Effects of intravenous infusion of conjugated diene 18:3 isomers on milk fat synthesis in lactating dairy cows

It has been previously established that trans-10, cis-12 conjugated linoleic acid plays an important role in milk fat depression (MFD). However, in many situations of dietary induced MFD, the reduction in milk fat synthesis is much greater than what would be predicted based on the milk fat concentration of trans-10, cis-12 18:2. These observations suggest that other biohydrogenation intermediates could be implicated in MFD. The objective of this study was to evaluate the effects on milk fat synthesis of an intravenous administration of 2 conjugated diene 18:3 isomers (cis-9, trans-11, cis-15 and cis-9, trans-13, cis-15 18:3), which are intermediates in ruminal biohydrogenation of α-linolenic acid. Three multiparous Holstein dairy cows (days in milk = 189 ± 37 d; body weight = 640 ± 69 kg; mean ± standard deviation), fitted with indwelling jugular catheters, were randomly assigned to a 3 × 3 Latin square design. For the first 5 d of each period, cows were infused intravenously with a 15% lipid emulsion providing 1) cis-9, trans-11, cis-15 18:3 + cis-9, trans-13, cis-15 18:3 + trans-10, cis-12 18:2 (CD18:3 + CLA); 2) cis-9, cis-12, cis-15 18:3 + cis-9, cis-12 18:2 as a control (ALA + LA); or 3) cis-9, cis-12, cis-15 18:3 + trans-10, cis-12 18:2, as a positive control (ALA + CLA). Milk production was recorded, and milk was sampled daily at each milking for analyses of fat, protein, lactose, milk urea nitrogen, and somatic cell count. Dry matter intake, milk yield, and milk protein were not affected by treatment. Over the experimental period, milk fat content was decreased by 7% for cows that received either ALA + CLA or CD18:3 + CLA compared with ALA + LA. The temporal pattern of milk fat content showed a linear decrease during the infusion period for ALA + CLA and CD18:3 + CLA treatment groups. The transfer efficiencies of conjugated diene 18:3 isomers into milk fat averaged 39 and 32% for cis-9, trans-11, cis-15 18:3 and cis-9, trans-13, cis-15 18:3, respectively. The CD18:3 + CLA treatment had no effect on milk fat concentration beyond that attributable to its trans-10, cis-12 18:2 content. In conclusion, results from the current study offered no support for a role of either cis-9, trans-11, cis-15 18:3 or cis-9, trans-13, cis-15 in MFD.     

Production of olive oil enriched with medium chain fatty acids catalysed by commercial immobilised lipases

Structured triacylglycerols, containing medium chain fatty acids, were produced by acidolysis of virgin olive oil with caprylic or capric acid, at a molar ratio of olive oil:fatty acid of 1:2, at 45 °C for 24 h, in solvent-free media or in n-hexane, catalysed by Thermomyces lanuginosa (Lipozyme TL IM), Rhizomucor miehei (Lipozyme RM IM) and Candida antarctica (Novozym 435) immobilised lipases. Incorporations were always greater for capric than for caprylic acid. For both acids, higher incorporations were always attained in solvent-free media: the highest caprylic acid incorporations were obtained with Novozym 435 (25.5 mol%) and Lipozyme RM IM (25.7 mol%), while similar capric acid incorporations were obtained with all biocatalysts (27.1–30.4 mol%).     

cis/trans-Isomerisation of triolein,trilinolein and trilinolenin induced by heat treatment

To estimate the trans-fatty acid production of edible oils during the frying process, 1.0 g of triolein, trilinolein and trilinolenin, as representative oils, were heated at 180 °C for a defined period. The amounts of trans-fatty acids in heated triacylglycerols were quantitatively determined by gas chromatography after methylation. It was revealed that heating induced cis to trans-isomerisation of unsaturated triacylglycerols, and that trans-fatty acid amounts increased gradually, depending on the heating period. For example, trans-isomer amounts in triolein, trilinolein and trilinolenin (per gram) were 5.8 mg, 3.1 mg and 6.5 mg, respectively, after 8 h incubation at 180 °C. At that time, the contents of polar compounds contained in the heated triolein, trilinolein and trilinolenin were 22%, 27% and 31%, respectively. When triolein was heated under a N₂ stream, neither trans-isomerisation nor polar compounds were detected. The addition of α-tocopherol (1.0%) to triolein significantly prevented not only lipid oxidation but also trans-isomerisation during heating. A commercially available vegetable oil was also heated under the same conditions as these model oils. Compared with the trans-isomerisation in model oils, the degree of trans-isomerisation in the edible oil was relatively low. Tocopherols in the oil would prevent not only lipid oxidation but also isomerisation. These results suggest that the geometric isomerisation of unsaturated fatty acids during heating accompanies lipid oxidation.     

