Fatty acids and sensory characteristics of Spanish dry-cured loin enriched in acid α-linolenic and α-tocopherol

The effects of using α-linolenic and α-tocopherol acid-enriched pork on the fatty acids and sensory characteristics of Spanish dry-cured loins were investigated. For the study, five batches of Spanish dry-cured loins were manufactured using pork loin enriched in polyunsaturated n − 3 fatty acids and α-tocopherol. Tissues were obtained from pigs fed on diets with the same ingredients, except for the oil source which corresponded to: [sunflower (C), linseed (L) and linseed and olive (1/1, w/w) (LO)] and two different amounts of α-tocopheryl acetate [20 (C, L and LO) or 200 (LOE and LE) mg/kg diet]. Dry-cured loins with polyunsaturated fatty acid n6/n3 ratios below 4 were obtained from linseed and linseed/olive oil-enriched batches. Dry-cured loin manufactured with pork from animals fed on diets enriched only with linseed oil presented the worst sensory characteristics and higher TBAR values than did dry-cured loins from animals fed on diets enriched with linseed and olive oil and linseed oil plus tocopheryl acetate.     

Enrichment of dry-cured ham with α-linolenic acid and α-tocopherol by the use of linseed oil and α-tocopheryl acetate in pig diets

The use of α-linolenic acid and α-tocopherol enriched pork on the fatty acids and the sensory characteristics of Spanish dry-cured hams have been studied. Five batches of hams were manufactured using the posterior legs of pigs fed on diets with the same ingredients except for the oil source: sunflower (C), linseed (L) or linseed and olive (1/1, w/w, LO). Two different α-tocopheryl acetate concentrations [20 (C, L and LO) or 220 (LOE and LE)mg/kg diet] were used. Biceps femoris and Semitendinosus/Semimembranosus muscles from hams with low polyunsaturated fatty acid n-6/n-3 ratio (less than 3) were obtained from animals fed on linseed and linseed/olive oil enriched diets. However, hams from animals fed on diets added with linseed and α-tocopheryl acetate (20mg/kg diet) (batch L) were rejected by consumers because of less acceptable sensory characteristics and higher TBARs. The remaining hams had satisfactory sensory and nutritional characteristics.     

Influence of dietary fat on pork eating quality

This study compared the influence of dietary fat sources on meat quality, fatty acid composition and sensory attributes in pork. The experiment was conducted with 43 entire male pigs (Pietrain×(Landrace×Large White)) which were fed a basal diet without added fat (control diet) or supplemented with different sources of fat: animal fat (1%, AF1; 3%, AF3), soyabean oil (1%, SBO1) and calcium soaps of palm oil (1%, CaSPO1). Dietary fat supplementation did not significantly affect ultimate pH, colour, Warner-Bratzler shear force values, sensory attributes or SFA. Pigs fed SBO1 had the lowest proportion of MUFA and the highest of PUFA. In conclusion, these dietary fat sources could be recommended for inclusion in diets, at these levels, with no detrimental effect on eating quality. Despite finding no significant differences, the PCA afforded a comprehensive view of the predominating attributes of pork from animals fed the different fats.     

Extensive feeding versus oleic acid and tocopherol enriched mixed diets for the production of Iberian dry-cured hams: Effect on chemical composition, oxidative status and sensory traits

The present study aimed to analyse the chemical composition and oxidative status of Iberian dry-cured hams from pigs fed different finishing diets: extensive feeding on acorns and pasture in a "Montanera" traditional system (MON), fed in confinement with a mixed diet containing high-oleic sunflower oil (115g/kg of diet) and supplemented with 250mg/kg α-tocopherol (HOVE), and fed in confinement control mixed diet (CON) without added tocopherol and oleic acid fat. Muscles from MON dry-cured hams contained significantly (p<0.05) higher amounts of intramuscular fat (IMF) than those from HOVE and CON hams. The feeding background affected the tocopherol levels in dry-cured hams as those from MON and HOVE pigs had significantly higher levels of α-tocopherol than those from CON pigs whereas the extensive feeding provided muscles from MON pigs with significantly higher levels of γ-tocopherol than the experimental diets did to CON and HOVE pigs. The HOVE diet significantly increased the levels of oleic acid in Iberian dry-cured hams with these levels being similar to the oleic acid levels found in MON hams and significantly higher than those in CON hams. Compared to dry-cured hams from CON pigs, those from MON and HOVE pigs exhibited a higher oxidative stability as a likely result of a most favourable fatty acid composition and the presence of higher tocopherol levels. The principal component analysis (PCA) successfully discriminated between dry-cured hams from pigs fed different finishing diets.     

