Effects of feeding different linseed sources on omasal fatty acid flows and fatty acid profiles of plasma and milk fat in lactating dairy cows

The aim of this experiment was to study the effects of feeding different linseed sources on omasal fatty acid (FA) flows, and plasma and milk FA profiles in dairy cows. Four ruminally cannulated lactating Holstein-Friesian cows were assigned to 4 dietary treatments in a 4×4 Latin square design. Dietary treatments consisted of supplementing crushed linseed (CL), extruded whole linseed (EL), formaldehyde-treated linseed oil (FL) and linseed oil in combination with marine algae rich in docosahexaenoic acid (DL). Each period in the Latin square design lasted 21 d, with the first 16 d for adaptation. Omasal flow was estimated by the omasal sampling technique using Cr-EDTA, Yb-acetate, and acid detergent lignin as digesta flow markers. The average DM intake was 20.6 ± 2.5 kg/d, C18:3n-3 intake was 341 ± 51 g/d, and milk yield was 32.0 ± 4.6 kg/d. Milk fat yield was lower for the DL treatment (0.96 kg/d) compared with the other linseed treatments (CL, 1.36 kg/d; EL, 1.49 kg/d; FL, 1.54 kg/d). Omasal flow of C18:3n-3 was higher and C18:3n-3 biohydrogenation was lower for the EL treatment (33.8 g/d; 90.9%) compared with the CL (21.8 g/d; 94.0%), FL (15.5 g/d; 95.4%), and DL (4.6 g/d; 98.5%) treatments, whereas whole-tract digestibility of crude fat was lower for the EL treatment (64.8%) compared with the CL (71.3%), FL (78.5%), and DL (80.4%) treatments. The proportion of C18:3n-3 (g/100 g of FA) was higher for the FL treatment compared with the other treatments in plasma triacylglycerols (FL, 3.60; CL, 1.22; EL, 1.35; DL, 1.12) and milk fat (FL, 3.19; CL, 0.87; EL, 0.83; DL, 0.46). Omasal flow and proportion of C18:0 in plasma and milk fat were lower, whereas omasal flow and proportions of biohydrogenation intermediates in plasma and milk fat were higher for the DL treatment compared with the other linseed treatments. The results demonstrate that feeding EL did not result in a higher C18:3n-3 proportion in plasma and milk fat despite the higher omasal C18:3n-3 flow. This was related to the decreased total-tract digestibility of crude fat. Feeding FL resulted in a higher C18:3n-3 proportion in plasma and milk fat, although the omasal C18:3n-3 flow was similar or lower than for the CL and EL treatment, respectively. Feeding DL inhibited biohydrogenation of trans-11,cis-15-C18:2 to C18:0, as indicated by the increased omasal flows and proportions of biohydrogenation intermediates in plasma and milk fat.     

Growth performance and fatty acid profiles of intramuscular and subcutaneous fat from Limousin and Charolais heifers fed extruded linseed

Forty-eight heifers, Limousin (LI) and Charolais (CH) breed, were used to evaluate the effect of a basal mixed diet with linseed supplementation (108g/kg DM) on performance and fatty acid (FA) composition of M. longissimus thoracis (MLT) and subcutaneous fat. The feed intake and weight gains were higher, and feed per gain ratio lower in CH heifers than in LI heifers. The muscle lipids and subcutaneous fat of LI heifers contained significantly more MUFA, PUFA, CLA, and less SFA than the lipids of CH heifers. The feeding of extruded linseed significantly increased the concentration of linolenic acid (C18:3n-3), CLA, and decreased PUFA n-6 to PUFA n-3 ratio in lipids extracted from both tissues. Linseed supplementation decreased SFA and increased PUFA in subcutaneous fat. In MLT lipids of linseed-fed heifers PUFA of the n-3 series were increased. It can be concluded that the growth performance of LI heifers was lower, but that their lipids contained more FA that are thought to be important for human health. The feeding of linseed at 108g/kg DM enhanced the nutritive value of beef in terms of FA profile. Breed differences were generally more important than effects of the diet. Dietary effects, however, were more pronounced in PUFA n-3 and arachidonic acid (C20:4n-6).     

