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.     

The influences of carcass weight and depot on the fatty acid composition of fats of suckling Manchego lambs

The effects of carcass weight (<5.5 kg, 5.5–6.5 kg, ⩾6.5 kg) of Manchego suckling lambs, type of fat depot of the leg (subcutaneous, intermuscular and intramuscular) and muscle (m. longissimus dorsi (LD) or m. quadriceps femoris (QF)) on the fatty acid composition were studied. Carcass fatness increased with increasing carcass weight. However, few differences in fatty acid proportion were observed between the three carcass weight groups. The lightest carcasses had lower proportions of myristic (C14:0) and palmitoleic (C16:1) acid and higher proportions of stearic (C18:0) acid, desirable fatty acids (DFA) (C18:0 + total unsaturated fatty acid (TUFA)) and a greater nutritive value ((C18:0 + C18:1)/C16:0). The fatty acid composition of subcutaneous and intermuscular fat depots of the leg were similar, whereas the intramuscular fat depot was different from both of these, since it had a lower proportion of saturated fatty acids (SFA), a greater proportion of TUFA, higher PUFA/SFA and n − 6/n − 3 ratios, and greater DFA and nutritive values. The intramuscular fat of the LD was more saturated than QF, higher SFA, and had lower value of PUFA/SFA ratio and DFA. These results indicated that the intramuscular fat quality of the leg was better than subcutaneous and intermuscular fat depots and also that intramuscular fat displayed better attributes of quality (lower SFA, higher TUFA, and greater PUFA/SFA ratio and DFA as well) than intramuscular fat of the LD from the consumer health standpoint. Despite carcass weight affected carcass fatness, it did not seem to influence the proportions of saturated or polyunsaturated fatty acids. For this reason, carcass weight probably had little effect on the organoleptic characteristics of the meat.     

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.     

Intramuscular lipid and fatty acid profile of sheep comprising four sex-types and seven slaughter weights produced following commercial procedure

The intramuscular lipid and fatty acid profiles of the m. longissimus dorsi from 84 sheep comprising four sex-types (enire ram, vasectomised ram, wether and ewe) and seven slaughter weights (32, 36, 40, 44, 48 and 52kg) were measured. Animals were reared following the commercial practice. Specifically, they were fed pasture and a concentrate diet, and age at slaughter ranged from 180 to 390 days. Differences between entire and vasectomised rams, and between wethers and ewes in intramuscular lipid content were not significant (P>0.05). However, entire and vasectomised rams were significantly lower (P<0.05) in intramuscular lipid content than ewes and wethers. Sex related differences in 14:0 (myristic acid), t18:1, c18:1, t18:2 and c18:2 proportions were not significant (P>0.05). Ewes and wethers were similar in 16:0 (palmitic acid) and 18:0 (stearic acid) proportions, but ewes contained significantly higher 16:0 and lower 18:0 proportions than entire and vasectomised rams (P<0.01). Entire and vasectomised rams recorded the highest c18:3 proportions, wethers were intermediate whilst ewes contained the lowest proportion (P<0.01). Although neither saturated fatty acid (SFA) nor monounsaturated fatty acid (MUFA) proportions varied with sex-type, vasectomised rams contained significantly higher polyunsaturated fatty acid (PUFA) proportion that the other sex-types (P<0.05). Whilst intramuscular lipid content, and 18:0 and c18:1 proportions were linearly correlated with slaughter weight (P<0.001), 14:0 and c18:3 proportions decreased quadratically with increasing slaughter weight (P<0.001). The vasectomised ram and the entire ram were similar in fatty acid profile, except the significantly higher PUFA proportion recorded by the vasectomised ram.     

