Both preformed fatty acids from plasma and de novo synthesized fatty acids in the mammary epithelial cell contribute to milk fat . Polyunsaturated fatty acids in milk fat are derived from the preformed fatty acids in plasma. Preformed fatty acids arise from free fatty acids mobilized from adipose tissue or from dietary fatty acids transported in the triglyceride portion of very low- density lipoproteins. Acetate serves as the primary sub- strate for de novo lipogenesis and is converted to malonyl-CoA by acetyl-CoA carboxylase and is chain- elongated by fatty acid synthase catalyzing the addition of volatile fatty acids . In adipose tissues, fatty acids are elongated to 16 carbons, forming palmitate, but in the mammary gland, short-chain fatty acids are rapidly released for esterification into triglycerides prior to complete elongation by chain-terminating transacyla- tion by fatty acid synthase . Saturated, long-chain fatty acids are shuttled to stearoyl-CoA desaturase, which inserts a double bond at the ninth position from the carboxyl end . Other, non-saturated substrates can also be used by stearoyl-CoA desaturase including several trans 18:1 isomers . Two trans 18:1 iso- mers, trans-11 and trans-7 18:1, produce conjugated linoleic acid isomers when desaturated at the ninth carbon [84, 83].
The supplementation of plant oils affected also the content of saturated fatty acids in milk, which confirms the potential for decreasing saturated fatty acids with lipid supplementation and thus, when the bioavailability of C18 fatty acids increases as a result of increased dietary intake, C10:0 to C16:0 de novo synthesis decreases as does their concentration in milk (Gómez-Cortés et al., 2008). This relation may be explained by the ruminal bio- hydrogenation of polyunsaturated fatty acids into e.g. C18:1 trans, which is one of the inhibitors of de novo fatty acid synthesis, mainly C8:0 to C16:0 (Chilliard et al., 2003). Both plant oils used as feed ingredients decreased the total content of saturated fatty acids in milk except 3.5% of LS that did not af- fect the content of this group of milk fatty acids.
This study demonstrated that homogenization did not increase the activity of lipoprotein lipase (LPL) in spite of a fast accumulation of free fatty acids (FFA). Two homogenization pressures (100 and 170 bar) and two temperatures (40˚C and 50˚C) were examined. The activity of LPL was analyzed and the formation of FFA was measured with two differ- ent methods, the B.D.I.-method and a nonesterified fatty acids (NEFA) method. A homogenization temperature of 50˚C resulted in a decreased LPL activity compared to 40˚C. No effect of homogenization pressure was found. Analyzing FFA concentration with the B.D.I.-method resulted in significant effect of homogenization temperature and no effect of pressure. The largest formation of FFA was found in milk homogenized at 40˚C. Using the NEFA method, another re- sult was obtained, indicating no effect of homogenization temperature and a larger FFA accumulation at 100 bar than at 170 bar. Both analytic methods demonstrated significant production of FFA during 60 min incubation at homogeniza- tion temperature after treatment. The level of FFA in the milk samples immediately after homogenization was very high, demonstrating that LPL cleaves the triglycerides very rapidly when the native membrane was damaged. The regression between the B.D.I.-method and the NEFA was fair in the interval between 4 and 14 mmol/100 g fat, whereas at higher concentrations, the correlation was poor.
Nutritionists also started to call for changes in milk composition. The former, commonly respect- ed outstanding role of milk and milk products in human nutrition was somewhat impaired by data on the participation of saturated fatty acids, trans- unsaturated fatty acids and cholesterol in cardio- vascular diseases (e.g. Welch et al., 1997; Precht and Molkentin, 2000; Playne et al., 2003; Parodi, 2004), despite of the frequently reported positive role of polyunsaturated fatty acids and of proved possibilities to increase their proportion in milk fat (e.g. Offer et al., 1999; Jensen, 2002; Lock and Bauman, 2004).
