Six-week antibiotic therapy after one-stage replacement arthroplasty for hip and knee periprosthetic joint infection.

OBJECTIVES: One-stage replacement arthroplasty for treatment of periprosthetic joint infection (PJI) results in similar cure rate than two-stage (around 85-92%), but antibiotic therapy duration is not well established. The aim of this study was to evaluate the efficacy of a short six-week antibiotic course in periprosthetic joint infections after onstage exchange. PATIENTS AND METHODS: Retrospective, observational study conducted at Orthopaedic Department of Cochin Hospital, Paris, between 1st January 2010 and 31 December 2015. Patients with a microbiologically proven PJI, treated with one-stage replacement and 6 weeks (+/1week) of antimicrobial therapy were included. Pearson's-χ2 and Wilcoxon tests were used to compare categorical and continuous variables. RESULTS: Fifty patients with periprosthetic joint infections (42 hip, 8 knee PJI) treated with one-stage replacement arthroplasty were included. Median age was 69.3 years (IQR 24.5-97.4). Infections occurred after a mean of 36 months (IQR 1-216). Bone biopsy cultures were positive for Staphylococcus spp. in 29 patients (58%), Cutibacterium acnes in 19 (38%), Gram-negative bacilli in 6 (12%). Polymicrobial infections occurred in 12 (24%). Intravenous antibiotics were administered for a median of 11 days (IQR 4-45) and 46 patients (92%) were switched to an oral therapy. Medium follow-up was of 32 months (IQR 12-101). Overall remission rate was 90%. CONCLUSIONS: A six-week course of antibiotics in knee and hip PJIs treated with one-stage RA has a satisfactory remission rate in this open study.

Effects of breed and a concentrate or grass silage diet on beef quality in cattle of 3 ages. I: Animal performance, carcass quality and muscle fatty acid composition.

An increase in the intake of the n-3 series polyunsaturated fatty acids (PUFA) is recommended by nutritionists for the human diet and beef is a significant source of these fatty acids. Enhancing the n-3 PUFA content of beef is important in view of the generally saturated nature of fatty acids in ruminant meats and the potentially negative effect this can have on human health. This study examined the effects of breed and diet on the fatty acid composition of beef M. longissimus. Ninety-six steers were used, 48 Aberdeen Angus cross (AA) and 48 Holstein-Friesian (HF). At 6months of age, 3 groups were identified, to be slaughtered at 14, 19 and 24months, respectively. Each group consisted of eight steers of each breed fed on a concentrate or a grass silage diet, rich in n-6 and n-3 PUFA, respectively. The intake of the concentrate diet was restricted so that steers of each breed grew at a similar rate on each diet. The early maturing AA produced heavier, fatter carcasses with better conformation. Animals fed grass silage had higher carcass fatness and conformation scores and higher levels of neutral lipid and total lipid in muscle than those fed concentrate. When all animals were pooled, a decline in PUFA% as total muscle lipid increased was evident. Feeding a grass silage diet rich in α-linolenic acid (18:3n-3) increased levels of this fatty acid in muscle neutral lipid by a factor of about 3.0 compared with the concentrate diet, as well as enhancing the synthesis of the n-3 series long-chain C20-22 PUFA in the phospholipid fraction, including docosahexaenoic acid (DHA, 22:6n-3). In contrast, both levels and proportions of linoleic acid (18:2n-6) and the n-6 series C20-22 PUFA were higher in animals fed the concentrate diet. The proportions of 18:1trans and conjugated linoleic acid (CLA) in muscle neutral lipid were higher in animals fed concentrate compared with silage in all 3 groups. This was partly due to increased consumption of 18:2n-6. The ratio of PUFA to saturated fatty acids (P:S) in muscle was reduced by feeding grass silage, partly as the result of increased fat deposition. However, the increase in levels of n-3 series fatty acids with silage-feeding resulted in beneficially low n-6:n-3 ratios in muscle in all age groups (approximately 1.2 compared with 12.0 in the concentrate diet). Subtle breed differences in PUFA amounts and proportions were noted. Holstein-Friesians had higher proportions of PUFA and higher P:S ratios compared with AA, partly due to a higher proportion of phospholipid in total lipid. In phospholipid itself, HF in the 19 and 24months groups had higher proportions of most n-3 PUFA. In all age groups the ratio of DHA to its precursor, 18:3n-3 was higher in HF.

