Hemp seed oil-supplemented finisher diets for lambs: Impact on meat physicochemical quality and oxidative stability

The growing interest in dietary lipid sources to improve lamb meat quality and oxidative stability has positioned hemp seed oil (HSO) as a potential functional lipid. However, evidence of its effects on ruminant meat quality and oxidative shelf life remains limited. This study evaluated the physicochemical attributes, fatty acid totals, chemical antioxidant capacity, and oxidative changes during retail display of meat from forty 4-month-old lambs randomly assigned to four dietary treatments (n = 10): control (no added oil), 2.5% canola oil, 2.5% HSO, or 5% HSO, fed for 42 days, with oils replacing maize grain on a 1:1 basis. Dietary HSO did not affect (P > 0.05) moisture, crude protein, ether extract, ash, pH, or drip loss. However, 24 h carcass temperature and thawing loss decreased linearly (P < 0.05), whereas total polyunsaturated fatty acids increased with HSO inclusion. Significant diet × retail display day interactions were observed for chroma (C*), metmyoglobin, and TBARS (P < 0.05). The 2.5% CAN and 2.5% HSO treatments produced the lowest C* values on day 1, intermediate values on days 5 and 7, and the highest values on day 9 (P < 0.05). Metmyoglobin values in the HSO treatments peaked on day 7 (16.1 and 16.0%) before declining by day 9. The 2.5% CAN treatment had lower (P < 0.05) TBARS values (2.11-2.83 mg MDA/kg meat) than the control and HSO treatments on day 9. Chemical antioxidant activity declined during display (P < 0.05), while lightness peaked on day 5 before stabilising (P < 0.05). Ageing improved tenderness, with shear force after 10 days half that at the initial ageing time (P < 0.05). Overall, dietary HSO up to 5% did not alter physicochemical attributes but increased oxidative deterioration during retail display.