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 an elevated monounsaturated fat diet on pork carcass and meat quality traits and tissue fatty acid composition from York-crossed barrows and gilts

Fifty-seven York-crossed barrows and gilts were fed either a grain and soy diet (CONTROL with 28% C18:1) or a similar diet enriched with oleic acid (HO with 43% C18:1, Greedy-Grass OLIVA®). There were no interactions between dietary treatment and gender and there were no differences in intramuscular and subcutaneous fatty acid composition between sexes (P > 0.05). Similar primal cut yields, composition of major primal cuts, and carcass and meat quality characteristics were found for HO and CONTROL fed pigs. Apart from a few significant but small differences for some fatty acids, intramuscular fatty acid composition was similar for both dietary treatments. Subcutaneous fat from HO fed pigs had a 6.9% increase in total monounsaturated fatty acids and a 9.3% reduction in total polyunsaturated fatty acids (P < 0.05) compared with CONTROL fed animals, without adversely affecting carcass quality and producing suitable hams for processing by the meat industry.     

Fatty acid composition of lambs of indigenous dairy Greek breeds of sheep as affected by post-weaning nutritional management and weight at slaughter

The objective was to assess the effect of breed, sex, post-weaning nutrition and weight at slaughter on the fatty acids (FA) composition in carcass fat of lambs of indigenous Greek dairy breeds of sheep, the Boutsko (B), Serres (S) and Karagouniko (K) breed. The lambs (weaned at approximately 42 days) had been reared under different conditions of housing and feeding in three consecutive experiments (Experiment). In Experiment 1, lambs (n=120) were individually penned and fed ad libitum on a concentrate feed (11.3MJ metabolisable energy (ME)/kg DM and 192g crude protein (CP)/kg DM) together with 100g/day of Lucerne hay (8.3MJ ME/kg DM and 182g CP/kg DM). In Experiment 2, lambs (n=108) were fed the same concentrate on 3 different levels: High (H), Medium (M) and Low (L) and ad libitum on Lucerne hay. In Experiment 3, lambs (n=108) were initially group fed indoors for 63 days on 3 different levels of concentrate (H, M and L) together with ad libitum Lucerne hay. Thereafter they were finished on irrigated, sown pasture. Lambs were slaughtered at one of 5 standard proportions of mature weight (PMW) for each breed in Experiment 1 (i.e. 0.20, 0.30, 0.45, 0.60 and 0.90); at 3 fixed live weights in Experiment 2 (TSLW; i.e. 23, 28 and 33kg) and at 3 fixed PMW in Experiment 3 (PMW; i.e. 0.20, 0.48 and 0.54). The right hand side of their carcasses was minced and a random sample, around 200g, was taken. It was freeze-dried and then grounded to obtain a quantity of 2g for lipid extraction and preparation of fatty acid methyl esters, which were assayed by gas-liquid chromatography to identify. Results were analysed separately for each experiment by analysis of variance. In Experiment 1, breed of lambs had significant effects (P<0.001) on C14:0, C16:0, C17:0, C18:2, C18:3 and C18:1 (P<0.05), whereas sex affected only the percentage of C15:0, C16:1 (P<0.001), C18:0 (P<0.01) and C18:2 (P<0.05). Live weight of lambs at slaughter had significant effects (P<0.05-0.001) on all the fatty acids. In Experiment 2, with the exception of C18:0 and C20:0, all other fatty acids were significantly affected by Breed (P<0.05-0.001). However, only C17:0, C18:0, C18:1 and C18:2 were significantly (P<0.001) affected by the level of concentrates in the diet. The major finding in Experiment 3 was the trend for saturated fatty acids to be lower; possibly due to the fact that lambs finished at pasture. It is concluded that there are possibilities of modifying FA composition in carcass fat of lambs by manipulation of post-weaning nutrition and slaughtering them at a wide range of live weights.     