Effect of sugarcane diets and a high fibre commercial diet on fresh meat and dry-cured ham quality in local Caribbean pigs

The effects sugar cane (SC) diets and a milling by product diet on meat quality characteristics of fresh meat and dry-cured ham were studied on a total of 48 Creole (CR) pigs. Pigs were fed with a control soya-bean meal corn diet (C1), a soya-bean meal wheat diet (C2), a SC fresh juice diet (SC-J), or a ground cane diet (SC-G). Average BW gain was 657, 530, 546, and 200 g/d for diets C1, C2, SC-J and SC-G, respectively. Lean cuts (i.e., ham and loin) were significantly higher in SC-G than in C1 pigs (472 vs. 424 g/kg; P < 0.01); intermediate values were found for C2 and SC-J pigs (427 and 412 g/kg, respectively). The ultimate pH in LD muscle was lower in SC-J than the other groups (5.44 vs. 5.65; P < 0.01). The intra muscular fat (IMF) content in LD was significantly higher in SC-J diet and lower in SC-G diet (1.9% and 1.0%, respectively); intermediates values were found for C1 and C2 diets (1.4% on average). Ham weight losses during 6 months drying period were lower for SC-G fed pigs (9.7% vs. 12.4%; P < 0.05) whereas weight losses during the 12 months drying period were not affected by diet. The TBA value in dry-cured ham was not affected by diet (P > 0.05) whereas the fatty acids profiles of subcutaneous fat in SC-J and SC-G pigs contained more mono-unsaturated and less polyunsaturated fatty acids than in C1 and C2 groups. Significant effects of dietary treatment were found for dry-cured ham sensory quality parameters.     

Nutritional and sensory quality of porcine raw meat, cooked ham and dry-cured shoulder as affected by dietary enrichment with docosahexaenoic acid (DHA) and α-tocopheryl acetate

The effects of dietary enrichment of pig diets with DHA from a marine source (Algatrium^®) and α-tocopheryl acetate on the nutritional and sensory characteristics of pork and pork products were evaluated. Raw and cooked hams, and dry-cured shoulders from pigs fed with three diets (control, control supplemented with 0.3% DHA plus 50 ppm α-tocopheryl acetate and control with 200 ppm α-tocopheryl acetate) were used. The treatments did not cause any significant differences in proteolytic and antioxidant enzyme activities, except on catalase (CAT) which increased significantly in raw hams from pigs fed DHA supplemented diets. Vitamin E accumulated in samples with α-tocopheryl acetate supplementation. DHA added to the diet increased the DHA level by 87% compared with the control treatment in both raw and dry-cured shoulders, and exceeded 82% in cooked hams. In consequence, the incorporation of the n − 3 source in the diet significantly reduced the n − 6/n − 3 ratio in all products. The ratio reduction ranged from 51% in dry-cured shoulders to 65% in cooked and raw hams.     

The effect of olive leaves supplementation on the feed digestibility, growth performances of pigs and quality of pork meat

The influence of olive leaves supplementation on feed digestibility, growth performance of pigs and pork meat quality was investigated. Pigs fed diets with olive leaves at 5% (OL5) and 10% (OL10) levels had lower daily weight gain (DG) and daily feed intake (DFI) than pigs fed a conventional diet (OL0) but differences were not observed between groups fed with the different quantities of leaves. Additionally, pigs fed diets with leaves had the worst feed:gain ratio and showed a decrease in overall backfat. Chops from pigs fed the leaf diets had lower peroxide (PV) and conjugated diene (CD) contents than chops from pigs fed conventional diets. Moreover, chops from pigs fed with the higher quantity of leaves also showed a lower drip loss. After a storage period of 8 days at 4 °C, meat obtained from both OL5 and OL10 animals also differed (P < 0.05) in PV and %CD values from those fed a conventional diet. Since the fatty acid composition of the longissimus muscles was not different, differences in oxidative stability could only be explained by the significantly higher α-tocopherol concentration in intramuscular fat and backfat in pigs fed with olive leaf diets.     

