Grazing lambs on a low-input, multispecies pasture for an extended period has no detrimental effect on meat nutritional or sensory quality

Abstract

There is an increasing interest in low-input, multispecies swards as a sustainable forage for ruminant production, but the impact of grazing these over extended periods of time on meat nutritional quality (fatty acid (FA) profile, trace minerals and oxidisability risk) and sensory properties is unclear. Thirty lambs were grazed for 133 days on either a perennial ryegrass (PRG) or botanically diverse (containing twelve plant species, BD), pasture. The effects on the FA composition of musculus longissimus thoracis (lean and subcutaneous fat), zinc and iron content (lean), glutathione perioxidase (GSH-Px) activity (lean and plasma) and thiobarbituric acid reactive substances (TBARS) content (lean) were determined, and cooked meat was assessed for sensory properties using a trained sensory panel. BD lambs were lighter (P = 0.014) and had a lower weekly live weight gain (P = 0.017) than PRG, which was probably due to the nutritional quality of the pasture. BD pasture increased (P < 0.05) 18:2 n-6 content in lean and subcutaneous fat, and there was no effect (P > 0.05) on other polyunsaturated FA (PUFA), GSH-Px activity or TBARS content. BD pasture increased (P = 0.038) lean tissue zinc content compared with PRG but did not affect iron (P > 0.05). Pasture type had no impact (P > 0.05) on meat aroma and flavour sensory properties. It was concluded that grazing BD for an extended period did not negatively affect the nutritional and eating quality of lamb meat compared with PRG, and as such is suitable for finishing lambs. In order to benefit economically from including a BD pasture in a lamb finishing system, producers may need to consider an earlier slaughter target weight, depending on live weight gain.