Influence of growth promoting implants on fatty acid composition including conjugated linoleic acid isomers in beef fat

The influence of the growth promoting implants Synovex (SYN), Ralgro (RAL), and Revalor (REV) on the fatty acid profiles of subcutaneous fat, intramuscular fat, and phospholipids of 32 beef steers (eight steers per treatment, and eight controls) was studied. Fatty acid compositions and profiles of conjugated linoleic acid (CLA) isomers were determined by a combination of GC and triple-column Ag⁺-HPLC. Only small differences could be observed between the different treatment groups. The amount of saturated fatty acids relative to monounsaturated fatty acids was increased by all growth promoting implants in subcutaneous fat (P<0.1) and also by SYN in intramuscular fat. RAL led to slightly higher amounts of trans fatty acids in subcutaneous and intramuscular fat (P<0.1). REV-implanted steers showed some significant differences in their profiles of polyunsaturated fatty acids compared to control steers. CLA content and isomeric distribution in subcutaneous fat were affected bySYN, which reduced amounts of total CLA (0.42 mg/g fat vs. 0.53 mg/g in control steers, P<0.001) and decreased the proportions of the primary 18:2 c9t11 isomer (73% of total CLA for SYN vs. 77-78% for all other treatment groups). Slight increases of c9t11 CLA in intramuscular fat were observed in RAL- and REV-implanted steers (P<0.1). Most differences in fatty acid composition observed in this study were probably due to shifts in the storage lipid/membrane lipid ratio.     

Quality of pig adipose tissue: relationship between solid fat content and lipid composition

The dependence of solid fat content at 20°C of adipose tissues on their fatty acid and triacylglycerol compositions was studied on lipids extracted from tissues from 166 pigs. The solid fat content (SFC20) was 20% on average but varied widely (9-35%). The SFC20 variability was closely related to the proportions of disaturated triacylglycerols and more specifically to palmitoyl-stearoyl-oleoyl-glycerol (R(2)=0.92). The SFC20 variability was also related to the proportions of the saturated fatty acids, palmitic and stearic acids (R(2)=0.94). The part of the variance of SFC20 explained by the proportion of polyunsaturated fatty acids was lower (R(2)=0.48). The iodine value showed a high correlation with SFC20 (R(2)=0.81) but carcass lean content was a poor indicator of the solid fat content of adipose tissues (R(2)=0.06).     

Effect of pasture vs. concentrate feeding with or without antioxidants on carcass characteristics, fatty acid composition, and quality of Uruguayan beef

Thirty Hereford steers were finished either on pasture (n=10) or concentrate (n=20) to determine dietary and antioxidant treatment effects on carcass characteristics, fatty acid composition, and quality of Uruguayan beef. Half of the steers finished on concentrate were supplemented with 1000 I.U. vitamin E head(-1) day(-1) for 100 days. Postmortem vitamin C was added to ground beef (0.05% v/w) displayed for 8 days at 2?°C. Carcasses from steers finished on concentrate had greater (P<0.05) carcass weight, conformation, degree of finishing, fat depth, and ribeye area than pasture finished animals. Carcasses from pasture-fed steers showed darker (P<0.05) longissimus color and yellower (P<0.05) fat at 24 h postmortem than concentrate-fed. Initial longissimus Warner-Bratzler shear force (WBSF) values were similar (P>0.05) between pasture- and concentrate-fed animals. However, beef from pasture-fed cattle had lower (P<0.05) WBSF values at 7 and 14 days postmortem. Longissimus α-tocopherol concentrations were greater (P<0.01) for pasture- and concentrate-fed animals that were supplemented with vitamin E compared to concentrate-fed. Steaks from pasture-fed and vitamin E supplemented cattle had similar (P>0.05) TBARS values, which were lower (P<0.05) than steaks from concentrate-fed steers during 21 days of display. Ground beef from vitamin E supplemented steers had the lowest TBARS values; whereas samples from pasture-fed animals had the lowest lipid stability with higher TBARS levels than other treatments. Vitamin C addition to ground beef did not (P>0.05) reduce lipid oxidation. Vitamin E supplementation of concentrate-fed cattle had no effect (P>0.05) on color stability of ground beef or steaks. The a(?) (redness) and b(?) (yellowness) values were higher (P<0.05) when vitamin C was added to ground beef. Longissimus fatty acid content of concentrate-fed animals was twofold greater (P<0.01) than pasture-fed. The percentages of C14:0, C16:0, and C18:1 fatty acids were higher (P<0.01) in the intramuscular fat of concentrate-fed steers, whereas pasture-fed cattle showed greater (P<0.01) proportions of C18:0, C18:2, C18:3, C20:4, C20:5, and C22:5. Total conjugated linoleic acid (CLA) and CLA isomer c9t11 were higher (P<0.01) for pasture- than concentrate-fed cattle. Vitamin E supplementation of concentrate-fed steers increased lipid stability of ground beef and steaks, but was unable to improve color stability; whereas vitamin C addition to ground beef increased color stability without altering lipid oxidation. Finishing cattle on pasture enhanced the unsaturated fatty acid profile of intramuscular fat in beef including CLA and omega-3 fatty acids.     

