Endocrine, blood metabolite, and meat quality changes in goats as influenced by short-term, preslaughter stress1

Abstract

The purpose of this study was to determine the effects of short-term, preslaughter stress on physiological responses and meat quality in goats of different age groups. The goats (n = 28) were classified into young (6 to 12 mo of age) and old (24 to 30 mo of age) groups, feed deprived overnight, and slaughtered at three different times (replicates). On each slaughter day, goats were either subjected to a 2-h transportation stressor (TS) or remained unstressed in holding pens (NS) before slaughter. Blood samples were collected via jugular venipuncture from TS and NS goats at 2, 1, and 0 h before slaughter. Muscle glycogen and pH were measured on samples from longissimus muscle (LM) collected at 15 min and 24 h postmortem, and instrumental measures of meat color were obtained on the LM after a 24-h chilling period at 4 degrees C. The TS goats had higher plasma cortisol (P < 0.01) and glucose (P < 0.05) concentrations than NS goats. The rates of increase in plasma cortisol, glucose, and nonesterified fatty acid concentrations were greater in TS than in NS goats (stressor treatment x blood sampling time, P < 0.01). Muscle glycogen concentrations were greater (P < 0.05) in NS than in TS goats and higher (P < 0.01) in old vs. young goats; however, pH measured at 15 min and 24 h postmortem was not (P > 0.05) influenced by stressor treatment. Water-holding capacity of meat was not (P > 0.05) influenced by stressor treatment. Older goats had lower (P < 0.01) L* values and greater (P < 0.01) a* and chroma values than the younger goats. The a* and chroma values of loin cuts from young goat carcasses were lower in the TS than NS treatment groups, but this effect was absent in the old goat carcasses (stressor treatment x age, P < 0.05). Cooking loss percentages and shear force values for loin chops aged for 7 d were not (P < 0.05) affected by stressor treatment; however, old goats produced tougher (P < 0.01) loin chops than young goats. These results indicate that short-term preslaughter transport can cause noticeable changes in stress responses and muscle metabolism in goats.

The effect of dietary supplementation with β-1,3/1,6-D-glucan on stress parameters and meat quality in lambs

“…Kadim et al (2006) observed that the meat of goats was darker and characterized by higher contribution of redness and lower contribution of yellowness (lower values of L* and b*, higher values of a*) after 2 h of transport in comparison with the meat of non-transported animals. Similar results were reported by Kannan et al (2003) in a study on goats. In a study by Kadim et al (2009), transport had no significant influence on the colour parameters of lamb meat.…”

“…Similar results were reported in goats after 2 h of transport (Kadim et al, 2006) and in lambs which were slaughtered after 75 min of transport and a short rest period (Ekiz et al, 2012a). In contrast, Apple et al (1995) reported lower shear force values in the meat of lambs subjected to pre-slaughter stress in comparison with the control group, whereas Kannan et al (2003) did not report any differences in the hardness of meat from transported and non-transported goats.…”

“…Kadim et al (2009) demonstrated that the meat of 12-month-old lambs was characterized by a significantly smaller area of expressed juice after 3 h of transport in comparison with animals that were not transported. In contrast, stress did not influence the water-holding capacity of goat meat in the study of Kannan et al (2003).…”

“…The value of pH u is determined by a combination of factors during pre-slaughter handling which influence muscle glycogen levels and glycolysis rate (Gregory, 1998). Pre-slaughter stress depletes glycogen reserves in muscles, which contributes to their insufficient acidification after slaughter, followed by an increase in the pH of meat (Apple et al, 1995;Kannan et al, 2003). The results of many studies demonstrated that stress factors significantly influence pH u values.…”

A note on the effects of pre-slaughter operations of llamas (Lama glama) on the concentrations of some blood constituents related to stress and carcass quality

“…observed the main increase in plasma cortisol level during the first 90 min of journey in sheep. Similarly Kannan et al (2003) found that the cortisol concentrations increased markedly within 1-h after the beginning of transportation in goats.…”