Fat deposition, fatty acid composition and meat quality: A review.

This paper reviews the factors affecting the fatty acid composition of adipose tissue and muscle in pigs, sheep and cattle and shows that a major factor is the total amount of fat. The effects of fatty acid composition on meat quality are also reviewed. Pigs have high levels of polyunsaturated fatty acids (PUFA), including the long chain (C20-22) PUFA in adipose tissue and muscle. The full range of PUFA are also found in sheep adipose tissue and muscle whereas cattle 'conserve' long chain PUFA in muscle phospholipid. Linoleic acid (18:2n-6) is a major ingredient of feeds for all species. Its incorporation into adipose tissue and muscle in relation to the amount in the diet is greater than for other fatty acids. It is deposited in muscle phospholipid at a high level where it and its long chain products eg aracidonic acid (20:4n-6) compete well for insertion into phospholipid molecules. Its proportion in pig adipose tissue declines as fat deposition proceeds and is an index of fatness. The same inverse relationships are not seen in ruminant adipose tissue but in all species the proportion of 18:2n-6 declines in muscle as fat deposition increases. The main reason is that phospholipid, where 18:2n-6 is located, declines as a proportion of muscle lipid and the proportion of neutral lipid, with its higher content of saturated and monounsaturated fatty acids, increases. Oleic acid (18:1cis-9), formed from stearic acid (18:0) by the enzyme stearoyl Co-A desaturase, is a major component of neutral lipid and in ruminants the same enzyme forms conjugated linoleic acid (CLA), an important nutrient in human nutrition. Like 18:2n-6, α-linolenic acid (18:3n-3) is an essential fatty acid and is important to ruminants since it is the major fatty acid in grass. However it does not compete well for insertion into phospholipid compared with 18:2n-6 and its incorporation into adipose tissue and muscle is less efficient. Greater biohydrogenation of 18:3n-3 and a long rumen transit time for forage diets also limits the amount available for tissue uptake compared with 18:2n-6 from concentrate diets. A positive feature of grass feeding is that levels of the nutritionally important long chain n-3 PUFA are increased ie EPA (20:5n-3) and DHA (22:6n-3). Future research should focus on increasing n-3 PUFA proportions in lean carcasses and the use of biodiverse pastures and conservation processes which retain the benefits of fresh leafy grass offer opportunities to achieve this. The varying fatty acid compositions of adipose tissue and muscle have profound effects on meat quality. Fatty acid composition determines the firmness/oiliness of adipose tissue and the oxidative stability of muscle, which in turn affects flavour and muscle colour. Vitamin E is an essential nutrient, which stabilises PUFA and has a central role in meat quality, particularly in ruminants.

Regional variation in the hedonic evaluation of lamb meat from diverse production systems by consumers in six European countries.

