Effect of dietary chicory on boar taint.

Following preliminary screening and feeding trials on farms supplying a commercial abattoir, 360 entire male pigs were used to evaluate the effects of different percentages of chicory (Cichorium intybus L.) on levels of boar taint compounds and sensory aspects in backfat. Pigs were fed 0, 3, 6 or 9% chicory in the diet, 30 pigs being sampled at 3 different times: initially to measure basal levels of skatole and androstenone and after 1 and 2 weeks on the test diets. Cooked samples of backfat were presented to a trained sensory panel for "sniff" tests. Chicory fed at 9% for 2 weeks reduced skatole levels significantly (P<0.001), with 0.55 of pigs below 0.05 µg/g, typical of levels in castrated males. Abnormal odour scores were significantly lower for pigs in this group compared with 0% pigs (P<0.001), however, androstenone concentration was significantly higher in this group after the 2 week feeding period (P<0.005). Thus, feeding 9% chicory for 2 weeks was effective in reducing backfat skatole concentrations and abnormal odour scores of cooked fat but not androstenone concentration.

Comparison of heating methods and the use of different tissues for sensory assessment of abnormal odours (boar taint) in pig meat.

Five heating methods (microwave, hotwire, boiling at 25 °C and 75 °C and melting) were used to generate cooking odours from backfat of entire male pigs and a 'composite' sample consisting of fat and muscle from the head along with salivary glands. The methods elicited significantly different scores for odours from 4 groups of 10 samples differing in their concentrations and ratios of skatole and androstenone. The odours (pork odour, abnormal odour, skatole odour and androstenone odour) were assessed by 3 experienced assessors. Correlations between skatole and androstenone concentrations and abnormal odour score in backfat were higher for skatole, suggesting it is the more important boar taint compound. In the composite sample, androstenone concentration was much higher than in backfat and androstenone was a more important contributor to boar taint. The microwave, hotwire and boiling (75 °C) methods produced the clearest separation between samples and the microwave method was considered the most suitable for on-line use.

Meat odour and flavour and indoles concentration in ruminal fluid and adipose tissue of lambs fed green herbage or concentrates with or without tannins.

A 2 × 2 factorial experiment was carried out to evaluate the effect of herbage or concentrate feeding system and tannin addition to diet on skatole and indole in ruminal fluid and adipose tissue and meat sensory properties. Twenty-eight male lambs aged 45 days were randomly assigned to one of two feeding systems (vetch green herbage or concentrates, n = 14) and within feeding system to one supplement (quebracho tannins added to the diet or none). Animals were kept in singular pens and slaughtered at the age of 105 days. Indole (P < 0.05) and skatole (P < 0.01) concentrations in ruminal fluid were higher in lambs fed herbage compared to those given concentrates. Skatole in ruminal fluid tended to be present at lower concentrations in animals that received the tannin supplementation (P = 0.07). Indole was also higher in the caudal fat of animals fed green vetch compared to those fed concentrate (P = 0.04). Skatole concentration was lower in the fat of lambs fed concentrates compared to those given herbage (P = 0.05) and was lower in the fat of animals supplemented with tannins compared to the animals not supplemented (P = 0.01). Sheep meat odour was lower in meat from animals supplemented with tannins compared to those not supplemented (P < 0.01). It is concluded that tannins are more effective in reducing skatole formation in ruminants when they are associated with concentrate diets than green herbages.

A comparison of organic and conventionally-produced lamb purchased from three major UK supermarkets: Price, eating quality and fatty acid composition.

