Sex and breed affect plasma glucose, lactate, cortisol, meat quality but not muscle glycolytic potential of Dorper and Merino lambs

Abstract

Response to pre-slaughter stress differs depending on animal-related factors such as sex and breed. The present study investigated breed and sex effects on plasma stress indicators, muscle glycolytic potential and the quality of meat from 8-month-old lambs of Dorper (n = 52) and Merino (n = 48) breeds. Blood samples were collected at exsanguination for the measurement of glucose, lactate and cortisol levels. Representative meat samples were collected from the Muscularis longissimus thoracis et lumborum for the measurement of glycogen, lactate, glycolytic potential levels, pH and colour coordinates. Results showed that the ewes had higher levels of plasma lactate, cortisol and meat pH than the rams, meaning that the ewes perceived the slaughter process to be more stressful compared with the rams. The Dorper also had higher levels of plasma lactate and lower meat lightness compared with the Merino breed. Significant sex and breed interactions on the meat pH45 min and colour coordinates were observed. Significant correlations were found among plasma cortisol, pH and colour. The results indicate that ewes and Dorper were more stressed than the rams and Merino breed respectively. In this study it can be concluded that the ewes and Dorper breed perceived the slaughter process to be more stressful compared with the rams and Merino breed.