This paper describes the responses of consumers in six European countries (Greece, Italy, Spain, France, Iceland and United Kingdom) tasting meat from twelve different local types of lambs produced in those same six countries. Animals represented 10 breeds and crossbreeds, three sexes, several diets composed of either milk, concentrates and various forages as main ingredients and different slaughter ages, from 1 and 12 months, and carcass weights, from 5.5 to 30.4kg. Tests were conducted by 36 volunteer families in each of the six countries involved in the study. Families were asked to roast the joints using their own cooking criteria, evaluating (from "dislike extremely" to "like extremely") flavour, tenderness, juiciness and overall liking. Also the cook was asked to rate the odour during cooking. Country and lamb type and their interaction were statistically significant for all the variables analysed. Results suggest a link between the assessments of a given lamb type and the consumers' culinary background, showing clear associations between country and lamb type preferences. It was possible to separate, independently of the country, different groups of families with similar preferences. Five family groups, which included 88 families (40.74%), had a clear Mediterranean origin and preferred types of lamb fed either milk or mainly concentrate diets. Seven family groups, which included 93 families (43.06%) with a clear northern origin, preferred types reared on grass or with grass included in the diet. The rest of the groups (four) that included 35 families (16.20%) had no clear composition (northern or Mediterranean), and they had a wider taste preference. It can clearly be seen that there are two categories of consumers of lamb in the analysed European market: those who prefer "milk or concentrate taste" and those who prefer "grass taste".

Flavour perception of oxidation in beef.

Lipid oxidation is a major factor in meat quality. In order to relate human perceptions of lipid oxidation, as determined by a trained taste panel, to a chemical measurement of oxidation, we studied meat from animals with a wide range of potential oxidation through differences in their PUFA composition and by displaying the meat in high oxygen modified atmosphere packs for varying lengths of time. Meat was obtained from 73 Angus- and Charolais-cross steers from different trials that had been raised on 10 different diets: grass silage (high in C18:3, n-3), cereal concentrate (high in C18:2, n-6), three diets with 3% added fat consisting of three levels of protected lipid supplement (high in C18:2, n-6 and C18:3, n-3, ratio 1:1), a control with Megalac(®) (relatively saturated), three diets with three levels of inclusion of protected fish oil (high in C20:5 n-3 and C22:6 n-3) plus a constant amount of unprotected fish oil and a final diet with an unprotected fish oil control. The longissimus dorsi muscle was excised from the left carcass side, aged vacuum packaged for 10-13 days depending on the projects and frozen for less than eight months. TBARS and sensory analyses were performed on steaks displayed for 0, 4 or 9 days under simulated retail conditions, exposed to light in modified atmosphere packaging (CO(2):O(2); 25:75). Meat oxidation increased throughout display for each of the diets, as shown by a rise in TBARS values. This increase was not linear, differences between 0 and 4 days of display were smaller than between 4 and 9 days of display. The lowest TBARS and lowest increment occurred in the two control diets and the grass-fed animals, probably due to the more saturated fat of meat from animals fed the control diets and the higher content of vitamin E. Sensory attributes were also influenced by time of display. Positive attributes, such as beef flavour or overall liking, decreased throughout display, whereas negative attributes, such as abnormal and rancid flavours, increased. The correlations between sensory and analytical attributes were high. TBARS were a good predictor of the perception of rancidity (Spearman's rho=0.84). Panellist preferences were related to the presence of beef flavour (rho=0.93) and to the absence of abnormal (rho=-0.88) and rancid flavours (rho=-0.83). Under the experimental conditions used, a TBARS value of around 2 could be considered the limiting threshold for the acceptability of oxidised beef.

Effect of the polyunsaturated fatty acid composition of beef muscle on the profile of aroma volatiles.

The effect of n-3 polyunsaturated fatty acids (PUFAs) in beef muscle on the composition of the aroma volatiles produced during cooking was measured. The meat was obtained from groups of steers fed different supplementary fats: (i) a palm-oil-based control; (ii) bruised whole linseed, which increased muscle levels of alpha-linolenic (C18:3 n-3) and eicosapentaenoic acid (EPA, C20:5 n-3); (iii) fish oil, which increased EPA and docosahexaenoic acid (C22:6 n-3); (iv) equal quantities of linseed and fish oil. Higher levels of lipid oxidation products were found in the aroma extracts of all of the steaks with increased PUFA content, after cooking. In particular, n-alkanals, 2-alkenals, 1-alkanols, and alkylfurans were increased up to 4-fold. Most of these compounds were derived from the autoxidation of the more abundant mono- and di-unsaturated fatty acids during cooking, and such autoxidation appeared to be promoted by increased levels of PUFAs.

