Conjugated linoleic acid regulates adipocyte fatty acid binding protein expression via peroxisome proliferator-activated receptor α signaling pathway and increases intramuscular fat content

Intramuscular fat (IMF) is correlated positively with meat tenderness, juiciness and taste that affected sensory meat quality. Conjugated linoleic acid (CLA) has been extensively researched to increase IMF content in animals, however, the regulatory mechanism remains unclear. Adipocyte fatty acid binding protein (A-FABP) gene has been proposed as candidates for IMF accretion. The purpose of this study is to explore the molecular regulatory pathways of CLA on intramuscular fat deposition. Here, our results by cell lines indicated that CLA treatment promoted the expression of A-FABP through activated the transcription factor of peroxisome proliferator-activated receptor α (PPARα). Moreover, in an animal model, we discovered that dietary supplemental with CLA significantly enhanced IMF deposition by up-regulating the mRNA and protein expression of PPARα and A-FABP in the muscle tissues of mice. In addition, our current study also demonstrated that dietary CLA increased mRNA expression of genes and enzymes involved in fatty acid synthesis and lipid metabolism the muscle tissues of mice. These findings suggest that CLA mainly increases the expression of A-FABP through PPARα signaling pathway and regulates the expression of genes and enzymes related to IMF deposition, thus increasing IMF content. These results contribute to better understanding the molecular mechanism of IMF accretion in animals for the improvement of meat quality.

Effect of n-6/n-3 PUFA ratio on body fat deposition, tissues fatty acid composition and key genes expression of liver lipid metabolism in silver foxes (Vulpes vulpes fulva) during the winter fur-growth period

Objective

The proportion of n-6/n-3 polyunsaturated fatty acid (PUFA) plays an important role in regulating lipid metabolism. This study aimed to investigate the effects of dietary n-6/n-3 PUFA ratios on body fat deposition, tissues fatty acid composition, and gene expression of liver lipid metabolism of silver foxes during the winter fur growth period.

Methods

Forty-eight age-matched male silver foxes with similar body weights were randomly divided into four dietary groups for 47 days, which were fed n-6/n-3 PUFA ratio with 3, 18, 41, and 136 experimental diets, respectively.

Results

Dietary n-6/n-3 PUFA ratio did not significantly influence fat deposition parameters except for hepatic fat content. The variation trend of the fatty acid composition of liver, intramuscular fat, and subcutaneous fat in silver fox was directly related to dietary fatty acid content (p < 0.05). With the dietary n-6/n-3 PUFA ratio increasing, the expression of liver fatty acid synthase (FAS) mRNA and peroxisome proliferator-activated receptor (PPAR) mRNA exhibited the trend of first decreasing and then increasing (p < 0.05), whereas L-fatty acid binding protein (L-FABP) mRNA expression showed a gradual increasing trend (p < 0.05).

Conclusion

In summary, silver foxes fed an n-6/n-3 PUFA ratio 18:1 diet (supplementing with 9.38% corn oil and 4.62% soybean oil) was more conducive to lipid decomposition, PUFA transport, and utilization of tissues, thereby meeting it for supplying energy and withstanding the cold.

CLA improves the lipo-nutritional quality of pork and regulates the gut microbiota in Heigai pigs

CLA improves the lipo-nutritional quality in muscle and these changes are associated with the production and functions of differential bacteria and SCFAs in the gut of Heigai pigs.

Evaluation of feeding periods of dietary conjugated linoleic acid supplementation on growth performance, nutrient digestibility, blood profiles, and meat quality in finishing pigs

This study was conducted to evaluate feeding periods of dietary conjugated linoleic acid (CLA) supplementation on growth performance, nutrient digestibility, blood profiles, and meat quality in finishing pigs. A total of 150 finishing pigs [(Yorkshire × Landrace) × Duroc] with an average body weight (BW) of 83.13 ± 1.91 kg were randomly allocated into one of three treatments (10 pens per treatment, five pigs per pen) based on their BW. Dietary treatments consisted of supplementing the basal diet with 1.0% CLA during 2, 3, and 4 wk prior to finishing. Pigs fed CLA diets 2 wk before finishing had a higher overall average daily gain (ADG) and gain-to-feed ratio (G/F) than those fed CLA diets 4 wk before finishing (P < 0.05). In the whole experiment, pigs fed CLA diets 2 wk before finishing had a higher serum low-density lipoprotein (LDL) than those fed CLA diets 3 and 4 wk before finishing. However, pigs that received CLA diets 4 wk before finishing had higher triglyceride levels (P < 0.05). Feeding 1% CLA diets 4 wk before finishing improved meat color and firmness. Taken together, feeding 1% CLA diet 4 wk before finishing increased ADG, G/F, and serum LDL, but reduced serum triglyceride.

