Acid Profile Of Milk Fat Research Articles

Effects of the percentage of concentrate on rumen fermentation, nutrient digestibility, plasma metabolites, and milk composition in mid-lactation goats

The aim of this work was to study the effects of the dietary percentage of concentrate on patterns of intake, the evolution of rumen fermentation characteristics and plasma metabolites after a meal, nutrient digestibility, and milk production and composition in a medium-term trial in dairy goats. These effects have been well studied in dairy cattle but seldom in goats. Thirteen ruminally and duodenally cannulated dairy goats (95±4 d in milk) fed ad libitum were used in this study. Goats were assigned to 1 of 2 dietary treatments: high-concentrate (70% concentrate on dry matter basis) or a low-concentrate (35%) total mixed rations. The experiment was conducted over a period of 10 wk, including 3 wk of adaption to the diets. Patterns of intake, rumen fermentation characteristics, and plasma metabolites after a meal and fatty acids profile of milk fat were compared at the onset and at the end of the experiment. The increase in dietary percentage of concentrate decreased rumen pH, acetate to propionate ratio, ammonia-N concentration, and plasma urea concentration. The percentage of concentrate did not affect total volatile fatty acid concentrations. The high-concentrate diet increased the rate of intake during the morning meal at the onset of the experiment, whereas it decreased total dry matter intake and the rate of intake during the morning meal at the end of the experiment. The high-concentrate diet resulted in greater organic matter digestibility. Raw milk yield and protein yield were greater in goats fed the high-concentrate diet, whereas fat yield was not affected by dietary treatments. The milk fat content was lower in goats fed the high-concentrate diet. Proportions of the trans-C18:1 isomer relative to total fatty acids in milk were higher with the high-concentrate diet, but no modification of the proportion of total trans-C18:1 was detected, in particular no shift from trans-11 C18:1 to trans-10 C18:1 was observed. Further, the isomer trans-10,cis-12 C18:2 was not detected. Data from this study could be used for a new modeling approach or to improve existing models.

Effects of long-term supplementation of dairy cow diets with rumen-protected conjugated linoleic acids (CLA) on performance, metabolic parameters and fatty acid profile in milk fat

The supplementation of conjugated linoleic acids (CLA) to the rations of dairy cows represents an opportunity to reduce the content of milk fat. Therefore, CLA have the potential beneficial effect of reducing energy requirements of the early lactating cow. The present study aimed at the examination of long-term and post-treatment effects of dietary CLA intake on performance, variables of energy metabolism-like plasma levels of non esterified fatty acids (NEFA) and ß-hydroxybutyrate (BHB), and fatty acid profile in milk fat. Forty-six pregnant German Holstein cows were assigned to one of three dietary treatments: (1) 100 g/d of control fat supplement (CON), (2) 50 g/d of control fat supplement and 50 g/d of CLA supplement (CLA-1) and (3) 100 g/d of CLA supplement (CLA-2). The lipid-encapsulated CLA supplement consisted of approximately 10% of trans-10, cis-12 CLA and cis-9, trans-11 CLA each. The experiment started 1 d after calving and continued for about 38 weeks, divided into a supplementation (26 weeks) and a depletion period (12 weeks). Over the first 7 weeks of treatment, 11 and 16% reductions in dry matter intake compared to control were observed for the cows fed CLA-1 and CLA-2 supplements respectively. Consequently, the calculated energy balance for these two CLA groups was lower compared to the control. Plasma levels of NEFA and BHB remained unaffected. Later in lactation the highest CLA supplementation resulted in a reduction of milk fat content of 0.7%. However, no reduction in milk fat yield, and accordingly no milk fat depression (MFD), could be shown. The trans-10, cis-12 CLA in milk fat increased with increasing dietary CLA supplementation in a dose-dependent manner. The proportion of C16 in milk fat was decreased by the highest CLA supplementation. With the exception of an increase in plasma glucose level in the CLA-2 group, no post-treatment effects were observed. Overall, under the conditions of the present study no improvement in the calculated energy balance by CLA supplementation could be shown for the entire evaluation period.