Fatty acid composition of triglycerides from adipose tissue transplanted between obese and lean mice.

The subcutaneous adipose tissue of genetically obese mice (ob/ob) differs from that of lean littermates not only by virtue of its larger cells but also in its fatty acid composition; it contains a higher proportion of palmitoleic acid and a lower proportion of linoleic acid. To determine whether these differences in fatty acid composition were inherent in fat cells, subcutaneous adipose tissue from obese and lean mice was transplanted under the kidney capsules of lean and obese host mice and the fatty acid composition of the neutral lipids of the graft and of the host perirenal and subcutaneous fat was determined 1 or 2 months later. The fatty acid composition of grafts from lean donors in obese mice resembled that of the perirenal adipose tissue of the obese hosts after 1 month, with a lower proportion of linoleic acid and a higher proportion of palmitoleic acid than in lean mice. Grafts from obese mice in lean mice had fatty acid compositions which were either unchanged, partially changed or which completely resembled that of the host. The use of grafts prelabeled by feeding the donor margaric acid indicated that total lack of fatty acid turnover, rather than selective metabolic processes, was responsible for the failure of some grafts from obese mice in lean mice to acquire the fatty acid composition of the perirenal adipose tissue of the host.

Brown adipose tissue triacylglycerol fatty acids of obese and lean mice: in situ and in transplants.

The triacylglycerols of white adipose tissue (WAT) from animals with high rates of lipogenesis, such as obese hyperglycemic mice or hypothalamically lesioned rats, contain high proportions of palmitoleic acid (16:1) and low proportions of linoleic acid (18:2). These differences appear to result from dilution of dietary 18:2 by synthesized fatty acids, particularly 16:1. To test this we have investigated the triacylglycerol fatty acid composition of brown and white adipose tissue of lean and obese mice, as brown adipose tissue (BAT) has a higher lipogenic rate than WAT and lipogenesis is faster in obese than in lean mice. Between three and eight weeks of age the proportions of fatty acids in the tissues changed, with a marked fall in milk-derived lauric and myristic acids. From 8 to 16 weeks they were more stable and the proportions of 16:1 and 18:2 in the different tissues were as expected, with the highest and lowest proportions, respectively, in BAT from obese mice. When BAT from obese mice was transplanted under the kidney capsule of lean mice, or vice versa, for one month, the fatty acid composition of the grafts changed toward that of the host BAT. The proportions of 18:2 and, to a lesser extent, 16:1 were slightly higher in the grafts than in the hosts but since this also occurred in lean-to-lean and obese-to-obese grafts it was probably a transplantation artifact. Overall, the results confirm that the physiological environment, rather than the source of the adipose tissue, is the major determinant of its fatty acid composition.

De novo design and structure-activity relationships of peptide emulsifiers and foaming agents.

A series of eight amphipathic peptides (8, 11, 15, 2 x 18, 22, 26, 29 amino acids in length) were designed to investigate the effects of amino acid composition, peptide length and secondary structure on surface activity assessed as emulsification and foaming activity. The potential for alpha-helix formation at the hydrophobic/hydrophilic interface was maximized through the use of helix-forming amino acids, a relatively large hydrophobic surface of 200 degrees of arc and ion pairs between basic and acidic amino acids on the hydrophilic surface. Emulsification activity increased rapidly between 11 and 22 residues as alpha-helicity in aqueous solution increased. Despite their small size, the peptides produced exceptionally stable emulsions, compared with proteins. Foaming activity was enhanced by the presence of aromatic amino acids and the activity of the best peptide examined was superior to that of bovine serum albumin and beta-lactoglobulin.

Effect of a high-linolenic acid diet on lipogenic enzyme activities, fatty acid composition, and meat quality in the growing pig.