Fatty acid composition of adipose depots of suckling lambs raised under different production systems

Forty-nine male Talaverana-breed suckling lambs slaughtered at 14 kg live weight were used to study the fatty acid composition of adipose depots of lambs raised under different management systems (pasture or drylot) and diets (maternal milk with or without a concentrate supplement). Drylot lambs displayed a higher fatness score, in addition to greater dorsal fat thickness; these parameters corresponded with a greater percentage of total fat at dissection. Addition of concentrate to the diet did not modify carcass fatness. Drylot lambs presented higher proportions of oleic acid (C18:1) and monounsaturated fatty acids (MUFA) and lower linolenic acid (C18:3) values in subcutaneous and intramuscular fat (muscle longissimus thoracis). The subcutaneous fat of these lambs thus displayed a higher n-6/n-3 PUFA ratio (C18:2/C18:3) than that of pasture-raised ones. Concentrate in the diet of both pasture and drylot lambs resulted in higher linoleic fatty acid (C18:2) and PUFA values and a greater PUFA/SFA ratio in intramuscular fat than the corresponding values of lambs which consumed maternal milk alone. Loin displayed a higher percentage of subcutaneous and intramuscular chemical fat than leg. Compared with intramuscular leg fat (muscle quadriceps femoris), intramuscular loin fat (muscle longissimus thoracis) had lower oleic acid (C18:1) and MUFA values, higher PUFA values and a higher PUFA/SFA ratio, due to greater linolenic acid (C18:3) levels.     

Effectiveness of extruded rapeseed associated with an alfalfa protein concentrate in enhancing the bovine milk fatty acid composition

Linseed and rapeseed, good sources of 18:3 n-3 and cis9-18:1, respectively, have been shown to improve the bovine milk fatty acid (FA) profile. However, rapeseed, unlike linseed, has little effect on the concentration of 18:3 n-3 in milk fat. Alfalfa protein concentrate (APC), besides being a valuable protein source for milk production, contains lipids rich in 18:3 n-3. Therefore, this experiment aimed at (1) evaluating the transfer efficiency of unsaturated FA (UFA), especially 18:3 n-3, of APC to bovine milk fat, and (2) evaluating whether extruded rapeseed (ER) associated with APC is as effective as extruded linseed (EL) in enhancing the bovine milk fat composition. Six lactating Holstein cows were used in a replicated 2 × 2 Latin square design with 2 iso-energy, iso-nitrogen and iso-FA corn silage-based diets (EL and ER-APC) and two 21-d periods. Extruded linseed, as main UFA source, was included in the first diet, whereas ER, as main UFA source, and APC, as supplemental 18:3 n-3, were included in the second diet. Diets were distributed as a restricted total mixed ration. Compared with the EL diet, the ER-APC diet, where ER was associated with APC, increased milk concentration of 18:3 n-3 (1.18 vs. 1.31% of FA) and cis9-18:1 (18.35 vs. 20.01% of FA). The apparent transfer efficiency of 18:3 n-3 from diet to milk was almost twice as much for the ER-APC diet than for the EL diet (7.4 vs. 3.8% of intake). Extruded linseed accounted for 84% of 18:3 n-3 provided in the EL diet, whereas ER and APC accounted for 33 and 38% of 18:3 n-3 provided in the ER-APC diet, respectively. Because both EL and ER underwent extrusion in similar conditions, these results suggest that 18:3 n-3 of EL in the EL diet and ER in the ER-APC diet were subjected to more extensive ruminal biohydrogenation than 18:3 n-3 of APC in the ER-APC diet. This experiment shows that corn silage-based diets supplemented with ER as the main UFA source, associated with APC as supplemental 18:3 n-3, are as effective as corn silage-based diets supplemented with EL as the main UFA source, in increasing bovine milk UFA and 18:3 n-3 contents. Furthermore, at similar levels of dietary incorporation, this experiment shows that the ruminal bypass of 18:3 n-3 is higher for APC compared with EL.     