Effects of Combined Supplementation of Conjugated Linoleic Acid, Methionine Chromium, Betaine, and Cysteamine on Meat Tenderness of Rats

A systemic design was carried out to investigate the optimal combination of BET, Met-Cr, CLA, and CS for improving the meat tenderness in rats. A total of 104 six-week old male Sprague-Dawley rats were randomly assigned to 13 treatments with 4 replicates of 2 rats each. The experiments lasted for 5 weeks. The results showed that inclusion of Met-Cr decreased the contents of intramuscular fat (IMF), fat among muscle cells, and lipid droplets inside muscle cells (P < 0.05), and inclusion of CLA or Met-Cr increased the contents of IMF, fat among muscle cells, and lipid droplets inside muscle cells (P < 0.05). CS increased the contents of total collagen (TC) and soluble collagen (SC), and CLA decreased the contents of TC and SC (P < 0.05). The combination of BET and CLA increased IMF and SC contents and decreased TC contents (P < 0.05). The combination of BET and CS could increase fat contents among muscle cells and decrease TC and SC contents (P < 0.05). The combination of CLA and Met-Cr decreased IMF contents (P < 0.05). The combination of CLA and CS, as well as Met-Cr and CS, decreased fat contents among muscle cells (P < 0.05). These combinations may regulate lipogenesis and decrease the deposition of fat in muscles. There existed a significant positive correlation between IMF and SC content, which might indicate that IMF content improves meat's tenderness partly by increasing SC content in muscle.

Chromium, CLA, and ractopamine for finishing pigs

This study aimed to evaluate the effects of dietary chromium, CLA, and ractopamine on performance, carcass traits, and pork quality of finishing pigs slaughtered at 115 kg BW. Ninety-six crossbred barrows (initial BW = 70.21 ± 1.98 kg) were randomly assigned to 1 of 6 dietary treatments. There were 8 replicates per treatment (48 pens; 2 pigs/pen). A diet formulated according to the nutritional requirements was used as the control (CON). The other 5 diets were based on the CON and supplemented as follows: 0.4 mg/kg Cr yeast (CrY); 0.5% CLA; 0.4 mg/kg CrY and 0.5% CLA (CrY + CLA); 20 mg/kg ractopamine (RAC); 0.4 mg/kg CrY and 20 mg/kg RAC (CrY + RAC). Lysine levels on diets containing ractopamine were raised by 20% compared to CON to meet the greater requirements of pigs fed ractopamine. Pigs fed RAC and CrY + RAC were fed CON for the first 17 d, and then the respective diets for the last 28 d on trial. Data were analyzed in a model including the fixed effect of treatment (6 levels) and initial BW as a covariate for all characteristics, with the exception of carcass traits, in which final BW was used as a covariate. Least-squares means were separated using Tukey-Kramer's method. Differences were considered when probability values were lower than 0.05. Pigs fed RAC and CrY + RAC had the greatest ( < 0.001) final BW and ADG. Pigs fed CrY + RAC had greater ( < 0.001) G:F than pigs within the other groups, except for those fed RAC. Pigs fed CrY + RAC and RAC had similar G:F, both greater ( < 0.001) than pigs fed CON. Average daily feed intake was similar ( = 0.83) for all diets. Pigs fed CrY + RAC had greater LM area ( = 0.01) and carcass yield ( < 0.02) than pigs fed CON, CrY, CLA, and CrY + CLA. Loin muscle area and carcass yield of pigs fed RAC were not different from pigs fed the others diets. Pigs fed CON diets had greater BF ( = 0.02) than pigs fed CLA diet. Additives did not affect ( > 0.05) pork quality, except for color. No differences ( > 0.05) were observed for carcasses pH and temperature. The values for pigs fed RAC were greater ( = 0.01) than pigs fed other diets. Pigs fed RAC had lower ( < 0.01) values compared to pigs fed other experimental diets. Serum urea nitrogen concentration (SUN) was lower ( = 0.02) in pigs fed CrY + RAC than in pigs fed CON and RAC and similar to pigs fed the other feeding additives. In summary, it was demonstrated that, when combined, CrY and RAC increase LM area and carcass yield, and reduce SUN, suggesting that chromium could improve nutrient utilization by muscle cells in RAC-fed pigs. Additionally, the additives have no major effects on pork quality.

