INFLUENCE OF REPEATED RESTRAINT AND ISOLATION STRESS AND ELECTROLYTE ADMINISTRATION ON CARCASS QUALITY AND MUSCLE ELECTROLYTE CONTENT OF SHEEP

Crossbred lambs were assigned, within weight blocks, to one of four tr eatments applied in a 2 X 2 factorial design (n = 6 per treatment). Tr eatment main effects included no stress (NS) or three consecutive days of restraint and isolation stress (RIS) and treatment with either wat er (W) or electrolytes (E). The experimental design resulted in four t reatments, namely NS-lambs given W, NS-lambs given E, RIS-lambs given W, and RIS-lambs given E. Stress treatment consisted of moving each la mb from its home stanchion to a separate location and isolation from v isual and tactile contact with other lambs for 6 hours daily for 3 day s before slaughter. All lambs received a 320 ml oral drench of either W or E on each day after the stress treatment. Stress treatment reduce d (P < 0.05) semitendinosus (ST) muscle glycogen by 4.8-fold. At 24 h post mortem, muscle pH for semimembranosus (SM), biceps femoris (BF) a nd infraspinatus (IF) was higher (P < 0-05) in RIS-lambs that in NS-la mbs. Hunter La*b* values, measured on muscle cross-section, revealed a lighter (P < 0.05) BF; more (P < 0-05) red BF, ST, and longissimus d orsi (LD); and more (P < 0.05) yellow ST, SM, BF, and LD for NS-than f or RIS-lambs. Muscle from RIS-lambs contained less (P < 0.05) potassiu m than that from NS-lambs. Restraint and isolation stress of lambs res ulted in a reduction in muscle glycogen, but only slight increases in ultimate pH and minimal influences on muscle color. Administration of electrolytes had no effect on lamb carcass quality.