Effect of anatomical location on the composition of fatty acids in double-muscled Belgian Blue cows

Double-muscled cows of the Belgian Blue breed, ranging from ca. 680 to 880 kg live weight were slaughtered and various fat depots sampled for lipid analysis. Subcutaneous fat (SCF), intermuscular fat in m. serratus (IMF1) and m. transversalis (IMF2), kidney fat (KF) and intramuscular fat in m. longissimus thoracis (IMF3) were sampled. In IMF3 samples, polar lipids were separated from other lipid classes by thin layer chromatography. Both the proportions (w w %) and gravimetric concentrations (mg g(-1) of sample) of long-chain fatty acids were determined in total lipids of SCF, IMF1, IMF2, KF and in lipid classes of IMF3 by gas chromatography. The greatest concentration of total fatty acids was found in KF (777.6 ± 82.6 mg g(-1)), followed by SCF (721.3 ± 92.2 mg g(-1)), IMF2 (709.8 ± 72.5 mg g(-1)) and IMF1 (682.1 ± 71.6 mg g(-1)). Triacylglycerol and polar lipid fatty acid content of m. longissimus thoracis (IMF3) were respectively 8.1 ± 3.3 and 3.1 ± 0.6 mg g(-1). Fatty acid content, particularly the triacylglycerol fatty acid content in IMF3, increased (p < 0.01) with increasing carcass fat content. Polar lipid fatty acids in IMF3 contained a higher proportion of polyunsaturated fatty acids (32.6 ± 4.8 %) and lower proportion of saturated fatty acids (27.4 ± 5.0%) compared to the triacylglycerol fatty acid fraction (p < 0.01), which may reflect a prerequisite for proper membrane functioning. Internal fat depots were more saturated (p < 0.01) compared to SCF. The proportion of monounsaturated fatty acids differed (p < 0.01) between IMF1 and IMF2, possibly reflecting differences in muscle activity and functioning. Oleic (C18:1) and stearic (C18:0) acids comprised more than 60% of the total fatty acids in all anatomical locations.     

Physico-chemical characteristics of carcass and meat Manchego-breed suckling lambs slaughtered at different weights

Forty-nine Manchego-breed lambs raised exclusively on their dams' milk until slaughter were used in this study. The effects of gender and slaughter weight (10, 12 and 14 kg) on carcass fatness, meat quality and the fatty acid composition of their fat were studied. Fatness, and in particular dorsal-fat thickness (P?0.01), increased with live weight. The effect of gender was even greater (P?0.001), as female lambs presented the highest fatness values for all parameters studied. The smallest drop in m. longissimus pH values was seen in the lowest-weight (10 kg) lambs. These same lambs displayed the highest L(?) value and thus the lightest colour. Fatty acid composition, which was not influenced by live weight, was affected by gender. The subcutaneous fat of female lambs contained more linolenic acid (C18:3) (P?0.01) and a greater proportion of polyunsaturated fatty acids than that of male lambs (P?0.001). Likewise, the intramuscular fat of female lambs displayed a greater proportion of monounsaturated fatty acids (P?0.001) than that of male lambs.     

