Lower Intramuscular Fat Content Research Articles

The Relation Between Intramuscular Fat Level in the Longissimus Muscle and the Quality of Pig Carcasses and Meat

Abstract This study evaluated the effect of intramuscular fat (IMF) content on the quality of pig carcass and meat. One hundred and twenty right half-carcasses of crossbred pigs (Pietrain × Duroc boars and Polish Large White × Polish Landrace sows) from a commercial farm were divided into two groups depending on the content of IMF in the longissimus muscle (LM): LIMF - lower content (mean 2.05% IMF; 28 gilts and 30 barrows) and HIMF - higher content (mean 3.08% IMF; 32 gilts and 30 barrows) were used. Pigs with a higher IMF content in LM (HIMF group) had a significantly lower (P≤0.01) percentage of lean meat in carcass, loin muscle area, level of polyunsaturated fatty acids (PUFAs) and PUFAs/SFAs ratio, whereas backfat thickness, content of cholesterol in LM, levels of saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) were significantly greater (P≤0.01) than those in pigs with lower IMF content (LIMF group).

Low intramuscular fat (but high in PUFA) content in cooked cured pork ham decreased Maillard reaction volatiles and pleasing aroma attributes

The influence of intramuscular fat content (high – HI versus low – LI) and fatty acid composition on pork cooked cured ham flavour was analysed by gas chromatography–olfactometry using nasal impact frequency (GC–O/NIF) and quantitative descriptive analysis (QDA). Potential relationships were studied by principal component analysis (PCA). Sixteen and fourteen odourants were identified by GC–O/NIF in LI and HI cooked hams, respectively. The two ham types differed in lipid oxidation odourants: polyunsaturated fatty acid (PUFA) derivatives hexanal, 1-octen-3-one and (E,E)-2,4-decadienal were higher in LI ham; while monounsaturated fatty acid (MUFA) derivative decanal was higher in HI. HI samples resulted in higher values for odour-active aroma compounds from Maillard reaction, which are related to roast flavour and a higher overall flavour liking. In summary, our results suggest that Maillard derived odour-active aroma compounds were partially inhibited in LI samples (high in PUFA), resulting in lower positive sensory ratings.

Impacts of genetic selection in meat quality of pigs

Advances in breeding pigs that have occurred in recent years have led to an increase in weight gain, decreased feed conversion and back fat thickness in swine. But this intense selection has caused some negative impacts on the final quality of the meat. The objective of this work was discussing the impact of genetic selection on the meat quality characteristics of pigs. Halothane gene carrier animals have lower meat quality, since this gene is related to the onset of PSE meat (pale, soft, exudative) presenting pale and low water retention capacity, one type of meat is not well accepted in the market because of their visual and organoleptic characteristics. The gene meat acidic pH promotes reduction in final pH meat around 5.4, which causes decrease in yield during the industrial processing and cooked cured products. The type of muscle fiber also affects the quality of meal; modern pigs have a higher proportion of modern glycolytic fibers, so meat lighter and less ability to retain water. The marbling is one of the main features related to tenderness and juiciness, but notes that breeds with high meat yield, have lower intramuscular fat content. Thus genetic selection for increasing the quantity of meat in the carcass led to a decrease in the rate of marbling. We conclude that it is important to have a breeding program aimed not only for the quality of housing, but also meets the requirements for better meat quality.

Effect of sex and slaughter weight on meat and fat quality of the Krškopolje pig reared in an enriched environment

Improvements in meat quality are sought through sources of variation along the meat chain, including breed and production system. Hence, the aim of this study was to determine slaughter weight and sex effects on the meat quality of the indigenous Krškopolje pig breed reared in a feed-enriched indoor environment for the growing-finishing periods. Raised in this enriched environment, the intramuscular fat (IMF) content of the loin was 1.5–2.5% higher than previously reported for other production systems. Slaughter weight (119–132 kg or >135–170 kg) influences on meat colour and IMF composition were observed. Animals from the light group had lighter coloured meat with lower Japanese colour scores as well as higher saturated fatty acid (SFA) and lower monounsaturated fatty acid (MUFA) proportions in the IMF. A lower proportion of MUFA was also observed in the IMF from gilts than barrows. Furthermore, a higher proportion of SFA was found in the IMF from the gilts. However, the lower IMF content in the gilts negates any apparent compositional advantages between the sexes. The IMF content and composition of the Krškopolje pig reared in an enriched environment suggests good commercial potential of this breed.