Milk Conjugated Linoleic Acid (CLA) Profile and Metabolic Responses of Dairy Cows Fed with High-temperature-micro-time (HTMT) Treated Diets Containing High Quantity Extruded Soybean (ESB)

A feeding trial was conducted to examine the effect of high-temperature-micro-time (HTMT) processing of diets containing extruded soybean (ESB) in high quantity on milk fat production, metabolic responses, and the formation of conjugated linoleic acid (CLA) and trans-vaccenic acid (TVA). Twenty-one multiparous Holstein cows in mid-lactation were blocked according to milk yield in the previous lactation. Cows within each block were randomly assigned to either normal concentrate or HTMT treated diets containing ESB (7.5% HTMT-ESB and 15% HTMT-ESB). It was hypothesized that the HTMT-ESB would affect the undegradable fatty acids in the rumen and, thus, would modify the fatty acid profile of milk fat. Both 7.5% and 15% HTMT-ESB did not affect milk yield, fat, protein, lactose and solid-not-fat (SNF), but the proportion of cis-9, trans-11 CLA in milk fat was significantly increased by these treatments. Content of TVA in milk fat was not affected by HTMT-ESB. The HTMT-ESB influenced the fatty acid profile in milk fat, but there was little difference between 7.5% and 15% of supplementation. HTMT-ESB feeding significantly decreased the concentration of plasma insulin and glucose, while plasma growth hormone (GH), triglyceride (TG), non-esterified fatty acid (NEFA) and HDL-cholesterol were increased by 7.5% and 15% ESB-HTMT supplementation in comparison to the control group (p 0.05). The present results showed that cis-9, trans-11 CLA production was increased by HTMT treatment of dietary ESB without reduction of milk fat, and the unchanged milk fat and yield was assumed to be associated with the constant level of thyroid hormones, leptin, and IGF-1.

Short communication: Assessment of the potential of cinnamaldehyde, condensed tannins, and saponins to modify milk fatty acid composition of dairy cows

This study was conducted to determine whether feeding cinnamaldehyde (main component of cinnamon bark essential oil; Cinnamon cassia), condensed tannins from quebracho trees (Schinopsis balansae), or saponins from Yucca schidigera altered the milk fatty acid profile of dairy cows. For this purpose, 4 lactating cows were used in 4 × 4 Latin square design (28-d period) and fed a total mixed ration containing no additive (control), or supplemented with cinnamaldehyde (1 g/d; CIN), quebracho condensed tannin extract (150 g/d; 70% of tannins; QCT), or Yucca schidigera saponin extract (60 g/d; 10% of saponins; YSE). Results revealed no effects of feeding CIN or QCT on milk fatty acid profile. Supplementation with YSE resulted in some modifications of milk fatty acid profile as suggested by the reduced proportions of C6:0 (2.71 vs. 2.95%), C8:0 (1.66 vs. 1.89%), and trans-11 C18:1 (0.92 vs. 1.01%). Results show low potential of cinnamaldehyde, condensed tannins, and saponins to alter ruminal biohydrogenation process and modify the fatty acid profile of milk fat at the feeding rates used in this study. Further investigations are needed to determine the factors that limit the effects of these secondary metabolites on ruminal microbial populations involved in the biohydrogenation processes of unsaturated fatty acids.

