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.     

Composition and estimation of intramuscular and subcutaneous fatty acid composition in Spanish young bulls

Sixty Pirenaica yearling intact bulls were raised and slaughtered at 519±50kg live weight and 371±18 days of age. Fatty acid composition of intramuscular lipids in longissimus dorsi muscle and subcutaneous fat were determined by capillary gas chromatography. Carcass conformation and fatness, carcass weight, ether extractable intramuscular fat percentage, marbling, dorsal fat thickness, and ultrasonic parameters were recorded to study the relationship between these traits and fatty acid profile. Lipids of subcutaneous adipose tissue had higher monounsaturated fatty acids (MUFA) percentage (49% vs. 33%) but lower saturated fatty acids (SFA) (51% vs. 46%) and polyunsaturated fatty acids (PUFA) (16% vs. 5%) percentages than intramuscular fat depots (p<0.001). Fatter carcasses had higher MUFA percentage and lower PUFA percentage (p<0.01) in intramuscular fat. Carcass weight and conformation would contribute to explain the fatty acid profile of subcutaneous fat (p<0.05). Ultrasound readings reflected the effect of fatness on fat composition.     

Effect of dietary energy and protein levels on fatty acid composition of intramuscular fat in double-muscled Belgian Blue bulls

Seventy six Belgian Blue (BB) bulls, with double-muscled conformation, were randomly allocated to six dietary treatments in a 2 × 3 factorial experiment. The treatments included low (N(L)=127 g CP/kg DM), medium (N(M)=153 g CP/kg DM) and high (N(H)=172 g CP/kg DM) levels of dietary protein in combination with low (E(L)=7.38 MJ ME/kg DM) and high (E(H)=8.03 MJ ME/kg DM) levels of dietary energy. Fatty acid composition was determined on total lipid samples of the M. longissimus thoracis of all animals and on the separated triacylglycerol and polar lipid fatty acid fractions of the medium-protein group. Dietary energy and protein levels influenced the carcass characteristics of BB bulls but the effects were small. Carcass fat cover score, carcass fat content and intramuscular fat content were slightly but significantly higher in the animals on the high versus the low energy diets. The overall intramuscular fat content was very low (<1%) and the overall polyunsaturated:saturated fatty acid ratio (0.39) high compared to normal figures for beef. The high versus the low dietary energy level increased the monounsaturated (P<0.001) and decreased the polyunsaturated (P<0.001) fatty acid proportion with no change in the saturated fatty acid proportion. This may have been due in part to the addition of beef tallow to increase the energy level of the diet. Concomitant shifts in the individual fatty acids included increased proportions of C14:0 (P<0.001), C16:0 (P<0.03), C16:1 (P<0.01), C18:1 (P<0.001) and decreased proportions of C18:2 (P<0.001) and C20:4 (P<0.001). Increasing dietary protein levels had inconsistent effects on the fatty acid profiles. The proportion of polar lipid fatty acids in the total fatty acids was 0.34 and 0.25 for the E(L) and E(H) group, respectively, in the Nm treatment group. Changes in fatty acid proportions of the triacylglycerol fatty acid fraction were similar to those seen in the total lipid fatty acids when related to dietary energy level, but no significant changes in the polar lipid fatty acid proportions were observed. Significant linear relationships were found between measures of carcass and muscle fatness and fatty acid proportions. With increasing muscle total fatty acid content, saturated and monounsaturated fatty acid proportions increased (r=0.38 and r=0.55, respectively, P<0.01) and the polyunsaturated fatty acid proportion decreased (r=-0.73, P<0.01). The diet had some effects but the relatively unsaturated intramuscular fatty acid composition was mainly related to the low total fat content of the BB animals.     