Enzymatic synthesis of lysophosphatidylcholine containing CLA from sn-glycero-3-phosphatidylcholine (GPC) under vacuum

Lysophosphatidylcholine (LPC) was successfully synthesised by enzyme-catalysed esterification of sn-glycero-3-phosphatidylcholine (GPC) with the acid form of conjugated linoleic acid (CLA), using a vacuum system. GPC was prepared from phosphatidylcholine (PC) by alkaline deacylation using a methanolic tetra-butylammonium hydroxide solution. Five enzymes were tested as biocatalysts for direct esterification, and lipases were found to be more effective than phospholipases for production of LPC. Amongst the enzymes tested, Novozym 435, from Candida antarctica, gave the highest yield of LPC. The optimal temperature, molar ratio of substrate, and vacuum were 40 °C, 1:50 (GPC to CLA), and 1 mm Hg, respectively. The maximum yield (70 mol%) of LPC was obtained under optimal conditions after a 48 h reaction time.     

Effect of dietary linseed on the nutritional value and quality of pork and pork products: Systematic review and meta-analysis

Nutritional quality of pork is a significant factor for consumers' health. Feeding n-3 PUFA to pigs, using linseed, improves pork nutritional quality. A meta-analysis involving 1006 pigs reported in 24 publications was carried out to assess the effects of dietary linseed on alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA) content in muscle and adipose tissue. Data showed positive effects of n-3 PUFA on muscle fatty acid composition: ALA + 137%, EPA + 188%, DPA + 51% and DHA + 12%. Same results were observed in adipose tissue: ALA + 297%, EPA + 149%, DPA + 88% and DHA + 18%. A positive correlation between dietary treatment and ALA and EPA content in muscle (P < 0.001) and adipose tissue (P = 0.036) was observed. A significant association between DPA (P = 0.04) and DHA (P = 0.011) and live weight in muscle was observed. Feeding linseed to pig improves the nutritional pork quality, raising the n-3 PUFA content in muscle and adipose tissue.     

Abomasal infusion of butterfat increases milk fat in lactating dairy cows

The objective of this study was to compare the effects of abomasal infusion of butterfat containing all fatty acids (FA) present in milk, including the short- and medium-chain FA, with infusion of only the long-chain FA (LCFA) present in milk, on the FA composition and milk fat yield in lactating dairy cows. Eight rumen-fistulated Holstein cows, in early lactation (49 ± 20 days in milk) were used in a replicated 4 × 4 Latin square design. Treatments were abomasal infusion of the following: 1) no infusion (control), 2) 400 g/d of butterfat (butterfat), 3) 245 g/d of LCFA (blend of 59% cocoa butter, 36% olive oil, and 5% palm oil) providing 50% of the 16:0 and equivalent amounts of C18 FA as found in 400 g of butterfat, and 4) 100 g/d of conjugated linoleic acid (CLA, negative control), providing 10 g of trans-10, cis-12 CLA. Fat supplements were infused in equal portions 3 times daily at 0800, 1400, and 1800 h during the last 2 wk of each 3-wk experimental period. Daily dry matter intake and milk production were unaffected by the infusion treatments. Butterfat infusion increased milk fat percentage by 14% to 4.26% and milk fat yield by 21% to 1,421 g/d compared with controls (3.74% and 1,178 g/d). Milk fat percentage and fat yield were decreased by 43% by CLA. Milk protein percentage was higher (3.70%) in CLA-infused cows than in control (3.30%), butterfat (3.28%), or LCFA (3.27%) treatments. Although LCFA had no effect on fat synthesis, abomasal infusion of butterfat increased milk fat percentage and yield, suggesting that the availability of short- and medium-chain FA may be a limiting factor for milk fat synthesis.     