Buffalo milk is contributing 12% of the total milk pro- duction in the world. About 80% of total buffalo milk is produced in India and Pakistan . In subcontinent, buffalo milk is preferred over cow milk due to white color, higher fat, protein, total solids contents and creamy taste . Buffalo milk is highly suitable for the manufacturing of wide range of value added dairy prod- ucts, such as, yoghurt, mozzarella and cheddar cheese . Buffalo milk is healthier than cow milk in terms of lower concentration of cholesterol and higher magnitude of un- saturated fatty acids . Fat content of buffalo and cow milk ranges from 6 to 7% and 3.5–4.5%, respectively . Protein content of buffalo and cow milk is 3.8–4% and 3.2–3.3%, respectively while ash content of buffalo and cow milk is 0.82% and 0.72%, respectively. The viscosity of buffalo milk is also greater than cow milk . In addition to the normal nutritional perspectives, certain milk con- stituents have functional value. Antioxidants are chemical substances than scavenge/neutralize the free radicals and foods should contain enough concentration of antioxi- dants to prevent oxidative stresses. Uninterrupted reactive oxygen species can lead to diabetes, atherosclerosis, accel- erated ageing, breakdown of DNA and several essential biochemical compounds . Increased incidences of meta- bolic diseases have led the consumers to make healthy choices of foods and demand for functional foods is mounting across the world. Changing life styles have led the food industry and researchers to develop functional foods and determine the functional value of traditional foods. Increased knowledge in free radical biology has led the consumer to consume functional foods containing natural antioxidants. Casein, whey, sulphur containing amino acids, selenium, zinc, catalase, glutathione peroxid- ase, superoxide dismutase, vitamin E, C and beta-carotene has antioxidant activity in milk . Concentration of vitamin E in buffalo and cow milk is 5.5 and 2.1 mg/ 100 ml, respectively while the amount of vitamin C in buffalo and cow milk is 3.66 and 0.94 mg/100 ml, respectively . Buffalo milk has higher magnitude of sulfur containing amino acids, selenium and zinc as compared to cow milk . Concentration of beta- carotene in cow milk is more than buffalo milk. Due to the difference in the concentration of antioxidant sub- stances, buffalo and cow milks may have different antioxi- dant capacity. Antioxidant capacity of few fermented dairy products is reported in literature. Antioxidant capacity of goat milk based kefir was investigated by 2-Diphenyl-1- picrylhydrazyl assays and antioxidant capacity of kefir was more than native milk . Antioxidant capacity of pro- biotic yoghurt was studied in cow, goat and camel milk using Pediococcus pentosaceus and it was observed that fermentation improved the antioxidant capacity of pro- biotic yoghurts . Pasteurization is one of the most
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(EFC) of the milk samples was determined by means of gravity and was expressed as % fat (w/w) per 100 g of milk. The fat-free dry matter (FFDM) content of milk was determined after the extraction of fat content, and the residue weighed on a filter paper after drying. The FFDM was calculated using the difference in weight of the initial milk sample before and after drying in the oven, and it was expressed as % FFDM (w/w) per 100 g milk. The moisture content of the milk sample was obtained using the formula as follows: 100% − % lipid − % FFDM. The moisture content was expressed as % moisture (w/w) per 100 g of the milk sample. From the extracted fat, 10 mg of total lipid was transferred