Pork quality from pigs fed on low glucosinate rapeseed meal: Influence of level in the diet,sex and ultimate pH

The appearance and eating quality of pork M. longissimus lumbrum from gilt and castrate pigs fed on diets containing a low glucosinate/low erucic acid rapeseed meal (cv. Tower) were assessed and compared with pork from pigs fed diets containing soya bean meal. At 90 kg liveweight, higher levels of either protein supplement, and therefore higher levels of dietary protein, gave slightly leaner meat. Meat from pigs fed rapeseed meal had more haem pigment and was slightly darker and redder than that from soya bean fed pigs. Differences in the quality of pork from the low glucosinate rapeseed meal and soya bean diets were small. Ratings for texture, juiciness and flavour of the lean varied little between the treatment groups. Suggestions that rapeseed meal as a protein supplement in diets might lead to inferior quality meat were not substantiated. The ultimate pH varied from 5.3 to 7.1 independently of the treatments and provided, for the first time, definitive relationships between pH and eating quality. Toughness and flavour were maximum and juiciness was a minimum after roasting meat of about pH 5.9. The ultimate pH had a larger effect on organoleptic quality than either sex or level of dietary inclusion of rapeseed or soya bean meals.     

Effects of triticale-based diets on finishing pig performance and pork quality in deep-bedded hoop barns

Effects of triticale diets on pig performance and pork quality were evaluated in summer and winter. Diets were: corn-soy, 40% triticale, or 80% triticale. Pigs (72 kg) were fed 49 d. Loins were evaluated for meat and fat quality and sensory evaluation. Average daily gain decreased as triticale inclusion increased (P < 0.01). Feed intake was similar. Pigs fed corn-soy had the greatest and those fed 80% triticale had least gain:feed ratio (P < 0.05). In summer, pigs fed corn-soy had largest and those fed 80% triticale diet had smallest loin muscle area (P < 0.05) based on ultrasound scan. During summer, ultimate pH was higher (P ? 0.001) and, loin purge and shear force were lower (P < 0.05). Diet did not affect sensory evaluation or fatty acid profile of loins. During summer, total MUFA were more and total PUFA were less (P ? 0.01). Triticale fed to pigs in hoop barns slightly decreased growth without compromising pork quality.     

INFLUENCE OF FEED FAT SOURCE ON FATTY ACID COMPOSITION, UNSATURATION AND LIPID OXIDATION OF BACKFAT AND SENSORY QUALITY OF PORK

The effect of different fats in a 9% fishmeal feed on backfat fatty acid composition, oxidation and pork sensory attributes was studied. The hydrogenated fish oil group (HFO) had significantly increased uptake of certain fatty acids in contrast to the other groups. Iodine values were highest in the fish oil group, followed by the lamb tallow group (LT) with the control group, containing no added fat, tailing. Backfat from the HFO group had more polyunsaturated fatty acids compared to the other groups and stearic/linoleic acid ratio suggested more oxidative problems with this group. The HFO group led the LT group in oxidation with the control group being most stable. Sensory traits of fresh and frozen pork chops correlated with the oxidation results. Fat from pigs fed hydrogenated fish oil in their diet are therefore more susceptible towards oxidation possibly due to more polyunsaturated fatty acids and oxidation products in the backfat.     

Changes in fatty acid composition and improved sensory quality of backfat and meat of pigs fed bacterial protein meal

A total of 48 pigs (11.4 and 107.2 kg initial and final weight) were used to evaluate increasing dietary levels of bacterial protein meal (BPM) produced on natural gas (0, 50, 100, or 150 g kg⁻¹) on fatty acid composition, sensory properties, and susceptibility of pork to lipid oxidation. Increasing levels of BPM to diets increased the content of C16:1 fatty acids in backfat and muscle and total monounsaturated fatty acids in muscle, but decreased the content of polyunsaturated fatty acids and iodine value in backfat and muscle. Pigs fed diets containing BPM had reduced thiobarbituric acid reactive substances (TBARS) value in backfat and muscle, reduced intensity of odor and rancid odor and taste in pork after short-time storage, and reduced off-odor and off-taste after intermediate-time storage. To conclude, adding BPM to diets for pigs changed the fatty acid profile, improved the oxidative stability, and sensory quality of pork.     

