Cellular conditions for intramuscular fat deposition in Japanese Black and Holstein steers

The experiment was conducted to study the development of intramuscular fat in Japanese Black (JB) compared to Holstein (HS) steers and to find breed differences for fat depot development and distribution in the carcass under equal feeding conditions. Additional to slaughter samples, biopsy samples of longissimus muscle (LM) and subcutaneous fat, taken at 10, 14, 18, and 22 months of age, were used for histological and molecular investigations. Japanese Black steers stored about 14% more fat in the LM (P = 0.001), resulting in larger marbling flecks (P < 0.001). Muscle fibers and intramuscular adipocytes in both breeds responded to the high energy feeding with significant enlargement, which was faster in JB. Histograms of intramuscular adipocytes size showed a shift toward larger cells during growth, but also the abundance of small, developing adipocytes. This development was accompanied by a correlated up-regulation of adipogenic genes until 22 months of age.     

Meat quality of Angus, Simmental, Charolais and Limousin steers compared at the same intramuscular fat content

Meat quality and marbling properties of Angus, Simmental, Charolais and Limousin steers (4×16) were compared at an average intramuscular fat content (IMF) of 3.25% in the M. longissimus dorsi. The steers were fattened on a forage-based diet until the desired, ultrasonically estimated IMF content was reached which resulted in considerably different growth and carcass characteristics. The Angus group showed a growth rate similar to Simmental and Charolais while Limousin grew slower, became oldest and provided the heaviest carcasses and best conformation. Angus carcasses showed the lowest weight but the highest fatness score. Marbling was equal for all breeds. Angus and Charolais provided pale meat with low haem iron content. Angus and Limousin beef was more tender on sensory assessment than Simmental beef, corresponding to differences found in shear force (non-significant) and myofibrillar fragmentation index measured at 48 h post mortem. Flavour was similar among breed groups while juiciness was highest for Limousin and lowest for Angus. The juicier beef simultaneously showed the highest drip but the lowest cooking losses. In conclusion, clear differences in meat quality were observed between breeds despite similar IMF contents.     

Effect of pasture finishing on the meat characteristics and intramuscular fatty acid profile of steers of the Rubia Gallega breed

The Rubia Gallega cattle breed is the most important stock for beef production in Spain. A study about the influence of feeding systems on beef quality is needed. Comparison of the effect of a pasture finishing system and an indoors finishing system (maize silage and concentrate) on the meat quality and intramuscular fatty acid profile of Rubia Gallega steers (slaughter age 30 months) was determined using samples of Longissimus thoracis muscle. There were no differences between treatments in meat pH, drip loss, water holding capacity, cooking loss and muscle colour. Meat from pasture-fed steers was more tender than meat from indoors finished ones at 24 h post-mortem, but differences disappeared at 7 days. Subcutaneous fat of grass-fed steers showed higher yellowness at 24 h and 7 days post-mortem and lower brightness at 7 days post-mortem than indoors finished ones. Intramuscular fat of indoors finished steers presented higher concentrations of C18:2 and a less favourable ratio of n-6/n-3 polyunsaturated fatty acids than pasture finished steers.     

Effect of a high dose of CLA in finishing pig diets on fat deposition and fatty acid composition in intramuscular fat and other fat depots

Sixteen gilts were fed a control (4% of sunflower oil) or an experimental diet (4% conjugated linoleic acid (CLA) oil). CLA had no effect on intramuscular fat (IMF) content neither in longissimus thoracis (LT) nor in semimembranosus (SM) muscles but increased liver weight, reduced perirenal fat and tended to reduce backfat between the last 3th–4th lumbar vertebrae. Despite the fact that 9c,11t and 10t,12c CLA isomers were included in the same proportion in the diet, the 9c,11t and 9c,11c were the isomers more deposited in all tissues. Addition of CLA in the diet affected fatty acid composition in a tissue specific manner, increasing percentages of SFA in all tissues, reducing percentages of MUFA in LT and LT subcutaneous fat, and of PUFA in LT subcutaneous fat, liver and SM. The FA modification by dietary CLA in LT IMF was reflected in the different lipid fractions, SFA and MUFA mainly in the neutral lipid fraction, and PUFA in the polar fraction.     