Meta-analysis of relationships between enteric methane yield and milk fatty acid profile in dairy cattle

Various studies have indicated a relationship between enteric methane (CH₄) production and milk fatty acid (FA) profiles of dairy cattle. However, the number of studies investigating such a relationship is limited and the direct relationships reported are mainly obtained by variation in CH₄ production and milk FA concentration induced by dietary lipid supplements. The aim of this study was to perform a meta-analysis to quantify relationships between CH₄ yield (per unit of feed and unit of milk) and milk FA profile in dairy cattle and to develop equations to predict CH₄ yield based on milk FA profile of cows fed a wide variety of diets. Data from 8 experiments encompassing 30 different dietary treatments and 146 observations were included. Yield of CH₄ measured in these experiments was 21.5 ± 2.46 g/kg of dry matter intake (DMI) and 13.9 ± 2.30 g/kg of fat- and protein-corrected milk (FPCM). Correlation coefficients were chosen as effect size of the relationship between CH₄ yield and individual milk FA concentration (g/100 g of FA). Average true correlation coefficients were estimated by a random-effects model. Milk FA concentrations of C6:0, C8:0, C10:0, C16:0, and C16:0-iso were significantly or tended to be positively related to CH₄ yield per unit of feed. Concentrations of trans-6+7+8+9 C18:1, trans-10+11 C18:1, cis-11 C18:1, cis-12 C18:1, cis-13 C18:1, trans-16+cis-14 C18:1, and cis-9,12 C18:2 in milk fat were significantly or tended to be negatively related to CH₄ yield per unit of feed. Milk FA concentrations of C10:0, C12:0, C14:0-iso, C14:0, cis-9 C14:1, C15:0, and C16:0 were significantly or tended to be positively related to CH₄ yield per unit of milk. Concentrations of C4:0, C18:0, trans-10+11 C18:1, cis-9 C18:1, cis-11 C18:1, and cis-9,12 C18:2 in milk fat were significantly or tended to be negatively related to CH₄ yield per unit of milk. Mixed model multiple regression and a stepwise selection procedure of milk FA based on the Bayesian information criterion to predict CH₄ yield with milk FA as input (g/100 g of FA) resulted in the following prediction equations: CH₄ (g/kg of DMI) = 23.39 + 9.74 × C16:0-iso – 1.06 × trans-10+11 C18:1 – 1.75 × cis-9,12 C18:2 (R² = 0.54), and CH₄ (g/kg of FPCM) = 21.13 – 1.38 × C4:0 + 8.53 × C16:0-iso – 0.22 × cis-9 C18:1 – 0.59 × trans-10+11 C18:1 (R² = 0.47). This indicated that milk FA profile has a moderate potential for predicting CH₄ yield per unit of feed and a slightly lower potential for predicting CH₄ yield per unit of milk.     

Thermo-oxidation of cholesterol: Effect of the unsaturation degree of the lipid matrix

The influence of the unsaturation degree of different triacylglycerols (tristearin, triolein, trilinolein and trilinolenin) on cholesterol oxidation at 180 °C, was evaluated. Cholesterol degraded faster when heated alone than in the presence of triacylglycerols; moreover, the more unsaturated the matrix, the slower the degradation of cholesterol. Both cholesterol and triacylglycerols degradation fit a first order kinetic model (R² > 0.9), except for the tristearin sample. Cholesterol oxidation products (COPs) and peroxides were formed during the heating treatment. The presence of any type of lipid matrix postponed and decreased the maximum concentration of both oxidation parameters. Maximum total COPs concentrations were achieved at 20 min in neat cholesterol, 120 min in tristearin and triolein and 180 min in polyunsaturated matrix samples. 7-Ketocholesterol was the main COP in most cases during the whole heating treatment. Both the presence of triacylglycerols and their unsaturation degree inhibited cholesterol thermooxidation at 180 °C.     

Effect of unsaturated fatty acids and triglycerides from soybeans on milk fat synthesis and biohydrogenation intermediates in dairy cattle