Effects of dietary magnesium and duration of refrigerated storage on the quality of vacuum-packaged, boneless pork loins

Quality data were initially collected on 78 pork loins from crossbred pigs fed diets containing 0, 1.25 or 2.5% magnesium mica (MM). Loins were then vacuum-packaged, and randomly assigned to either 4 or 8 weeks of storage at 2°C. Dietary MM had no (P > 0.05) effect on moisture loss/retention or subjective and objective color measurements. Purge volume increased (P<0.05) and drip loss decreased (P<0.05) as storage time increased. Moreover, longissimus thoracis et lumborum (LM) chops became lighter (P<0.05), redder (P<0.05), and more yellow (P<0.05) during 8 weeks of storage. Although TBARS values increased linearly (P<0.001) during extended storage, LM chops from pigs fed 2.5% MM tended to have lower (P<0.07) TBARS values after 4 weeks of storage than chops from pigs fed 0 and 1.25% MM. After 8 weeks of storage, however, there was a tendency for TBARS values of chops from pigs fed 1.25% MM to be lower (P<0.07) than chops from pigs fed 2.5% MM. Even though feeding swine diets containing MM did not affect color and water-holding capacity of pork loins during storage, the data indicated inclusion of MM in swine diets may retard onset of oxidative rancidity in vacuum-packaged pork loins.     

原料肉特性对湖南腊肉品质的影响

为比较瘦肉型的杂交商品猪肉和本地猪肉对湖南腊肉品质的影响,实验选取三元杂交商品猪的背最长肌(A)和腹部五花肉(B)、本地宁乡猪的背最长肌(C)和腹部五花肉(D)为原料加工湖南腊肉。测定了加工过程中腊肉理化指标变化和腊肉的颜色、挥发性性成分等。实验结果表明:在腊肉成品中,相同部位原料肉加工的腊肉,杂交商品猪肉的水分含量显著高于宁乡猪加工的腊肉样品(AC,BD),但食盐含量和亚硝酸盐含量呈现相反的变化趋势,即商品杂交猪肉腊肉具有较低的食盐含量和亚硝残留量(AC,BD);4组实验腊肉样品中,L*值均呈下降趋势,两个品种的猪肉中背最长肌的a*值呈现先下降后上升趋势,腹部五花肉的变化规律不明显;样品A、B、C、D分别鉴定出挥发性成分40种、24种、54种、23种。说明了不同原料肉品种和不同部位对湖南腊肉的品质有一定影响。     

Growth, carcass and meat characteristics of Karayaka growing rams fed sugar beet pulp, partially substituting for grass hay as forage

Twenty-one growing male Karayaka sheep were divided into three groups of seven at 12 months of age. All groups received a commercial feed (60%) and roughage (40%). One group received grass hay as roughage (control, C), the other two groups received a mixture in which 40 (0.40SBP) or 60% (0.60SBP) sugar beet pulp (SBP) was used in partial replacement of grass hay in the C group during 56 days. Dry matter (DM) intake and DM conversion index (kg DM per kg weight gain) of the C group were higher (P<0.01) than that of the 0.40SBP and 0.60SBP groups. While the 0.60SBP increased (P<0.05) the L* of meat from the Karayaka young rams, the 0.40SBP or 0.60SBP decreased the ultimate pH (P<0.05) and cooking loss (P<0.01) compared to the C group. Means for redness (a*), yellowness (b*), Hue (H*) and Chroma (C*) and sensory characteristics indicated that there were no significant differences between dietary treatments. Inclusion of 60% SBP increased the palmitic (P<0.02) and linoleic (P<0.01) acid contents of the meat, it decreased (P<0.01) stearic, oleic and arachidonic acid contents compared to the C group. The 0.40SBP also increased (P<0.01) the linoleic acid content of the meat, but it decreased (P<0.01) stearic and arachidonic acid contents compared to the control. Although meat from young rams fed 0.60SBP diet had a higher value of lightness and linoleic acid, and a lower value of cooking loss than those from animals fed the C diet, sensory evaluation did not discriminate the meat from young rams fed with control and/or SBP diets. Therefore, grass hay can be replaced by 60% of SBP in the growing diet for Karayaka rams without a reduction in meat quality.     

葱姜蒜混合物对炖煮猪肉感官品质、脂肪氧化及脂肪酸组成的影响

研究了不同添加量葱姜蒜混合物(onion-ginger-garlic,OGG)(5%、10%、15%)对炖煮猪肉感官品质(色泽、质地、滋味、香气)、基本理化指标(脂肪和水分)、脂肪氧化程度(过氧化值(POV)和硫代巴比妥酸值(TBA))及脂肪酸组成的影响。结果表明:OGG的添加能够提高炖煮猪肉的感官品质、改善肉的持水力,且随着OGG添加量的增大,炖煮猪肉的持水力显著提高(P0.05)。OGG能够抑制炖煮猪肉过氧化物及TBARS的产生,且添加量为15%的效果最显著(P0.05)。炖煮猪肉中添加OGG能显著抑制猪肉脂肪酸氧化,尤其是不饱和脂肪酸的氧化,且随着添加量的增加其抑制效果也明显提高。此外,OGG的添加还影响炖煮猪肉脂肪酸含量,添加OGG制得的炖煮猪肉,其单不饱和脂肪酸和多不饱和脂肪酸含量显著升高(P0.05),提高了不饱和脂肪酸(UFA)和饱和脂肪酸(SFA)的比例(P0.05),从而改善了猪肉的营养价值。     