Fatty Acid Profile in Milk Fat from Qinghai Plateau Yak at Different Altitudes and Parities

Qinghai Plateau yak are the most important grazing livestock for milk and beef production on the Qinghai-Tibetan plateau because they are adapted to extremes of cold environment and higher elevation and can be grazed throughout the year. Milk samples (n = 47) from Qinghai Plateau yak cows of different parities and milk samples (n = 6) from Qinghai yellow cattle cows were analyzed using gas chromatography-mass spectrophotometry. Differences in fatty acid profiles of Qinghai Plateau yak milk fat from rangelands at 3 different elevations, at 2 parities, and between species were compared. Additionally, fatty acid profiles of forages from different elevations were analyzed. Fatty acid percentages (g/100 g total fatty acids) in milk fat of Qinghai Plateau yak from different rangelands were largely similar, but there were differences (P < 0.05) in individual fatty acids, including conjugated linoleic acid. There were also elevation differences in fatty acid percentages (e.g., cis-9, cis-12 C18:2 and cis-9, cis-12, cis-15 C18:3; g/100 g total fatty acids) of forage plants. Milk from multiparous Qinghai Plateau yak cows showed greater (P < 0.01) percentages of C18:1 and C18:2, total unsaturated fatty acids, total monounsaturated fatty acids, and total polyunsaturated fatty acids and lesser (P < 0.01) percentages of total saturated fatty acids than primiparous counterparts. The cis-9, trans-11 conjugated linoleic acid isomer percentage in milk fat from multiparous cows was greater (P < 0.01) than from primiparous cows. The study results also suggested that short-chained, medium-chained, and saturated fatty acid percentages of milk fat were greater (P < 0.05) for Qinghai Plateau yak compared with those of Qinghai yellow cattle.

Effect of Dietary Fish oil and Soybean Oil on Milk Production and Composition of Holstein Cows in Early Lactation

Milk was collected from 20 primiparous Holstein cows that were distributed into four groups and arranged in a completely randomized design with a 35-day period to determine the effect of feeding fish oil, soybean oil, or their combination on milk production and composition. Experimental diets consisted of: 1) control diet; 2) a diet with 3% (DM basis) added fat from menhaden fish oil; 3) a diet with 3% added fat from soybean oil; and 4) a diet with 1.5% added fat from fish oil and 1.5% fat from soybean oil. The dry matter intake (18.5, 18.9, 18.3, and 18.6 kg/d, for control, fish oil, soybean oil and combination diets, respectively) and milk production (30.31, 32.15, 31.19, and 31.59 kg/d, respectively) were higher for cows that consumed the 3% fish oil-containing diet. Milk from cows fed control, fish oil, soybean oil and fish oil with soybean oil diets contained 3.45, 2.72, 2.96, and 2.87% fat, respectively. Concentration of total omega-3 fatty acids (0.87, 1.28, 0.96, and 1.18 g/100 g of fatty acids, respectively) in milk fat were higher for cows that consumed either fish oil-containing diet, especially the 3% fish oil diet. The n-6:n-3 ratio (4.57, 2.62, 6.17, and 4.08, respectively) in milk fat was lower for the fish oil diet. These results showed that fish oil modified fatty acid profile of milk fat and increased the proportion of beneficial fatty acids for human health.

Terpenes and fatty acid profiles of milk fat and “Bitto” cheese as affected by transhumance of cows on different mountain pastures

The evolution of fatty acid (FA) and terpenoid profiles was studied in milk (n=20) and “Bitto” (n=3), a protected designation of origin cheese produced in a restricted Italian alpine area. Milk came from 25 Italian Brown cows successively grazing pastures at 1400, 2100 and 2200m during transhumance in June–September 2006. The fat matter was analyzed for FAs and terpenes by means of gas chromatography and purge & trap/gas chromatography–mass spectrometry, respectively. FA composition of milk fat varied significantly (p<0.0001) in relation to contents of conjugated linoleic acid (CLA), stearic, linoleic and trans-vaccenic acids. Similar monoterpene profiles characterized milk fat from cows grazing the different pastures and the highest amount of terpenes was measured in milk coming from cows grazing at 1400m. High levels of δ3-carene in milk fat were likely related to the important presence of Ligusticum mutellina in the pasture. Only negligible amounts of sesquiterpenes were detected in milk fat whereas they were the most abundant class in fodder. Both FA and terpene profiles of ripened (70 days) cheeses resembled those of the original milks. Overall, results confirm the influence of the botanical composition of mountain pastures both in enhancing the ruminal synthesis of CLA and in modifying the FA and terpenoid profiles of milk and “Bitto” cheese. Nevertheless, neither the FA nor the terpenoid profiles revealed here can be considered as “unique” to “Bitto” cheese and, for this reason, they can hardly be assumed to be biomarkers for defining a specific relationship among grazing area, milk and “Bitto” cheese. They better represent the chemical fingerprint of the cow feeding, adopted in mountain areas.