Effects of high hydrostatic pressure on the quality and safety of beef after the addition of conjugated linoleic acid

Abstract We evaluated the effect of high pressure (HP) for infusing of conjugated linoleic acid (CLA) on the quality and storage stability of beef loin. To beef loins in a bag before sealing, CLA alone (1%; CLA), CLA + 0.15% lecithin (CL), or CL + 0.001% α-tocopherol (CLT) were poured into the bag, vacuum-packed, and HP-treated with 0.1, 300, 450, and 600 MPa for 5 min. CLA level, cooking loss, and pH were significantly increased, when pressure increased from 0.1 to 600 MPa. Increases in pressure levels and storage periods increased TBARS about 1.04 and 3.85 fold values. Total aerobic bacteria were not detected in HP treated samples (450 and 600 MPa). CL or CLT with HP (300 MPa) caused higher overall acceptance and willingness to buy. Hence, the addition of CLA with HP (300 MPa) can improve the nutritional and microbiological quality of beef loin with acceptable sensory quality. Industrial relevance High pressure (HP) processing is a safe and consumer-friendly preservation technology that can eliminate pathogenic and spoilage microorganisms and extends product shelf-life without detrimental effects of thermal processing or use of preservatives or additives. However, meat with lower intramuscular fat content can be rejected by some consumers due to the lack of suitable sensorial qualities. On the other hand, meat with higher intramuscular fat content, beef in particular, may also cause consumers' concern because of the elevated level of saturated fatty acids. This particular study demonstrated that HP in combination with the infusion of CLA can be used for the enhancement of nutritional and microbiological quality of beef. Based on the results, it can be suggested that not only the infusion of CLA but also other oils originated from plants in combination with HP treatment can modify fatty acid composition.

Effects of β-agonist zilpaterol hydrochloride feeding and supplementation period on growth and carcass characteristics of Lori-Bakhtiari lambs

Fifty six Lori-Bakhtiari feedlot lambs (initial BW=44±4.7kg) were used in a 2×3+1 factorial experimental design to evaluate the effects of 3 feeding regimens of zilpaterol hydrochloride (ZH) for the last 28 and 42dbefore slaughter on growth performance, carcass characteristics and some plasma metabolites. The continuous feeding of ZH (daily regimen), intermittent 1d feeding ZH followed by 1d of withdrawal (1 on 1 off regimen), and intermittent 2d feeding ZH followed by 2d of withdrawal (2 on 2 off regimen) were employed as the different regimens. The lambs were assigned to one of seven treatments (8 lambs/treatment) based on initial BW. Lambs were fed a diet formulated to contain 14% CP and 2.45Mcal/kgDM of metabolizable energy (ME) supplemented with 0.2mg ZH/kg of live weight d−1. The basal diet without ZH was the added control group. Lambs fed ZH continuously for 28d had higher (P<0.001) feed efficiency compared to the control group and other intermittent regimens. Neither feeding regimen nor period had any significant effect (P>0.05) on final BW, total weight gain, average daily gain and dry mater intake. Hot and cold carcass weights and dressing percentage were greater for daily feeding for either 28 or 42d and for the 1 on 1 off-42d treatments than for the control and the other groups fed ZH (P<0.05). Longissimus dorsi muscle area was increased (P<0.01) by daily-28d compared to the control. Back fat thickness tended to be lower (P=0.063) in pooled ZH-treated groups whereas there was no effect of ZH on the proportion of final weight of the fat-tail. Daily-28d and 1 on 1 off-42d groups had lower intramuscular fat content (P<0.01) than the control group. Plasma concentrations of urea were decreased (P<0.05) in daily-28/42d groups compared to the control. Also, there were lower concentrations of urea after 42d of ZH feeding compared to 28d of ZH feeding (P<0. 05). Overall, feeding ZH in daily for either 28 or 42d before slaughter as well as for 42d on alternate days improved feed efficiency ratio and some carcass characteristics. While backfat tended to be decreased by ZH there was no effect on fat-tail in Lori-Bakhtiari lambs.