by means of a disposable glass Pasteur pipette into a Teflon-lined screw-top test tube. Fatty acids were determined from the fat extracts by trans-esterification to form methyl esters using the method as described by Park and Goins (1994). This was done by using 0.5 N of NaOH in a mixture of 14% boron trifluoride and methanol solution. The fatty acids in the milk sample extracts were then quantified using a Varian GX 3400 GC with a flame ionization detector, by means of a fused silica capillary column, Chrompack CPSIL 88 (100-m length, 0.25-μm ID with 0.2-μm film thicknesses). The column temperature used for the fatty acids in milk ranged between 40 and 230 °C (hold 2 min; 4 °C/min; hold 10 min). After quantification of fatty acid methyl esters, 1 μ of the sample in hexane was injected into the column (using a Varian 8200 CX autosampler) in a ratio of 100:1. The temperature of the injection port and the detector was maintained at 250 °C. Nitrogen was used as the make-up gas while hydrogen, at 45 psi, was used as the carrier gas. The chromatograms were recorded using a chromatography software known as Varian Star Chroma- tography Software. The fatty acid methyl ester (FAME) samples were recognized by means of comparing the rela- tive retention times of the FAME peaks from samples ob- tained from the that of the standards i.e. from Sigma (Sigma-Aldrich, St. Louis, MO) (18919). Additional CLA standards were gotten from Matreya, Inc. (Pleasant Gap, PA) which include the following: trans-10, cis-12 18:2 iso- mers, trans-9, trans-11, cis-9, cis-11, cis-9, trans-11. The fatty acid from the milk samples were calculated as the relative % of each separate fatty acid as a percentage of the total of all fatty acids found in the sample. Other known fatty acid combinations and ratios were expressed by using the fatty acid data including total polyunsaturated fatty acids (PUFA), total omega-3 fatty acids, total omega-6 fatty acids, total saturated fatty acids (SFA), total monoun- saturated fatty acids (MUFA), PUFA/SFA and omega-6/ omega-3 fatty acid ratio. Atherogenicity index was calcu- lated as the content ratio of SFA/unsaturated FA, using the following formula proposed by Ulbricht and Southgate (1991): atherogenicity index: [C12 + 4 (C14) + C16]:(sum of unsaturated FA).
Milk fat samples from cow, camel, goat and mare milk were obtained for this study. The extraction and de- termination of fatty acids were carried out by the method of butylation to produce the corresponding ethers. For this purpose a 100 ml volumetric flask was filled with 50 ml of predistilled n-butanol and 2 ml of concentrated sulfuric acid was added.
ABSTRACT: Ten Czech Pied cows in the mid-lactation stage were fed diets based on grass silage and maize silage. The composition of milk fats differed. The proportions of even-chain saturated fatty acids (SFAs) up to C 14:0 were insignificant and the content of C 16:0 was significantly higher (P < 0.05) when feeding a diet based on maize silage, while the proportions of the individual polyunsaturated fatty acids (PUFAs) were significantly (except for C 18:2 ) higher when feeding a diet based on grass silage. The total SFA proportions were 67.60 and 62.93% (P < 0.05) of maize and grass silages, respectively, while an opposite relation was observed for the sum of PUFAs (3.56 and 4.74%; P < 0.001). Feeding of grass silage resulted in a significantly lower proportion of hypercholesterolaemic fatty acids C 12:0 , C 14:0 and C 16:0 (49.38 and 44.98%, respectively; P < 0.05) and in lower values of the atherogenic index (3.03 and 2.44; P < 0.05). Thus, the results could be used for the improvement of milk fat composition.