Interactions between genotype,dietary fat saturation and vitamin A concentration on intramuscular fat content and fatty acid composition in pigs

The effect of dietary fat saturation (dFat) and dietary vitamin A (dVitA) level (0 IU vs. 100,000 IU) on performance, carcass characteristics and fatty acid composition in the offspring of two terminal sires: Duroc (DU) and Landrace × Large White (LD × LW) was studied. In the inner backfat layer, the DU-sired pigs had higher C16:0 proportion (P < 0.05) and tended (P < 0.07) to have higher total saturated fatty acids (SFA) and lower C18:1 n-9 proportions than LD × LW-sired pigs. An interaction sire line × dVitA was observed for intramuscular fat (IMF) content (P < 0.005). The effect of supplementation with the high dVitA level in DU-sired pigs was associated with a 20% increase in IMF while no effect was observed in LD × LW pigs. Fatty acid pattern was affected by dFat and sire line. In the inner backfat layer, LD × LW-sired pigs receiving the low dVitA level increased C18:0 proportions by 8% in comparison to animals receiving the high dVitA, whereas in DU-sired pigs the effect of vitamin A was opposite. It is concluded that the effect of dFat and dVitA concentration on IMF content and fatty acid profile of subcutaneous backfat and IMF is variable according to pig genotype.     

Effect of body fat distribution on the fatty acid composition of the depot fat of cattle

The influence of liveweight, total carcass fat and the amount of fat at five specific anatomical locations on the fatty acid composition of the depot fat of adult ruminants was examined. The total carcassfat and the amount offat at specific locations seem to affect the fatty acid composition significantly. No important significant correlation between liveweight and fatty acid composition was found. There was an increase in odd, even and branched chain fatty acids, and a decrease in linoleic acid, with increase in animal age.     

Genetic and nutritional effects on the fatty acid composition of subcutaneous and intramuscular lipids of steers

Genetic and nutritional influences on fatty acid composition of subcutaneous (SNL) and intramuscular neutral lipids (IMNL) and intramuscular phospholipids (IMPL) of steer carcasses were investigated by removing the effect of carcass fat percentage (CFP) or slaughter age (SA) on the fatty acid composition. To investigate the genetic influences, steer progenies from two dam breed-types (Japanese Black (JB) and f(1) between JB bull and Holstein cows) and three different maturing types of JB sires were used. Dam breed-type did not affect any of the fatty acids except 17:0 in SNL and none of those in IMNL. Percentages of 16:0, 16:1, 18:2, SFA, MUFA and PUFA in SNL differed among sires of JB dam breed-type group (p < 0.05) even after removing the effect of CFP. Studies on the effects of two nutritional planes [high(H) and medium-high(MH)] on the fatty acid composition of SNL, IMNL and IMPL were done using JB steers. The SNL and IMNL of the H plane steers contained greater percentages of saturated fatty acids at the same CFP but less at the same SA than the MH plane animals. The reverse was true for the unsaturated fatty acid contents.     

CLA对体脂和癌症的影响及作用机理

CLA具有多种生物学功能,其中对体脂和癌症的影响尤为显著.CLA主要通过影响脂肪转运、代谢和储存的关键酶来降低体脂和改变体脂中脂肪酸的组成;通过抑制血管的生长、诱导癌细胞凋亡、影响细胞间隙连接通讯、抑制蛋白质和核酸的生物合成、降低DNA加合物的形成、增强机体免疫力和抗氧化能力以抵抗癌症的发生.     

Effect of dietary energy content on the intramuscular fat depots and triglyceride composition of river buffalo meat

The production of river buffalo meat in Italy has long been under discussion due to poor acceptance by consumers. In order to understand whether dietary energy content may affect the organoleptic characteristics of buffalo meat, two groups of river buffalo calves were fed on two diets, with high (H) and low (L) energy contents. The animals were slaughtered at 4-monthly intervals starting from 6 months old (10, 14 and 18 months) and five muscles were dissected on the half-carcass: Caput longum tricipitis brachii (CloTB), Gluteobiceps (Gb), Semitendinosus (St), Semimembranosus (Sm) and Longissimus dorsi (LD). The results showed that from 6 to 10 months of age the meat lipid content decreases and protein content increases for both diets. The lipid content increases slowly with both diets from 10 to 14 months. In the last experimental period (from 14 to 18 months) an increase in the percentage of lipids with diet H and a decrease with diet L was observed. At all slaughtering ages the meat from the animals fed on diet H had a higher energy content. The different energy content of the two diets did not significantly influence the composition of triglycerides only formed by SFA and triglycerides with a higher degree of unsaturation. The triglycerides with an unsaturated fatty acid in position sn 2 did not show the same behaviour in relation to age and diet. The energy content of the feed did influence the unsaturated fatty acid composition: MUFA increased with an increased energy level of the diet, while PUFA increased with a reduction in the energy level of the diet. The muscle LD showed a significantly higher (P<0.05) content of SFA and lower (P<0.05) of MUFA and PUFA than the other muscles. On the basis of our results, the better TAG's composition is found in the meat of animals fed on diet H and slaughtered at 4 months of age.     