Effect of Ensiled Mulberry Leaves and Sun-Dried Mulberry Fruit Pomace on Finishing Steer Growth Performance, Blood Biochemical Parameters, and Carcass Characteristics

Fifty-one Simmental crossbred steers (357.0±16.5 kg) were used to compare a standard total mix ration (TMR) with variants on animal performance, ruminal fermentation, blood biochemical parameters, and carcass characteristics. Corn grain and cotton seed meal were partially replaced by ensiled mulberry leaves (EML) or sun-dried mulberry fruit pomace (SMFP). Experimental diets had similar amounts of crude protein (CP), acid detergent fiber (ADF), and metabolizable energy (ME). Animals were divided into three groups: control group (CONT), 8% EML group, and 6.3% SMFP group. Performance, including average daily weight gain (ADG), and dry matter intake (DMI), was measured. Blood and rumen samples were collected at the end of the experiment (16 weeks). There were no differences in final body weight (P = 0.743), ADG (P = 0.425), DMI (P = 0.642), or ADG/DMI (P = 0.236) between the groups. There were no differences (P = 0.2024) in rumen pH values; ammonia N was lower (P = 0.0076) in SMFP than in the EML and CONT groups. There were differences in the concentrations of total and individual volatile fatty acids, while no differences were determined in blood biochemical parameters (i.e., plasma glucose, urea concentrations, triglycerides, total protein, insulin, IgG, alanine transaminase, and aspartate aminotransferase, P ≥ 0.098). No differences were observed in carcass characteristics (P ≥ 0.513), tenderness (P = 0.844), adipose and lean color values (P ≥ 0.149), and chemical composition (P ≥ 0.400); however, intramuscular fat was lower in the EML and SMFP groups compared to the CONT animals (P = 0.034). In conclusion, diets supplemented with these two mulberry products in an isocaloric and isonitrogenous manner have similar effects to corn grain and cotton seed meals on steer performance, blood biochemical parameters and carcass characteristics, with the exception of ruminal VFA concentrations and lower intramuscular fat content.

Transcriptional background of beef marbling — Novel genes implicated in intramuscular fat deposition

The purpose of this study was to identify novel marbling-related genes by comparison of the global gene expression in semitendinosus muscle of 15-month-old Limousin (LIM), Holstein-Friesian (HF) and Hereford (HER) bulls. Muscle of LIM was lean with low intramuscular fat (IMF) content (0.53%) unlike the marbled muscles of HER and HF characterized by higher amounts of IMF (1.10 and 0.81%, respectively). The comparison of muscle transcriptional profile between marbled and lean beef revealed significant differences in expression of 144 genes, presumably involved in consecutive stages of adipose tissue development, such as preadipocyte proliferation and differentiation, adipocyte maturation, lipid filling and lipid metabolism leading to increased IMF deposition and marbling development. Correlation coefficients and regression analysis for nine of them (gadd45a, pias3, ccrn4l, diras3, pou5f1, hoxa9, atp2a2 and pim1) validated by real-time qPCR confirmed their moderate-high correlation with IMF% and explained up to 70.5% of the total variability in IMF deposition in the bulls.

Comparison of carcass yields and meat quality between Baicheng-You chickens and Arbor Acres broilers