Effects of low protein diets on pigs with a lean genotype 2. Compositional traits measured with computed tomography (CT)

The effects on compositional changes across the growing-finishing period (40–115 kg) of feeding pig diets with different protein and amino acid levels were investigated using CT scanning (at 60, 85 and 115 kg live weight). Pigs of a lean commercial genotype were fed a commercial control regime (C), or a low protein regime with either high (LP1) or low (LP2) essential amino acid levels, all balanced for net energy. In vivo CT measurements agreed well with post-slaughter sample joint dissection results for carcass tissue weights/proportions, and CT-measured muscle density predicted intramuscular fat accurately. Pigs on C and LP1 regimes did not differ significantly in composition during growth. However, pigs on the LP2 regime had significantly more fat (in carcass, internal and intra-muscular depots) and less muscle, from 85 kg onwards. Although fat levels differed depending on diet regime (LP2 > others), proportions of fat in different body depots were unaffected.     

Physico-chemical characteristics of carcass and meat Manchego-breed suckling lambs slaughtered at different weights

Forty-nine Manchego-breed lambs raised exclusively on their dams’ milk until slaughter were used in this study. The effects of gender and slaughter weight (10, 12 and 14 kg) on carcass fatness, meat quality and the fatty acid composition of their fat were studied. Fatness, and in particular dorsal-fat thickness (P0.01), increased with live weight. The effect of gender was even greater (P0.001), as female lambs presented the highest fatness values for all parameters studied. The smallest drop in m. longissimus pH values was seen in the lowest-weight (10 kg) lambs. These same lambs displayed the highest L* value and thus the lightest colour. Fatty acid composition, which was not influenced by live weight, was affected by gender. The subcutaneous fat of female lambs contained more linolenic acid (C18:3) (P0.01) and a greater proportion of polyunsaturated fatty acids than that of male lambs (P0.001). Likewise, the intramuscular fat of female lambs displayed a greater proportion of monounsaturated fatty acids (P0.001) than that of male lambs.     

Effects of supplemental dietary fatty acids on milk yield and fatty acid composition in high and medium yielding cows

The present study tested the hypothesis that supplemental dietary fatty acids (FA) affect the energy corrected milk yield in proportion to the milk production level of dairy cows, and increase both long chain FA proportion of milk FA and milk fat globule diameter. Sixteen Danish Holstein cows were divided into four 4x4 Latin squares with two squares of medium yielding cows (32.2 kg energy corrected milk (ECM)/d; 158 days in milk (DIM)) and two squares of high yielding cows (40.0 kg ECM/d; 74 DIM). Experimental length was 12 weeks, with three weeks for each of the four periods. The four treatments were no supplementation (17 g FA/kg dry matter (DM)) and three diets with supplemented FA (29, 40, and 52 g total FA/kg DM, respectively) obtained by substituting barley with Palm Fatty Acid Distillate (PFAD) fat. Diets were offered as total mixed rations with 63% grass/clover silage (DM basis). Dry matter intake decreased with increasing FA supplementation, but net energy intake was not affected. The general linear responses to 10 g/kg DM increase in FA level were 1.1 kg ECM (P<0.0001), 0.061 kg milk fat (P<0.0001), 0.012 kg milk protein (P=0.09) and 0.052 kg lactose (P=0.0002) per day, and linear responses in milk composition were 0.39 g fat (P=0.07), -0.71 g protein (P<0.0001) and 0.05 g lactose (P=0.3) per kg milk, and 0.092 microm (P<0.0001) in milk fat average globule diameter. Fatty acid supplementation decreased short- and medium-chain FA and C16:0 and increased C18:1 proportions of total FA in milk. Supplemental dietary FA increased ECM yield but not in proportion to production level as anticipated, and increased average FA chain length and milk fat globule diameter.     