Forty-eight Duroc-cross gilts (40 kg initial BW) were fed a control or a linseed diet containing 60 g of whole crushed linseed/kg. Both diets were supplemented with 150 mg of vitamin E/kg. Eight pigs from each dietary treatment were slaughtered at 20, 60, or 100 d after the start of the experiment. There was no effect (P > 0.05) of diet on growth, carcass characteristics, or foreloin tissue composition. Feeding the linseed diet increased (P < 0.05) the content of n-3 PUFA in plasma, muscle, and adipose tissue, but docosahexaenoic acid was not (P > 0.05) altered by diet. The proportions of n-3 PUFA were highest (P < 0.01) in pigs fed the linseed-diet for 60 d, regardless of tissue (plasma, muscle, or adipose tissue) or lipid (neutral lipids and phospholipids) class. The linseed diet produced a PUFA:saturated fatty acid ratio > or = 0.4 in all groups and tissues, which is close to the recommended value for the entire diet of humans, as well as a robust decrease in the n-6:n-3 ratio. The decrease (P < 0.01) in the percentage of oleic acid in adipose tissue of pigs fed the linseed diet for 60 d could be attributed to a 40% decrease (P < 0.001) in stearoyl-CoA-desaturase activity. Diet did not (P > 0.05) affect the activities of acetyl-CoA-carboxylase, malic enzyme, or glucose-6-phosphate-dehydrogenase in any tissues. Muscle vitamin E content was decreased (P < 0.001) 30% in pigs fed crushed linseed for 60 d, whereas lower (P < 0.001) concentrations of skatole in pork fat were observed in linseed-fed pigs at all slaughter times. Inclusion of linseed (flaxseed) in swine diets is a valid method of improving the nutritional value of pork without deleteriously affecting organoleptic characteristics, oxidation, or color stability.

Manipulation of the n-3 polyunsaturated fatty acid content of muscle and adipose tissue in lambs.

Fifty Suffolk-crossbred wether lambs, with an initial live weight of 29 +/- 2.1 kg, were allocated to one of five concentrate-based diets formulated to have a similar fatty acid content (60 g/kg DM), but containing either linseed oil (high in 18:3n-3); fish oil (high in 20:5n-3 and 22:6n-3); protected linseed and soybean (PLS; high in 18:2n-6 and 18:3n-3); fish oil and marine algae (fish/algae; high in 20:5n-3 and 22:6n-3); or PLS and algae (PLS/algae; high in 18:3n-3 and 22:6n-3). Lambs were slaughtered when they reached 40 kg. Growth performance and intake were similar (P > 0.35) among treatments. By contrast, gain:feed was higher (P < 0.05) in lambs fed the fish oil compared with the linseed oil or PLS/algae diets. Total fatty acid concentration (mg/100 g) in the neutral lipid of the longissimus muscle was not affected by treatment (P > 0.87) but was least (P < 0.05) in the phospholipid fraction in lambs fed the linseed oil diet. Lambs fed either diet containing marine algae contained the highest (P < 0.05) percentage of 22:6n-3 in the phospholipid (mean of 5.2%), 2.8-fold higher than in sheep fed the fish oil diet. In lambs fed the fish/algae diet, the percentage of 20:5n-3 was highest (P < 0.05), contributing some 8.7, 0.8, and 0.5% of the total fatty acids in the muscle phospholipid, neutral lipids, and adipose tissue, respectively. The percentage of 18:3n-3 in the phospholipid fraction of the LM was highest (P < 0.05) in lambs fed the linseed oil diet (6.9%), a value double that of sheep fed the PLS diet. By contrast, lambs fed the PLS diet had twice the percentage of 18:3n-3 in the muscle neutral lipids (3.8%) than those offered the linseed oil diet, and 5.5-fold greater than lambs fed the fish/algae treatment (P < 0.05), an effect that was similar in the adipose tissue. The percentage of 18:2n-6 was highest (P < 0.05) in lambs fed the PLS diet, where it contributed 33.7, 10.1, and 11.2% in the muscle phospholipid, neutral lipids, and adipose tissue, respectively. The highest (P < 0.05) muscle PUFA-to-saturated fatty acid (P:S) ratio was obtained in lambs fed the PLS diet (0.57), followed by the PLS/algae diet (0.46), and those fed the fish oil or linseed oil diets had the lowest ratios (0.19 and 0.26, respectively). The favorable P:S ratio of lambs fed the PLS/algae diet, in conjunction with the increased levels of 20:5n-3 and 22:6n-3, enhanced the nutritional qualities of lamb to more closely resemble what is recommended for the human diet.