Organic and conventional lamb loin chops, labelled as British lamb, were bought from three major UK supermarket chains (designated A, B and C) in the Bristol area on 10 occasions over a six week period. Samples (n=360) were from unknown production systems but representative of what is available to UK consumers. The nutritional quality of muscle was assessed in terms of its fatty acid composition and eating quality was assessed by a trained sensory panel. Lamb prices varied between £9 and £12.50 per kg, with a relatively modest price differential between organic and conventional lamb chops of £1.10, £1.88 and £1.16 £/kg for supermarkets A, B and C, respectively. On average, organic chops were 20g heavier than conventional chops. Chops were relatively lean, having just 14% of subcutaneous fat, approximately half that of a similar survey 10 years ago. Organic lamb had a better eating quality than conventional lamb in terms of juiciness (p<0.05), flavour (p<0.05) and overall liking (p<0.05) thus providing some evidence for the perception among consumers that organic products 'taste better'. Differences in juiciness were attributed to the higher intramuscular fat content of organic meat whilst differences in flavour were attributed to differences in fatty acid composition, in particular, the higher level of linolenic acid (18:3) and total n-3 PUFA in organic chops. Conventional chops had a higher percentage of linoleic acid (18:2). Chops from both productions systems had a favourable n-6:n-3 ratio. The most important difference between the three supermarkets was that lamb flavour was significantly lower in chops from supermarket A, probably due to differences in their 'display until' dates. Chops from supermarket A were also the cheapest.

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.

Relationship between carcass weight, adipose tissue androstenone level and expression of the hepatic 3ß-hydroxysteroid dehydrogenase in entire commercial pigs.

Boar taint is a major meat-quality defect in pigs and is due to excessive accumulation of skatole and androstenone in adipose tissue. The present work investigated the relationship between carcass weight, levels of skatole and androstenone in adipose tissue, and expression of the hepatic androstenone-metabolising enzyme 3ß-hydroxysteroid dehydrogenase (3ß-HSD), in 22 entire male and 22 entire female crossbred pigs (Large White (40%) × Landrace (40%) × Duroc (20%)). Animals of each gender were divided into two subgroups (11 pigs in each subgroup): (i) conventional weight (carcass weight 59 to 77 kg) and (ii) heavy weight (carcass weight 84 to 95 kg). No relationship between carcass weight and adipose tissue skatole level was found for entire male pigs (r2 = 0.013, P > 0.05). There was a significant negative relationship between carcass weight and expression of the hepatic 3ß-HSD protein (r2 = 0.502, P < 0.001) and a significant negative relationship between 3ß-HSD protein expression and androstenone level in adipose tissue (r2 = 0.24, P < 0.05) in entire males. No relationship was found between carcass weight and 3ß-HSD protein expression in female pigs (r2 = 0.001, P > 0.05). 3ß-HSD expression was 59% higher in conventional-weight male pigs when compared with heavy-weight animals (P < 0.05) and 36% higher in heavy-weight females when compared with heavy-weight males (P < 0.05). It is concluded that an increase in slaughter weight of entire commercial crossbred Large White pigs is accompanied by inhibition of expression of the hepatic 3ß-HSD protein, which might result in a reduced rate of hepatic androstenone clearance with its subsequent accumulation in adipose tissue. It is suggested that regulation of pig hepatic 3ß-HSD expression is under the control of sex hormones.

Relationship between the expression of hepatic but not testicular 3beta-hydroxysteroid dehydrogenase with androstenone deposition in pig adipose tissue.

This study investigated the relationship between expression of hepatic and testicular 3beta-hydroxysteroid dehydrogenase (3beta-HSD) and accumulation of androstenone in adipose tissue because of its relation to boar taint. The experiments were performed on 13 Large White (50%) x Landrace (50%) and Meishan (25%) x Large White (25%) x Landrace (50%), pigs, which differed in the level of backfat androstenone. Our previous work showed that the major product of the hepatic androstenone metabolism is 3beta-androstenol. In this study, the formation of 3beta-androstenol was inhibited by the specific 3beta-HSD inhibitor trilostane. These results are the first direct confirmation that 3beta-HSD is the enzyme responsible for androstenone metabolism in the pig. The expression of the hepatic but not testicular 3beta-HSD protein showed a negative relationship with the level of backfat androstenone (r2 = 0.64; P < 0.001) and was accompanied by a reduced rate of the hepatic androstenone clearance. Low expression of 3beta-HSD protein in the liver of high androstenone pigs was also accompanied by a reduced level of 3beta-HSD mRNA (P < 0.001), which suggests a defective regulation of the hepatic 3beta-HSD expression at the level of transcription. In contrast, expression of the testicular 3beta-HSD protein did not differ between animals with high and low androstenone levels (P > 0.05) and was lower compared with the hepatic 3beta-HSD expression. Cloning and sequencing of the 3beta-HSD coding regions established that the hepatic and testicular 3beta-HSD cDNA have identical sequences, which were 98% similar to the human 3beta-HSD isoform I. It is suggested that expression of a single 3beta-HSD gene is regulated by different mechanisms in pig liver and testis. The liver-specific regulation of 3beta-HSD expression contributes to the low rate of hepatic androstenone metabolism and therefore can be considered as one of the factors regulating deposition of androstenone in pig adipose tissue and subsequent development of boar taint.