Postnatal high-fat diet enhances ectopic fat deposition in pigs with intrauterine growth retardation

OBJECTIVES

Intrauterine growth retardation (IUGR) and postnatal nutrition are risk factors for adult metabolic syndrome. However, the influences of long-term high-fat diet (HFD) intake on ectopic fat deposition in non-adipose tissues in IUGR pigs remain unclear. The present study was to determine whether HFD consumption would enhance ectopic fat deposition in IUGR pigs.

METHODS

At day 28, IUGR and control pigs were fed ad libitum to either a regular diet or a HFD. Lipid store, enzymatic activities and mRNA expression of lipid metabolism-related factors in liver and semitendinosus muscle (SM) were quantified at postnatal day 178.

RESULTS

Feeding a HFD to IUGR pigs but not to control pigs significantly increased daily weight gain, carcass fat mass, plasma leptin level and lipid content and lipoprotein lipase (LPL) activity and mRNA abundances of LPL and peroxisome proliferator-activated receptor gamma (PPARγ) in liver and SM, but decreased daily feed intake and mRNA expression of hormone-sensitive lipase (LIPE) and carnitine palmitoyl transferase-1 (CPT-1) in liver and SM (P < 0.05). Compared with control pigs, IUGR pigs had a lower body weight but higher plasma levels of total cholesterol (TC) and insulin (P < 0.05). HFD-fed pigs exhibited greater body weight, plasma concentrations of triglyceride (TG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C), regardless of birth weight (P < 0.05).

CONCLUSION

Our results suggested that IUGR increased the vulnerability of HFD-fed pigs to ectopic fat deposition via enhanced fatty acid flux toward ectopic sites and reduced lipolysis and fatty acid oxidation.

Effects of conjugated linoleic acid and lutein on the growth performance and immune response of broiler chickens

The effects of lutein and conjugated linoleic acid (CLA) on growth performance and immune response of broiler chickens were evaluated in the presence and absence of Salmonella lipopolysaccharide (LPS) immune challenge. Cobb chicks (360; 1 to 22 d of age) were used in a 3 × 2 factorial arrangement of CLA (0, 1, and 2%) and lutein (0 and 50 mg/kg) dietary levels. At d 8 and 15, birds were injected with BSA to assess IgY production. At d 20, birds were injected with LPS. Samples of liver, spleen, and duodenum were collected at 3 and 16 h post-LPS challenge for RT-qPCR analysis of RXRα, RXRγ, PPARα, PPARγ, TLR-4, IL-1β, IL-2, IL-10, and IL-12 gene expression. CLA decreased BW, BW gain (BWG), and G:F from d 1 to 20, but these effects were reversed when lutein was included in the 1% CLA diet (P < 0.001). The production of IgY anti-BSA increased following a 2% CLA supplementation (P < 0.01). LPS increased the liver:BW ratio at 3 h post-injection (P < 0.001) and decreased BWG at 3, 16, and 40 h (P < 0.001). Lutein decreased plasmatic nitric oxide levels (P < 0.01). LPS downregulated PPARα mRNA in the duodenum (P = 0.02) and liver (P = 0.04), and PPARγ (P = 0.01) and RXRα (P = 0.08) in the spleen; these effects were not reversed by CLA or lutein as initially hypothesized. Although LPS upregulated IL-1β (P = 0.02) and IL-12 (P = 0.07) expression, lutein downregulated these pro-inflammatory cytokines in the liver (P = 0.03 and P = 0.07, respectively). Lutein decreased splenic (P = 0.09) but increased hepatic (P = 0.06) TLR-4 mRNA. A dietary CLA supplementation of 2% increased hepatic RXRα (P = 0.10). In conclusion, CLA decreased broiler chicken growth performance, but lutein could prevent this negative effect (depending on CLA dose). Lutein had an anti-inflammatory effect, and a 2% CLA supplementation improved the humoral immune response.

