Carcass and Meat Quality of Lambs From Intensive Grazing Systems Differing in the Age of Slaughter

Abstract

Ninety lambs reared on pastures were slaughtered for 2 y corresponding to 3 ages of slaughter: at weaning with 4 mo of age (4M), at 6–7 mo of age (6M), and at 12 mo of age (12M; last treatments were weaned at 4 mo). With the purpose of deseasonalizing high-quality meat lamb production in the year, the present work aimed to achieve hot carcass weight (HCW) of 18–20 kg on average in each lamb group. Hot carcass weight, carcass yield (CYd), subcutaneous tissue depth, leg, frenched rack, and loin weights were determined. After meat ageing for 7 and 14 d from the 3 groups of lambs, instrumental color, Warner-Bratzler shear force (WBSF), consumer sensory analysis (n=200), and fatty acid profile of intramuscular fat (IMF) were determined on longissimus lumborum muscle. Lambs of 12M resulted in greater HCW (P<0.05). The young lambs (4M) presented a greater subcutaneous fat coverage and CYd (P<0.05). Lambs of 12M presented a greater proportion of legs (P<0.05) regarding HCW. Meat color from 4M lambs was lighter (greater L* values) when aged for 7 and 14 d and showed lower WBSF values with 14 d of ageing (P<0.05). A greater proportion of IMF (P<0.05) was observed in 12M and 4M lambs, but the latter presented a greater proportion of conjugated linoleic acid (P<0.05) and polyunsaturated fatty acid to saturated fatty acid ratio (P<0.05). Older lambs (12M) showed a lower n6/n3 fatty acid ratio (P<0.05) and a greater concentration of α-tocopherol (P<0.05). Meat from the 3 groups of lambs was scored positively (i.e., at least between “I like moderately” and “I like slightly”) for overall liking when evaluated by consumers. Although significant differences were observed among the 3 groups of lambs, slaughter age in lambs until 12M seems to have a minor effect on product quality from a practical standpoint.

Keywords

• de-seasonalize
• meat quality
• pasture-based systems