A reduced protein diet induces stearoyl-CoA desaturase protein expression in pig muscle but not in subcutaneous adipose tissue: relationship with intramuscular lipid formation.

A reduced protein diet (RPD) is known to increase the level of intramuscular lipid in pig meat with a smaller effect on the amount of subcutaneous adipose tissue. This might be due to tissue-specific activation of the expression of lipogenic enzymes by the RPD. The present study investigated the effect of a RPD, containing palm kernel oil, soyabean oil or palm oil on the activity and expression of one of the major lipogenic enzymes, stearoyl-CoA desaturase (SCD) and on the level of total lipids and the fatty acid composition of muscle and subcutaneous adipose tissue in pigs. The RPD significantly increased SCD protein expression and activity in muscle but not in subcutaneous adipose tissue. The level of MUFA and total fatty acids in muscle was also elevated when the RPD was fed, with only small changes in subcutaneous adipose tissue. A positive significant correlation between SCD protein expression and total fatty acids in muscle was found. The results suggest that an increase in intramuscular but not subcutaneous adipose tissue fatty acids under the influence of a RPD is related to tissue-specific activation of SCD expression. It is suggested that the SCD isoform spectra in pig subcutaneous adipose tissue and muscle might be different.

Influence of dietary oils and protein level on pork quality. 2. Effects on properties of fat and processing characteristics of bacon and frankfurter-style sausages.

Palm kernel oil (PKO) and palm oil (PO) are used in tropical countries as cheaper substitutes for conventional feed sources such as soya bean oil (SBO) but little is known about their effects on meat quality. This study, therefore, evaluated the effects of these three dietary oils on the fatty acid composition (FA) of pork fat and the qualities of belly bacon and frankfurter sausage. The 3×2 factorial design also included high and low dietary protein. Total cooking loss, water loss and fat losses were determined in frankfurter sausages at chopping temperatures from 2 to 24°C. PKO resulted in a poor P:S ratio (0.34) and a relatively hard fat (slip point 32.8°C), but resulted in bacon with a higher tensile cohesive force and more high quality slices, judged subjectively. PO had a fatty acid composition closer to the SBO control, a better P:S ratio than PKO (0.48) and softer fat. There was a trend for total cooking losses and fat losses to be higher in PKO compared with PO and SBO at all chopping temperatures, suggesting that the firmest, most saturated fat (PKO) was least suitable for frankfurter production. The low protein diet increased the concentration of saturated fatty acids and increased fat firmness but its effect on fatty acid composition and other properties were less marked than those of oil type.

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 skatole and androstenone accumulation, and cytochrome P4502E1 expression in Meishan×Large White pigs.

The effects of age, castration and diet on accumulation of skatole and androstenone in the backfat of 50% Meishan male pigs, was studied in relation to boar taint. Skatole and androstenone deposition in backfat of entire males was increased with age (114, 144 and 174 days). Castration significantly decreased skatole and androstenone levels in all age groups. The level of cytochrome P4502E1, the initial enzyme involved in hepatic skatole metabolism, was increased by castration at all ages. These results suggest that the decrease in androstenone levels following castration affects the regulation of cytochrome P4502E1 expression, and as a consequence, results in a decrease in skatole levels. The use of sugar beet feed in the diet decreased the level of skatole and increased that of cytochrome P4502E1 expression, but did not affect androstenone levels. It is suggested that skatole accumulation is reduced both by castration and by diet via induction of cytochrome P4502E1. However, the mechanism of induction of cytochrome P4502E1 by diet is different from that involved in its induction by castration.

