The effect of Asparagopsis oil supplementation level on tissue residues and meat quality of Merino sheep fed high- or low-quality basal diets

The use of antimethanogenic feed additives in ruminant diets is gaining attention as a strategy to mitigate greenhouse gas emissions. Asparagopsis spp. (Asparagopsis), a red alga which naturally contains bromoform (CHBr 3 ), has demonstrated methane abatement potential in small ruminants. In large ruminants, previous research has shown equally promising results for Asparagopsis supplementation in the diet and its minimal effects on CHBr 3 residue and meat quality. This study aimed to address the limited knowledge on sheep meat characteristics for Asparagopsis-oil supplementation. Merino wethers were administered 100 g of supplementary pellets daily with increasing levels of formulated Asparagopsis-oil (A0: 0 mg CHBr 3 /kg DM; A1: 36 mg CHBr 3 /kg DM; A2: 72 mg CHBr 3 /kg DM; A3: 108 mg CHBr 3 /kg DM and A4: 144 mg CHBr 3 /kg DM) and fed either a high- or low-quality chaff diet. After a 119-d feeding period, 20 wethers ( n = 2 per treatment) were slaughtered. Carcasses were evaluated, and meat and offal samples were collected for residue and meat quality testing. Bromoform was not detected in meat or offal samples (at a minimum detection level of < 0.1 mg/kg wet matter basis). The kidneys contained the greatest detectible concentrations of bromide and iodine. The inclusion of Asparagopsis-oil had no impact on cooking loss, pH ultimate and intramuscular fat in longissimus lumborum and semimembranosus muscles. Similarly, supplementation of Asparagopsis-oil had no effect on any color parameters. The results from this study demonstrate that the use of Asparagopsis-oil in supplementary pellets in sheep diets does not compromising meat quality and there is minimal residue risk, but studies with a greater sample size are required to confirm this. A mitigation approach using Asp-oil can produce meat that meets industry standards without compromising quality or residue safety. • Bromoform was not detected in meat and offal samples. • Iodine and bromide residues in the kidney are reported. • Asparagopsis oil had little impact on meat quality.