The effect of maternal linseed supplementation and/or lamb linseed supplementation on muscle and subcutaneous adipose tissue fatty acid composition of indoor lambs

Eighty eight lambs were used in a 2 × 2 factorial arrangement 1) to investigate the effect of maternal dietary linseed supplementation and/or lamb linseed supplemented concentrate on growth performance, carcass fat quality and fatty acid (FA) composition of muscle and dorsal adipose tissue of indoor lambs 2) to study the relationships between subcutaneous fat quality and FA composition. Feeding linseed to ewes increased C18:3 n-3 (ALA) proportion in milk and therefore the ALA supply to suckling lambs. However, ALA and n-3 polyunsaturated FA (n-3 PUFA) proportions in lamb tissues were not affected. Feeding linseed to lambs during the post-weaning period significantly increased the proportions of ALA and n-3 PUFA in tissues. Softer and more colored fat was associated with a decrease in even medium-chain saturated FA and increases in odd and methyl FA proportions but not with ALA proportion in subcutaneous adipose tissue.     

Effect of a linseed diet on lipid oxidation, fatty acid composition of muscle, perirenal fat, and raw and cooked rabbit meat

Forty Californian×New Zealand rabbits (1kg initial body weight) were fed a control or a linseed isoenergetic diet containing 30g of extruded linseed/kg. Twenty rabbits for each dietary treatment were slaughtered at 11 weeks of age, at 35 days after the start of the experiment. Feeding the linseed diet increased (P<0.005) the content of 18:2n-3 in muscles, perirenal fat, and raw and cooked meat. The long chain n-3 polyunsaturated fatty acid (PUFA) contents were also increased (P<0.01) in the meat. The linseed diet produced a robust decrease in the n-6/n-3 ratio. Cooking did not alter n-3 PUFA more than saturated fatty acids (SFA) or monounsaturated fatty acids (MUFA). However, n-6 PUFA were altered by cooking. The oxidative stability of Longissimus dorsi was not affected by the linseed diet, even after 300min of forced-oxidation. Inclusion of linseed in rabbit diets is a valid method of improving the nutritional value of rabbit meat.     

Effects of forage type, forage to concentrate ratio, and crushed linseed supplementation on milk fatty acid profile in lactating dairy cows

The effects of an increasing proportion of crushed linseed (CL) in combination with varying forage type (grass or corn silage) and forage to concentrate ratio (F:C), and their interactions on milk fatty acid (FA) profile of high-producing dairy cows was studied using a 3-factor Box-Behnken design. Sixteen Holstein and 20 Swedish Red cows were blocked according to breed, parity, and milk yield, and randomly assigned to 4 groups. Groups were fed different treatment diets formulated from combinations of the 3 main factors each containing 3 levels. Forage type (fraction of total forage dry matter, DM) included 20, 50, and 80% grass silage, with the remainder being corn silage. The F:C (DM basis) were 35:65, 50:50, and 65:35, and CL was supplied at 1, 3, and 5% of diet DM. Starch and neutral detergent fiber content (DM basis) of the treatment diets ranged from 117 to 209 g/kg and 311 to 388 g/kg, respectively. Thirteen treatment diets were formulated according to the Box-Behnken design. During 4 experimental periods of 21 d each, all treatment diets were fed, including a repetition of the center point treatment (50% grass silage, 50:50 F:C, 3% CL) during every period. Intake, production performance, and milk FA profile were measured, and response surface equations were derived for these variables. Shifting from 80% grass silage to 80% corn silage in the diet linearly increased dry matter intake (DMI), net energy for lactation (NE_L) intake, cis-9,cis-12-C18:2 (C18:2n-6) intake, and milk yield, and linearly decreased cis-9,cis-12,cis-15-C18:3 (C18:3n-3) intake and milk fat content. Shifting from a high forage to a high concentrate diet linearly increased DMI, NE_L intake, C18:2n-6 intake, and milk yield, and decreased milk fat content. Supplementation of CL linearly increased C18:3n-3 intake, but had no effect on DMI, NE_L intake, milk yield, or milk fat content. Shifting from 80% grass silage to 80% corn silage linearly increased proportions of trans-10-C18:1 and C18:2n-6 in milk fat, whereas the proportions of trans-11,cis-15-C18:2 and C18:3n-3 linearly decreased. Significant interactions between CL supplementation and F:C were found for proportions of trans-10-C18:1, trans-15-C18:1, cis-15-C18:1, trans-11,cis-15-C18:2, and C18:3n-3 in milk fat, with the highest levels achieved when the diet contained 5% CL and a 35:65 F:C ratio. The effect of supplementing CL on several milk FA proportions, including C18:2n-6 and C18:3n-3, depends significantly on the F:C ratio and forage type in the basal diet.     

