Subcutaneous and intramuscular adipose tissue stearoyl-coenzyme A desaturase gene expression and fatty acid composition in calf- and yearling-fed Angus steers1

Abstract

We proposed that stearoyl-CoA desaturase (SCD) activity dictates fatty acid composition of adipose tissue and muscle in beef cattle, regardless of ruminal or hepatic fatty acid hydrogenation or desaturation. Twelve Angus steers were assigned to a calf-fed (CF) group and slaughtered at weaning (8 mo of age; n=4), 12 mo of age (n=4), or 16 mo of age (n=4). Twelve steers were assigned to a yearling-fed (YF) group and slaughtered at 12 mo of age (n=4), 16 mo of age (n=4), and 17.5 mo of age (n=4; 525 kg, market weight). Data were analyzed based on time on the corn-based finishing diet, with terminal age as a covariate, and orthogonal polynomial contrasts were tested on the main effects of treatment group and time on the finishing diet. Fatty acids from duodenal digesta, plasma, liver, LM, and subcutaneous and intramuscular adipose tissue were measured, and SCD gene expression was measured in intramuscular and subcutaneous adipose tissues. In duodenal digesta, palmitic and linoleic acids increased by 100% over the sampling period, α-linolenic acid decreased over the sampling period, and trans-vaccenic acid was greater in YF than in CF steers (all P < 0.01). The proportion of α-linolenic acid decreased over time in all tissues, including liver. The SCD index (ratio of SCD fatty acid products to SCD fatty acid substrates) increased over time in LM and in intramuscular and subcutaneous adipose tissues. The SCD:glyceraldehyde 3-phosphate dehydrogenase mRNA ratio was virtually undetectable at the initial sampling periods in subcutaneous adipose tissue of YF and CF steers, and it increased over time (P < 0.01). The SCD index and SCD:glyceraldehyde 3-phosphate dehydrogenase ratio were greater in intramuscular adipose tissue of CF steers than in that of YF steers. The SCD index did not change over time in liver and decreased over time in duodenal digesta. We conclude that, unlike essential fatty acids, the SFA and MUFA composition of adipose tissue is regulated by adipose tissue fatty acid desaturation, with little contribution from hepatic or duodenal fatty acids.

Ground beef patties prepared from brisket, flank and plate have unique fatty acid and sensory characteristics

“…The primals used for the current study were obtained at random from a commercial abattoir, and graded USDA Select. We have demonstrated that the MUFA:SFA ratio increases with USDA Quality Grade (Brooks et al, 2011;Chung et al, 2006), and the low MUFA:SFA ratios observed in the current study in part can be explained by the lesser quality grades of these beef carcasses. However, the unusually low MUFA:SFA ratios also suggest that these cattle spent a limited amount of time on a grain-based diet; pasture feeding of cattle strongly depresses SCD activity and the concentration of MUFA in beef cattle (Brooks et al, 2011;Chung et al, 2006Chung et al, , 2007Duckett, Pratt, & Pravan, 2009;Gilmore et al, 2011;Leheska et al, 2008).…”

“…SCD is responsible for the synthesis of MUFA from SFA in animal tissues and its activity is highly sensitive to dietary manipulation and animal age. In beef cattle fed grain-based diets, the concentration of MUFA (and especially oleic acid) increases with time on feed Gilmore et al, 2011;Huerta-Leidenz et al, 1996;Smith et al, 2012), as SCD activity and gene expression increases with time fed a high-grain diet (Brooks, Choi, Lunt, Kawachi, & Smith, 2011;Chung, Yano, Kawachi, Smith, & Lunt, 2007). Slip point values differ between adipose tissue depot depending on the size and extent of differentiation of adipocytes (i.e., larger adipocytes have higher concentrations of MUFA) (Smith et al, 2006).…”

Comparative Transcriptome Analysis of Adipose Tissues Reveals that ECM-Receptor Interaction Is Involved in the Depot-Specific Adipogenesis in Cattle

“…Especially, intramuscular fat (marbling) plays important roles in eating quality and composition of meat compared to other fats [1], [2]. Some literatures reported that intramuscular fat is different from other fats in three respects: adipocyte size, metabolic activities, and developmental timing [29]–[31].…”

“…It is restricted to certain areas in the body such as subcutaneous layer between muscle and dermis, around internal organs and between muscles. The amount and distribution of fat are important factors that influence the meat quality in the beef industry [1], [2]. For several decades, it has been known that adipose tissues are regionally heterogeneous with respect to metabolic activities and functions [3]–[5].…”

Increased adipocyte differentiation may be mediated by extracellular calcium levels through effects on calreticulin and peroxisome proliferator activated receptor gamma expression in intramuscular stromal vascular cells isolated from Hanwoo beef cattle

“…Microscopically, marbling fat appears in specific adipose depots wherein adipocytes are embedded in a connective tissue matrix close to a blood capillary (Albrecht et al 2006). Intramuscular adipose tissue has direct impact on improving the quality of beef products and is the basis of quality grading (Lengi & Corl 2010;Brooks et al 2011;Dodson et al 2010). With the aim to produce livestock with better quality meat for consumers, intramuscular fat content has been at the centre of high quality beef production because it positively affects the sensory quality traits such as taste and flavour.…”