Effects of breed, diet and muscle on fat deposition and eating quality in pigs.

A study in 192 entire male pigs examined the effects of breed, diet and muscle on growth, fatness, sensory traits and fatty acid composition. There were four breeds: two modern breeds, Duroc and Large White and two traditional breeds, Berkshire and Tamworth. The diets differed in energy:protein ratio, being conventional (C) and low protein (LP) diets, respectively. Muscles investigated were the `white' longissimus dorsi (LD) and the `red' psoas major (PS). Breed influenced growth rate and fatness, the modern breeds being faster-growing with leaner carcasses. However, the concentrations of neutral lipid fatty acids and marbling fat (neutral lipid+phosopholipid fatty acids) were higher in Berkshire and Duroc, in both LD and PS. Relationships between marbling fat and P2 fat thickness showed clear breed effects, with Duroc having high marbling fat at low P2 and Tamworth low marbling fat at high P2. Breed effects on sensory scores given by the trained taste panel to griddled LD and PS steaks were relatively small. Breed affected the fatty acid composition of intramuscular neutral lipid, with high % values for the saturated fatty acids, 14:0 and 16:0 in Berkshire and Tamworth (fat carcasses) and high values for polyunsaturated fatty acids in Duroc and Large White (lean carcasses). Duroc had particularly high concentrations of the long-chain polyunsaturated fatty acids, 20:5n-3 and 22:6n-3 in phospholipid of both muscles. Diet influenced growth rate and fatness, the LP diet slowing growth and producing fatter meat, more so in the two modern breeds, and particularly in intramuscular rather than subcutaneous fat. This diet produced more tender and juicy meat, although pork flavour and flavour liking were reduced. The PS muscle had higher tenderness, juiciness, pork flavour, flavour liking and overall liking scores than LD. The concentration of phospholipid fatty acids was higher in PS than LD but neutral lipid fatty acid content and marbling fat were higher in LD.

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.

Genotype with nutrition interaction on fatty acid composition of intramuscular fat and the relationship with flavour of pig meat.

The effects of genotype, diet and the genotype with diet interaction on fatty acid composition of neutral lipid and phospholipid of intramuscular fat in pigs were examined. Pigs from four selection lines and a control line were fed isoenergetic diets, which differed in ileal digestible lysine:digestible energy (A: 0.40, C: 0.76 and E: 1.12 g lysine/MJ DE). The selected lines resulted from seven generations of selection for high daily food intake (DFI), lean food conversion ratio (LFC) and lean growth rate on ad-libitum (LGA) or restricted feeding regimes in a Large White population. During performance test, from 30 to 90 kg, pigs were fed on either ad-libitum or restricted (0.75 g/g ad-libitum daily food intake) feeding regimes. A trained sensory panel assessed intensities of pork flavour and abnormal flavour and the hedonic characteristics of flavour liking and overall acceptability. The proportion of neutral lipid in the LGA line was lower (0.64 v 0.75, s.e.d. 0.03) while the polyunsaturated:saturated (P:S) ratio of the LFC line (0.53 v 0.41, s.e.d. 0.05) was higher than the control line and other selection lines. The DFI line had a higher phospholipid n-6:n-3 ratio than other selection lines (14 v 11, s.e.d. 1.0). Diets C and E resulted in lower neutral lipid:phospholipid ratio (0.7 v 0.8, s.e.d. 0.01), n-6:n-3 ratios for both neutral lipid (5 v 13, s.e.d. 0.8) and phospholipids (7 v 20, s.e.d. 0.6) and a higher P:S ratio (0.5 v 0.3, s.e.d. 0.03) for neutral lipid than diet A. Neutral lipid fatty acids C18:2 n-6, C18:3 n-3, C20:3 n-6, C20:4 n-6, C20:5 n-3, C22:5 n-3 and C22:6 n-3 were negatively correlated with pork flavour (-0.30, s.e.d. 0.10), flavour liking (-0.33) and overall acceptability (-0.30). In contrast, the fatty acids C16:1, C18:1 ω9 and C18:1 ω11 were positively correlated with pork flavour (0.36), flavour liking (0.39) and overall acceptability (0.40). However, correlations for fatty acids in the phospholipid class were positive for C18:2 n-6, C20:4 n-6 and C22:4 n-6 with pork flavour (0.33), flavour liking (0.23) and overall acceptability (0.23). The proportion of neutral lipid had non-significant correlations with flavour traits; pork flavour (0.01), abnormal flavour (0.08), flavour liking (-0.03) and overall acceptability (0.03). The selection lines responded in a similar manner to the different diets, such that there was little evidence for genotype with nutrition interactions for fatty acid concentrations of neutral lipids and phospholipids. Selection for high lean growth will reduce intramuscular fat, but the increased relative amount of phospholipid and concentration of polyunsaturated fatty acids are unlikely to reduce eating quality. Nutritional effects on intramuscular fat characteristics were greater than genetic effects, such that nutritional approaches to feeding pigs will provide effective methods of reducing the n-6:n-3 fatty acid ratio of human dietary fat from pigmeat and improving human health.

