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ABSTRACT: In order for livestock industries to consistently produce high quality meat, there must be an understanding of the factors that cause quality to vary, as well as the contribution of genetics. A brief overview of meat tenderness is presented to understand how genotype and environment may interact to influence this trait. Essentially, meat tenderness is determined from the contribution of connective tissue, sarcomere length determined pre-rigor and rate of proteolysis during ageing, as well as contributions from intramuscular fat and post-mortem energy metabolism. The influence of mutations in myostatin, the callipyge gene, the Carwell or rib eye muscle gene as well as the calpain system on meat tenderness is presented. Specific examples of interactions between the production or processing environment and genetics are presented for both sheep and cattle. The day-to-day variation in tenderness is evident across experiments and this variation needs to be controlled in order to consistently produce tender meat.
Meat Science 09/2010; 86(1):171-83. · 2.28 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: In order for livestock industries to consistently produce high quality meat, there must be an understanding of the factors that cause quality to vary, as well as the contribution of genetics. A brief overview of meat tenderness is presented to understand how genotype and environment may interact to influence this trait. Essentially, meat tenderness is determined from the contribution of connective tissue, sarcomere length determined pre-rigor and rate of proteolysis during ageing, as well as contributions from intramuscular fat and post-mortem energy metabolism. The influence of mutations in myostatin, the callipyge gene, the Carwell or rib eye muscle gene as well as the calpain system on meat tenderness is presented. Specific examples of interactions between the production or processing environment and genetics are presented for both sheep and cattle. The day-to-day variation in tenderness is evident across experiments and this variation needs to be controlled in order to consistently produce tender meat.
Meat Science 01/2010; 86:171-183. · 2.28 Impact Factor
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ABSTRACT: Stress is the inevitable consequence of the process of transferring animals from farm to slaughter. The effects of chronic stress on muscle glycogen depletion and the consequent dark cutting condition have been well documented. However, there has been little examination of the consequences of acute stress immediately pre-slaughter on ruminant meat quality. New evidence is emerging to show that non pH-mediated effects on meat quality can occur through pre-slaughter stress in cattle and sheep. This paper reviews the general aspects of pre-slaughter stress in the pre-slaughter context. It then examines the impacts of pre-slaughter stressors on ruminant carcass and meat quality and considers remedial strategies for remediating and preventing pre-slaughter stress. Further quantification of the biological costs of pre-slaughter stress and the consequences to meat quality is required.
Meat Science 09/2008; 80(1):12-9. · 2.28 Impact Factor
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ABSTRACT: The associations between the muscle glycogen concentration and form and the rate of post-mortem glycolysis in ovine muscle were investigated. Twenty-two merino wethers (18-24 months) were allocated to either roughage or concentrate pelleted diets for 34 days prior to slaughter. An exercise depletion/repletion model was applied four days prior to slaughter to generate differences in muscle glycogen levels at slaughter. Muscle biopsies were taken from the m. semimembranosus (SM) and m. semitendinosus (ST) prior to and immediately after exercise for muscle glycogen determination. At slaughter, one side was electrically stimulated and both sides were conventionally chilled for 24h. The pH response to electrical stimulation (ΔpH) and the rate of pH decline adjusted to a constant temperature of 38°C over the initial 6h post-mortem period was determined in three muscles (m. longissimus thoracis et lumborum LTL, SM and ST). In addition, the concentrations of glycogen, proglycogen (PG), macroglycogen (MG) and lactate in the three muscles immediately after slaughter were determined. The glycogen loss due to exercise was influenced by diet (P<0.01; concentrate 63% and roughage 73%) but did not differ between muscles. The rates of repletion significantly varied between muscles (SM>ST) and diet (concentrate>roughage). The available glycogen (glycogen(A)) and MG concentrations at slaughter varied significantly depending on the diet (P<0.01) and muscle (P<0.001). The percentage of MG relative to MG+PG varied between muscles (46%, 50% and 57% for the ST, LTL and SM). The concentration and form of available glycogen at slaughter did not influence the response to electrical stimulation after adjusting for pre-stimulation pH (P<0.01). The ΔpH varied significantly between muscles (0.39±0.03, 0.26±0.02 and 0.20±0.03 for the ST, LTL and SM) after adjusting for pre-stimulation pH. Differences in the temperature adjusted rate of pH decline were observed between the muscles (LTL>SM>ST). Importantly, a positive linear association (P=0.05) was found between muscle glycogen(A) concentration at slaughter and the rate of pH decline (temperature adjusted).