Effect of Dietary Omega-3 and Omega-6 Fatty Acids Sources on Milk Production and Composition of Holstein Cows in Early Lactation

The objective of this research was to determine the effect of feeding fish oil, soybean oil, or their combination on milk fatty acid profiles, especially omega-3, omega-6 and omega-3/omega-6 ratio. Milk was collected from 20 primiparous Holstein cows that were distributed into four groups and arranged in a completely randomized design with 35 days period to determine the effect of feeding fish oil, soybean oil, or their combination on milk production and composition. Experimental diets consisted of: 1) control diet; 2) a diet with 3% (DM basis) added fat from menhaden fish oil; 3) a diet with 3% added fat from soybean oil and 4) a diet with 1.5% added fat from fish oil and 1.5% fat from soybean oil. Dry matter intake (18.47, 18.87, 18.33 and 18.63 kg day(-1), for control, fish oil, soybean oil and combination diets, respectively) and milk production (30.31, 32.15, 31.19 and 31.59 kg day(-1)) were higher for cows that consumed 3% fish oil containing diet. Milk from cows fed control, fish oil, soybean oil and fish oil with soybean oil diets contained 3.45, 2.72, 2.96 and 2.87% fat, respectively. Concentration of total omega-3 fatty acids (0.87, 1.28, 0.96 and 1.18 g/100 g of fatty acids) in milk fat were higher for cows that consumed either fish oil-containing diet, especially the 3% fish oil diet. The n-6:n-3 ratio (4.57, 2.62, 6.17 and 4.08) in milk fat was lower for fish oil diet. These results showed that fish oil modifies fatty acids profile of milk fat and increased the proportion of beneficial fatty acids for human health.

Seasonal Variation in Compositions and Fatty Acids Profile (with Emphasis on CLA) in Iranian Buffalo’s Milk

In this study the seasonal variations of milk compositions and fatty acids profile with emphasis on Conjugated linoleic acid (CLA) and vaccinic acid (VA) concentrations of buffalo’ s Milk in North of Iran was investigating. In each season (2006)we had 30 samples (10 samples for each month ) of milk from bulk milk and sent them to laboratory for determination of It’s Compositions .Then fatty acids profile of milk fat was determined by Gas Chromatograph. The mean of Data from 120 samples for 4 seasons of year (2006) were compared using Duncan’s Multiple Range Test with an alpha of 5% and the results show that: The range of total solids (TS) in milk samples were 16.15 – 18.93 percent so that high percent of TS was in April to July. There was no significant difference in amount of lactose in each of the seasons and it, S range was 4.93 –5.12 percent. The range of milk protein was 3.60 – 3.88 percent, there was significant difference between seasons so that the high content of protein was in April to July and the low content of it was in December to March. There was significant difference in content of milk fat in samples of various season .It was 6.78 – 9.25 percent, so that the high percent of milk fat was in December to June. The content of Unsaturated fatty acids was 50.50 to 58.23 percent of total milk fat .The content of Unsaturated fatty acids (C14 – C18) were higher in Spring season .These Data show That season of Year can influence on milk compositions and fatty acids profile of milk via the type and quality of forages that buffalos use it in grazing or feeding, the amount and kind of supplementation of used diet.