Fatty acid composition of lipid in Longissimus dorsi muscle of Duroc and British Landrace pigs and its relationship with eating quality.

The fatty acid composition of intramuscular fat from Duroc and halothane negative British Landrace pigs was determined and the relationships between fatty acid concentrations and aspects of eating quality were estimated from data on 160 pigs. Boars and gilts from each breed were performance tested on ad libitum or restricted feeding regimes with an average slaughter weight of 80 kg. Eating quality was assessed by ten experienced taste panelists. Intramuscular fat of Duroc pigs had higher concentrations of saturated and mono-unsaturated fatty acids and lower concentrations of poly-unsaturated fatty acids than Landrace pigs. With increasing intramuscular fat content, concentrations of saturated and mono-unsaturated fatty acids increased and concentrations of poly-unsaturated fatty acids decreased and the rate of change in fatty acid concentrations was greater in Landrace pigs than in Duroc pigs. Eating quality traits were generally improved as the concentration of mono-unsaturated fatty acids increased and poly-unsaturated fatty acids decreased.

The effects of diet and breed on the volatile compounds of cooked lamb.

The effect of varying the n-3 polyunsaturated fatty acid (PUFA) composition of lamb muscle on the formation of aroma volatiles during cooking has been examined. The meat was obtained from four groups of Suffolk and Soay lambs fed different supplementary fats: a palm-oil based control; bruised whole linseed, which increased muscle levels of α-linolenic acid (C18:3 n-3); fish oil, which increased eicosapentaenoic acid (EPA, C20:5 n-3) and docosahexaenoic acid (DHA, C22:6 n-3); and equal quantities of linseed and fish oil (fat basis). Higher quantities of lipid oxidation products were found in the aroma volatiles of lamb muscle from animals fed fish oil, compared to the control. In particular, unsaturated aldehydes, unsaturated hydrocarbons and alkylfurans increased up to fourfold. These compounds derived from the autoxidation of PUFAs during cooking. Although some of these volatiles were increased in meat from animals fed the linseed supplement, the effect was not as great as with the fish oil fed lambs. Levels of volatiles derived from the Maillard reaction, such as pyrazines and sulfur compounds, were up to four times higher in Soays than Suffolks.

The polyunsaturated fatty acid composition of beef and lamb liver.

The effect on liver fatty acids of two typical beef production systems, steers fed grass (grazing) and bulls fed concentrates, was investigated. Liver fatty acids were also studied in lambs grazing grass. Total fatty acid content of liver in the beef animals was not affected by production system, being 3.5% for grass and 3.7% for concentrates although carcasses of the latter animals were leaner. The percentages of the major non polyunsaturated fatty acids (PUFA) were also similar: (concentrates in parentheses) 18:0, 25.2% (25.1%); 16:0, 13.3% (14.5%); 18:1 12.6% (14.0%). Total liver PUFA contents were similar for the two production systems and much higher than in muscle from the same animals. All n-3 PUFA were present in greater amounts in liver from grass fed animals and n-6 PUFA were higher in concentrate fed animals: mg/100g liver, 18:3n-3 92 (32); 20:5 n-3, 151 (17); 22:5 n-3, 283 (108); 22:6 n-3, 83 (32); 18:2 n-6, 172 (444); 20:4 n-6, 194 (270). The P:S ratios were 0.20 (grass) and 0.32 (concentrates) and the n-6:n-3 ratios were 0.71 and 4.8, respectively. Livers from grass-fed lamb had a higher fat content, 4.9%, than the beef livers and a lower percentage of 18:0, (21%); but more 16:0, (16%) and 18:1 (21 %). Total PUFA content of lamb's liver resembled that of beef liver and the composition was similar to that of the steers fed grass. However the concentrations of 18:3 n-3 and 22:6 n-3 were higher in lamb and contributed to a lower n-6: n-3 ratio of 0.46 although the P:S ratio of 0.18 was similar to that in beef liver. Ruminant liver is potentially a good source of C20 and C22 PUFA in the human diet particularly from grass fed animals, with a highly desirable n-6:n-3 ratio and this may be more important nutritionally than the low P:S ratio since people can offset this elsewhere in the diet.