肌内脂肪与背最长肌肉质、脂肪酸组成的关系

研究肌内脂肪（IMF）含量与肉质以及脂肪酸含量和组成比例之间的关系。以北京黑猪背最长肌（n=20）为实验材料,测定肌内脂肪含量、肉质以及脂肪酸含量和组成。结果显示,肌内脂肪含量与滴水损失呈显著正相关（p<0.05）,与蒸煮损失、剪切力、肉色的相关性不显著（p>0.05）。随着肌内脂肪含量升高,除长链多不饱和脂肪酸(C_20:3n6、C_20:4n6)以外的大多数脂肪酸含量增加,相对比例也上升;多不饱和脂肪酸的含量增加,但是相对比例下降;长链多不饱和脂肪酸的含量和相对比例都降低。随着肌内脂肪含量的升高,饱和脂肪酸（SFA）和单不饱和脂肪酸（MUFA）的含量升高,回归方程斜率分别为197.3和248.31,多不饱和脂肪酸（PUFA）增加的幅度不大,回归方程的斜率为11.43。结果提示:肌内脂肪含量较低时（本实验平均值2.86%）,对肉质的影响不显著。随着肌内脂肪含量升高,总脂肪酸含量（TFA）增加,主要归因于SFA和MUFA含量的增加。PUFA的含量相对稳定,受肌内脂肪含量变化的影响较小。      

金华火腿中肌内脂肪的提取和脂肪酸分析研究

通过正交实验,确定金华火腿中肌内脂肪的最佳提取条件是:氯仿和甲醇(2:1,v/v)的用量为样品重量的14倍,振荡1.5h,取滤液加其1/2体积的1%NaCl溶液.处理60d的金华火腿中肌内脂肪的含量为12.4%,甘油酯、磷脂、游离脂肪酸分别占76.5%、18.8%、4.7%.甘油酯中单不饱和脂肪酸的含量最高,为47.89%;而磷脂中多不饱和脂肪酸的含量最高,为50.94%;游离脂肪酸中则含有较多的饱和脂肪酸(41.56%).甘油酯、磷脂和游离脂肪酸中都是以C16.0、C18:1、C18:2为主要成分.     

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

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

肌内脂肪细胞生长及调控因子的研究进展

肌内脂肪沉积是决定肉质风味、嫩度等的关键因素。一般认为,肌内脂肪细胞与肌细胞在发育中相互作用,并且肌内脂肪的生长与肌肉的生长速率和肌纤维类型密切相关。近年来,Wnt蛋白、HSPB1和Zfp423被认为是影响肌内脂肪沉积、肌内脂肪细胞和肌细胞相互作用的关键因子,对肌内脂肪细胞的生长及改善肉品质有重要作用。本文主要探讨了肌内脂肪与肉品质的关系,对肌内脂肪细胞与肌细胞相互作用进行阐述,并对影响肌内脂肪沉积的关键因子作一简要综述,为改善肉品提供理论依据。      

Lipid composition and nutritional quality of intramuscular fat in Charneca-PDO beef

This paper characterizes the intramuscular fat from longissimus lumborum (LL, relatively red) and semitendinous (ST, relatively white) muscles of Charneca beef from young bulls reared according to the protected designation of origin (PDO) specifications. The content of total lipids, total cholesterol, α-tocopherol and β-carotene, as well as the fatty acid composition, including the isomeric distribution of conjugated linoleic acid (CLA), was assessed. Charneca young bulls (n = 10) were raised on a semi-extensive production system, in which animals fed pasture plus concentrate during 15 months. The ST muscle was leaner and had higher percentages of PUFA, in contrast to the LL muscle, which presented higher percentages of SFA and MUFA. Thus, the ST muscle had a higher PUFA/SFA ratio than the LL muscle, although the ratio values of both muscles were inside the recommended figures for the human diet. In contrast, the contents of CLA isomers, total cholesterol, α-tocopherol and β-carotene, as well as the n-6/n-3 ratio, were not influenced by muscle type, thus suggesting no carcass variation for these compounds. In both muscles, the n-6/n-3 ratios were slightly above the dietary guideline for human diet, and the contents of α-tocopherol were very high, indicating a good lipid stability of Charneca-PDO beef. Overall, the results suggest that intramuscular fat of Charneca-PDO beef has good human health–related parameters, with small carcass variation, since the PUFA/SFA and n-6/n-3 ratio values are inside or very close to the recommended figures for the human diet, and the content of α-tocopherol is very high.     