The effects of supplementation with sunflower and soybean oils on the fatty acid profile of milk fat from grazing dairy cows

The objective of this study was to observe the effect of supplementation with vegetable oils (VO) on the fatty acid profiles and conjugated linoleic acid (CLA) content of milk fat. Twelve dairy cows in mid lactation fed on pasture were blocked by body weight, milk production and days in lactation and randomly allocated from blocks to 3 treatments repeated in a Latin square design with periods of 28 day duration. The treatments were as follows: cows on pasture supplemented with 5 kg concentrate per head per day (C), supplemented with 4.5 kg concentrate + 0.5 kg sunflower oil per head per day (SFO) and supplemented with 4.5 kg concentrate + 0.5 kg soybean oil per head per day (SBO). The animals were grazed as a group and were stocked at 2.5 heads per hectare. The treat- ments had no effect on milk yield or protein yield and content, but decreased milk fat yield and content (P < 0.05). Milk fat from the cows supplemented with VO had a lower concentration of short and medium chain fatty acids (P < 0.05) and a higher concentration of long chain fatty acids (P < 0.05). The addition of VO to the diet also resulted in a reduction in saturated and an increase in unsaturated fatty acids of milk fat (P < 0.05). The hypercholesterolemic fatty acids in milk fat (i.e. C12:0, C14:0 and C16:0) decreased while the concentration of oleic and linoleic acids increased with VO (P < 0.05). There was no effect on linolenic acid. Finally, the inclusion of VO in the diet increased (P < 0.05) the contents in milk fat of the various cis/trans isomers of oleic acid (including trans-vacenic, TVA) and of CLA which increased by 61%. dairy cow / conjugated linoleic acid / fatty acids / pasture / vegetable oils

The Effects of Feeding Fish Oil on Uterine Secretion of PGF2α, Milk Composition, and Metabolic Status of Periparturient Holstein Cows

The objectives were to determine the effect of dietary fish oil (FO) on uterine secretion of PGF2alpha, milk production, milk composition, and metabolic status during the periparturient period. Holstein cows were assigned randomly to diets containing FO (n = 13) or olive oil (OO, n = 13). Cows were fed prepartum and postpartum diets that provided approximately 200 g/d from 21 d before the expected parturition until 21 d after parturition. The FO used contained 36% eicosapentaenoic acid (EPA, C20:5, n-3) and 28% docosahexaenoic acid (DHA, C22:6, n-3). Blood samples were obtained from 14 d before the due date until d 21 postpartum. A total of 6 FO and 8 OO cows without periparturient disorders were used in the statistical analyses of PGF2alpha-metabolite (PGFM) and metabolite concentrations. Length of prepartum feeding with OO or FO did not differ. Proportions of individual and total n-3 fatty acids were increased in caruncular tissue and milk of cows fed FO. The combined concentrations of EPA and DHA in caruncular tissue were correlated positively with the number of days supplemented with FO. Cows fed FO had reduced concentrations of plasma PGFM during the 60 h immediately after parturition compared with cows fed OO. Concentrations of prostaglandin H synthase-2 mRNA and protein in caruncular tissue were unaffected by diet. Production of milk and FCM were similar between cows fed the two oil diets. However, cows fed FO produced less milk fat. Feeding FO reduced plasma concentrations of glucose. Dietary fatty acids given during the periparturient period can reduce the uterine secretion of PGF2alpha in lactating dairy cows and alter the fatty acid profile of milk fat.

Influence of pasture and concentrates in the diet of grazing dairy cows on the fatty acid composition of milk.