Meat Science 03/2008; 78(3):202-10. · 2.28 Impact Factor
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Australian Journal of Experimental Agriculture 07/2007; 47:782-788. · 0.92 Impact Factor
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Australian Journal of Agricultural Research - AUST J AGR RES. 01/2006; 57(11).
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ABSTRACT: Consumer sensory requirements for beef vary as a function of the market in which the product is being sold and, within any market, they can vary also over time. These conclusions are demonstrated using the Australian domestic and Japanese export markets as examples. In Australian studies, consumers buying meat for home consumption place more emphasis on leanness than do food service operators, with whom marbling rates more highly. Both household consumers and food service operators rate tenderness as the most important attribute of eating quality for cooked beef. This is followed by flavour. In a restaurant situation, marbled steaks (AUSMEAT score 2-3) have a higher acceptability than for home consumption. In the Japanese market, consumer-purchasing criteria are somewhat more sophisticated but tenderness is again the most important attribute of eating quality. This is perhaps surprising, considering the traditional cultural differences. It suggests that intrinsic factors in the consumer requirements for of beef may be similar worldwide.
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[show abstract]
[hide abstract]
ABSTRACT: Stress is the inevitable consequence of the process of transferring animals from farm to slaughter. The effects of chronic stress on muscle glycogen depletion and the consequent dark cutting condition have been well documented. However, there has been little examination of the consequences of acute stress immediately pre-slaughter on ruminant meat quality. New evidence is emerging to show that non pH-mediated effects on meat quality can occur through pre-slaughter stress in cattle and sheep. This paper reviews the general aspects of pre-slaughter stress in the pre-slaughter context. It then examines the impacts of pre-slaughter stressors on ruminant carcass and meat quality and considers remedial strategies for remediating and preventing pre-slaughter stress. Further quantification of the biological costs of pre-slaughter stress and the consequences to meat quality is required.
Meat Science.
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[show abstract]
[hide abstract]
ABSTRACT: The associations between the muscle glycogen concentration and form and the rate of post-mortem glycolysis in ovine muscle were investigated. Twenty-two merino wethers (18–24 months) were allocated to either roughage or concentrate pelleted diets for 34 days prior to slaughter. An exercise depletion/repletion model was applied four days prior to slaughter to generate differences in muscle glycogen levels at slaughter. Muscle biopsies were taken from the m. semimembranosus (SM) and m. semitendinosus (ST) prior to and immediately after exercise for muscle glycogen determination. At slaughter, one side was electrically stimulated and both sides were conventionally chilled for 24 h. The pH response to electrical stimulation (ΔpH) and the rate of pH decline adjusted to a constant temperature of 38 °C over the initial 6 h post-mortem period was determined in three muscles (m. longissimus thoracis et lumborum LTL, SM and ST). In addition, the concentrations of glycogen, proglycogen (PG), macroglycogen (MG) and lactate in the three muscles immediately after slaughter were determined. The glycogen loss due to exercise was influenced by diet (P < 0.01; concentrate 63% and roughage 73%) but did not differ between muscles. The rates of repletion significantly varied between muscles (SM > ST) and diet (concentrate > roughage). The available glycogen (glycogenA) and MG concentrations at slaughter varied significantly depending on the diet (P < 0.01) and muscle (P < 0.001). The percentage of MG relative to MG + PG varied between muscles (46%, 50% and 57% for the ST, LTL and SM). The concentration and form of available glycogen at slaughter did not influence the response to electrical stimulation after adjusting for pre-stimulation pH (P < 0.01). The ΔpH varied significantly between muscles (0.39 ± 0.03, 0.26 ± 0.02 and 0.20 ± 0.03 for the ST, LTL and SM) after adjusting for pre-stimulation pH. Differences in the temperature adjusted rate of pH decline were observed between the muscles (LTL > SM > ST). Importantly, a positive linear association (P = 0.05) was found between muscle glycogenA concentration at slaughter and the rate of pH decline (temperature adjusted).
Meat Science.