Dehulled-micronised lupin (Lupinus albus L. cv. Multitalia) as the main protein source for broilers: influence on growth performance, carcass traits and meat fatty acid composition

BACKGROUND: A study was carried out to compare the effect of diets containing micronised-dehulled lupin (Lupinus albus L. cv. Multitalia) on growth performance, carcass yields and meat fatty acid profile of broiler chickens. RESULTS: Hubbard strain chicks receiving from 14 d to slaughtering age (49 d) a wheat middlings-based diet containing either deffatted soybean meal (195 g kg(-1), control) or dehulled micromicronised lupins (240 g kg(-1)) as the main protein source were used. The inclusion of treated lupin meal in the diet did not result in lower growth rates of chicks. Lupin diet had no effect on dressing percentage, or breast and drumstick muscles relative weights, but a reduction of abdominal fat content was reported (P < 0.05). White and dark meats of birds fed lupin diet had significant (P < 0.05) lower L* (lightness) values and fat content (P < 0.05). Total collagen and water-holding capacity values were higher in lupin treatment. Feeding the lupin diet resulted in lower saturated fatty acid content in breast and drumstick meat, as well as the n-6/n-3 polyunsaturated fatty acid (PUFA) ratio and saturation, atherogenic and thrombogenic indexes, while total PUFA and monounsaturated fatty acids levels increased (P < 0.05). Conclusion: These results suggest that replacing soybean meal with dehulled-micronised lupin meal in diet for broiler chickens can produce meat with favourable lipid profile and quality, with no adverse effects on productive parameters.     

Influence of fishmeal, rape-seed, and rape-seed meal in feed on the fatty acid composition and storage stability of porcine body fat

One hundred and ten pigs were fed test diets containing 1·1%, 3·3% or 5·5% fishmeal, 10% rape-seed or 15% rape-seed meal. The control diet contained soya-bean meal. From each carcass M. longissimus dorsi, including subcutaneous fat, was taken and analysed for fatty acid composition and intramuscular fat content. Accelerated oxidation test was carried out on fresh samples. Sensory analyses as well as peroxide and aldehyde analyses were carried out after 0, 4, 6 and 9 months of freezer storage. The sensory properties of fresh meat and fat were not affected by any of the feed components tested. After 6 months of freezer storage slightly increased levels of off-flavours were noted with 3% fishmeal or more in the diet. Also, the peroxide value after storage increased at the same fishmeal level. With rape-seed or rape-seed meal in the diet the scores for off-flavours increased only slightly. A much lower storage stability was noted in fat from pigs fed a combination of rape-seed and fishmeal. Extra vitamin E in diets did not increase the storage stability of pork fat. Special attention was paid to the incorporation of dietary polyunsaturated fatty acids (PUFA), especially marine-PUFA, into body fat. It was found that the incorporation of C22:6 was a very good indicator of the amount of fishmeal in the diet.     

EFFECTS OF DIETARY GLYCINE BETAINE ON BLOOD CHARACTERISTICS AND PORK QUALITY

This study was conducted to determine the effects of dietary glycine betaine on pork quality and blood characteristics. A total of 80 female pigs (Landrace  ×  Yorkshire  ×  Duroc) were randomly allotted into one of four experimental diet groups. Each group of pigs fed with a commercial diet (control) added with 0.2 g glycine betaine (T1), 0.4 g glycine betaine (T2) and 0.6 g glycine betaine (T3)/kg diet during 40 days. Glycine betaine concentrations in plasma and loin muscle were significantly increased by dietary glycine betaine; however, triglyceride concentration in serum was decreased by dietary glycine betaine. Creatine phosphokinase concentrations in plasma had no significant difference among the dietary groups. Redness ( a* ) was significantly higher in T2 and T3; however, at the first and seventh days of storage, redness ( a* ) was not significantly different between dietary groups. Shear force was significantly higher in dietary glycine betaine groups at the first day of storage. Cholesterol content was significantly lower in T2 and T3, whereas T1 was not significantly different compared with the control group. In fatty acid composition, the ratio of saturated fatty acids was increased, whereas unsaturated fatty acids were decreased by dietary glycine betaine.