Influence of dietary oils and protein level on pork quality. 1. Effects on muscle fatty acid composition, carcass, meat and eating quality

This study evaluated the effects of three dietary oils - palm kernel (PKO), palm (PO) and soyabean (SBO) - and two protein levels - high (HP) and low (LP) in a 3×2 factorial design involving 60 pigs on growth performance, muscle fatty acid composition and content, carcass, meat and eating qualities. Oil type did not have a significant effect on growth and carcass quality. PKO significantly reduced the polyunsaturated (PUFA) to saturated (SFA) fatty acid (P:S) ratio in longissimus muscle (P<0.001). PKO increased the concentrations of lauric (12:0), myristic (14:0), palmitic (16:0) and stearic (18:0) fatty acids and decreased linoleic acid (18:2). The LP diet increased intramuscular fat (IMF) from 1.7g/100g muscle in HP to 2.9g/100g (P<0.001), increased tenderness by 0.6 units (P<0.01) and juiciness by 0.5 units (P<0.01) on the 1-8 scale, but at the expense of lower daily weight gain (P<0.01), lower feed conversion efficiency (P<0.01), reduced P:S ratio (P<0.001) and increased lipid oxidation (P<0.01). The results suggest that PKO and PO could be used in tropical developing countries as cheaper alternatives to SBO for the production of good quality and healthy pork, but their limits of inclusion need to be determined.     

Relationships between intramuscular fat content, selected carcass traits, and fatty acid profile in bulls using a F2-population

The quality and nutritional value of beef is related to the amount of intramuscular fat (IMF) as well as to its fatty acid composition. In this study the relations between the IMF content and the total fatty acid composition, the fatty acids (FA) of triacylglycerols (TG) and the FA of phospholipids (PL) in longissimus muscle of F₂ Charolais × German Holstein crossbred bulls have been analysed. Polyunsaturated fatty acids (PUFA, C18:2n-6; C18:3n-3) and stearic acid (C18:0) are strongly positively correlated to IMF in longissimus muscle at the quantitative level (mg/100 g fresh tissue), but there are negative correlation coefficients for the relative proportion of these fatty acids to IMF. The relationships between IMF and the fatty acid profile of the subfractions TG and PL are lower compared to total muscle fat. Selected carcass fat traits are positively correlated to most of the fatty acids.     

Omega-3 fatty acids in pig nutrition: Implications for the intrinsic and sensory quality of the meat

Seventy-eight hybrid pigs (Piétrain × Seghers hybrid cross, 38 barrows and 40 gilts) were fed ad libitum diets, containing either 0.4%, 0.7% or 1.0% α-linolenic acid (C18:3n-3), originating from linseed. The variation in polyunsaturated fatty acid content in the feed (1.19%, 1.52% and 1.88%, respectively) was mainly attributed to variations in α-linolenic acid content. Meat quality evaluated by physical measurements (pH, light scattering, conductivity, colour, light reflection, tenderness, water holding capacity) was not influenced, to any significant extent, by the fatty acid composition of the feed. A subjective judgement of cohesiveness revealed no abnormalities. Dietary fat source, sex and intramuscular fat (IMF) level affected the fatty acid pattern of the IMF. The α-linolenic content in the IMF increased from 1.2% to 2.3% for the barrows and from 1.4% to 2.9% for the gilts with increasing αlinolenic acid content in the feed. A multiple paired comparison test for taste, tenderness and juiciness on 45 meat samples (M. longissimus thoracis) revealed no significant differences among the feed groups.     

冷冻对香猪组织和器官中脂类成份的影响研究

为了探明冷冻贮藏对香猪组织和器官中脂类成分的影响,本研究选择3 头相同日龄的香猪,选取皮下脂肪、背最长肌及肝脏组织为实验样品,分析冷冻贮藏前后样品的脂肪含量、脂肪与脂肪酸组成、丙二醛含量(TBARS 值)。结果显示：冷冻贮藏对各组织的脂肪含量无明显影响;贮藏后皮下脂肪、肌肉和肝脏的磷脂含量均显著下降(P ＜ 0.01),其中以肝脏的磷脂含量下降幅度最大(从45.61% 下降至34.96%);皮下脂肪、肌肉和肝脏中游离脂肪酸的含量贮藏以后分别增加到原来的6.6 倍、7.7 倍和9.1 倍。－ 18℃冷藏150 d 后,各样品的脂肪酸组成差异明显,但中性脂肪的饱和脂肪酸含量都显著升高(P ＜ 0.01),而磷脂的多不饱和脂肪酸含量则显著下降(P ＜0.01),游离脂肪酸的饱和脂肪酸含量大幅度降低(P ＜ 0.01)。皮下脂肪、肌肉和肝脏的TBARS 值分别为0.7、16.7、120.5mg/kg,且3 种组织间差异显著(P ＜ 0.01)。研究结果表明,冷冻贮藏中饱和脂肪酸的水解速度相对较慢,而不饱和脂肪酸有大量水解。冷冻贮藏过程中肝脏的脂肪组分最容易发生氧化,其次是肌肉中的脂肪,而皮下脂肪的氧化稳定性最高。     

