Influence of feeding system on carcass and meat quality: fat colour as a tool of classification

Abstract

Forty-five Rasa Aragonesa lambs were allocated in four treatments: GR, lambs and ewes grazing on alfalfa pasture, no concentrate was available; GR + S, as the previous one, but additionally lambs had free access to concentrate; DRL-GRE, lambs remained indoors with free access to concentrate and ewes grazed during 8 h a day, thereafter remaining with lambs; and DRL, lambs and ewes were kept always in confinement, ewes had free access to dry unifeed and lambs to concentrate. In DRL-GRE and DRL lambs were weaned at 45 days old. Lambs were slaughtered at a live weight of 22-24 kg. The live weight, carcass weight, dressing percentage, subjective carcass classification, and meat quality (pH, instrumental toughness, meat colour) were recorded. Moreover the integral of the translated spectrum of renal and caudal fat (SUM) was studied looking for a non-destructive technique to discriminate carcasses from alfalfa grazing-based systems. Extensive lambs (GR and GR + S) had greater dressing percentage than indoors lambs (DRL-GRE, DRL). Feeding system had influence on subjective and instrumental meat colour, being darker in grazing lambs. Renal fat from grazing treatments (GR and GR + S) was lighter and more yellow. Caudal fat colour and SUM allowed too classify 91.1% of carcasses into grazing or non grazing groups. Hence, this is a feasible method to be used in abattoirs to trace alfalfa-fed lambs. It is concluded that feeding system had slightly influence on meat colour.