Increasing dietary levels of docosahexaenoic acid-rich microalgae: Ruminal fermentation,animal performance,and milk fatty acid profile of mid-lactating dairy cows

This study aimed to evaluate the effects of increasing dietary levels of microalgae (ALG), rich in docosahexaenoic acid (DHA; All-G-Rich, Alltech, Nicholasville, KY), in isolipidic diets, on animal performance, nutrient digestibility, ruminal fermentation, milk fatty acid profile, energy balance, microbial protein synthesis, and blood serum metabolites in mid-lactating dairy cows. Twenty-four Holstein cows [130.3 ± 15.4 d in milk, and 30.8 ± 0.543 kg/d of milk yield (mean ± standard error)] were used in a 4 × 4 Latin square design experiment to evaluate the following treatments: control diet, without addition of ALG; and increasing levels of ALG [2, 4, and 6 g/kg of dry matter (DM)]. The ALG decreased DM intake and increased total-tract DM apparent digestibility. A tendency was observed for a quadratic effect on total-tract NDF digestibility by ALG inclusion, with peak value of the quadratic response at 4.13 g/kg of DM dose. Moreover, ALG increased ruminal pH and decreased acetate and total volatile fatty acid concentrations. Fat-corrected milk and energy-corrected milk were quadratically affected, and a tendency for a milk yield effect was observed when ALG levels increased, whereas maximal yields were observed with intermediate doses. Milk fat, protein, and lactose concentrations were diminished, whereas productive efficiency was improved by the increase of ALG levels. Saturated fatty acid proportions were decreased, whereas polyunsaturated fatty acid proportions were increased when ALG was fed. There was low DHA transfer into milk; however, ALG inclusion decreased C18:0, C18:1 cis-9, C18:2 cis-9,12, and C18:3 cis-9,12,15 proportions, and increased C18:2 cis-9,trans-11, C18:1 trans-9, and C18:1 trans-11 proportions. Gross energy intake was decreased, whereas no effect was observed on digestible, metabolizable, or net energy intake. The ALG inclusion quadratically affected the microbial protein synthesis, with maximal enhancement at 3.24 g/kg of DM dose, and also increased serum cholesterol concentration. Under the conditions of this experiment, the inclusion of ALG in diets for mid-lactating dairy cows decreased feed intake and increased nutrient digestibility, improving productive efficiency and modifying milk fatty acid profile. Estimated intermediate doses (1.22 to 2.90 g/kg of DM) of DHA-rich ALG may be beneficial to milk, fat-corrected milk, and energy-corrected milk yields, and is recommended for dairy cows.     

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.     

Fatty acids in the subcutaneous adipose tissue of intensively fed SA Mutton Merino and Dorper wethers

Recent ambiguity about the role of animal fat in causing coronary heart disease, coupled with the controversy regarding the effect of various levels of energy nutrition on ruminant depot fats, prompted an investigation into the influence of high-energy nutrition, breed and slaughter weight on the fatty acid profiles of ruminants. Two isonitrogenous and isomineral diets containing 11·76 MJ ME/kg DM and 10·18 MJ ME/kg DM were fed to Dorper and SA Mutton Merino wethers of ± 20 kg to 37 and 43 kg live weight. Subcutaneous fat samples and feed samples were collected for fatty acid analysis. Treatment significantly affected the subcutaneous fatty acid profiles of wethers, which includes C15:0, C16:0, C17:0, C17:1, C18:0, C18:1, C18:2 and C18:3. Treatment also influenced the concentration of saturated and unsaturated fatty acids in the subcutaneous adipose tissue as well as the concentration of trans-fatty acids. The results obtained suggest that dietary energy levels may significantly affect the fatty acids in the subcutaneous fat of wethers. Breed differences, after correcting for carcass fatness, occurred in C16:0.     