Enrichment of eggs in n-3 polyunsaturated fatty acids by feeding hens with different amount of linseed oil in diet

The production of n-3 polyunsaturated fatty acid enriched eggs by addition of linseed oil to the laying hens' diet has been evaluated in terms of production parameters and n-6/n-3 ratio. A total of 150 18weeks old Lohmann Brown laying hens were housed in cages and fed with basal diet and four experimental diets containing 1%, 2%, 3% or 4% of linseed oil added to the basal diet. The effect of the altered level of linseed oil on hens laying performance, fatty acid content and composition and cholesterol content in egg yolk has been evaluated during 13weeks of experiment. Egg weight, yolk fat content, yolk weight, yolk percentage and shape index were not influenced by dietary treatment. The ratio between n-6 and n-3 polyunsaturated fatty acids in eggs decreased in first 5weeks and then remained stable until the end of the experiment for all experimental groups. Different contents of linseed oil in feed highly influenced the n-6/n-3 ratio (P<0.0001). Addition of linseed oil did not influence the cholesterol content in yolks (P=0.5200) while the only factor affecting the cholesterol content was the hens age (P<0.0001).     

Dietary manipulation of fatty acid composition in lamb meat and its effect on the volatile aroma compounds of grilled lamb

The effect on lamb muscle of five dietary supplements high in polyunsaturated fatty acids (PUFA) was measured. The supplements were linseed oil, fish oil, protected lipid (high in linoleic acid (C18:2 n-6) and α-linolenic acid (C18:3 n-3)), fish oil/marine algae (1:1), and protected lipid/marine algae (1:1). Eicosapentaenoic acid (C20:5 n-3) and docosahexaenoic acid (C22:6 n-3) were found in the highest amounts in the meat from lambs fed diets containing algae. Meat from lambs fed protected lipid had the highest levels of C18:2 n-6 and C18:3 n-3, due to the effectiveness of the protection system. In grilled meat from these animals, volatile compounds derived from n-3 fatty acids were highest in the meat from the lambs fed the fish oil/algae diet, whereas compounds derived from n-6 fatty acids were highest in the meat from the lambs fed the protected lipid diet.     

Effect of dietary linseed oil and α-tocopherol on pork tenderloin (Psoas major) muscle

The effect of linseed oil and α-tocopheryl acetate on the fatty acid composition and the susceptibility to oxidation of lipid fraction from pork tenderloin (Psoas major) muscle has been studied. Muscles were obtained from animals fed on diets with the same ingredients excepting the oil source [sunflower (C), linseed (L) and linseed and olive (1/1, w/w) (LO)] and α-tocopherol [20 (C, L and LO) or 200 (LOE and LE) mg/kg diet]. The n-6/n-3 ratio in pork tenderloin was markedly modified by dietary linseed oil administration, which was due to the increase in the C18:3n-3 (and total n-3 fatty acids) and the decrease in the C18:2n-6 (and total n-6 fatty acids) contents (P<0.05). The α-tocopherol content of tenderloin from batches LE and LOE was about 2.8 mg/kg of muscle, significantly greater (P<0.05) than about 0.7 mg/kg muscle found in tenderloin from pigs receiving C, L and LO. Dietary supplementation with α-tocopheryl acetate markedly reduced tenderloin lipid oxidation from animals fed diets enriched in n-3 fatty acids (L or LO vs LE or LOE).     

