Relationship between muscle antioxidant status, forms of iron, polyunsaturated fatty acids and functionality (retail colour) of meat in lambs

Influence of redox reactive iron, lactate, and succinate on the myoglobin redox stability and mitochondrial respiration

Metabolic intermediates of glycolysis and the tricarboxylic cycle can stabilize beef color through improved metmyoglobin-reducing activity. Inorganic redox reactive iron (RRI) forms are pro-oxidants that have been shown to oxidize myoglobin in model systems. This study investigated how RRI, in the presence of added metabolic intermediates lactate and succinate, influences myoglobin (Mb) redox stability and color of beef strip loin homogenates and how it affects mitochondrial respiration. Homogenates with added RRI and either lactate or succinate had lower (p < 0.05) a* values than control homogenates. Oxymyoglobin increased (p < 0.05) as ferrous ion increased in the lactate and succinate treatments. The presence of ferrous or ferric ions reduced the mitochondrial oxidation rates of lactate and succinate (p < 0.05). The benefit of color stability offered by the metabolic intermediates and mitochondria-assisted metmyoglobin reduction was reduced by inorganic iron ions.

Antioxidant dynamics in the live animal and implications for ruminant health and product (meat/milk) quality: role of vitamin E and selenium

The global population is predicted to grow to over 9 billion by the middle of 21st century, with 70% of people living in urban areas, and food demand is projected to grow by 70% by 2050. Climate change presents a series of challenges for global animal agriculture. As a result of thermal challenges associated with climate variability, availability of quality pasture, animal behaviour, physiological and immunological functions are potentially impacted. Oxidative status plays an important role in the regulation and maintenance of several physiological and immunological functions of the body. Ruminants are exposed to several environmental and metabolic challenges that can trigger oxidative stress. In this scenario, it is possible for an increase in free radical production and a depletion of antioxidant reserves, resulting in damage to lipids, proteins and DNA. Since oxidative stress can affect animal health and the quality of their products (meat/milk), antioxidant supplementation of ruminant diets represents a useful tool to sustain redox homeostasis when the ruminants are exposed to oxidative stress. This paper will examine the roles that oxidative stress plays in some physiological functions, and it will discuss the implications of antioxidant supplementation on ruminant health and production. Physiological levels of dietary antioxidants underpin efficient energy utilisation, optimal antioxidant potential, and balanced mitochondrial function to enhance protein deposition without impacting animal health. The research conducted over the last decade has improved the understanding of physiological functions of antioxidants, with selenium and vitamin E receiving particular attention. There is evidence that the functions of selenium and vitamin E extend beyond the classical antioxidant properties to immunomodulation especially when administered at higher doses than recommended. Improving the oxidative status of ruminants will play an important role in delivering high-quality milk and meat products to consumers. Considering the growing awareness among consumers of the benefits of antioxidant-rich food, there is a great opportunity for the livestock industries to focus on producing antioxidant-enriched milk and meat products or functional foods. Therefore, the premise of this paper is to review the recent developments in understanding antioxidant dynamics in ruminants and their role in reducing the impact of environmental stress and metabolic diseases. In addition, the paper will explore the putative implications that antioxidant supplementation has on the quality animal products and how the improved understanding can be best utilised to achieve efficient and sustainable animal production systems to ensure quality animal products for human consumption.

The effect of palm oil or canola oil on feedlot performance, plasma and tissue fatty acid profile and meat quality in goats

Twenty-four entire male Kacang kid goats were fed diets containing 3% canola (n=12) or palm oil (n=12) supplements for 16 weeks. The goats had an initial live weight of 14.2±1.46 kg and were fed a mixed ration ad libitum (10.4 MJ/ME and 14% crude protein). There was no difference in feedlot performance due to diet. Inclusion of canola oil reduced (P<0.05) kidney fat weight and increased (P<0.05) linolenic acid (18:3n-3) concentration in the blood plasma, m. longissimus lumborum (LL), liver, and kidney. The palm oil diet increased (P<0.05) myristic (14:0) and palmitic (16:0) acid content in the blood, but this did not alter these fatty acids in the LL muscle. Lipid oxidative substances in the liver and LL from palm oil fed kids were higher (P<0.05) than those from canola supplemented kids. The incorporation of canola oil into the goats' diet increased muscle omega-3 fatty acid content, but lipid oxidation was lowered in the blood and muscle LL.

Vitamin E and fatty acid content of lamb meat from perennial pasture or annual pasture systems with supplements

The present study investigated the effect of a perennial lucerne and phalaris pasture, or annual pasture with lucerne hay and a range of supplements provided as pellets (700 g/day) on Vitamin E and fatty acid content of skeletal muscle and oxidative stability of lamb meat post-farm gate. Treatments were lambs grazing perennial pasture only (PP); lambs grazing annual pasture with lucerne hay and oat grain pellet supplement (AP); AP with cracked flaxseed (AP+FS); and AP with flaxmeal (AP+FM). After 7 weeks of feeding, lambs were slaughtered after an overnight fast. At 24 h post-slaughter, samples of muscle longissimus lumborum (LL) were collected for determination of fatty acid profile and antioxidant status, as measured by Vitamin E content. Samples were also collected for retail colour assessment of fresh meat at 24 h, 48 h, 72 h and 96 h of post-slaughter. Vitamin E content of the LL from lambs grazing PP was higher (5.9 v. 3.4 mg α-tocopherol/kg, P < 0.01) than that of lambs grazing other treatments. Long-chain n-3 and total n-3 fatty acid contents in the muscle were similar among treatment groups and adequate to claim as a source of n-3. Inclusion of oat grain at 245 g (AP) or at 175 g with flaxseed (AP+FS) or 175 g with flaxmeal (AP+FM) per day in the diet of lambs increased the linoleic acid content (P < 0.05) and the ratio of n-6 : n-3 (P < 0.007) in the LL, compared with lambs grazing PP. Oxidative stability of fresh meat evaluated by retail shelf life (retention of redness) and formation of lipid oxidative substance showed no differences among treatment groups and, as indicated by redness (a*-value) over a 96-h display, all values were within the range (>9.5) for quality meat over the time frame used in the present study. The results provided some evidence that inclusion of PP in the diets of lambs during dry seasons (late summer to autumn) is an effective tool of improving the Vitamin E content of muscle tissues at slaughter.