Increased rumen unsaturated fatty acid (FA) load is a risk factor for milk fat depression. This study evaluated if increasing the amount of unsaturated FA in the diet as triglycerides or free FA affected feed intake, yield of milk and milk components, and feed efficiency. Eighteen Holstein cows (132 ± 75 d in milk) were used in a replicated 3 × 3 Latin square design. Treatments were a control (CON) diet, or 1 of 2 unsaturated FA (UFA) treatments supplemented with either soybean oil (FA present as triglycerides; TAG treatment) or soybean FA distillate (FA present as free FA; FFA treatment). The soybean oil contained a higher concentration of cis-9 C18:1 (26.0 vs. 11.8 g/100 g of FA) and lower concentrations of C16:0 (9.6 vs. 15.0 g/100 g of FA) and cis-9,cis-12 C18:2 (50.5 vs. 59.1 g/100 g of FA) than the soybean FA distillate. The soybean oil and soybean FA distillate were included in the diet at 2% dry matter (DM) to replace soyhulls in the CON diet. Treatment periods were 21 d, with the final 4 d used for sample and data collection. The corn silage- and alfalfa silage-based diets contained 23% forage neutral detergent fiber and 17% crude protein. Total dietary FA were 2.6, 4.2, and 4.3% of diet DM for CON, FFA, and TAG treatments, respectively. Total FA intake was increased 57% for UFA treatments and was similar between FFA and TAG. The intakes of individual FA were similar, with the exception of a 24 g/d lower intake of C16:0 and a 64 g/d greater intake of cis-9 C18:1 for the TAG compared with the FFA treatment. Compared with CON, the UFA treatments decreased DM intake (1.0 kg/d) but increased milk yield (2.2 kg/d) and milk lactose concentration and yield. The UFA treatments reduced milk fat concentration, averaging 3.30, 3.18, and 3.11% for CON, FFA, and TAG treatments, respectively. Yield of milk fat, milk protein, and 3.5% fat-corrected milk remained unchanged when comparing CON with the UFA treatments. No differences existed in the yield of milk or milk components between the FFA and TAG treatments. The UFA treatments increased feed efficiency (energy-corrected milk/DM intake), averaging 1.42, 1.53, and 1.48 for CON, FFA, and TAG treatments, respectively. Although milk fat yield was not affected, the UFA treatments decreased the yield of de novo (<16-carbon) synthesized FA (40 g/d) and increased the yield of preformed (>16-carbon) FA (134 g/d). Yield of FA from both sources (16-carbon FA) was reduced by the UFA treatments but to a different extent for FFA versus TAG (72 vs. 100 g/d). An increase was detected in the concentration of trans-10 C18:1 and a trend for an increase in trans-10,cis-12 C18:2 and trans-9,cis-11 C18:2 for the UFA treatments compared with CON. Under the dietary conditions tested, UFA treatments supplemented at 2% diet DM as either soybean FA distillate or soybean oil increased milk yield but did not effectively cause a reduction in milk fat yield, with preformed FA replacing de novo synthesized FA in milk fat. Further research is required to determine if the response to changes in dietary free and esterified FA concentrations is different in diets that differ in their risk for milk fat depression.     

Effect of weaning status on lipids of Galician Blond veal: Total fatty acids and 18:1 cis and trans isomers

The effect of weaning at different ages (NW = not weaned, W5 = 5.5 months and W2 = 2 months) on fatty acids (FA) of the Longissimus thoracis (LT) muscle was studied in 36 Galician Blond (GB) calves. Total FA (TFA) were determined by gas chromatography (GC) and 18:1 isomers by a combination of reversed-phase high performance liquid chromatography (HPLC) and GC. NW group showed higher (P < 0.001) values of n-3 polyunsaturated FA (PUFA), conjugated linoleic acid (CLA) and 18:1trans-11 compared to LT from W5 and W2 calves. W2 calves showed the highest levels of n-6 PUFA (P < 0.01), 18:1trans-10 and 18:1trans-6/7/8 (P < 0.001). Generally, W5 calves had intermediate values for TFA and 18:1 isomers. As the suckling period was longer, GB milk and veal FA profiles became more similar, it seems that muscle FA were partially transmitted by the milk FA intake due to the persistence of the reticular grove closing reflex.     

Fatty acid profile of yak milk from the Qinghai-Tibetan Plateau in different seasons and for different parities

Yaks are the most important grazing livestock for milk production on the Qinghai-Tibetan plateau because these animals are adapted to the high elevations and extremes of cold and can graze throughout the year. In the present study, 30 yaks were selected and the fatty acid (FA) profile of yak milk at different seasons and parities was investigated using gas chromatography. The concentrations of cis-9 C18:1, cis-11 C18:1, cis-9,trans-11 C18:2, and C18:3 n-3 in yak milk were higher in summer (25.26, 1.50, 1.46, and 0.33 g/100 g of total FA, respectively) than in winter (22.17, 0.77, 1.27, and 0.28 g/100 g of total FA, respectively). The contents of monounsaturated and polyunsaturated FA in milk fat of multiparous (parities 2 to 5) yaks (31.61 and 4.20 g/100 g of total FA, respectively) were higher than those in primiparous yaks (29.61 and 3.80 g/100 g of total FA, respectively). These results suggest (1) that the potential exists to improve the FA composition of yak milk by developing local supplement resources during the winter and (2) that multiparous yaks have a more favorable FA profile than primiparous yaks.     

