The effect of extensive and intensive production systems on the meat quality and carcass characteristics of Dohne merino lambs

[摘要] ENGLISH ABSTRACT: The aim of this study was to investigate the impact of an extensive (free-range) and intensive(feedlot) production system on the consumer's intrinsic preference cues (physical attributes,chemical composition, fatty acid profile, aroma, flavour, initial juiciness, sustained juiciness, firstbite, residue, instrumental tenderness) for three muscles (Biceps femoris, Longissimus dorsi,Semimembranosus) of Dohne Merino lambs (8 months). Secondly to investigate the effect ofnatural exercise (grazing, extensive production systems) or restrictive movement (intensiveproduction systems), on the muscle fiber type composition of the same lamb muscles and thesubsequent effect on the meat quality characteristics.Intensively raised lambs produced carcasses with a significantly higher dressingpercentage, thicker subcutaneous fat layer (13th rib and 3rd/4th lumbar vertebra) and a greater fatratio (carcass composition). Meat of intensively raised lambs had a higher (p < 0.050) Homo-glinolenic(C20:3n6), Eicosapentaenoic (C20:5n3), Docosapentaenoic acid (C22:5n3) content andn3:n6 ratio. Extensively reared lambs had a higher (p < 0.050) slaughter weight, cold carcassweight and the meat of these lambs had a higher myoglobin content.Results of this study indicate that intensively reared lambs produced meat with morefavourable sensory characteristics compared to the extensive production system as well as asignificant increase in sensory tenderness for Biceps femoris muscle. Overall the Biceps femorismuscle was the muscle that was primarily affected by the treatment (production systems). TheBiceps femoris from intensively raised lambs contained significantly more intramuscular fat andtype IIB muscle fibers whereas the Bicpes femoris of the lambs from the extensive productionsystem contained more (p < 0.050) insoluble collagen and type I muscle fibers.During texture profile analysis (instrumental tenderness test) the Longissimus dorsi andSemimembranosus of extensively raised lambs required a higher (p < 0.050) compression forceduring the first cycle of compression, indicating that these muscles are tougher.The results of this study provided valuable insight into the impact of production systems onlamb meat quality and that the application of intensive production systems will increase thesensory characteristics of the selected muscles from Dohne Merino lambs, especially thetenderness of the Biceps femoris, which has a high retail value. On the other hand healthconscious consumers will prefer extensively produced meat due to the favourable n3:n6 ratio,intramuscular fat content and the presences of less visible fat (subcutaneous).

[发布机构] Stellenbosch University