In five short-term experiments conducted in Victoria in 1997 and 1998, grazing dairy cows were given either pasture alone or pasture supplemented with high-energy concentrates, and the fatty acid profiles of milk fat were measured. We established the effects of these feeds on some aspects of milk fat of importance for human nutrition, but we specifically focused on the hypothesis that conjugated linoleic acid (CLA) concentrations in milk fat increase as pasture intake increases, and decrease as more concentrates are fed. In agreement with previous research, feeding fresh pasture alone resulted in high concentrations (1.0-1.8 g/100 g milk fat) of CLA. When the effect of level of pasture consumption on CLA content was examined, a significant positive relationship (r2 = 0.35; P < 0.05) was obtained. When cereal grain concentrates were used to supplement pasture intake, the CLA content of milk fat generally declined (P < 0.05), except where the amount of concentrates given led to a marked reduction in total milk fat concentration. The use of cereal grain concentrates also generally resulted in significant (P < 0.05) increases in medium-chain saturated fatty acids, but always reduced the contribution of butyric acid to milk fat, from 4.5 to 3.9 g/100 g milk fat, on average.

Effect of kind of dietary fat on the quality of milk fat from Italian Friesian cows

Four diets, supplemented with different fats of vegetable origin, were compared in a 4×4 Latin square design with eight primiparous Italian Friesian cows (two cows per cell). The four fats were: toasted full fat soy bean in diet WS; toasted full fat linseed in diet WL; calcium soap of palm oil in diet PS; and calcium soap of olive oil in diet OS. Scope of the trial was to study the effect of the four different fat sources on milk yield and composition and on the quality of milk fat in terms of safety for the consumer health, with particular attention to trans fatty acids and to conjugated linoleic acid isomers (CLA). Diet OS induced the highest milk yield ( P<0.05), while diet PS gave the fattest milk ( P<0.05), and the highest milk content of both saturated and medium chain fatty acids ( P<0.05). Saturated to unsaturated ratio of milk fat was decreased when cows were fed diet WS ( P<0.05), while the ratio was increased with cows fed on diet PS ( P<0.05). With a closely similar behaviour milk CLA content was enhanced with diet WS and strongly depressed ( P<0.05) with diet PS. Diet OS increased total CLA as well, probably as a consequence of the bio-hydrogenation process of large amounts of oleic acid, transformed into trans isomers of C 18:1, including vaccenic acids. Full fat soy bean promoted some milk fatty acids with beneficial effects on consumer health, but calcium soap of olive oil similarly improved the fatty acid profile of milk fat, while meeting the cows’ requirements as an energy supplement.

Efeito da Suplementação de Lipídios na Ração sobre a Produção de Ácido Linoléico Conjugado (CLA) e a Composição da Gordura do Leite de Vacas

O objetivo deste trabalho foi verificar o efeito de fontes de lipídios (soja integral moída ou óleo de soja) adicionados à dieta sobre o perfil de ácidos graxos da gordura do leite, especialmente sobre o aumento do CLA. Foram utilizadas 6 vacas multíparas 7/8 holandês-zebu, 30 dias após o parto, com peso vivo médio de 500 kg e produção média de 20 quilos de leite ao dia. Os animais foram divididos em três grupos para recebimento das dietas (tratamentos), isoprotéicas e isoenergéticas, em que o tratamento controle continha 3% de extrato etéreo na ração total e os demais 7%. Os tratamentos contendo fontes de lipídios, quando comparados com o controle, diminuíram o percentual de ácidos graxos de cadeia curta e diminuíram os teores dos ácidos butírico, capróico, caprílico, cáprico, láurico, mirístico e o percentual de ácidos graxos saturados. Os mesmos tenderam, ainda, a reduzir os teores de ácido palmítico e palmitoléico e tenderam a aumentar o percentual de ácidos graxos insaturados e de cadeia longa. Por outro lado, esses tratamentos aumentaram o teor de ácido esteárico e tenderam a aumentar os teores de ácido oléico e CLA. O óleo de soja, comparado ao grão de soja moído, diminuiu os teores de ácido linoléico e linolênico e aumentou o CLA, tendeu a aumentar o teor de ácidos graxos não identificados e a diminuir os ácidos graxos saturados. Concluindo, a inclusão de óleo de soja na dieta, e não soja grão, aumenta o teor de CLA na gordura do leite.