Effect of grass or concentrate feeding systems and rate of growth on triglyceride and phospholipid and their fatty acids in the M. longissimus thoracis of lambs

Thirty-two male Ile-de-France lambs were used in a factorial 2×2 design to analyse the effects of feeding systems (grass outdoor, G, or concentrate and hay indoor: stall, S) and of growth rate (low, L, or high, H) on total lipids, triglyceride (TG) and phospholipid (PL) contents and their fatty acid composition in the longissimus thoracis muscle (L.T.). Contents were lower for TG (10.4 vs. 15.8 mg/100 g fresh tissue, P<0.05) and higher for PL (6.4 vs. 5.8 mg/100 g fresh tissue, P <0.05) in grass-fed lambs compared to stall-fed ones. TG of grass fed lambs displayed lower proportions of palmitic acid (C16:0), monounsaturated fatty acids (MUFAs), linoleic acid (C18:2n-6) and other (n-6) polyunsaturated fatty acids (PUFA) and higher proportions of stearic acid (C18:0), linolenic acid (C18:3n-3), cis 9, 11 trans C18:2 and trans monounsaturated fatty acids. In PL of the same lambs only lower MUFA, C18:2n-6 and (n-6) PUFA and higher C18:3n-3, (n-3) PUFA and cis 9, 11 trans C18:2 were observed. Growth rate had no effect on lipid, TG or PL contents of longissimus thoracis. However C18:0 proportions were higher in TG and lower in PL for low growth rate lambs. Low growth rate lambs had also lower cis 9, 11 trans C18:2 in TG. Thus, irrespective of growth rate, the muscle lipids characteristic of grass fed lambs fulfilled the recommended features of human food components much better than that of stall fed lambs, namely for CLA and C18:3n-3. The lower ratios of (n-6) to (n-3) PUFA displayed in grass fed lambs both in TG and in PL were also useful to discriminate all the grass fed lambs from all the stall fed animals.     

无量山乌骨鸡腿肌营养成分分析和评价

通过对无量山乌骨鸡腿肌的营养成分进行测定,对比不同性别无量山乌骨鸡腿肌的营养成分差 异,评价其营养价值。结果表明：无量山乌骨鸡腿肌的粗蛋白含量为（23.02±0.69）%、粗脂肪含量为 （2.00±0.97）%、灰分含量为（1.25±0.06）%、水分含量为（73.63±1.29）%;腿肌冻干粉中17 种氨基酸的总量 达（82.59±4.30）%,鲜味氨基酸总量为（28.78±1.56）%,必需氨基酸含量为（34.08±1.83）%,必需氨基酸/ 总氨基酸的值为（41.26±0.52）%,必需氨基酸/非必需氨基酸的值为（70.26±1.52）%,氨基酸组成比例均衡; 腿肌冻干粉中18 种脂肪酸的总量为（33.88±9.41） mg/g,必需脂肪酸含量为（10.21±2.89） mg/g,饱和脂肪酸 含量为（14.13±4.41） mg/g,不饱和脂肪酸含量为（19.75±5.22） mg/g,不饱和脂肪酸占比高于50%;腿肌中 磷元素含量为（721.25±294.75） mg/kg,镁、钙、铁、锌、铜含量分别为（240.03±63.06）、（24.28±5.56）、 （14.94±2.76）、（11.40±1.94）、（1.51±0.85） mg/kg。无量山乌骨鸡腿肌的营养成分具有性别差异性,公鸡 腿肌的水分含量、17 种氨基酸总量、鲜味氨基酸、必需氨基酸及磷元素含量显著（P＜0.05）或极显著（P＜0.01） 高于母鸡,且公鸡腿肌的氨基酸比值系数分高于母鸡;母鸡腿肌的粗脂肪、灰分、饱和脂肪酸、单不饱和脂肪酸及 锌元素含量显著（P＜0.05）或极显著（P＜0.01）高于公鸡。     

Meat quality characteristics of springbok (Antidorcas marsupialis). 3: Fatty acid composition as influenced by age, gender and production region

