Micronutrients affecting adipogenesis in beef cattle

Intramuscular adipogenesis in cattle: Effects of body fat distribution and macrophage infiltration

Ectopic fat is defined by the deposition of adipose tissue within non-adipose tissue such as skeletal muscle. Japanese Black cattle (Wagyu) are characterized by the ability to accumulate high amounts of intramuscular adipose tissue. Obese conditions enhance the accumulation of ectopic fat. This review shows the effects of subcutaneous and visceral fat distribution on Wagyu intramuscular adipogenesis. Obese conditions also stimulate the macrophage infiltration into adipose tissues. Adipose tissue macrophages have reported to regulate adipose tissue growth and ectopic fat accumulation in humans and rodents. Wagyu is characterized by the higher capacity for intramuscular adipogenesis than Holsteins. This review discusses the depot-specific effects of macrophage infiltration among subcutaneous, visceral, and intramuscular adipose tissue on intramuscular adipogenesis in Wagyu and Holstein cattle. Recently, metabolome analysis has been used to identify obesity-related biomarkers by comparing the biological samples between lean and obese patients. This review introduces the metabolomic profiles of plasma and intramuscular adipose tissue between Wagyu and Holsteins.

Main regulatory factors of marbling level in beef cattle

The content of intramuscular fat (IMF), that determines marbling levels is considered as one of the vital factors influencing beef sensory quality including tenderness, juiciness, flavour and colour. The IMF formation in cattle commences around six months after conception, and continuously grows throughout the life of the animal. The accumulation of marbling is remarkably affected by genetic, sexual, nutritional and management factors. In this review, the adipogenesis and lipogenesis process regulated by various factors and genes during fetal and growing stages is briefly presented. We also discuss the findings of recent studies on the effects of breed, gene, heritability and gender on the marbling accumulation. Various research reported that feeding during pregnancy, concentrate to roughage ratios and the supplementation or restriction of vitamin A, C, and D are crucial nutritional factors affecting the formation and development of IMF. Castration and early weaning combined with high energy feeding are effective management strategies for improving the accumulation of IMF. Furthermore, age and weight at slaughter are also reviewed because they have significant effects on marbling levels. The combination of several factors could positively affect the improvement of the IMF deposition. Therefore, advanced strategies that simultaneously apply genetic, sexual, nutritional and management factors to achieve desired IMF content without detrimental impacts on feed efficiency in high-marbling beef production are essential.

Diet and Genetics Influence Beef Cattle Performance and Meat Quality Characteristics

A comprehensive review of the impact of tropical pasture grazing, nutritional supplementation during feedlot finishing and fat metabolism-related genes on beef cattle performance and meat-eating traits is presented. Grazing beef cattle on low quality tropical forages with less than 5.6% crude protein, 10% soluble starches and 55% digestibility experience liveweight loss. However, backgrounding beef cattle on high quality leguminous forages and feedlot finishing on high-energy diets increase meat flavour, tenderness and juiciness due to improved intramuscular fat deposition and enhanced mono- and polyunsaturated fatty acids. This paper also reviews the roles of stearoyl-CoA desaturase, fatty acid binding protein 4 and fatty acid synthase genes and correlations with meat traits. The review argues that backgrounding of beef cattle on Desmanthus, an environmentally well-adapted and vigorous tropical legume that can persistently survive under harsh tropical and subtropical conditions, has the potential to improve animal performance. It also identifies existing knowledge gaps and research opportunities in nutrition-genetics interactions aimed at a greater understanding of grazing nutrition, feedlot finishing performance, and carcass traits of northern Australian tropical beef cattle to enable red meat industry players to work on marbling, juiciness, tenderness and overall meat-eating characteristics.

4',6-dimethoxyisoflavone-7-O-β-D-glucopyranoside (wistin) is a peroxisome proliferator-activated receptor γ (PPARγ) agonist that stimulates adipocyte differentiation

Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-dependent transcription factor that directly activates the expression of adipocyte-specific genes, and is universally accepted as the master regulator for adipocyte differentiation. Using a PPARγ luciferase reporter assay system, we showed that 4',6-dimethoxyisoflavone-7-O-β-D-glucopyranoside (wistin) dose-dependently activates PPARγ. Treatment with wistin enhanced the marker of adipocyte differentiation, such as triglyceride accumulation in 3T3-L1 cells. Real-time quantitative polymerase chain reaction showed that wistin increased the expression of PPARγ2 messenger RNA. Moreover, the addition of wistin upregulated the expression of PPARγ-target genes, aP2 and adiponectin in 3T3-L1 cells. To our knowledge, wistin is the first isoflavonoid O-glycoside that exhibits PPARγ agonist activity.

Potential nutritional strategies for the amelioration or prevention of high rigor temperature in cattle – a review

Environmental conditions influence animal production from an animal performance perspective and at the carcass level post-slaughter. High rigor temperature occurs when the animal is hyperthermic pre-slaughter, and this leads to tougher meat. Hyperthermia can result from increased environmental temperature, exercise, stress or a combination of these factors. Consumer satisfaction with beef meat is influenced by the visual and sensory traits of the product when raw and cooked, with beef consumers commonly selecting tenderness of the product as the most important quality trait. High rigor temperature leads to a reduction in carcass and eating quality. This review examines some possible metabolic causes of hyperthermia, with focus on the importance of adipose tissue metabolism and the roles of insulin and leptin. Potential strategies for the amelioration or prevention of high rigor temperature are offered, including the use of dietary supplements such as betaine and chromium, anti-diabetic agents such as thiazolidinediones, vitamin D, and magnesium (Mg) to provide stress relief.

Nutritional strategies affect carcass and pork quality but have no effect on intramuscular fat content of pork

Fifty crossbred (Large White × Landrace × Duroc) female finisher pigs were used to determine the effect of nutritional strategies on intramuscular fat content. The dietary treatments were (A) Control: commercial grower and finisher diet, (Day 68–166), (B) –15% P : E and –vitamin A: a 15% reduced protein : energy grower diet with no supplemental vitamin A (Day 68–110), followed by a commercial finisher diet (Day 111–166), (C) sugar: a grower diet supplemented with 10% sugar (Day 68–110), followed by a commercial finisher diet (Day 111–166), (D) zinc: a grower diet supplemented with 250 ppm zinc (Day 68–110), followed by a commercial finisher diet (Day 111–166), and (E) lecithin: a diet supplemented with 3 g/kg lecithin in the grower and finisher diet (Day 68–166). The effects of lecithin supplementation on compression characteristics of the M. semitendinosus were also studied. These data indicate that there were no significant effects of dietary manipulations on intramuscular fat content. During the grower phase (Day 68–110) pigs offered the low protein : energy and vitamin A-deficient diet had a poorer feed : gain compared with those offered diet containing supplemental sugar. Dietary lecithin supplementation decreased (P < 0.05) hardness and chewiness values for the M. semitendinosus compared with pigs offered the Control diet. Pigs offered the lecithin-supplemented diet also tended (P = 0.090) to have lower cook loss compared with pigs offered the Control diet. Dietary zinc supplementation during the grower phase improved (P < 0.05) the carcass dressing % compared with pigs offered the other diets. Dietary sugar or zinc increased (P < 0.05) the amount of lean in the belly and may be a means to control the rapid rise in the ratio of fat to lean in the belly during the finisher phase. These data indicate that dietary lecithin supplementation has the potential to improve the tenderness of pork but that intramuscular fat is difficult to manipulate nutritionally from an already moderate amount.