Fatty acid content and composition of UK beef and lamb muscle in relation to production system and implications for human nutrition.

Although ruminant meats normally have a low ratio of polyunsaturated fatty acids (PUFA) to saturated fatty acids (P:S ratio), the muscle contains a range of C(20) and C(22) PUFA of both the n-6 and n-3 series of potential significance in human nutrition. However, information on the amounts of these fatty acids in muscle and how they are modified by production system is limited In this study, the content and composition of fatty acids was determined in several muscles from beef steers fed grass (grazed) and bulls fed cereal concentrates. These are the two main types of beef production in the UK and Europe. Muscle fatty acids were also determined in lambs fed grass (grazed on pasture). The total fatty acid content of all muscles studied was less than 35 g kg(-1). The percentages in total fatty acids of all n-3 PUFA were higher in muscles from steers fed grass than from bulls fed concentrates whereas all n-6 PUFA were higher in the latter. The gluteobiceps muscle contained the largest amounts of fatty acids including PUFA and the m. longissimus dorsi the least amounts of PUFA in beef and lamb, and m. longissimus contained the lowest percentages of PUFA. Arachidonic acid was the major fatty acid in the C(20) + C(22) PUFA in beef from both production systems with twice as much in muscles from bulls fed concentrates. The P:S ratios were higher in the latter animals, range 0.21-0.34 compared with 0.08-0.13 in the steers fed grass. However, the n6:n-3 ratio was much less desirable in the bulls, 15.6-20.1 compared with 2.0-2.3 in the steers fed grass. These effects of production system in ruminants are larger than previously reported. Lamb muscle P:S ratios resembled those in grass-fed beef but the n-6:n-3 ratios were lower. The percentage of trans unsaturated 18:1 fatty acids was similar in both cattle production systems but lamb muscles contained twice as much as beef. Although the concentrations of the C(20) and C(22) PUFA are much lower than in fish, maintaining high n-3 levels in ruminant meats through grass feeding may be advantageous in human nutrition since meat is more widely consumed.

Fatty acid content and composition of english beef, lamb and pork at retail.

We have determined the fatty acid content and composition of retail samples of meat and assessed them with respect to UK dietary recommendations. Fifty beef sirloin steaks, pork chops and lamb chops were purchased from four supermarkets on separate occasions. The percentage of muscle (boneless basis) in the samples was 84.4 ± 4.3, 69.8 ± 7.7 and 78.9 ± 7.1 for beef, lamb and pork, respectively, with fatty acid contents of 3.84 ± 1.3, 4.73 ± 1.66 and 2.26 ± 0.7 g per 100 g muscle, respectively. Adipose tissue fatty acid contents were 70.0 ± 8.2, 70.6 ± 8.6 and 65.3 ± 9.4 g per 100 g tissue. A range of C20 and C22 polyunsaturated fatty acids (PUFA) was present in the muscle of all three species and pork adipose tissue but their concentrations in lamb and beef adipose tissue were too low to measure. The mean P:S ratios for beef, lamb and pork muscle were (adipose tissue values in parentheses): 0.11 (0.05); 0.15 (0.09) and 0.58 (0.61), and the n-6:n-3 ratios were 2.1 (2.3), 1.3 (1.4) and 7.2 (7.6). We conclude that the muscles of red meat species are a valuable source of PUFA, particularly the C20 and C22 n-3 fatty acids, in the human diet and that, considered as part of a varied diet, the low P:S ratio of the ruminant muscle, the high n-6:n-3 ratio of pork and the total fatty acid contents do not detract significantly from the nutritional value of lean meat.