The effects of age, gender and production region on the fatty acid composition of springbok Musculus longissimus dorsi (LD) were investigated. The major fatty acid of the LD muscle was stearic acid (C18:0), which contributed 23.92–27.02%. Oleic acid (C18:1) represented the largest component (16.33–20.45%) of the mono-unsaturated fatty acids (MUFA). The major n − 6 polyunsaturated fatty acid (PUFA) was C18:2n − 6, which formed 18.77–21.62%, whereas C18:3n − 3 (3.33–4.00%) was the most abundant n − 3 PUFA. The n − 6:n − 3 ratio of the meat varied from 3.02 to 3.35, with an average ratio of 3.2. Polyunsaturated to saturated (P:S) ratios varied between 0.96 and 1.18 and averaged at 1.06. Total MUFA was found to be higher (P < 0.05) in males (20.99%) than females (16.67%). The cholesterol content of the meat varied from 54.45 to 59.34 mg/100 g muscle. Linear correlations between the fatty acid and the intramuscular fat (IMF) content indicated a significant increase in certain saturated and mono-unsaturated fatty acids with increasing IMF content of the meat.     

Comparison of the color stability and lipid oxidative stability of fresh and vacuum packaged lamb muscle containing elevated omega-3 and omega-6 fatty acid levels from dietary manipulation

A series of three experiments were conducted with second cross ([Merino×Border Leicester]×Poll Dorset) wether lambs to evaluate the effects of dietary treatments on manipulation of muscle long-chain (LC) omega-3 fatty acids (FA) on the color stability and oxidative stability of fresh and vacuum packaged lamb. At the end of 7-, 6- and 6-week experimental periods for experiments (Exp.) 1-3 respectively, lambs were slaughtered at a commercial abattoir. At 24 h post-mortem, muscle longissimus lumborum (LL) and longissimus thoracis (LT) were removed and evaluated for color and lipid oxidative stability under specified commercial storage and display condition. Of the dietary supplements used, fish meal and fish oil moderately (P<0.01) and markedly (P<0.001) increased muscle omega-3 FA content, while both protected canola seed (P<0.001) and protected sunflower meal protein significantly (P<0.02) increased muscle omega-6 FA content or ratio of omega-6/omega-3 of the longissimus muscle. In all experiments, the substantial increase (P<0.001) in muscle LC omega-3 and omega-6 FA had no consistent significant effect on color values (redness (a*), yellowness (b*) and lightness (L*)) for fresh and vacuum packaged lamb over a 6-day display period. Lipid oxidation, determined by the levels of thiobarbituric acid reactive substances (TBARS) indicated the enrichment of muscle polyunsaturated fatty acid (PUFA) levels in lambs did not produce significant differences resulting either from main treatment effects or for treatment×day×type interactions (where type was fresh and vacuum packaged). Present results demonstrated the color and lipid oxidative stability of lamb longissimus muscle during refrigerated display was not affected by enhanced levels of omega-3 and omega-6 FA due to dietary treatments.     

The eating quality of Canadian pork and its relationship with intramuscular fat

This study was undertaken to assess the effect of various levels of intramuscular fat (IMF: <1%, 1.0-1.49%, 1.5-1.99%, 2.0-2.49% and 2.5-3.0%) produced from Canadian pigs on the eating attributes of pork loin. Sensory and instrumental eating attributes were determined on 85 pork loins (m. longissimus lumborum and thoracis). The following correlations were found between IMF and eating attributes: softness, -0.32 (P<0.01); initial tenderness, -0.31 (P<0.01); chewiness, -0.27 (P<0.01); rate of breakdown, -0.20 (P=0.07); juiciness, 0.17 (P>0.05); flavour intensity, 0.24 (P=0.02); off-flavour, 0.13 (P>0.05); mouth coating, 0.13 (P>0.05); amount of perceptible connective tissue, -0.02 (P>0.05), and instrumental tenderness (Warner-Bratzler shear force), -0.41 (P<0.001). As tenderness is considered the most important attribute that determines overall acceptance of pork, the threshold level of IMF for ensuring a positive eating experience was identified as a function of the attributes describing tenderness. Increasing the level of IMF past 1.5% did not change (P<0.05) the panelists scores for softness and initial tenderness. Average shear force, an instrumental measure of tenderness, was higher (P<0.05) at less than 1% IMF but did not change past 1.0% IMF (P>0.05). It is proposed that the threshold level of IMF that will ensure a pleasing eating experience is 1.5% IMF.     

