (P = 0.005), backfat thickness (P = 0.029), and intramuscular fat (P < 0.001) all increased with feedlot duration. Longissimus muscles from D0 carcasses exhibited higher redness (P = 0.019) but less favourable hue angle values over a seven-day display period compared with feedlot groups. Fat from D0 also received higher (P < 0.05) scores for aromas typical of Karoo lamb, whereas ‘pastoral’ fat aromas were most pronounced in D21 and D28. In conclusion, although feedlot finishing increased carcass size and fatness, the distinctive sensory character of Karoo lamb was not maintained when veld-grazed lambs were finished on a grain/alfalfa diet for up to 28 days. • Feedlot lambs reached desirable carcass size within Karoo standards. • Faster pH decline in heavier lambs did not harm initial meat colour. • Feedlot diets with alfalfa linked to “pastoral” and rancid aromas. • Karoo veld lambs retained sweeter, herbaceous flavours. • Regulations on 30-day feedlot finishing may need reconsideration.