Comparative analysis of the fatty acid and sterol profiles of widely consumed Mediterranean crustacean species

Comparative analysis of FA, NL and sterol profiles in the Nephropsnorvegicus (langoustine), Palinurusvulgaris (lobster) and Penaeuskerathurus (shrimp) muscle and cephalothorax showed that C16:0, C16:1ω-7, C18:0, C18:1ω-9, C20:4ω-6, EPA and DHA were found to be their major FA. Highest EPA occurred in langoustine muscle TL, DHA in both shrimp tissues TL while C20:4ω-6 in lobster muscle and cephalothorax TL. Muscle and cephalothorax NL consisted mainly of sterols (42.5–54.4% and 13.7–43.1%) and triacylglycerols (35.4–45.8% and 44.6–59.4%). Cholesterol was the major sterol (70.90–98.58% and 97.10–98.31% of total sterols in muscle and cephalothorax respectively) followed by avenasterol (0.18–20.32% and 0.07–0.70%) and β-sitosterol (0.29–7.30% and 0.23–0.75%). Lower concentrations of brassicasterol, stigmasterol, Δ7-stigmasterol, campesterol and campestanol were also found. The examined crustaceans muscle (edible part) was found to be a good ω-3 PUFA source for the consumers, while the cephalothorax (which is usually discarded) could be used effectively as a source for ω-3 PUFA production.     

Triacylglycerols and their fatty acid composition in edible Mediterranean molluscs and crustacean

The triacylglycerol (TAG) composition of edible Mediterranean molluscs (Eledone moschata, Sepia officinalis, Todarodes sagittatus) and crustacean (Penaeus kerathurus) was studied using a combination of preparative RP–HPLC and GC/MS. In S. officinalis and T. sagittatus mantle TAG, the main fatty acids were C16:0 and C18:0 while in E. moschata they were C18:1ω-9, C16:0, C20:5ω-3 and C22:6ω-3. In P. kerathurus muscle and cephalothorax TAG, the main fatty acids were C16:0, C18:0, C18:1ω-9, C20:4ω-6, C20:5ω-3, C22:6ω-3 and C16:0, C18:1ω-9, C20:4ω-6, C20:5ω-3, C22:6ω-3, respectively.     

Milk fatty acids in dairy cows fed whole crude linseed, extruded linseed, or linseed oil, and their relationship with methane output

This experiment studied the effect of 3 different physical forms of linseed fatty acids (FA) on cow dairy performance, milk FA secretion and composition, and their relationship with methane output. Eight multiparous, lactating Holstein cows were assigned to 1 of 4 dietary treatments in a replicated 4 × 4 Latin square design: a control diet (C) based on corn silage (59%) and concentrate (35%), and the same diet supplemented with whole crude linseed (CLS), extruded linseed (ELS), or linseed oil (LSO) at the same FA level (5% of dietary dry matter). Each experimental period lasted 4 wk. Dry matter intake was not modified with CLS but was lowered with both ELS and LSO (−3.1 and −5.1 kg/d, respectively) compared with C. Milk yield and milk fat content were similar for LSO and ELS but lower than for C and CLS (19.9 vs. 22.3 kg/d and 33.8 vs. 43.2 g/kg, on average, respectively). Compared with diet C, CLS changed the concentrations of a small number of FA; the main effects were decreases in 8:0 to 16:0 and increases in 18:0 and cis-9 18:1. Compared with diet C (and CLS in most cases), LSO appreciably changed the concentrations of almost all the FA measured; the main effects were decreases in FA from 4:0 to 16:0 and increases in 18:0, trans-11 16:1, all cis and trans 18:1 (except trans-11 18:1), and nonconjugated trans 18:2 isomers. The effect of ELS was either intermediate between those of CLS and LSO or similar to LSO with a few significant exceptions: increases in 17:0 iso; 18:3n-3; trans-11 18:1; cis-9, trans-11 conjugated linoleic acid; and trans-11, trans-13 conjugated linoleic acid and a smaller increase in cis-9 18:1. The most positive correlations (r = 0.87 to 0.91) between milk FA concentrations and methane output were observed for saturated FA from 6:0 to 16:0 and for 10:1, and the most negative correlations (r = −0.86 to −0.90) were observed for trans-16+cis-14 18:1; cis-9, trans-13 18:2; trans-11 16:1; and trans-12 18:1. Thus, milk FA profile can be considered a potential indicator of in vivo methane output in ruminants.     