Effect of different feeds on meat quality and fatty acid composition of lambs fattened at pasture

Two kinds of feed (commercial concentrate vs whole supplemented barley) were compared in unweaned lambs and lambs weaned at 40 days of age, fattened at pasture and slaughtered at 28 kg live weight, in order to observe their effects on meat quality and fatty acid composition. The weaning status influenced fatness; unweaned lambs displayed a greater carcass fatness score and more kidney knob and channel fat than weaned lambs. Compared with the unweaned animals, weaned lambs exhibited higher pH values at 0 h and 45 min in the m. longissimus thoracis (LT) and at 45 min and 24 h in the m. semitendinosus. The redness index (a*) of the m. LT of weaned lambs was higher than that of unweaned lambs, and lambs fed concentrate displayed a higher yellowness index (b*) and a higher Hue value than those given whole barley. Water-holding capacity did not vary with the treatments studied. The proportion of saturated fatty acids (SFA) in intramuscular fat was higher (P?0.001) in unweaned lambs than in weaned ones while, on the other hand, the latter displayed a higher proportion of monounsaturated fatty acids (MUFA) and a higher n-6/n-3 ratio in the same tissue. As was the case with intramuscular fat, the subcutaneous fat of unweaned lambs exhibited higher proportions of medium-chain fatty acids (C12:0, C14:0 y C16:0) and lower ones of stearic (C18:0) and oleic (C18:1) fatty acids than that of weaned lambs. Higher levels of heptadecenoic acid (C17:1) were found in the subcutaneous fat of lambs fed whole barley than in that of lambs given concentrate. PUFA/SFA and n-6/n-3 ratios were lower in the m. LT than in the m. quadriceps femoris.     

Milk fatty acid composition and production performance of Danish Holstein and Danish Jersey cows fed different amounts of linseed and rapeseed

Fat supplements are used in diets for dairy cows to increase energy intake and milk production and the fatty acid composition of the feed affects milk fatty acid composition. A total of 74 Danish Holstein and 41 Danish Jersey cows were divided into 4 groups and the cows within each group were fed a mixed ration supplemented with 0, 3.5, 6.8, or 10.2% of dry matter of a linseed:rapeseed (1:3) mixture during lactation wk 6 to 30. Milk yield, fat, and lactose contents were not affected by treatments for Danish Holsteins, whereas these parameters increased when increased amounts of oilseeds were fed to Danish Jerseys. For both breeds, milk protein content decreased when increased amounts of oilseeds were fed. The milk fatty acid composition showed higher concentrations of saturated fatty acids and lower concentrations of unsaturated fatty acids in milk fat from Danish Jerseys compared with Danish Holsteins. Increased amounts of oilseeds in feed increased milk fat concentration of all C18 fatty acids except C18:2 n-6, whereas the content of C6 to C14, C11 to C17, and in particular, C16, decreased. This effect was more pronounced for Danish Holsteins than for Danish Jerseys. The apparent recovery of C18:2 n-6 and C18:3 n-3 decreased when increased amounts of oilseeds were fed; however, this was most likely due to increased amounts of fatty acid from feed used for other energy demands than milk production. It was concluded that up to 6.8% of oilseed supplementation can be fed without production problems and, in many cases, with positive production responses, including an improved milk fatty acid profile.     

Sensitivity of pig genotypes to short-term manipulation of plasma fatty acids by feeding linseed