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.

Comparison of Duroc and British landrace pigs for meat a and eating quality.

Duroc and halothane negative British Landrace boars and gilts were performance tested from 30 to 80kg on ad-libitum or restricted feeding regimes, with like-sexed non-littermate groups of pigs penned together. Meat and eating quality was determined using objective laboratory measurements and by taste panel and consumer panel assessment on 160 pigs with 20 full-sib families for each breed, and two boars and two gilts per family. Duroc M. longissimus(†) was darker in colour, had a more intense, redder colour and contained more fat and less moisture than Landrace muscle. Duroc subcutaneous fat was less firm, had a higher water content and concentrations of linoleic acid and lower concentrations of stearic acid than Landrace fat. The taste and consumer panels scored Duroc meat as being more juicy, but less tender, having poorer flavour and being less acceptable than Landrace meat. The higher juiciness scores of Duroc meat were probably attributable to the higher intramuscular fat content compared to Landrace meat. Duroc boars had lower values for flavour liking and acceptability compared to other breed-sex combinations which may be due to the particular fatty acid composition of the subcutaneous fat in Duroc boars.

Modelling the effect of fatty acids in odour development of cooked meat in vitro: part I-sensory perception.

We have investigated the contribution of muscle components to the development of cooked meat odour in an aqueous model system using trained taste panels. Reaction mixtures were prepared with oleic, linoleic and linolenic acids with or without cysteine and ribose in a buffer with or without ferrous sulphate. Odour profiles were assessed and triangular tests were used to determine the ability of panellists to discriminate between mixtures. The presence of sugar and amino acid was highly detectable by panellists independently of the fatty acid considered (P<0.001). However, the presence of C18:3 made differences more obvious between mixtures than the presence of C18:1 or C18:2. 'Meaty' notes were only associated with cysteine and ribose. 'Fishy' notes were only apparent in C18:3 mixtures with or without sugar and amino acid, although the presence of cysteine and ribose decreased the perception. The addition of Fe(++), a pro-oxidant present in the muscle, produced a reduction in the score of the attributes although the pattern was the same as when Fe was not used in the mixtures. Only 'fishy' notes that were exclusively perceived in C18:3 mixtures showed a higher score in the presence of iron. Iron also produced a better discrimination in C18:3 mixtures, which were closely related to 'grassy' notes in the presence of cysteine and ribose.

Fatty acid composition of backfat in large white pigs selected for low backfat thickness.

Samples of midback fat were taken from 157 Large White boars and analysed for fatty acid composition and melting point of lipid. Seventy-seven boars were from a line showing fast efficient growth and low backfat depth (selection line) and 80 from a random-mated control line. All were performance-tested from 27 to 87 kg liveweight on ad libitum feeding. Selection line pigs required 6 % less feed per kilogramme liveweight gain and had thinner backfat at each point of measurement (16-27 %) than the controls but there was no line difference in daily liveweight gain. Selection line pigs had 'eye muscles' which were slightly paler and had a greater drip loss than the controls. The fatty acid composition and melting point of the lipid extracted from backfat was similar between the lines except that the concentration of linoleic acid (C18:2) in both inner and outer layers was some 14% higher in the selection line. There were significant negative correlations between the concentration of C18:2 and the various backfat measurements. Positive correlations were found between some backfat measurements and the concentration of stearic acid (C18:0), particularly in the selection line. Variation in melting point in both layers was more strongly related to variation in the concentration of C18:0 than to that of any other fatty acid.