kept in an intensive stable system, documented a significantly (P < 0.01) lower value of HCFA after the NEB period (–1.86%). Thus, the early overcom- ing of NEB is important for the respective cows’ health and reproduction ability (Patton et al. 2007; Podpečan et al. 2008) as well as for the quality of milk used for human consumption (Pešek et al. 2006; Hanuš et al. 2010). It is possible to state that cows with the earlier overcoming of NEB started to produce milk healthier for human consumption sooner after calving. Although a higher proportion of SFA was detected after the NEB period, simul- taneously a significantly lower HCFA proportion was determined as well (P < 0.01). The higher SFA proportion does not necessarily mean the worse quality of milk with respect to the paradoxically declined HCFA proportion. The reason for the op- posite results for SFA and HCFA has a physiological background. Approximately half of the fatty acids in ruminant milk fat (FA from C 4:0 to C 14:0 and half of C 16:0 ) is synthesised in the mammary gland “de novo” from short-chain FA with two carbon seg- ments (acetyl CoA) (Kaylegian & Lindsay 1995; Bauman & Griinari 2003). The rest of fatty acids (half of C 16:0 and C 18:0 and FA with more carbons) is transported to the mammary gland by blood, especially in the form of the highly labile ß-lipo- protein fraction of non-esterified FA absorbed di- rectly from the feed ration (Harvatine et al. 2009)
changes in the microbial population (Boeckaert et al., 2006), influences on animal metabolism (Bauman et al., 2011) or to enhancement of the overall performance of offspring, when fed to dams during pregnancy and lactation (Pickard et al., 2008; Or-Rashid et al., 2010). There are known differences between the FA profile of meat of grass fed animals and animals fed silage or concentrate-based diets (Poulson et al., 2004; Noci et al., 2005), but there is little information regarding the FA profile of cattle fed tropical grasses. Lipid profile and concentration in the diet are two factors that can influence the profile of fat in muscle and milk. Some isomers resulting from the biohydrogenation process are known to have effects on fat synthesis, and the longer RT of fluid in the rumen of animals fed tropical grasses may affect the extent of biohydrogenation and hence FA profile compared to other basal diets. One hypothesis in this study was that a higher polyunsaturated FA content of the supplement (highest being fish oil) was associated with a higher total unsaturated fatty acids (TUFA) of RF. A second hypothesis was that
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In mammals, the chain-length of the FAS I re- leased fatty acid is usually C16, being generally restricted to carbon chains longer than C12 (lau- ric acid), due to the low specificity of acyl-ACP thioesterase (EC 126.96.36.199). However, milk fats from humans, ruminants, and most other non- ruminant mammals contain high proportions of medium-chain saturated fatty acids (C8-C14). Medium-chain fatty acids are synthesised de novo within the mammary epithelial cell in the mammary gland during lactation as a result of a tissue-specific modification of the universal FAS I reaction (BARBER et al. 1997; HUNT & ALE- XON 2002). The alteration of the specificity of the acyl-chain termination results from an interac- tion of FAS I with a second thioesterase that is not part of FAS I but is present in the cytosol as a discreet monomeric peptide. This thioesterase has an access to the elongating acyl chain on the 4´-phosphopantetheine prosthetic group of FAS I and can hydrolyse the thioester bond which re- sults in the release of medium-chain fatty acids of chain length from C8 to C12.
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requirements (Knop and Cernescu, 2009). Loss of energy in feed reduces the ability of rumen microbes to digest plant proteins and synthesize animal proteins, thus reducing the protein percentage in milk. The mobilization of body fat increases the concentration of non-esterified fatty acids in the liver and consequently the percentage of fat in milk; the resulting effect is that the fat to protein ratio in milk increases. The resulting NEB and metabolic demands influence the postpartum interval to first ovulation, thereby affect the interval to conception (Butler, 2003) and the reproductive potential of the affected cows. Conception rates are thought to be low in animals that experienced NEB pre-partum and early post-partum because of the poor quality of oocytes generated during this stage (Knop and Cernescu, 2009). Many studies have shown that while feed intake and milk production both increase during early lactation, maximum feed intake is only achieved some weeks after maximum milk yield (Garnsworthy, 1988). A relationship that involves three components, dry matter intake, live weight and milk production comes into play throughout lactation (Figure 2.3). Most of the cows have a peak of milk production after calving that is impaired by a decrease in dry matter intake resulting in a loss of live weight, leading to a NEB during the first 6 to 8 weeks of lactation (Heuer, 2000). It would therefore be a challenging task to prevent NEB in cows that are naturally high producers because of the interplay of these factors.