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

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

Effects of breed, feed level and conditioning time on the tenderness of pork.

This study of 80 pigs compared the effects of breed (Duroc vs Large White), feed level (High vs 0.8 High, termed Low) and conditioning time (1 vs 10 days at 1 °C) on the tenderness and other aspects of the eating quality of pork. Conditioning time had the biggest effect (increase of 1.0 units on 1-8 taste panel scale between 1 and 10 days) and this was associated with an increase in the myofibrillar fragmentation index (MFI) from 19 to 24 units. Tenderness was not different between the two breeds although pork flavour intensity and overall liking scores were higher in Durocs. Durocs had higher concentrations of total lipid (marbling fat) in muscle (13.7 and 5.4 mg/g) and most polyunsaturated fatty acids except α-linolenic (C18:3 n-3) were at lower concentrations in Durocs, reflecting dilution of phospholipid fatty acids within a larger total lipid pool. Pigs fed at the high level were fatter than those fed restrictedly in terms both of P2 fat thickness and marbling fat. There was also a tendency, although not significant, for the meat to be more tender. When the data from all pigs were pooled, MFI was shown to correlate well with tenderness (r = 0.45) and marbling fat with juiciness (r = 0.36).

Effects of litter size and subsequent gold-thioglucose-induced obesity on adipose tissue weight, distribution and cellularity in male and female mice: an age study.

1. Over- or undernutrition of newborn mice was caused by suckling in litters consisting initially of four or eighteen pups. After weaning mice were fed ad lib. At 13 weeks of age some mice from large litters received gold thioglucose (GTG: 600 mg/kg intraperitoneally) to induce hyperphagia, and mice were killed at 13, 19.5, 26, 39 and 52 weeks. 2. Total carcass lipid and the size and number of adipocytes in the inguinal subcutaneous, genital, perirenal and mesenteric depots were determined. 3. Mice, both male and female, raised in small litters were heavier and had more carcass fat at all ages than mice raised in large litters. After GTG-treatment mice from large litters were heavier and fatter than mice raised in small litters. 4. Fat distribution between the depots was related to carcass lipid content and not to treatment. The order of depot development was subcutaneous, parametrial, perirenal and mesenteric in females and epididymal, subcutaneous, perirenal and mesenteric in males. At 13 weeks the depots in males were more developed than those in females. 5. Litter size had no effect on adipocyte volume in female mice at 13 weeks but by 52 weeks small-litter mice had larger cells in all depots and more cells in the parametrial and perirenal depots. 6. Male mice from small litters had bigger cells at 13 weeks in all depots compared with males from large litters but by 52 weeks no significant differences remained. Greater numbers of cells were present only in the perirenal and mesenteric depots of small-litter males at some ages. 7. Depots of GTG-treated large-litter female mice had larger cells than those of small-litter females, while a similar number of cells was found by 52 weeks in all but the perirenal depot, which had significantly more cells. 8. GTG treatment of male mice from large litters also caused bigger cells than in small-litter mice, and an increased depot cell number at earlier ages in all but the epididymal depot. By 52 weeks cell numbers were similar in depots from small-litter and GTG-treated large-litter mice, except for the epididymal depot from the latter which had fewer cells. 9. Increases in cell numbers with age in different depots occurred independently of existing cell mean volume and even of tissue growth, suggesting the presence of an in-built chronology, at least in older mice.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of sodium 2-n-pentadecyl-benzimidazole-5-carboxylate (M & B 35347B), an inhibitor of acetyl-CoA carboxylase, on lipogenesis and fat deposition in obese hyperglycaemic (ob/ob) and lean mice.