Prediction of total body lipid from total body water in rats. Part 1. Relations between directly measured major body components

Aimed to the construction of a prediction equation for estimations of lipid content from animal water content body composition was determined by whole body analysis of male rats (1) given access, ad libitum, to a commercial standard diet (n = 144; ranging from 60 to 600 g in weight, and from the 4th to the 34th week of age), and (2) showing striking variations with regard to nutritional state, dietary history, enlarged fat deposition, genetic origin, intestinal microbial status, and advanced age (n = 75). It was shown that a unique coefficient of water content in lipid-free body mass does not exist. The results of statistical analysis for the grouped values of percentage body dry matter (x) and percentage body lipid (y) indicate that the latter can be estimated accurately from body water content directly determined by the use of the quadratic regression equation y = ?0.2864×+0.01615 x² with a standard deviation of the procedure s_y = ±1.40. This prediction equation is valid for a wide developmental span even under highly different experimental states. Differences between the calculated body lipid contents vs. analytically determined values are smaller than by using a linear regression equation or coefficient(s) of hydration of lipid-free body mass.     

Genetic relationships between calving interval and body condition score conditional on milk yield

Body condition score (BCS) is a useful tool in assessing the energy status of dairy cattle. Previous research has shown that it is heritable and genetically correlated to reproductive performance. Currently, interest exists in developing selection indexes for fertility that include BCS information. Before such indexes are developed, it is important to assess the genetic covariance between BCS and fertility after fully accounting for the covariance of both traits with milk yield, as indices to predict selection responses require knowledge of these (co)variances. In the present study, calving interval (CI) was used as a measure of reproductive performance. The genetic correlations between BCS and CI before and after genetically adjusting for milk yield were -0.48 and -0.22, respectively. Thus, cows with low BCS have longer CI, which is exacerbated by high levels of milk production. Using selection index theory, we showed that selecting for milk yield alone will result in an increase of 768 kg of milk, an increase of 4.46 d in CI and a reduction of 0.41 BCS units for every standard deviation change in the index. Restricting BCS to no genetic change, whereas still selecting for milk yield will result in an increase of 653.1 kg of milk per standard deviation of the selection index. However, CI will still continue to increase at a rate of 3.20 d per standard deviation of the selection index. The selection indices used here are not optimum, in that they are not economically driven and do not consider all traits that contribute to profitability. However, they demonstrate that, even though restricting BCS may be seen as an attractive way of limiting reliance of body tissue mobilization to fuel milk production, this is unlikely to result in improvements in CI, although the rate of increase in CI will be reduced.     

Seasonal changes and muscle type effect on the nutritional quality of intramuscular fat in Mirandesa-PDO veal

The influence of slaughter season and muscle type on the detailed fatty acid composition, including conjugated linoleic acid isomers, and contents of total cholesterol and lipid-soluble antioxidant vitamins (α-tocopherol and β-carotene) in Mirandesa-PDO veal was assessed. Mirandesa purebred calves (n = 29) were raised in a traditional production semi-extensive system, slaughtered in late spring (June) or early autumn (October) and the longissimus lumborum and semitendinosus muscles were sampled for analysis. Although the lipid composition of PDO veal was only slightly affected by the slaughter season, it was markedly changed by the muscle type. However, PDO veal had values of pasture-fed cattle for lipid grass intake indicators, in both seasons and muscles. From a human health standpoint, intramuscular fat in Mirandesa-PDO veal has a high nutritional value throughout the year, with favorable ratios of n− 6/n− 3 and contents of n− 3 PUFA and α-tocopherol, as a result of the beneficial effects of grass feeding.     

Prediction of total body lipid from total body water in rats. Part 1. Relations between directly measured major body components.

Aimed to the construction of a prediction equation for estimations of lipid content from animal water content body composition was determined by whole body analysis of male rats (1) given access, ad libitum, to a commercial standard diet (n = 144; ranging from 60 to 600 g in weight, and from the 4th to the 34th week of age), and (2) showing striking variations with regard to nutritional state, dietary history, enlarged fat deposition, genetic origin, intestinal microbial status, and advanced age (n = 75). It was shown that a unique coefficient of water content in lipid-free body mass does not exist. The results of statistical analysis for the grouped values of percentage body dry matter (x) and percentage body lipid (y) indicate that the latter can be estimated accurately from body water content directly determined by the use of the quadratic regression equation y = -0.2864 x +0.01615 x2 with a standard deviation of the procedure Sy = +/- 1.40. This prediction equation is valid for a wide developmental span even under highly different experimental states. Differences between the calculated body lipid contents vs. analytically determined values are smaller than by using a linear regression equation or coefficient(s) of hydration of lipid-free body mass.