PRACTICAL APPLICATIONS

Glycine betaine is an amino acid (trimethylglycine) present in most organisms, and is an obligatory intermediate in the catabolism of choline. Glycine betaine has been reported to affect some aspects of pork qualities. As a result of this study, dietary glycine betaine should improve meat redness and reduce cholesterol. However, dietary glycine betaine did not influence creatine phosphokinase levels in plasma. These results will be helpful to the pork industry and meat scientists for improving meat qaulity.     

Significance of fat supplemented diets on pork quality - Connections between specific fatty acids and sensory attributes of pork

The influence of two diets with different fatty acid compositions has been studied with regard to overall pork quality and significance of specific fatty acids on sensory attributes in fried chops and oven roasts. Twenty castrates and 20 females were in a balanced experimental set-up fed with a standard diet supplemented with α-tocopherol (200mg/kg feed) where the fat source was either 3% of palm oil or 3% rapeseed oil. After slaughter, despite differences in lipid composition and sensory attributes, no significant difference in overall meat quality parameters and flavour precursors was found. Comparison of the two diets showed that supplementation with rapeseed oil resulted in a significantly higher content of C18:3n-3 (polar lipid (PL), neutral lipid (NL)), C18:2n-6c (NL) and C20:2 (NL) in LD and C18:1n-9c, C18:2n-6c, C18:3n-3, C20:3n-3, C22:5n-3 in backfat, while supplementation with palm oil resulted in a higher content of C16:0 (NL), C16:1 (PL), C18:1n-9t (NL) in LD and C16:0, C17:0, C18:0, C16:1, C20:4n-6 in backfat. A positive and significant correlation between the contents of C18:2n-6c, C20:3n-6 in the PL fraction and the sensory attributes fried meat odour and sweet odour were found in fried pork chops from female pigs. Likewise, positive correlations were seen between the content of C18:1n-9c in the PL fraction and sensory attributes such as sourish odour, piggy odour and piggy flavour in whole oven roasts. These data substantiate the view that specific fatty acids in the PL fraction influences flavour attributes in pork.     

Effects of metabolic modifiers on carcass traits and meat quality

Much research has been conducted and published about metabolic modifiers that increase growth rate, improve feed efficiency, increase carcass leanness, and decrease carcass fatness. Most of these metabolic modifiers have been developed to improve efficiency and profitability of livestock production and to improve carcass composition, with fewer of them developed and researched specifically to improve meat quality. Some of the metabolic modifiers can have negative effects on visual and sensory meat quality, especially when not used as recommended. This review evaluates the various kinds of metabolic modifiers that have been researched for their effects on production efficiency, carcass composition, and meat quality. Nutritional composition of meat generally is improved from use of most of the metabolic modifiers, visual quality is improved by others, but some can have a negative effect on marbling and tenderness. Anabolic steroid implants are very cost effective and practical for beef cattle production but aggressive implants used within 70 days of slaughter or too frequent use of them will reduce tenderness and marbling. Somatatropin and approved β-agonists are very effective in improving growth performance and carcass leanness in pigs, and β-agonists are effective in cattle, but improper use of them can have negative effects on marbling and tenderness. Feeding supplemental levels of vitamin E is quite beneficial for improving meat color and shelf-life of beef, lamb, and pork, whereas not supplementing diets with vitamin A has potential for improving marbling in cattle. Immunocastration shows promise for capitalizing on the efficiency of muscle growth of young boars up to a few weeks before slaughter, at which time boar taint is prevented and marbling is improved by immunocastration. Potential exists for improving the fatty acid profile of lipids and increasing conjugated linoleic acid content in beef through dietary manipulation. Supplementing swine diets with conjugated linoleic acid can improve carcass composition of swine, but is not yet cost effective to use. Dietary inclusion of magnesium, manganese, or chromium in diets of pigs and sheep has potential to improve meat color and water-holding capacity. Although, not all of these metabolic modifiers are approved in all countries, proper use of the ones that are approved offers opportunities for economically improving production efficiency and carcass leanness while maintaining acceptable marbling and tenderness, while some provide opportunities to enhance meat color and quality.