The sensitivity of pigs selected for high daily food intake (DFI), low lean food conversion (LFC) and high lean growth rate (LGS) to dietary change of plasma fatty acids was assessed. The difference between the two diets was effectively a substitution of palmitic (C16:0), oleic (C18:1 n-9) and linoleic (C18:2 n-6) with linolenic (C18:3 n-3) fatty acids. Fatty acid compositions of plasma free fatty acids, neutral lipids and phospholipids were measured in 90 kg animals fed a base or high linolenic (C18:3 n-3) fatty acid diet, based on whole linseed, for four days. There were 24 animals from each selection line and 24 animals from an unselected control line, with boars and gilts represented equally in each line. Half of the selection line animals were fed the base diet and half were fed the high C18:3 diet, but all control animals were fed the base diet. Prior to slaughter, animals were fasted for 18 h. The fatty acids primarily affected by dietary change were C18:3 n-3 and its products, C20:5 n-3 (EPA) and C22:6 n-3 (DHA). The sensitivity of a selection line to dietary change was parameterised by the relative shift in fatty acid composition through changing from the base diet to the high C18:3 diet. In neutral lipids, the sensitivities of C18:3 n-3 in the DFI and LFC lines were similar but greater than in the LGS line (3.0 v. 1.8, S.E.D. 0.15), while, for phospholipid and free fatty acids, the sensitivity of the DFI line was greater than in the LFC and LGS lines (2.3 v. 1.8 and 2.0 v. 1.4, respectively). For C20:5 n-3 and C22:6 n-3, the DFI and LFC lines were more sensitive to dietary change than the LGS line (total lipid : 2.3 v. 1.9 and 1.5 v. 1.2). In general, the DFI line was most sensitive to dietary change and the LGS line was the least sensitive. The difference in sensitivities of the lipid classes to the high C18:3 diet between the selection lines could result from differences in body fat content and may explain the general lack of genotype with nutrition interactions in post-1990 genotypes in comparison with fatter circa-1970 genotypes.     

Effects of different sources of fat (calcium soap of palm oil vs. extruded linseed) in lactating ewes' diet on the fatty acid profile of their suckling lambs

The main objective of this study was to evaluate the effects of supplementing lactating ewe diets with extruded linseed on the fatty acid (FA) composition of intramuscular and subcutaneous fat depots of suckling lambs. Twenty-four pregnant Churra ewes were divided into two groups based on the milk production, age, body weight and parity, and assigned to one of two treatments. Each ewe of the Control treatment was supplemented with 70 g/day of FAs from a calcium soap of palm oil, while the other treatment group (Lin) was supplemented with 128 g/day of extruded linseed. All lambs were reared exclusively on milk and were slaughtered when they reached 11 kg live weight. FA profiles of ewe milk, lamb meat and subcutaneous adipose tissue were determined by GC. Lamb performance was not affected by the treatments. Muscle fat and adipose tissue from the Lin treatment showed higher proportions of polyunsaturated fatty acids (PUFA). The percentages of α-linolenic (C18:3 n − 3), docosahexaenoic (C22:6 n − 3), vaccenic (trans-11 C18:1) and rumenic (cis-9, trans-11 C18:2) acids in both fat depots were higher in Lin than in Control suckling lambs. Furthermore, meat fat from Lin carcasses displayed a lower n − 6/n − 3 ratio than Control samples. Intramuscular depots clearly showed a greater content of PUFA, including cis-9, trans-11 C18:2, and a lower n − 6/n − 3 ratio than subcutaneous fat. The results from this study demonstrate that dietary extruded linseed supplementation of lactating ewes enhances the nutritional quality of suckling lamb fat depots such as intramuscular and subcutaneous fats.     

蒙古斑点马不同部位脂肪和肌肉组织中脂肪酸组成的比较研究

通过对蒙古斑点马不同部位脂肪和肌肉组织中脂肪酸组成进行分析比较,旨在明确蒙古斑点马体脂脂肪酸组成特点。选择3 匹成年蒙古斑点马,屠宰后采集肾周、肠周和皮下脂肪以及肩肌、背最长肌和臀肌样品,利用气相色谱法测定脂肪酸组成及含量。结果表明：蒙古斑点马不同脂肪组织中均检出19 种脂肪酸,其中饱和脂肪酸（saturated fatty acid,SFA）含量34.77%～37.38%,不饱和脂肪酸（unsaturated fatty acid,UFA）含量达60%以上,UFA中单不饱和脂肪酸（monounsaturated fatty acid,MUFA）含量33.04%～36.39%,多不饱和脂肪酸（polyunsaturated fatty acid,PUFA）含量26.47%～27.51%,其中皮下脂肪C10:0、C18:0、C20:0含量显著低于肾周和肠周脂肪（P＜0.05）;MUFA在皮下脂肪的沉积程度较其他2 个部位高,但均无统计学差异;PUFA中C18:3 n-3含量最高,其在各脂肪组织间无显著差异。3 个不同部位肌肉中均检出15 种脂肪酸,其中SFA含量占总脂肪酸含量的38.32%～40.04%,MUFA含量占35.70%～40.19%,PUFA含量占15.25%～20.33%;SFA中背最长肌和臀肌C12:0含量显著高于肩肌（P＜0.05）,其余SFA在不同部位肌肉间无显著差异;MUFA中背最长肌C16:1含量显著高于肩肌和臀肌（P＜0.05）;肩肌n-6/n-3 PUFA比值显著高于背最长肌和臀肌（P＜0.05）;皮下脂肪的C18:3 n-3和总PUFA含量显著高于背最长肌（P＜0.05）。综上所述,蒙古斑点马不同部位脂肪和肌肉组织脂肪酸组成各具特点,但UFA含量均较高。     