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The camel milk is receiving more recognition as a global product in optimizing human health. The FAO predicts the camel dairy products will appear on Euro- pean supermarket shelves. However, logistic challenges in manufacturing and processing must be overcome. De- spite the increasing demands from Sahara to Mongolia, the annual 5.4 million tones camel dairy products are greatly inadequate. Sector and local investments must escalate to meet demands and create profitable markets both in the Middle East and the Western world. There are about 300 million potential customers in the Middle East and millions more in Africa, Europe and the Americas for camel dairy products. Although somewhat saltier than cow milk, camel milk represents a cost-effective hus- bandry under toughest conditions. Camel milk is 3 times richer in vitamin-C than cow milk. In many regions of Iran, Russia, Kazakhstan and India, camel milk has tradi- tionally been prescribed as a food treatment for multiple diseases recovery [16-18]. Oral camel milk administra- tion has proved protective against cadmium induced to- xicity in rats . Camel milk is also known for its rich iron, unsaturated fatty acids and B-vitamins.
adding rolled flaxseed to dairy cow diets up to 10% of DM or as in  ground linseed up to 7.5% of the DM and  cows fed with 4% Ca-salts of canola oil, soybean oil, or linseed oil. The data obtained in the present study revealed that milk fat percentage was not affected by dietary treatments; however, cows fed GNC based concentrate (T1) tended to have higher milk fat as compared to other groups (Table 3.3). On the contrary, a reduction of milk fat due to inclusion of linseed in the diets at the rate of 4-5%  or 5.1-7.5% as ground linseed ;  in dairy cows has been reported. However, when the effect of supplementary oilseeds and Ca-salt of fatty acids on milk fat is compared, milk fat concentration was found to be higher or similar  in cows fed Ca-salt of fatty acids of palm oil than those fed formaldehyde-treated linseed, while in other studies feeding of Ca-salt of linseed oil (4% of DM) to dairy cows resulted in decreased milk fat percentage compared with a control diet . Milk fat depression can occur if fat supplementation increases the synthesis of certain trans FA such as trans -10 C18:1 or trans-10, cis-12 C18:2 in ruminal fluid ; . However, in the present study lower doses of linseed products in the diet might be a reason for the lack of significant differences between treatments. Milk protein, lactose and MUN concentrations were did not show significant difference among the treatment groups (Table 3.3).
In general, factors that influence volatile fatty acid concentrations in the rumen affect fatty acid synthesis in the mammary gland through the availability of precursors. Therefore, milk fat concentration varies directly with the forage to concentrate ratio or the fiber content of the diet (Sutton, 1985). However, it is also suggested that synthesis of short-chain fatty acids can be inhibited by diets with high proportions of starchy concentrates or long- chain fatty acids (Thomas and Martin, 1988; Beaulieu and Palmquist, 1995). High starch, low fiber diets result in milk with a low fat content, which has characteristic increases in trans fatty acids, especially t10-C18:1 and t10,c12 CLA (Griinari and Bauman, 2003). Relation between intake CSFA and fat yield response in dairy ewes show in figure 2.
In our study, the percentages of C 16:1 t9, C 18:1 t9, C 18:2 t9t12, and C 18:2 t9c12 ranged from 0.00% to 0.07%, 0.00% to 0.72%, 0.00% to 0.19%, and 0.00% to 0.05%, in chocolates groups, respectively (Table 1). The percentages of C 16:1 t9, C 18:1 t9, C 18:2 t9t12, and C 18:2 t9c12 ranged from 0.03% to 0.03%, 0.56% to 1.19%, 0.03% to 0.13%, and 0.03% to 0.04%, in chocolate wafers groups, respectively (Table 2). Total trans fatty acids contents were found to be higher in chocolate wafers with nuts than in other samples (1.39%). C 18:1 t9 elaidic acid, was found to be the most abundant trans fatty acid in all samples. TFAs were found in all samples of milk chocolates, pure chocolate wafers, other chocolates, chocolates with pistachio, chocolates with almond, chocolate wafers with nuts and chocolates with nuts but none of the TFAs was determined in bitter chocolates. Minimum and maximum ranges of TFAs were de- termined as 0.00–6.23% in the chocolate samples and 0.00–7.92% in the wafer chocolate samples (Table 3). The percentages of TFAs were determined as 0.407% and 1.019% in chocolates and chocolate wafers groups, respectively (Tables 1 and 2).
