Effects of pre-slaughter diet/management system and fasting period on physiological indicators and meat quality traits of lambs

• Pre-slaughter diet/management systems were compared in Norduz lambs.
• Short-term barley supplement improved daily live weight gain and carcass conformation.
• Diet and fasting period had limited effect on muscle glycogen content and ultimate pH.
• Fasting 24 h or longer resulted in physiological stress in lambs.
• Fasting longer than 24 h had a negative effect on some meat quality traits.

This study determined the effects of pre-slaughter diet/management system on blood and rumen parameters and meat-quality traits of Norduz lambs. Eighty lambs were divided into two groups according to diet (AH: alfalfa hay; BAH: alfalfa supplemented with 500 g/head barley) for 21 days. Following this period, lambs from each group were distributed among four groups according to pre-slaughter fasting period as 0, 12, 24 or 48 h. Cortisol concentrations were found to be significantly higher in the 24 h and 48 h groups when compared to the 0 h group (p < 0.01). Diet and fasting period had limited effect on muscle glycogen content and ultimate pH·L*, WHC and moisture decreased in line with increases in the fasting period (p < 0.01). In conclusion, carcass conformation and some meat quality traits were better in BAH lambs. Fasting had a negative effect on some meat quality parameters, with significant increases in some physiological stress indicators after fasting periods of 24 h or longer.