Effect of forage species on fatty acid content and performance of pasture-finished steers

Consumers are increasingly concerned with the form and quantity of fat present in the foods they consume. This is leading to a shift in the way food is produced. In particular the animal industry is increasing the number of organic and naturally finished meat animals rather than finishing them on grains. The objective of this study was to determine if different pasture compositions (i.e. grass only or grass legume mixtures) would impact the fatty acid (FA) meat composition of beef steers (Bos taurus L.). The pasture treatments were tall fescue [Lollium arundinaceum (Schreb.) S.J. Darbysh] only, or tall fescue combined with either red clover (Trifolium pretense L.) or alfalfa (Medicago sativa L. ssp. sativa L.). Beef steers (n = 9–10 per treatment) rotationally grazed each pasture treatment. Forage from treatments were different for crude protein (CP), in vitro true digestibility (IVTD) and the FA myristric (C14:0), palmitic (C16:0), palmitoleic (C16:1), stearic (C18:0), oleic (C18:1), linoleic (C18:2), and total FA. Steers grazing mixtures with either red clover (RC) or alfalfa (ALF) had greater average daily gains (ADG) than tall fescue only. Additionally, RC treatment steers had larger ribeye areas (REA) and greater finishing weights than those in the ALF treatment. However, the differences found between pasture treatments in FA concentration did not translate to any differences in the FA concentration of meat harvested from steers. Thus, it is concluded that although the pastures contained different FA concentrations, with the levels of legumes present, this does not influence the FA composition of beef.     

Influence of a supplement containing conjugated linoleic acid on dairy performance,milk fatty acid composition,and adipose tissue reactivity to lipolytic challenge in mid-lactation goats

The objective of this work was to evaluate the effect of the supplementation of conjugated linoleic acid (CLA; 4.5 g of cis-9,trans-11 C18:2 and 4.5 g of trans-10,cis-12 C18:2) on milk performance, milk fatty acid (FA) composition, and adipose tissue reactivity in dairy goats fed a high-concentrate diet based on corn silage. Twenty-four multiparous dairy goats in early to mid lactation were used in a 10-wk trial, with a 3-wk adaptation to the experimental total mixed ration that contained corn silage (35%, dry matter basis), beet pulp (20%), barley (15%), and a commercial concentrate (30%). Goats were randomly allocated to 2 experimental groups and they were fed 45 g/d of a lipid supplement (either CLA or Ca salts of palm oil added on top of the total mixed ration). Individual milk production and composition were recorded weekly, and milk FA composition was analyzed in wk 2, 5, and 6. In the last week of the trial, an isoproterenol challenge was performed for 12 goats before morning feeding. The CLA supplementation had no effect on dry matter intake (DMI), body weight (BW), milk yield, milk protein content, and lactose yield and content, but it significantly decreased milk fat yield and content by 18 and 15%, respectively. The decrease in milk fat yield was related to a lower secretion of FA synthesized de novo, of the medium-chain FA, and to a lesser extent of the long-chain FA that are taken up from the peripheral circulation. The CLA supplementation decreased the proportion of the sum of C16:0 and C16:1 and the sum of total cis C18:1, and it increased the proportions of the sum of long-chain (C >16) and the sum of iso FA without modification of the total trans C18:1 and the sum of FA synthesized de novo (C <16). During the first 25 min relative to isoproterenol injection, the maximal concentrations, the increases above basal concentration, the changes in area under the curve, and the total area under the curve for glucose and nonesterified FA were not affected by CLA treatment. In conclusion, CLA supplementation associated with a high-concentrate diet based on corn silage resulted in decreased milk fat yield, increased net energy balance, and it did not affect the sensitivity of the adipose tissue to lipolytic challenge in lactating goats.     