Influence of a severe reduction of the feeding level during the period immediately prior to free‐range fattening on performance and fat quality in Iberian pigs

BACKGROUND: Restricted feeding before fattening is a common procedure in the production of Iberian pigs, but little scientific information about its consequences on productive traits and characteristics of fat is available. This work studied the effect of a severe feeding restriction previous to the free‐range fattening on carcass and fat quality traits in Iberian pigs, considering two different feeding levels (high restriction: HR; versus maintenance level: M) before free‐range fattening. RESULTS: Animals from the M group showed longer and higher‐perimeter hams and tended (P < 0.10) to show higher slaughter and carcass weights, carcass inner length and loin and sirloin weights than HR ones. Animals from the HR group showed lower proportions of total saturated fatty acids (SFA) and higher total monounsaturated fatty acids in the backfat inner layer than those from the M group. Total polyunsaturated fatty acids in intramuscular neutral lipids were higher in HR pigs than in M ones, while stearic acid (C18:0) was lower. The average daily gain, fatty acid profile of the outer backfat layer and that of the hepatic polar and neutral lipids and the rheological features of backfat inner layer remained unaffected. CONCLUSION: A severe reduction of the feeding level previous to free‐range fattening does not produce compensatory growth, tends to diminish carcass quality and to slightly increase IMF content and improves the fatty acid profile of the inner backfat layer. Copyright © 2007 Society of Chemical Industry     

Conjugated linoleic acid concentration in M. Longissimus dorsi from heifers offered sunflower oil-based concentrates and conserved forages

Dietary inclusion of polyunsaturated fatty acid (PUFA)-rich plant oils is one approach to improving the fatty acid profile of ruminant meat and meat products from a human health perspective. Whole crop wheat silages represent a possible alternative forage to grass silage for beef production, however, they may adversely impact the fatty acid profile of ruminant muscle since grass silage is rich in C18:3n-3. The first objective of this experiment was to investigate the relationship between an increase in the dietary supply of C18:2n-6 from sunflower oil (SFO) and conjugated linoleic acid (CLA) concentration in the muscle tissue of beef cattle. The second objective was to investigate the effect of the basal forage type on the muscle fatty acid composition and its response to increasing inclusion of SFO. One hundred and five heifers were blocked according to initial bodyweight and assigned to one of seven silage treatments. The silage treatments were: (1) grass silage (GS), (2) whole crop wheat silage with 38% dry matter (DM) (W1), (3) GS and W1 at a ratio of 1:2 (DM basis) (W1GS) (4) GS and W1 at a ratio of 2:1 (DM basis) (GSW1), (5) whole crop wheat silage with 52% DM (W2), (6) GS and W2 at a ratio of 1:2 (DM basis) (W2GS), (7) GS and W2 at a ratio of 2:1 (DM basis) (GSW2). Within each silage treatment, 5 animals were assigned to one of three concentrate rations, differing in the content of SFO. The levels of inclusion of SFO in the concentrate were 0, 55, 110 g/kg concentrate. Inclusion of SFO in the diet led to an increase in the n-6:n-3 fatty acid ratio in muscle. In animals fed grass silage or mixed silages the n-6:n-3 ratio was lower in muscle compared with those fed whole crop wheat silages, with the exception of animals fed 55 g SFO/kg, for which feeding W1GS led to a higher ratio than W1. Other than the n-6:n-3 ratio there were no significant interactions between the effect of type of silage and the level of SFO on the concentration of fatty acids in intramuscular fat. Increasing the inclusion of SFO led to a linear increase in the CLAcis-9,trans-11 and PUFA concentration in intramuscular fat (P<0.001). This study confirmed the potential for modification, and improvement from a human health perspective, of the fatty acid composition of beef muscle by dietary manipulation.