Influence of ewe feeding systems on fatty acid composition of suckling lambs

The main objective of this study was to evaluate the effects of ewe dietary treatments on the intramuscular fatty acid composition of suckling lambs. Twenty-four pregnant Italian Merino ewes were divided into two equal groups. One group (pasture-fed group) was allowed to graze a natural pasture and the other group (stall-fed group) was penned indoors and fed with hay and concentrate. After lambing, all ewes stayed with their respective lambs for the whole experimental period. Lambs were slaughtered at 100 days of age with an average live weight of 20kg. Fatty acid profiles of milk and lamb meat (longissimus lumborum muscle) were analysed. Intramuscular fat from pasture-fed lambs showed higher (P<0.001) proportions of polyunsaturated fatty acids. The percentage of lauric (C12:0; P<0.05), palmitic (C16.0; P<0.001) and oleic (C18.1; P<0.001) fatty acids were higher in the intramuscular fat from stall-fed lambs, whereas pasture-fed lambs showed greater proportions of linolenic (C18:3; P<0.001), eicosapentaenoic (C20:5; P<0.001) and docosapentaenoic (C22:5; P<0.05) fatty acids. Moreover, the intramuscular fat from pasture-fed lambs displayed a higher (P<0.001) PUFA/SFA ratio, and a lower (p<0.001) n-6/n-3 ratio. The conjugated linoleic acid (CLA) tended to be higher (P=0.07) in the intramuscular fat from pasture-fed lambs. This study confirmed that pasture enhanced the unsaturated fatty acid profile of intramuscular fat in lambs including n-3 fatty acids.     

Dietary vitamin A concentration alters fatty acid composition in pigs

This experiment was conducted to study the effect of vitamin A concentration in the diet on fatty acid composition in pigs. One-hundred and twenty eight Duroc × (Large White × Landrace) castrated male pigs were used. Pigs were randomly distributed and located in cages of four pigs each to the following treatment: vitamin A-enriched diet (100,000IU/kg) (n=16) and control diet with a basal level (7500IU/kg) (n=16). The pigs were slaughtered at an average weight of 125.9kg. No effect of diet vitamin A level on performance, carcass traits and intramuscular fat percentage was observed. The retinol concentration in subcutaneous backfat and retinol and retinol palmitate contents in liver were higher in the pigs that were given the vitamin A enriched diet than in those receiving the control diet. However the vitamin A supplementation did not increase the retinol content in the muscle. Pigs receiving the vitamin A enriched diet showed a higher C16:0 and ∑SFA proportions in the outer layer and C18:0 and ∑SFA proportions in the inner layer. Moreover, the diet rich in vitamin A led to a reduction of C18:1 n-9 and ∑MUFA proportions in subcutaneous backfat inner layer. Dietary vitamin A concentration had not influence on main fatty acids composition of intramuscular lipids. Dietary vitamin A enrichment lead to a higher C16:0, ∑SFA concentration in liver lipids.     