Effects of different forage:concentrate ratios in dairy ewe diets supplemented with sunflower oil on animal performance and milk fatty acid profile

The aim of this study was to evaluate the effect of different forage:concentrate (FC) ratios in dairy ewe diets supplemented with sunflower oil (SO) on animal performance and milk fatty acid (FA) profile, particularly focusing on trans C18:1 FA and conjugated linoleic acid (CLA). Sixty lactating Assaf ewes were randomly assigned to 6 treatments in a 3 × 2 factorial arrangement: 3 FC ratios (30:70, 50:50, and 70:30) and 2 levels of SO addition (0 and 20 g/kg of dry matter). Both the diet FC ratio and SO supplementation affected milk yield, but differences between treatments were small. Although the proportion of concentrate induced limited changes in milk FA profile, dietary SO significantly decreased saturated FA and enhanced total CLA. Furthermore, the incorporation of SO in ewe diets decreased the atherogenicity index value by about 25% and doubled the contents of potentially healthy FA such as trans-11 C18:1 and cis-9,trans-11 CLA. However, the inclusion of SO in a high-concentrate diet (30:70) could switch linoleic acid biohydrogenation pathways, resulting in a significant increase in trans-10 C18:1, trans-9,cis-11 C18:2, and trans-10,cis-12 C18:2 milk fat percentages.     

Interpretation of triacylglycerol profiles of palm oil,palm kernel oil and their binary blends

The effects of lipase-catalyzed interesterification (IE) on changes in the chemical composition of palm oil (PO), palm kernel oil (PKO) and their binary blends at 3:1, 1:1 and 1:3 (w/w) ratios, using both 1,3 specific Rhizomucor miehei, (Lipozyme™) and non-specific Pseudomonas sp. lipases were evaluated. IE of the native PO and PKO showed very distinct chemical composition changes. Catalysis of PO, using both lipases, caused synthesis of more medium and long chain triacylglycerols (TAG), with MMM/OLL, MMP, OOO and PPP (M, myristic acid; O, oleic acid; L, linoleic acid; P, palmitic acid) increasing in concentration. In contrast, IE of PKO resulted in the formation of more short and medium chain TAG, with LaLaO and LaMO (La, lauric acid; C, capric acid) experiencing noteworthy increments. Both Rhizomucor miehei and Pseudomonas sp. lipases showed high affinity in hydrolyzing PO fatty acids, resulting in high TAG losses and formation of high percentages of partial glycerides while these lipases were found to enhance the synthesis process in IE of PKO. Catalysis of the three binary blends caused similar TAG compositional changes where the synthesis process focussed on the medium chain TAG, while hydrolysis was observed in the short and long chain TAG that showed corresponding decreases. Catalysis of the three blends was influenced by the major fraction of these blends. Among these blends, PO: PKO at a 1:1 ratio exhibited the highest degree of IE. The diversity and quantity of available TAG are postulated to be the main causes of the different catalytic activities in these binary blends with Pseudomonas sp. lipase showing a higher degree and rate of IE than R. miehei.     

Control of the Maillard reaction by ferulic acid

This study investigated how ferulic acid (FA) affects the formation of certain Maillard reaction products (MRPs), i.e., early MRPs, fluorescent and non-fluorescent advanced glycation end products (AGEs), and melanoidins in model systems. Glycation mixtures were prepared containing soy glycinin or bovine serum albumin (final concentration 10 mg/ml) and fructose (222 mM) in 0.2% KOH in the presence or absence of FA (12.95 mM) and incubated at 60 °C for 60 min. The extent of the MR was estimated by analysis of free amino groups, the incorporation of sugar into the protein backbone as well as the formation of N^?-(carboxymethyl)lysine (CML), fluorescent AGEs (λ_exc = 337 nm, λ_em = 350–550 nm) and melanoidins (absorbance at 420 nm). Formation of CML and fluorescent AGEs was reduced by nearly 90% by the addition of FA while early MRPs and melanoidins were inhibited to a lesser extent (∼10% and 28%, respectively) compared to AGE formation. A controlled formation of early MRPs was achieved by use of FA, and it is a new finding. To the best of our knowledge, for the first time the use of FA as a reliable means of obtaining novel glycoprotein preparations containing low amounts of AGEs, with the potential to be used as functional food ingredients, is proposed.