alteration in rumen fermentation rather than an inhibition of mammary gland acetyl-CoA carboxylase activity (Banks et al., 1983; Storry, 1980; Thomas, 1980). The effect on rumen fermentation is most pronounced with unsaturated fatty acid feeding. Long-chain fatty acid sources (more than 20 carbons) such as fish oils and Seterculia seed fats have a specific inhibitory action on the uptake of preformed fatty acids by the mammary gland. The changes in milk fat composition that occur with fat feeding are predominantly in the triglyceride fraction, with very little change occurring in the phospholipid and fat membrane fractions (Storry, 1980). Protected polyunsaturated fatty acids appear to be the most promising for consistently increasing milk fat percentage and altering milk fat composition. Protected oil-seeds or oils rich in linoleic acid (sunflower, corn, and soybean) produce large, rapid increases in the linoleic acid content of milk fat when fed. The increases in linoleic acid content are generally associated with declines in myristic, palmitic, and oleic acids. Transfer of linoleic acid from protected supplements to milk is reported to be between 20 and 40 percent (Christie, 1979; Fogerty and Johnson, 1980).
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The research was performed on abdominal adipose tissue of seven South African Black ostriches (Struthio camelus var. domesticus), bred in Republic of Macedonia. Ostriches were reared on a farm in Demir Kapija and were fed with 40% alfalfa and 60% mixture of maize, barley, soya bean, sunfl ower meal, bran, salt, limestone and vitamins. The birds were slaughtered at the age of 13 to 14 months. The content of fatty acids was determined in seven samples which were frozen and stored into polyethylene bags for 21 days at a temperature of 21°C and then slowly thawed.
Matsubara et al. reported that in the peripheral circula- tion, more than 97% of soluble Aβ is bound to lipoprotein particles . Our previous study revealed that of those lipoprotein-bound Aβ in plasma, approximately 60% is as- sociated with triglyceride rich lipoproteins (TRLs), that are of intestinal and hepatic origin . We also reported that such lipogenic organs can synthesize and secrete Aβ complexed to lipoproteins into the circulation [15–18]. Moreover, the synthesis of Aβ within the small intestinal epithelial cells was regulated by the ingestion of dietary SFA . In wild-type C57BL/6 mice, the chronic feeding of SFA significantly increased the enterocytic production of Aβ compared to the mice that were maintained on low- fat standard chow, whilst the fasting of the mice for 12 h completely abolished the enterocytic Aβ . These data consistently suggest that different types of fatty acids may differentially influence the postprandial production and secretion of TRL-associated Aβ, and by extension modu- late plasma Aβ homeostasis. However, to date, the effects of unsaturated fatty acids on enterocytic Aβ abundance and secretion into the circulation have not been reported. Therefore, in this study, we have tested the effects of chronic MUFA and PUFA feeding in comparison to SFA on the abundance of enterocytic and plasma Aβ.
Fatty acids are a group of lipids that are most commonly analyzed by GC. This method is used for biological sam- ples containing compounds with chain lengths in the range C4 to C24. GC analysis of fatty acids was performed following conversion to apolar methyl ester derivatives. The GC can be used to analyze fatty acids either as free fatty acids or as fatty acid methyl esters. Methyl esters are favorite derivatives for GC analysis of fatty acids. GC-FID with a methylation process allows polar compounds to be analyzed more readily, and the results can be quantified more generally, economically, and simply than the GC- MS method (Young et al. 2012; Zhang et al. 2015). After fatty acid extraction, it is necessary to transform the con- stituents into specific derivatives to render them more volatile. In fingerprints, free fatty acids appear in the form of triglycerides composed of glycerol and three fatty acids. Thus, polar solvents and non-polar solvents can be effect- ive in degrading non-polar fatty acids and polar glycerol (Emerson et al. 2011).
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