Stress reactivity and its relationship to beef quality in Nguni steers supplemented with Acacia karroo leaves

Abstract

The objective of this study was to determine the levels of catecholamines and their relationship to beef quality in Nguni steers fed on Acacia karroo leaves. A total of 30 19-month-old steers were randomly assigned to A. karroo leaves (AK), sunflower cake (SF) and the control with no supplement (CN) diets. The AK and SF diets provided the steers with an additional 150 g of protein per day for 60 days. Catecholamine levels were determined from urine samples collected from each steer before and after slaughter. The Musculus longissimus thoracis et lumborum was sampled for selected meat quality measurements. Nguni steers on the CN diet had higher ( P , 0.05) concentrations of post-mortem urinary norepinephrine and dopamine compared with those that received the AK and SF diets. Norepinephrine was negatively linearly related ( P , 0.05) to the Warner-Bratzler shear force value of meat aged for 21 days and cooking loss of meat aged for 2 days (CL2) in steers that were given the SF diet. Meat pH and drip loss values were inversely related ( P , 0.05) to epinephrine concentration in steers that received the AK diet. Dopamine concentration was negatively linearly related ( P , 0.05) to water holding capacity and CL2 for steers on the CN diet. For steers on the CN diet, lightness ( L*) values increased ( P , 0.05) with increase in dopamine concentration. It was concluded that stress responsiveness and its relationship to certain beef quality attributes could be positively manipulated by supplementation with A. karroo leaves.

Effects of animal class and genotype on beef muscle nanostructure, pHu, colour and tenderness

“…66 The observed darker meat in Bonsmara cattle was also linked to reduced intramuscular fat, as fat also plays a role in the brightness of meat. 11 In addition, darker meat was caused by an increased ultimate pH as a result of depleted glycogen levels and reduced production of lactic acid. Li et al 53 highlighted that pH u influenced the extent of protein denaturation, colour and water-holding capacity of fresh meat.…”

“…9 Furthermore, muscle development in cattle has an effect on muscle structure, connective tissue and tenderness and the quantity of meat produced for human consumption. 10 Mapiye et al 11 highlighted that the appropriate utilisation of cattle genotypes with the necessary dietary regimes could be the way forward in order to meet the quality that is required by consumers. According to Strydom et al 12 and Muchenje et al 13 , among the local genotypes, Nguni cattle have favourable genes that contribute to better outcomes of this genotype in terms of meat quality.…”

“…16,18 Variability in meat products prevents the industry from marketing its produce according to quality (tenderness, colour, water-holding capacity and juiciness). Previous studies have been conducted on the improvement of meat quality using genetic variation 16,19 , optical scattering and absorption coefficients 9 , sensorial consumer evaluation 13,20 , and use of video image analysis 13,11,21 to measure sarcomere length -with a longer sarcomere resulting in more tender beef. However, there is little information with regard to the influence of genotype and distance travelled by cattle on the tenderness of beef.…”

Change in physiological parameters of calves of various breeds under the transport and pre-slaughter stress

“…To find a stress relieving factor, various researches developing antistress preparations (Mapiye et al 2011;Cooke et al 2013a;Guarnieri Filho et al 2014), a combination of different diets (Belyaev and Gorlov 2010;Gorlov et al 2011;Goldhawk et al 2014aGoldhawk et al , 2014c, a microclimate control in the vehicle (Cooke et al 2011b;Goldhawk et al 2014b), change in the supply chain (Romero et al 2013; Miranda-de la Lama and Villarroel María 2014) had been conducted. The possibility of making breaks during a long carriage with a feed table (Cooke et al 2013b), as well as the influence of the density of cattle transported in a vehicle on the number of bruises, abrasions, and the decrease in the pH of the final product (Merrill et al 2007;Earley et al 2013) had also been studied.…”