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.     

Composition of Bovine Muscle Lipids at Various Carcass Locations

SUMMARY— Bovine intramuscular lipids extracted from the semitendinosus, triceps brachii and longissimus dorsi muscles were fractionated into phospholipids and neutral fats by silicic acid column chromatography. In spite of the wide range in total fat content at each location, phospholipids were present in all three muscles at a level of approximately 500 mg per 100 g of muscle tissue. This result, coupled with the lower total fat content of the semitendinosus as compared to the other two muscles, indicated a significantly higher percentage of phospholipid material in the total fat from the semitendinosus as compared to the triceps brachii or longissimus dorsi.
The fatty acids were identified in both lipid fractions using retention time data obtained on both a polar and a non-polar column. The identity of the unsaturated fatty acids was confirmed when their peaks did not appear on the chromatographs obtained from brominated samples. There was significantly more C14:0 in the longissimus dorsi neutral fat fractions than in the semitendinosus neutral fat fractions. In the phospholipids, there was significantly more C16:0 and significantly less C18:0 in the longissimus dorsi as compared to either the semitendinosus or triceps brachii. Although the two lipid fractions of the longissimus dorsi contained slightly higher percentages of total saturated fatty acids than the corresponding fractions in the other two muscles, the effects were not significant.     

Subcutaneous and intramuscular lipid traits as tools for classifying Iberian pigs as a function of their feeding background

The present work was aimed to study the feasibility of classifying Iberian pigs fattened with two different diets, acorns and grass (AG) and oleic acid enriched concentrate (HO), by means of comparing the fatty acid profile and the content of different compounds of the unsaponifiable lipid fraction (neophytadiene and α- and γ-tocopherol) of subcutaneous (SCF) and intramuscular (IMF) fat of Biceps femoris and Semimembranosus muscles. The proportions of palmitic (C16:0), stearic (C18:0) and linoleic (C18:2 n-6) acids of the three studied tissues did not show a consistent behaviour as influenced by the feeding. The proportion of oleic acid (C18:1 n-9) was significantly affected by the diet in SCF and IMF of Semimembranosus muscle but not in IMF of B. femoris. Some minor fatty acids, such as arachidonic (C20:4 n-6) and linolenic (C18:3 n-3) acids, showed the best ability for the classification of the animals according to their feeding background and the obtained values showed significant differences caused by the diet in the three studied tissues. Neophytadiene and γ-tocopherol contents were statistically higher in AG than in HO pigs, while there were not differences in the α-tocopherol levels between experimental groups. Thus, it seems that procedures based on the quantification of arachidonic (C20:4 n-6) and linoleic (C18:3 n-3) acids as well as neophytadiene and γ-tocopherol levels would be useful to differentiate Iberian pigs fattened outdoors on acorns and grass from those fed MUFA enriched diets.     

Conjugated linoleic acid (CLA) and polyunsaturated fatty acids in muscle lipids of lambs from the Patagonian area of Argentina

The concentrations of fatty acids were measured in total lipids, triacyglycerol and phospholipid fractions of intramuscular fat (IMF) from the Longissimus dorsi (LD) muscle of 10 lambs reared to approximately 30kg live weight on natural pasture with their dams. Fatty acid composition was also measured in 25 (five of each) Semitendinosus (ST), Semimembranosus (SM), Rectus femoris (RF), Gluteus (GLU) and Tensor fascia latea (TFL) muscles. Intramuscular fat percentages were similar for all muscles. Aspects of the fatty-acid patterns of relevance to human nutrition tended to favor the leg muscles with lower saturated fatty acids (SFA %), n-6/n-3 fatty acid ratios (p<0.01) and higher concentrations of the conjugated linoleic acid (CLA) (p<0.05). The estimated fatty acid concentrations (mg/100g of meat) showed higher contribution of arachidonic (C20:4 n-6), eicosapentanoic (C20:5 n-3), docosapentanoic (C22:5 n-3) and docosahexanoic (C22:6 n-3) acids in leg compared to LD lipids.     