Associação entre o óleo de soja e o óleo de peixe na dieta de cabras em lactação como estratégia para melhorar o perfil de ácidos graxos do leite

RESUMOOs objetivos neste experimento foram avaliar os efeitos da associação entre o óleo de soja e o óleo de peixe na dieta de cabras em lactação sobre o consumo de matéria seca e de nutrientes, a variação do peso corporal, a produção e composição do leite, assim como o perfil de ácidos graxos. As cabras foram alocadas em baias individuais, onde receberam dieta composta por 50% de feno de "coastcross" e 50% de concentrado. Foram utilizadas nove cabras mestiças Boer x Saanen multíparas, distribuídas em três quadrados latinos 3 X 3. O experimento teve duração de 51 dias, divididos em três períodos de 17 dias, sendo os 13 primeiros dias para adaptação dos animais às dietas e os 4 dias subsequentes para colheita de amostras e de dados. Os tratamentos experimentais foram: a) dieta controle (CT), sem adição de óleo; b) dieta contendo 3% de óleo de soja (OS); e c) dieta contendo 2,5% de óleo de soja + 0,5% de óleo de peixe (OS+P). A inclusão dos óleos reduziu (P<0,05) o consumo de matéria seca, no entanto aumentou (P<0,05) a eficiência alimentar dos animais, sem afetar (P>0,05) a produção de leite. Houve efeito (P<0,05) da dieta no perfil de ácidos graxos do leite, sendo que ambos os tratamentos com adição de óleo elevaram as concentrações de ácidos graxos de cadeia média e longa, reduzindo os de cadeia curta. O tratamento com a combinação do óleo de soja com o óleo de peixe foi o que promoveu os maiores aumentos na concentração de ácido vacênico (398%), rumênico (352%) e de CLA total (341%) no leite. Os resultados permitem concluir que a suplementação lipídica elevou a eficiência alimentar dos animais e que o fornecimento de óleo de soja em combinação ao óleo de peixe aumentou a concentração no leite dos ácidos graxos benéficos à saúde humana.

Conjugated linoleic acid and betain prevent pork quality issues from diets containing distillers’ dried grains with solubles

Su, B., Wang, L., Wang, H., Shi, B., Shan, A. and Li, Y. 2013. Conjugated linoleic acid and betain prevent pork quality issues from diets containing distillers’ dried grains with solubles. Can. J. Anim. Sci. 93: 477–485. An experiment was conducted to evaluate the effects of conjugated linoleic acid (CLA) or betaine (BET) in diets containing distillers’ dried grains with solubles (DDGS) on the fatty acid profile and the shelf-life attributes of pork. Thirty-two (60±2 kg) crossed-bred barrows (Duroc×Landrace×Yorkshine) were randomly assigned to one of four diets: (1) the control diet containing no corn DDGS (control group); (2) the diet containing 30% corn DDGS (DDGS-fed group); (3) the diet containing 30% corn DDGS and 10 g kg−1 CLA (CLA-fed group); (4) the diet containing 30% corn DDGS and 1 g kg−1 BET (BET-fed group). Dietary DDGS decreased the proportion of saturated fatty acids (SFA) (P<0.05), and increased the proportion of unsaturated fatty acids (UFA) and polyunsaturated fatty acids (PUFA) (P<0.05) in pork with respect to the control group, whereas dietary CLA and BET decreased the proportion of PUFA and increased the proportion of SFA in pork compared with DDGS-fed group. Pork treated with DDGS alone had higher total volatile basic nitrogen (TVB-N) value (P<0.05) and thiobarbituric acid reactive substances (TBARS) value (P<0.05) with respect to the control diet during display, whereas CLA-fed group and BET-fed group had lower TVB-N concentration and TBARS value (P<0.05) in pork than DDGS-fed group. There was no significant difference of instrumental color (L*, a*, b*) between DDGS-fed group and the control group (P>0.05). However, CLA-fed and BET-fed groups maintained lower L* values and higher a* values (P<0.05), but did not affect b* values with respect to the DDGS-fed group and the control group. Results confirmed that diets containing 30% DDGS have some adverse effects on pork freshness and lipid peroxidation; However, supplementation with CLA or BET can partially reverse these effects and improve color image of pork during display.

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.

Backfat Fatty Acid Profile of Crossbred Pigs Fed a Diet Supplemented with Conjugated Linoleic acid or Sunflower Oil

The aim of the study was to investigate the impact of feeding pigs with different levels of conjugated linoleic acid (CLA) or sunflower oil (SFO) on the backfat fatty acid profile. The subjects of research were 60 crossbred gilts divided into 6 groups, which were fed different levels of conjugated linoleic acid or sunflower oil (0.5, 1.0 and 2.0%, respectively). All fatteners were kept and fed under standardized conditions. Animals were slaughtered at 95 kg of body weight. Fatty acid profile was determined in samples of backfat from each animal using gas chromatography. The significance of differences between groups was verified by Duncan's test. In the present study, a beneficial effect of adding CLA was that it reduced saturated fatty acids and increased unsaturated fatty acids in the adipose tissue (backfat) of pigs as compared to fatteners receiving SFO. The amount of monounsaturated fatty acids in the backfat decreased with increasing amounts of CLA or SFO. Modifying the fatty acid profile of pig backfat through addition of CLA or SFO would be beneficial to the health of consumers because relatively large amounts of fat pork, including backfat, are added to the sausages.