Effects of Duodenal Infusions of Palmitic, Stearic, or Oleic Acids on Milk Composition and Physical Properties of Butter

Four dairy cows fitted with a duodenal cannula were used in a 4 × 4 Latin square design to investigate the effects of daily duodenal infusion of 500g of fatty acids (containing mainly C16:0, C18:0, or cis-C18:1) on fecal concentrations of fatty acids, fatty acid profiles of milk fat, and solid fat content of butter. Fecal concentrations of C16:0 and especially of C18:0 were increased by duodenal infusion. Infusion with C16:0 increased the proportion of C16:0 in milk fat and delayed softening of butter when the temperature rose. Infusion with C18:0 resulted only in a slight increase of C18:0 proportion in milk fat and did not significantly affect solid fat in butter between -10 and 30°C. With the infusion of cis-C18:1, the proportion of cis-C18:1 in milk fat was more than twice that of control, to the detriment of C16:0. Butter contained low proportion of solid fat, even at low temperatures. Increasing C16:0 or cis-C18:1 in milk fatty acid via duodenal infusion can be used to study their specific effects on butter characteristics, but, because of a low transfer from infusion to milk, this method is less efficient with C18:0.

Effect of modified dairy fat on fasting and postprandial haemostatic variables in healthy young men

It has been suggested that milk fat, due to its content of saturated fatty acids, may have a thrombogenic effect. In the present study the fatty acid profile of milk fat was modified by changing the feeding regimens of cows and the effect on haemostatic variables of a diet containing the modified milk fat (M) was compared with that of a diet containing milk fat of typical Danish composition (D). In the modified fat 16% of the saturated fatty acid (C12-C16) content was replaced mainly by oleic acid. Eighteen subjects were fed on two strictly controlled isoenergetic diets containing 40% energy from total fat (30% energy from the test fats) for periods of 4 weeks in a study with a crossover design. Fasting samples were taken in the last week of each study period. Postprandial samples were taken on day 21, 3 h after lunch (n 18), and on the last day of the study 2, 4, 6 and 8 h after a fat load containing 1.2 g of one of the milk fats/kg body weight (n 8). After 4 weeks' dietary intervention fasting plasma factor VII coagulant (FVIIc) activity, tissue-type plasminogen activator (t-PA) activity, plasminogen activator inhibitor (PAI-1) antigen and beta-thromboglobulin did not differ between diets M and D. Postprandially FVIIc and t-PA activities increased (P < 0.001) and PAI-1 antigen and PAI-1 activity decreased (P < 0.001) as compared with fasting values, regardless of diet. After the fat load, the postprandial increase in FVIIc was marginally lower after diet M than diet D (diet effect, P < 0.05). In conclusion, the modified milk fat obtained by the applied feeding strategy had virtually the same effects on haemostatic variables as conventional milk fat.

Dietary Soybeans Extruded at Different Temperatures: Milk Composition and In Situ Fatty Acid Reactions

Twenty-four multiparous Holstein cows, 4 of which were ruminally fistulated, were assigned to one of four diets containing full-fat soybeans, either raw or extruded at 120, 130, or 140°C. Our hypothesis was that the extrusion of full-fat soybeans, as well as the extrusion temperature, would affect the bypass of fatty acids in the rumen and, thus, would modify the fatty acid profile of milk fat. Total mixed diets containing 23.7% soybeans (percentage of DM) were fed for 8 wk. Milk yield was lower, and the proportion of milk CP was higher, for cows fed raw soybeans than for cows fed extruded soybeans. Compared with raw soybeans, extruded soybeans increased the concentration of Δ-11-trans-C18:1 from 2.72 to 11.41% in milk fat but had no effect on yield or percentage of milk fat. Polyunsaturated fatty acids of raw soybeans disappeared more rapidly than did those of extruded soybeans from bags incubated in the rumen of fistulated cows. However, more Δ-11-trans-C18:1 and C18:0 appeared in bags containing extruded soybeans than in bags containing raw soybeans. Extrusion of full-fat soybeans influenced the metabolism of fatty acids in the rumen and the fatty acid profile of milk fat, but the temperature of extrusion had only minor effects on these parameters.

