Differing effects of forage and concentrate diets on the oleic acid and conjugated linoleic acid content of sheep tissues: The role of stearoyl-CoA desaturase1,2

In the meat industry, the manipulation of fat deposition in cattle is of pivotal importance to improve production efficiency, carcass composition and ultimately meat quality. There is an increasing interest in the identification of key factors and molecular mechanisms responsible for the development of specific fat depots. This study aimed at elucidating the influence of breed and diet on adipose tissue membrane permeability and fluidity and their interplay on fat deposition in bovines. Two Portuguese autochthonous breeds, Alentejana and Barrosã , recognized as late-and early-maturing breeds, respectively, were chosen to examine the effects of breed and diet on fat deposition and on adipose membrane composition and permeability. Twenty-four male bovines from these breeds were fed on silage-based or concentrate-based diets for 11 months. Animals were slaughtered to determine their live slaughter and hot carcass weights, as well as weights of subcutaneous and visceral adipose depots. Mesenteric fat depots were excised and used to isolate adipocyte membrane vesicles where cholesterol content, fatty acid profile as well as permeability and fluidity were determined. Total accumulation of neither subcutaneous nor visceral fat was influenced by breed. In contrast, mesenteric and omental fat depots weights were higher in concentrate-fed bulls relative to silage-fed animals. Membrane fluidity and permeability to water and glycerol in mesenteric adipose tissue were found to be independent of breed and diet. Moreover, the deposition of cholesterol and unsaturated fatty acids, which may influence membrane properties, were unchanged among experimental groups. Adipose membrane lipids from the mesenteric fat depot of ruminants were rich in saturated fatty acids, and unaffected by polyunsaturated fatty acids dietary levels. Our results provide evidence against the involvement of cellular membrane permeability to glycerol on fat accumulation in mesenteric fat tissue of concentrate-fed bovines, which is consistent with the unchanged membrane lipid profile found among experimental groups.

Section: Discussionsupporting

confidence: 92%

Differential mesenteric fat deposition in bovines fed on silage or concentrate is independent of glycerol membrane permeability

Martins

Lopes²,

Costa³

et al. 2011

“…The CLA index suggests a reduction in SCD activity associated with the Trial 1 linseed and soya bean diets, which also had a stronger negative relationship with 18:3n-3 than 18:2n-6 concentrations in the muscles. Dietary PUFA from both the n-6 and n-3 series have been reported to reduce SCD mRNA expression (Ntambi, 1999), with 18:3n-3 having a stronger inhibitory effect than 18:2n-6 (Daniel et al, 2004). A similar trend was also present for the CLA index among the Trial 2 blended diets in relation to the concentration of linseed and soya bean present.…”

Section: Total Lipidssupporting

confidence: 66%

Influence of oilseed supplement ranging in n-6/n-3 ratio on fatty acid composition and Δ5-, Δ6-desaturase protein expression in steer muscles

Turner

Mitchell

Duynisveld

et al. 2012

This study investigated effects of roasted or extruded oilseed supplementation ranging in n-6/n-3 ratios from 0.3 to 5.0 on the fatty acid composition and expression of delta-5 desaturase (D5d) and D6-desaturase (D6d) protein in commercial steer cheek (m. masseter) and diaphragm (pars costalis diaphragmatis) muscles. In general, the n-6/n-3 ratio of the diet had a subsequent effect on the muscle n-6/n-3 ratio (P , 0.05), with muscle 18:2n-6 and 18:3n-3 content relating to proportion of dietary soya bean and linseed (P , 0.01). Compared with canola, pure linseed and soya bean diets reduced 14:1c-9 and 16:1c-9 (P , 0.05) but increased 18:1t-11 and c-9,t-11 conjugated linoleic acid (CLA) content (P , 0.01). Oilseed processing had a minor influence but extruded oilseeds increase 18:1t-11 and c-9,t-11 CLA compared with roasted (P , 0.05). Polar lipid 18:3n-3 and n-3 long-chain polyunsaturated fatty acid (LC, >20 carbons PUFA) derivative content increased in relation to dietary linseed supplementation in the diaphragm (P , 0.01), whereas only 18:3n-3 was increased in the cheek (P , 0.01). Protein expression did not differ between diets; however, in each muscle the D5d protein expression had a stronger association with the desaturase products rather than the precursors. The relationship between D5d protein expression and the muscle LC n-6/n-3 ratio was negative in both muscles (P , 0.05). The relationship between D6d protein expression and the LC n-6/n-3 ratio was positive in the cheek (P , 0.001) and negative in the diaphragm (P , 0.05). In conclusion, diet n-6/n-3 ratio affected muscle 18:2n-6 and 18:3n-3 deposition, whereas the D5d and D6d protein expression had some influence on the polar lipid LC-PUFA profile. Results reaffirm that processed oilseeds can be used to increase the proportion of fatty acids potentially beneficial for human health, by influencing the formation of LC-PUFA and reducing the n-6/n-3 ratio.