Intramuscular fatty acid profile of longissimus dorsi and semitendinosus muscle from Pateri goats fed under traditional feeding system of Sindh, Pakistan

The present study was undertaken to assess the intramuscular fatty acid composition of different muscles taken from male Pateri (n=15) goats, reared on naturally grown grasses, leaves and pods of Acacia nilotica and crushed cereal, under traditional way of feeding. Goats were slaughtered with an average weight of 68±7kg and age 12±1 month. The samples were taken from longissimus dorsi region (between the 12th and 13th rib) and distal region of semitendinosus muscle. Results of total fat content and fatty acids composition does not show significant (P>0.05) variation among muscles investigated. The fatty acid composition of muscles studied were primarily composed of oleic (31.50-33.38%), followed by palmitic acid (19.84-22.05%) and stearic acid (22.25-24.91%) respectively. Muscle tissue in general contained an average 51.13% of saturated fatty acids and 48.87% of unsaturated fatty acids. The mean conjugated linoleic acid was found 0.41%, 0.43% and 0.47% in ribeye and loin portion of longissimus dorsi muscle and distal region of semitendinosus muscle, respectively.     

Manipulation of the fatty acid composition of pig meat lipids by dietary means

Pigmeat products have been associated with an unhealthy image due to the relative proportions of polyunsaturated and saturated fatty acids. The aim of this experiment was to improve the fatty acid profile of the carcass fat by feeding various dietary sources of fat. Groups of 10 female Large While × Landrace pigs were fed one of four experimental diets. Five in each group were slaughtered at 70 kg live weight and the remaining five at 100 kg live weight. The diets were offered ad libitum and daily intake was recorded. The diets were based on barley, soya bean meal and fishmeal. Diet 1 contained 50 g tallow kg^?1, a relatively saturated fat, and diets 2, 3 and 4 contained 50 g soya oil kg^?1, an unsaturated fat. Diet 3 also contained 7.5 g GLA oil kg^?1, which is rich in gamma linolenic acid, with the aim of increasing the production of arachidonic acid in the body fat. Diet 4 was supplemented with 9.5 g EPAnoil kg^?1, which is rich in eicosapentaenoic acid and docosahexaenoic acid. There were no significant differences between dietary treatments in performance (daily liveweight gain or the efficiency of food conversion to liveweight gain) of the pigs slaughtered at 70 kg live weight, but small differences were observed at 100 kg live weight, where pigs on treatments 2, 3 and 4 performed slightly better than those on treatment 1. At both slaughter weights the lipid content of the m semitendinosus was higher than that of the m longissimus dorsi (approximately 24 and 13 g kg^?1, respectively). The pattern of fatty acids in the dietary fat was reflected to varying degrees in the carcass fat. Diet 1 resulted in the highest levels of palmitic, palmitoleic, stearic and oleic acids whereas diets 2, 3 and 4 gave high levels of linoleic and linolenic acids. The extra gamma linolenic acid in diet 3 did not result in a consistently significant increase in the production of arachidonic acid. The supplement of EPAnoil gave significant increases in the levels of eicosapentaenoic and docosahexaenoic acids in the body lipids. The polyunsaturated to saturated fatty acid ratio of the body lipid was increased with diets 2, 3 and 4 to about 1.0. In spite of high levels of linoleic acid, there were no adverse effects during the processing of the carcasses and the taste panel evaluation did not reveal any treatment differences.     

LIPIDS IN SUBCUTANEOUS TISSUES AND LONGISSIMUS MUSCLES OF FEEDLOT AND GRASS-FED EWES1

Subcutaneous and intramuscular lipids from feedlot-and grass-fed ewes were studied to determine if diet would influence fatty acid composition of these older animals. Subcutaneous lipid of ewes from the feedlot-fed group contained more 4-methyl branched acids, less iso and anteiso branched acids, less stearic acid and more octadecenoic acid than grass-fed ewes. Only small amounts of medium chain acids (10–15 carbons) were noted in longissimus muscle lipids from both dietary groups and essentially all of them were in the triglycerides. Lipids in longissimus muscle of feedlot ewes contained more monounsaturated and less polyunsaturated acids and this was due to higher levels of triglycerides in longissimus lipid of feedlot-fed ewes. Approximately three times as much high melting stearic acid was present in subcutaneous lipid of both dietary groups of ewes as has been noted in subcutaneous lipid of lambs. Reduction of high melting stearic acid in mutton fat by a short grain feeding period should make mutton more acceptable.