The Effect of Forage Level and Oil Supplement on Butyrivibrio fibrisolvens and Anaerovibrio lipolytica in Continuous Culture Fermenters

The objective of this study was to evaluate the effects of forage level and oil supplement on selected strains of rumen bacteria believed to be involved in biohydrogenation (BH). A continuous culture system consisting of four fermenters was used in a 4×4 Latin square design with a factorial arrangement of treatments, with four 10 d consecutive periods. Treatment diets were: i) high forage diet (70:30 forage to concentrate (dry matter basis); HFC), ii) high forage plus oil supplement (HFO), iii) low forage diet (30:70 forage to concentrate; LFC), and iv) low forage plus oil supplement (LFO). The oil supplement was a blend of fish oil and soybean oil added at 1 and 2 g/100 g dry matter, respectively. Treatment diets were fed for 10 days and samples were collected from each fermenter on the last day of each period 3 h post morning feeding. The concentrations of vaccenic acid (t11C18:1; VA) and c9t11 conjugated linoleic acid (CLA) were greater with the high forage diet while the concentrations of t10 C18:1 and t10c12 CLA were greater with the low forage diet and addition of oil supplement increased their concentrations at both forage levels. The DNA abundance of Anaerovibrio lipolytica, and Butyrivibrio fibrisolvens vaccenic acid subgroup (Butyrivibrio VA) were lower with the low forage diets but not affected by oil supplement. The DNA abundance of Butyrivibrio fibrisolvens stearic acid producer subgroup (Butyrivibrio SA) was not affected by forage level or oil supplement. In conclusion, oil supplement had no effects on the tested rumen bacteria and forage level affected Anaerovibrio lipolytica and Butyrivibrio VA.

Promotion of intramuscular fat accumulation in porcine muscle by nutritional regulation

Recently, pork with marbling has received attention as good quality pork and scientists are required to develop methods to produce pork with reasonable amounts of intramuscular fat (IMF). The aim of this review is to describe studies relevant to promotion of IMF accumulation in porcine muscle by nutritional regulation. The main focus is on effect of dietary lysine levels. First, we found dietary low lysine up-regulated glucose transporter protein 4 messenger (m)RNA expression in Longissimus dorsi (L. dorsi) and Rhomboideus muscles. In addition, the proportion of oxidative fiber of both muscles was also enhanced by dietary low lysine. Because it has been observed that higher oxidative capacity is associated with higher IMF content, we hypothesized that dietary low lysine would promote IMF accumulation. Further, higher mRNA abundance of peroxisome proliferator-activated receptor γ, a master regulator of adipogenesis, in both muscles induced by dietary low lysine, supported this hypothesis. Indeed, IMF content of L. dorsi muscle of finishing pigs given a low lysine diet for 2 months until reaching the market weight was twice that of pigs given a control diet. Possible underlying mechanisms of IMF accumulation in porcine muscle and future perspectives are also discussed in this review.

Relationship between proteome changes of Longissimus muscle and intramuscular fat content in finishing pigs fed conjugated linoleic acid

The present experiment was conducted to determine proteome changes in Longissimus muscle of finishing pigs fed conjugated linoleic acid (CLA), in association with alteration of intramuscular fat content. Previously, seventy-two Duroc × Landrace × Large White gilts (approximately 60 kg) had been fed maize–soyabean meal-based diets with 0, 12·5 and 25 g CLA/kg diet. The CLA contained 369·1 mg/g cis-9, trans-11 CLA, 374·6 mg/g trans-10, cis-12 CLA and 53·7 mg/g other isomers. Six pigs per treatment were slaughtered when they reached a body weight of approximately 100 kg. Data published from a previous experiment demonstrated that supplementation with 12·5 or 25 g CLA/kg diet increased intramuscular fat content (P < 0·05). The present study investigated the proteome changes in Longissimus muscle of control and pigs supplemented with 25 g CLA/kg diet. CLA significantly influenced the abundance of proteins related to energy metabolism, fatty acid oxidation and synthesis, amino acid metabolism, defence, transport and other miscellaneous processes (P < 0·05). The increase in intramuscular fat content was positively correlated with the increased abundance of carbonic anhydrase 3 and aspartate aminotransferase (P < 0·05). We suggest that the proteome changes in Longissimus muscle contributed to greater intramuscular lipid content in CLA-supplemented pigs.