This study examined carcass yields and meat quality traits between Baicheng-You (BCY) chickens and Arbor Acres (AA) broilers. Thirty birds for each strain were selected and slaughtered at market ages of 49 d for AA broilers and 120 d for BCY. The results showed that BCY chickens had lower dressing (2.99%), semi-evisceration (5.10%), breast muscle (5.80%), and abdominal fat (1.55%) than those for AA broilers (P < 0.05). However, the leg muscle (%) of BCY chickens was greater (3.14%) than that of AA broilers (P < 0.05). The meat pH45min and pH24h value variations of these 2 breeds were within the normal range (5.53-6.70). The meat color density (optical density, OD) of thigh muscle was darker than breast muscles in both strains (P < 0.05). The cooking loss (%) of breast and thigh muscles of BCY chickens (18.81 and 20.20%, respectively) was also significantly lower (P < 0.05) than that of same muscles of AA broilers (26.41 and 27.33%, respectively). The shear force of breast meat in both breeds was lower (P < 0.05) than that of their thigh meat. The moisture of breast muscle of BCY chickens (72.93%) was lower (P < 0.05) than breast muscles of AA broilers (74.43%). The CP content of breast muscles was greater (P < 0.05) than its thigh muscles of same strain, but it had no significant (P > 0.05) difference of CP content in the same muscles of the 2 strains. The intramuscular fat (IMF) content was greater (P < 0.05) in thigh muscles of BCY chickens (6.80%) than those of AA broilers (4.28%), and inosine-5'-monophosphate (IMP) content was greater (P < 0.05) in breast and thigh muscles of BCY chickens (IMP: 3.79 and 1.47 mg/g) than same muscles in AA broilers (1.42 and 0.47 mg/g). In this study, muscle from 120-d-old BCY chickens was judged to have better quality traits with regard to cooking loss, drip loss, contents of IMF, and IMP compared with meat from 42-d-old AA broilers. At the same time, greater carcass yields, greater thigh pH24, and lower IMF content were observed in AA broilers compared with the BCY chickens.

Effect of pig breed and dietary protein level on selected fatty acids and stearoyl-coenzyme A desaturase protein expression in longissimus muscle and subcutaneous fat1

The aims of the study were 1) to investigate effects of a low protein diet on fatty acids content and composition of the LM and subcutaneous adipose tissue in 3 genetically diverse breeds, Large White × Landrace, Alentejano, and Bizaro, and 2) to determine whether the effect of the low protein diet of fatty acid composition is associated with dietary modulation of stearoyl-CoA desaturase (SCD) protein expression. The experiments were conducted on 12 Large White × Landrace, 12 Alentejano, and 10 Bízaro female and male pigs. The average animal BW at the beginning of experiments was 40.8, 40.7, and 38.3 kg for Large White × Landrace, Alentejano, and Bízaro, respectively, and the BW of animals at slaughter was 90 kg. The diets contained 202 or 169 g/kg DM of CP (high and low protein diets, respectively) and were balanced in essential AA. The diets were fed until the animals reached 90 kg BW (approximately 73 d). It was established that Large White × Landrace pigs had a less (P = 0.001) total fatty acid content in subcutaneous adipose tissue when compared with Alentejano and Bízaro and less (P < 0.001) intramuscular fat (IMF) content when compared with Alentejano. There was a positive relationship between SCD protein expression in the LM and MUFA content (r = 0.627, P = 0.029) and SCD protein expression and total muscle fatty acids content (r = 0.725, P = 0.008) in Large White × Landrace but not in Alentejano and Bizaro breeds. It has been suggested that SCD protein expression is associated with regulation of fat deposition only in breeds with genetic predisposition to a low IMF content.

Amino acid and nucleotide contents and sensory traits of dry-cured products from pigs with different genotypes

The free amino acid and nucleotide contents of dry-cured ham, shoulder and loin from two genetic lines selected from pigs according to the paternal allele (homozygous AA and heterozygous AG) of the insulin-like growth factor-II gene were studied by HPLC. Their influence on the flavor and taste characteristics was also studied. The increase of lean content caused by the IGF-II mutation could affect proteolysis during the ripening process and therefore the sensory characteristics. The lower intramuscular fat content in the AA ham batch had a positive effect on the free amino acid content. However, similar flavor traits between ham batches were found, but the AG loin batch showed greater value. The enhancing effect of the IMP on the overall flavor intensity was limited by the amino acid and the IMF contents in dry-cured ham and loin, while in dry-cured shoulder, the IMP could be the reason for the significant differences in after taste and cured flavor scores.