The fatty acid composition of milk fat as influenced by feeding oilseeds

The fatty acid composition of bovine milk fat can be substantially altered by feeding lipid sources which alter the fatty acid profile of lipid entering the intestine from the rumen. As long-chain fatty acids of dietary origin can be incorporated directly into milk fat the opportunity exists to alter the ratio of short and long-chain fatty acids as well as the degree of saturation of milk fat. In practice our ability to alter the fatty acid profile of milk fat is limited not by the synthetic capacity of the mammary gland, but rather by the challenge of achieving effective protection of unsaturated dietary fatty acids from biohydrogenation in the rumen, as well as keeping the level of polyunsaturated fatty acids within the range where the organoleptic quality and shelf-life of milk and dairy products are not compromised. The fatty acid composition of oilseeds such as canola are considered desirable from a human health perspective and thus their inclusion in the diet of dairy cattle as a means of achieving a more desirable fatty acid profile in milk fat may enhance the nutritive quality of milk.

Effects on milk fat composition and cow performance of feeding concentrates containing full fat rapeseed and maize distillers grains on grass-silage based diets

Two experiments were carried out to determine the effect on milk fat composition and cow performance of including ground full fat rapeseed (FFR) and maize distillers grains (MDG) in the concentrate supplement. Unwilted grass-silage was the basal forage in both experiments. In Expt. 1, 8 kg/day of concentrate containing 0 (control), 80 (low), 140 (medium) or 200 g/kg (high) FFR was fed to four groups of 16 cows each for 7 weeks. Milk yield, milk constituent yield and milk composition which was compared using 13 cows per treatment were not significantly affected by FFR inclusion. The milk fat (using all 64 animals) from cows on the high FFR concentrate contained significantly lower proportions of C6:0, CS:O, C14:0, C14:l (P <0.05) compared to those produced by cows on the other three concentrates. It also contained lower proportions of ClO:O and C12:O (P<O.OS) compared to that from cows on the control or medium FFR concentrate. Cows on the high and medium FFR concentrate had significantly lower proportions of C 16:0 (P < 0.01) and significantly higher proportions of C 18: 1 (P < 0.05) in their milk fat compared to the other two treatments. Solid fat content in the milk fat at 10°C was also significantly lower on the former two treatments (P < 0.05). In the second experiment 6 kg/day of concentrate containing 0 (control), 700 (MDG 1) and 920 g/kg (MDGZ) MDG was fed to three groups of 12 cows each for 6 weeks. Silage intake, milk yield or the concentration or yield of milk fat and lactose were not significantly different between treatments. Milk protein concentration and yield were depressed (P < 0.05) by the inclusion of both levels of MDG. Including both levels of MDG significantly reduced the proportions of ClO:O, C12:0, C14:0, C14:1, C16:0, C16:l and Cl&3 (P<O.O5) and significantly increased the proportions of C4:0, C18:0, C 18: 1 and Cl&2 (P < 0.05). The changed fatty acid composition resulted in a softer fat as indicated by the solid fat content at 10°C which was 480,355 and 314 g/kg on the control, MDGl and MDG2 concentrates, 8 days after feeding commenced. The results of these experiments show that, on a grass-silage based diet, the fatty acid profile of milk fat can be significantly altered, resulting in a softer fat, by feeding 1.12 or 1.60 kg of FFR or 4.20 or 5.52 kg of MDG in the concentrate supplement daily. FFR may be the supplement of choice because the levels of MDG required to give similar changes in milk fat composition and softness had negative effects on milk protein concentration.