Feeding linseed to increase the n-3 PUFA of pork: fatty acid composition of muscle, adipose tissue, liver and sausages

Eighty pigs, male and female littermate pairs, were fed a control or a test diet from 25 to 95 kg live weight. The diets, as fed, contained 15.5 g/kg linoleic acid (18:2) and 1.9 g/kg α-linolenic acid (18:3) (control) or 10 g/kg linoleic acid and 4 g/kg α-linolenic acid (test). The test diet, with added linseed, was, therefore, high in the main n-3 polyunsaturated fatty acid (PUFA) 18:3 and low in the main n-6 PUFA 18:2. Making this relatively small change led to a 56% increase in the content of 18:3 in muscle and major increases in the contents of the beneficial longer chain PUFAs EPA (20:5n-3) (100% increase) and DHA (22:6n-3) (35% increase) which are synthesised from 18:3n-3. Levels of EPA and DHA in pigmeat adipose tissue were also increased by the test diet. In liver, the test diet resulted in an 18:3 level 4× higher than in muscle, with 10× more EPA and 20× more DHA. Sausages, analysed after 6 months frozen storage also had high n-3 PUFA levels, due to the contribution of these fatty acids from both muscle and adipose tissue. From a health perspective these results confirm the potential of pigmeat to supply valuable n-3 PUFA to the human diet. The test diet produced a PUFA:saturated FA ratio in muscle of 0.4, close to the minimum recommended value for the diet as a whole and an n-6:n-3 ratio of 5, a significant improvement on the current average for pigmeat (7). It is estimated that the test diet would provide 12 g of long chain n-3 PUFA to the human diet per annum at current pigmeat consumption levels in the UK, about a third of that from oily fish.     

Effect of crossbreeding and gender on meat quality and fatty acid composition in pork

This study considers the effect of crossbreeding and gender (barrows; gilts) on meat quality and intramuscular and subcutaneous fatty acid composition in pork. The sire lines included Large White (LW), Duroc (D) and Pietrain (P) and the dam line was Landrace (LR)×LW, producing LW×(LR×LW), D×(LR×LW) and P×(LR×LW). Pork samples were removed from Longissimus dorsi (LD) and Semimembranosus (SM) muscles and subcutaneous fat (SCF). There were no important differences in meat quality parameters but D×(LR×LW) had the highest percentage of intramuscular fat. Castrated males had more intramuscular fat and more intense meat colour than female pigs. The Large White and Duroc sire line had saturated fatty acids (SFA) in SM, whereas the Pietrain sire line was significantly higher than Duroc sire line in the concentration of polyunsaturated fatty acids (PUFA), PUFA/SFA (P/S) and the n-6/n-3 ratio. The concentrations of SFA and monounsaturated fatty acids (MUFA) in SCF were significantly higher in LW×(LR×LW) and P×(LR×LW), respectively. No differences were found in the percentage of PUFA, P/S and n-6/n-3 ratio between D×(LR×LW) and P×(LR×LW). Female pigs had the most polyunsaturated intramuscular and subcutaneous fat. The results demonstrate small differences in fatty acid compositions among sires.     

How do n-3 fatty acid (short-time restricted vs unrestricted) and n-6 fatty acid enriched diets affect the fatty acid profile in different tissues of German Simmental bulls?

This study investigated the effect of n-6 (control group) and n-3 polyunsaturated fatty acids (PUFA) supply (treatment group unrestricted) and a short-time feed restriction for n-3 PUFA supply (treatment group restricted) on intramuscular fat content and the total fatty acid composition in different tissues (muscle, subcutaneous fat, liver, serum and erythrocytes) and lipid classes of intramuscular fat of German Simmental bulls (n = 25). Exogenous n-3 PUFA caused a higher concentration of the sum of all single n-3 and n-3 long-chain polyunsaturated fatty acids (LC PUFA) in all analysed tissues. Feed restriction compared to control feeding induced a significant decrease of C18:1cis-9 in the phospholipid fraction of longissimus muscle and in subcutaneous fat. The concentration of C18:3n-3 in liver of treatment groups was between 34 and 44% higher compared to control. PUFA in serum and the sum of n-3 PUFA in erythrocytes were significantly higher in both treatment groups compared to control. The synthesis and deposition of n-3 LC PUFA seems to be tissue dependent according to different relative amounts.