Effect of slaughter weight and breed on instrumental and sensory meat quality of suckling kids

The effects of breed and slaughter weight on chemical composition, fatty acid groups, texture, and sensory characteristics of meat of 141 suckling male kids from 5 Spanish breeds were studied. There was a decrease in texture and lightness and hue angle with the increase of the slaughter weight. Fatty acid composition was correlated with the intramuscular fat content. All the breeds except MO had values of n−6/n−3 ratio below 4, which is the healthy limit recommended, and a low atherogenic index as well as a low intramuscular fat content. A multivariate analysis discriminated light kid, which had the most tender and juicy meat, from heavy kid which had more intense kid and milk odours. Blanca Andaluza and Pirenaica had most tender and juicy meat. The effect of slaughter weight on meat traits should be considered separately for each breed to find the most appropriate meat according to consumers preferences.

Effect of low- and high-forage diets on meat quality and fatty acid composition of Alentejana and Barrosã beef breeds

This study investigated the effects of genotype and diet on meat fat composition and palatability obtained from Alentejana (AL) and Barrosã (BA) breeds. Herein, 20 males from each breed allocated at 11 months of age were fed ad libitum a low-forage diet or a high-forage diet and slaughtered at 18 months of age. Trained sensory panel analysis found that the longissimus lumborum (Ll) muscle from BA had higher tenderness, juiciness and overall acceptability scores than the AL breed. The highest scores for those attributes were observed in the BA breed fed the high-forage diet. Regarding the semitendinosus (St) muscle, breed was a source of variation of tenderness scores. In contrast to the Ll muscle, the highest tenderness scores for the St muscle were observed in the AL breed. The intramuscular fat (IMF) content was positively correlated with tenderness, juiciness and overall acceptability in Ll muscle and negatively correlated with flavour in the St muscle. The levels of 14:0 and 16:0, 16:1c9, 18:1c9 and 18:1c11 were positively correlated to juiciness, tenderness and overall acceptability in the Ll muscle. These correlations were not observed in the St muscle, which may be related to its low IMF content. Nonetheless, negative correlations were observed for the St muscle between flavour and 14:0, 16:0 and 18:0 FA contents.The IMF varied widely in the Ll but not in the St muscle. The latter had higher levels of 16:1c9 and trans fatty acids (∑TFA) in the BA than in the AL breed. Regarding the Ll muscle, the BA had higher amounts of 14:0, 16:0, 16:1c9, 18:0, 18:1c9, 18:1c11, saturated fatty acids (∑SFA), cis monounsaturated fatty acids (∑cis MUFA), ∑TFA and n-3 polyunsaturated fatty acids (∑n-3 PUFA) than the AL breed. The diet exerted an influence on the IMF content and on the levels of 14:0, 16:0, 16:1c9, 18:0, 18:1c9, 18:1c11, ∑SFA, ∑cis MUFA and ∑TFA in both Ll and St muscles. Moreover, the levels of ∑n-3 PUFA in the Ll muscle and 18:2n-6, 20:4n-6, ∑n-6 PUFA and ∑PUFA in the St muscle were influenced by diet. The results obtained in this study, with two Portuguese breeds, confirm that genetic background plays a major role in the determination of meat eating quality.

The mRNA of lipin1 and its isoforms are differently expressed in the longissimus dorsi muscle of obese and lean pigs

Lipin1 has been documented to play an important role in adipogenesis. In the present study, the mRNA expression level of lipin1 and its isoforms in longissimus dorsi muscle were determined by semi-quantification RT-PCR in lean PIC and obese Rongchang pigs. Further, we determined mRNA expression for lipin1 and its two isoforms in Rongchang obese pigs which had either a high or low intramuscular fat content. We demonstrate for the first time that porcine lipin1 has two alternative forms, lipin-α and lipin-β. Unlike mice and humans where the lipin-β has 99 more nucleotides than lipin-α, we found that in swine, lipin-β has 108 more nucleotides than lipin-α. Our results indicate that the longissimus dorsi muscle of Rongchang obese pigs have a higher level of mRNA expression for lipin1 and its isoforms than PIC lean pigs. Furthermore, Rongchang pigs with higher intramuscular fat content had a higher lipin1 and lipin-β mRNA expression in longissimus dorsisi muscle than Rongchang pigs with lower intramuscular fat content (P<0.05), whereas no difference was seen in lipin-α mRNA expression between Rongchang pigs with high or low intramuscular fat. The ratio of lipin-β mRNA to lipin-α mRNA was also significantly different between Rongchang pigs distinguished by a high intramuscular fat content compared with those with low intramuscular fat (P<0.05). These data suggested that the lipin1 gene may have a crucial effect on body lipid accumulation in pigs, whereas the lipin-β isoform may play an important role in intramuscular fat deposition in obese pigs.