“…In all cases, t10-18:1 was the major isomer, representing 55%, 45%, 49% and 45% of total trans-18:1 fatty acids for C, L, OC and OCL treatments, respectively. High levels of t10-18:1 in the intramuscular fat have been previously reported in intensively reared lambs fed with a forage : concentrate ratio similar to that applied in the Table 3 Effect of stoned olive cake and rolled linseed in the diet of intensively reared lambs on the concentration of total fatty acids (mg/g fresh muscle) and on the fatty-acid composition (g/100 g of fatty acids) of total lipids in the Longissimus dorsi muscle Dietary olive cake and linseed on meat fatty acid present study, especially when unsaturated fat has been added to the diet (Daniel et al, 2004;Bas et al, 2007). All trans-18:1 isomers were preferentially incorporated in neutral lipids, where they represented 5.06%, 10.89%, 7.49% and 8.57% of the total fatty acids for C, L, OC and OCL treatments, respectively (Table 5).…”

Section: Resultsmentioning

confidence: 99%

The use of stoned olive cake and rolled linseed in the diet of intensively reared lambs: effect on the intramuscular fatty-acid composition

Mele

Serra

Pauselli

et al. 2014

The aim of the present study was to evaluate the effect of the inclusion of stoned olive cake and rolled linseed in a concentratebased diet for lambs on the fatty-acid composition of polar and non-polar intramuscular lipids of the longissimus dorsi muscle. To achieve this objective, 32 Appenninica lambs were randomly distributed into four groups of eight lambs each and were fed conventional cereal-based concentrates (diet C); concentrates containing 20% on a dry matter (DM) basis of rolled linseed (diet L); concentrates containing 35% DM of stoned olive cake (diet OC); and concentrates containing both rolled linseed (10% DM) and stoned olive cake (17% DM; diet OCL). The concentrates were administered together with grass hay at a 20 : 80 forage : concentrate ratio. Growing performances and carcass traits were evaluated. The fatty-acid composition was analysed in the total intramuscular lipids, as well as in the polar and neutral lipids. The average feed intake and the growth performance of lambs were not affected by the dietary treatments, as a consequence of similar nutritional characteristics of the diets. The inclusion of rolled linseed in the L and OCL diets increased the content of C18:3 n-3 in intramuscular total lipids, which was threefold higher in meat from the L lambs and more than twofold higher in meat from the OCL lambs compared with the C and OC treatments. The n-6 : n-3 ratio significantly decreased in the meat from lambs in the L and OCL groups, reaching values below 3. The L treatment resulted in the highest level of trans-18:1 fatty acids in the muscle. Regardless of the dietary treatment, the t10-18:1 was the major isomer, representing 55%, 45%, 49% and 45% of total trans-18:1 for C, L, OC and OCL treatments, respectively. Neutral lipids from the OC-fed lambs contained the highest amount of c9-18:1 (more than 36% of total fatty acids); however, the content of c9-18:1 did not differ between the OC and C lambs, suggesting an intensive biohydrogenation of dietary c9-18:1 in the case of OC treatment. The highest content of c9,t11-18:2 was detected in the intramuscular fat from the L-fed lambs, followed by the OCL treatment. A similar trend was observed in the neutral lipid fraction and, to a lower extent, in the polar lipids.