A high rate of lipogenesis in obese mice plays a major role in their excessive deposition of body lipid. Inhibition of lipogenesis may decrease their obesity. Therefore, we have investigated the effects of sodium 2-n-pentadecyl-benzimidazole-5-carboxylate (M & B 35347B), an inhibitor of acetyl-CoA carboxylase, on in-vivo lipogenesis in obese and lean mice. It significantly inhibited hepatic cholesterol and fatty acid synthesis, measured using 3H2O, in both lean and obese mice, with or without a glucose load. Brown adipose tissue (scapular) lipogenesis was decreased by M & B 35347B in obese mice but not in lean mice. In white adipose tissue, M & B 35347B did not affect the rates of lipogenesis in either scapular white, inguinal or epididymal depots of obese mice, or the inguinal and scapular white depot of lean mice. However, it doubled lipogenesis in the epididymal fat pad of lean mice. After a glucose load, lipogenesis in the lean epididymal fat pad was not inhibited but that in the inguinal depot was. M & B 35347B inhibited acetyl CoA carboxylase of adipose tissue in vitro but only a small inhibition was detected after in-vivo treatment. These different responses according to type of mouse, treatment and tissue site appear to stem from differences in inhibitor concentration and the importance of acetyl CoA carboxylase as the rate-limiting enzyme of lipogenesis. The weight gain of obese mice dosed orally (200 mg M & B 35347B/kg daily) for 60 days was unaffected and they continued to deposit excess body fat. This presumably occurred because of the lack of inhibition of fatty acid synthesis in white adipose tissue.

The actions of dichloroacetic acid on blood glucose, liver glycogen and fatty acid synthesis in obese-hyperglycaemic (ob/ob) and lean mice.

Obese-hyperglycaemic mice and lean mice were injected with dichloroacetate to determine the significance of gluconeogenesis in maintaining the hyperglycaemia of obese mice and to investigate the effects of a fall in blood glucose on fatty acid synthesis. One hour after the second of two, hourly, injections of dichloroacetate the blood glucose concentrations in fed and starved lean mice were decreased, whereas in obese mice they were sharply increased. In obese and lean mice, both fed and starved, dichloroacetate decreased plasma lactate but insulin was unchanged. The quantity of liver glycogen was decreased in all dichloroacetate treated mice, with the largest falls in fed and starved obese mice, which had much larger glycogen stores than lean mice. Dichloroacetate treatment decreased the concentration of plasma non-esterified fatty acids in fed and starved obese mice and fed lean mice but not in starved lean mice. Fatty acid synthesis in white (inguinal, subcutaneous) adipose tissue was stimulated by dichloroacetate in fed obese mice and inhibited in fed lean mice. Fatty acid synthesis in brown adipose tissue (scapular) was faster than in white adipose tissue and was less affected by dichloroacetate although the changes were in the same direction as in white adipose tissue. We attribute the increased hyperglycaemia of obese mice treated with dichloroacetate to increased glycogenolysis coupled with a failure to secrete additional insulin in response to the raised blood glucose. This high blood glucose concentration in dichloroacetate treated obese mice may in turn explain the increased fatty acid synthesis in their white adipose tissue.