The effect of seasonality of the growing–finishing period on carcass, meat and fat characteristics of heavy barrows and gilts

A trial was conducted to study the effect of gender (barrows; gilts) and seasonality of growing–finishing period (S, summer; W, winter) on the carcass and meat characteristics and fatty acid (FA) profile of subcutaneous fat of pigs slaughtered at 131 kg of body weight. No significant gender × seasonality interaction was detected and the differences between genders were scarce. The S pigs had a 13.2% thinner fat depth over the Gluteus medius muscle and a higher yield of shoulders and loins by 10.6% and 10.0%, respectively than W pigs. Meat from S pigs had 32.5% lower intramuscular fat content and higher cooking losses (9.1%) and shear force (6.4%) than meat from W pigs. Subcutaneous fat from S pigs had a 7.8% higher percentage of saturated FA and 4.9% lower monounsaturated FA than that from W pigs. It is concluded that in Spanish natural-environment facilities, the seasonality of the growing–finishing period affects the carcass, and meat and fat quality of heavy pigs.

Nutrient composition and technological quality of meat from alpacas reared in Peru

The aim of this study was to increase the knowledge on alpaca meat quality characteristics. Twenty Huacaya breed alpacas, reared under a traditional unspecialized production system at the Andean region of Peru, were slaughtered at ages between 18 and 24 months. Analyses were carried out on Longissimus thoracis and lumborum muscle ( LTLM), unless otherwise specified. These included composition parameters: moisture, fat, protein, ash, minerals, amino acids, fatty acid profile (of both LTLM and perirenal fat), retinol and tocopherol concentrations and myoglobin and collagen contents. Other meat quality parameters were evaluated: pH, colour, water holding capacity and Warner–Bratzler shear-force. Alpaca LTLM was characterized by a low intramuscular fat content and mineral and amino acid compositions, polyunsaturated to saturated fatty acids ratio and conjugated linoleic acid content comparable to those found for beef and sheep meat. However, specifically, alpaca meat showed a relatively high n−6 to n−3 (3.7) ratio and low vitamin E concentration. Values of alpaca meat technological quality parameters were in the ranges reported for more conventional red meats, the exception being a lower b ∗ value.

The pig p160 co-activator family: Full length cDNA cloning, expression and effects on intramuscular fat content in Longissimus Dorsi muscle

Evidence has shown in mouse that the p160 co-activator family, consisting of nuclear receptor co-activators 1 (NCOA1), 2 (NCOA2) and 3 (NCOA3) plays a critical role in adipogenesis. In the present study, we cloned these three porcine genes, identified their transcript variants and analyzed their expression level in relation to intramuscular fat (IMF) content in Longissimus Dorsi (LD) muscle. Both in silico cloning and PCR amplification revealed a full length cDNA sequence of 6591 bp for NCOA1 (EU346671), 7628 bp for NCOA2 (EU346672) and 5005 bp for NCOA3 (EU346674) in pigs, respectively. Interestingly, three transcript variants were identified for the porcine NCOA1 and two for the porcine NCOA2 gene. In addition, the deduced amino acid sequences indicated that isoform 2 of NCOA2 lacks the fourth LXXLL motif, the number of which has been shown to influence the selectivity and affinity for different nuclear receptors. Finally, 15 animals with high IMF content and fifteen animals with low IMF content ( p < 0.05) selected from 60 individuals were used to investigate how the family members and their variants affect the phenotype in pigs using real-time PCR. Our results showed that both NCOA1 transcript variant 2 ( r = −0.554, p < 0.01) and total NCOA1 ( r = −0.516, p < 0.01) expression levels were negatively correlated with IMF contents, while NCOA2 transcript variant 1 ( r = 0.605, p < 0.01) and NCOA3 ( r = 0.435, p < 0.05) were positively associated with IMF content in LD muscle. Overall, the present study provides evidence for the first time that the p160 co-activator family might have a concordant effect on lipid metabolism in mammals.

