Physicochemical properties and fatty acid profile of meat from lambs fed with a blend of spineless cactus and sugarcane

Abstract

Context Cactus is an important feed resource, widely cultivated in the semi-arid Brazilian north-east owing to its resistance to drought, high production potential and high nutritional value. It is also an excellent source of energy. Therefore, its use in the diet of sheep should be optimised. Aims This study was designed to evaluate effects of different ratios of a spineless cactus (Nopalea cochenillifera) to sugarcane (Saccharum officinarum) (Cac:Sug ratio) as source of dietary roughage on the physicochemical properties and fatty acid (FA) profile of meat from lambs. Methods Experimental treatments were diets with four Cac:Sug ratios (0:3, 1:2, 2:1 and 3:0) (477 g/kg as fed) in a complete randomised block design, using 36 uncastrated male lambs (Santa Ines breed) of average initial bodyweight 22.0 ± 2.3 kg housed in individual pens. Lambs were slaughtered after 100 days and meat samples (longissimus lumborum (LL) muscle) taken. Key results Cac:Sug ratio in the roughage of the diet did not influence (P > 0.05) moisture, protein, total lipid or ash contents, pH24h, expressed juice, cooking weight losses, shear force, or colour parameters of LL muscle. However, there was a linear increase in cholesterol (P = 0.013) concentration of the meat. Increasing Cac:Sug ratio in the diet did not affect (P > 0.05) the saturated FAs (SFAs) C10:0, C12:0, C14:0, C15:0, C16:0, C17:0 and C20:0; monounsaturated FAs (MUFAs) C14:1 n–5cis, C17:1 n–7cis and C20:1 n–9cis; polyunsaturated FAs (PUFAs) C18:2 n–6cis, C18:3 n–6, C18:3 n–3, C20:2 n–6cis, C20:5 n–3cis (eicosapentaenoic acid) and C22:5 n–3 (docosapentaenoic acid); ∑n–6:∑n–3 ratio; or nutraceutical compounds. There was a linear decrease in Δ9-desaturases C16 (P = 0.042) and C18 (P < 0.001) with the increasing Cac:Sug ratio, and a quadratic decrease in C18:2 n–6trans concentration (P = 0.045). The ∑SFAs and ∑MUFAs of LL muscle tended to increase linearly with increasing Cac:Sug ratio. Conclusion Most of the physicochemical parameters of the meat of lambs were not changed by the Cac:Sug ratio in the diets. A diet containing up to 48% of DM as spineless cactus plus sugarcane in a 1:2 ratio was found to be satisfactory for finishing lambs. Implications Cac:Sug ratio up to 1:2 (spineless cactus 159 g and sugarcane 318 g/kg DM total diet) may be a useful feed strategy for lamb meat producers because improved lipid composition enriched with C18:0 and higher ∑PUFA:∑SFA ratio is considered healthy for human consumption without affecting most physical and chemical properties.