AMP-activated protein kinase is negatively associated with intramuscular fat content in longissimus dorsi muscle of beef cattle

Marbling, or intramuscular fat, is an important factor in meat quality. As a key regulator of lipid metabolism, AMP activated protein kinase (AMPK) may be associated with intramuscular fat accumulation. Our objective was to evaluate the relationship among AMPK and its associated signaling mediators, with marbling and lean growth in beef cattle. Steers with high intramuscular fat content (High IMF, 5.71 ± 0.36%, n = 5) and low intramuscular fat content (Low IMF, 2.09 ± 0.19%, n = 5) were selected. High IMF was associated with increased tenderness ( P < 0.05) and backfat thickness ( P < 0.01). Muscle weights were higher in Low compared to High IMF ( P < 0.05). High IMF steers had a reduced AMPK activity ( P < 0.01), reduced acetyl-CoA carboxylase phosphorylation ( P < 0.05), and reduced total mTOR ( P = 0.02) content. Data provide evidence that AMPK is involved in IMF deposition in beef cattle.

Correlation between carcass conformation and fat cover degree, and muscle fatty acid profile of yearling bulls depending on breed and mh-genotype

Abstract The objective was to study the relationships between the actual European beef carcass classification scale, which classifies carcasses with regard to conformation and degree of fat cover scores, and muscle fat quality, depending on breed and mh-genotype. For this purpose samples from 100 yearling bulls from “Asturiana de los Valles” (24 AV(mh/mh), 26 AV(mh/+), 25 AV (+/+)) and “Asturiana de la Montana” (25 AM) were analysed. The results of the study showed that breed or genotype affect carcass measurement scores and muscle fatty acid profile through its important effect on animal overall fatness. Homozygous double-muscled animals produced carcasses with high conformation and low intramuscular (IM) fat content. While early-maturing and rustic AM animals produced low carcass yield and high IM fat content. The other genotypes (mh/+, +/+) showed, in general, intermediate characteristics. Referring to correlations, carcass conformation was negatively related to saturated (SFA) (r = − 0.69, P 0.46, P

Effect of genotype and overfeeding on lipid deposition in myofibres and intramuscular adipocytes of breast and thigh muscles of ducks

We conducted a study to evaluate the effects of genotype (Muscovy, Pekin and their crossbred, hinny and mule) and overfeeding (14 days from 12 weeks of age) on lipid deposition in myofibres and intramuscular adipocytes of breast and thigh muscles of ducks. Birds of the four genotypes were also reared contemporaneously with a growing diet distributed ad libitum. Muscle samples (Pectoralis major and Sartorius) were collected at 14 weeks of age on 8 ducks per treatment. The muscle fibre typing, the total lipid and triglyceride contents in myofibres and the relative surface occupied by adipocytes on the cross-sectional area of the muscles were determined by histological and image analysis. Overfeeding induced a marked increase of body weight but had no significant effect on the muscle weight, the cross-sectional area (CSA) of myofibres and the muscle typology. In muscles, overfeeding induced a large accumulation of lipids, mainly in adipocytes whose relative surface increased 1.5 fold in P. major and 2.1 fold in Sartorius and an increase in triglyceride content of fast twitch oxydo-glycolytic and glycolytic fibres in P. major only (+ 37 and + 16% respectively). Genotype had no significant effect on the muscle typology. By comparison with the other genotypes, Muscovy ducks exhibited the highest body weight, the highest muscle weight which could partly be explained by the highest fibre CSA and the lowest intramuscular fat content in adipocytes and myofibres (only fast twitch oxydo-glycolytic fibres in P. major). We observed the reverse situation for the Pekin ducks. The crossbred ducks always presented intermediate values except for body weight.