Fatty Acids In Milk Fat Research Articles

Some effects of acute fasting and climatic stresses upon milk secretion in friesland sheep

1. 1. Five lactating Friesland sheep were exposed to control conditions and to the stresses of fasting for 24 hr, a hot (40°C) environmental temperature for 48 hr, and a cold (1°C) temperature for 48 hr. 2. 2. Between 17 and 24 hr after withdrawal of food, milk secretion rate was not significantly reduced, but milk osmolality and the concentration of citrate in milk were reduced. 3. 3. In the hot environment, rectal temperature averaged 1.7°C above normal. After 24 to 48 hr of exposure, milk secretion rate was not significantly reduced but milk osmolality, total nitrogen concentration and potassium concentration were reduced, and in milk fat 16-carbon fatty acid was less prevalent and 18-carbon fatty acids more prevalent. Mean plasma prolactin concentration was high during heat exposure but individual results were very variable. lti]4. In the cold environment, total oxygen consumption averaged 2.2 ml · kg −1 · min −1 above normal. After 24 to 48 hr of exposure, milk secretion was reduced, the concentration of total nitrogen increased and the prevalence of short-chain fatty acids in milk fat also increased. Mean plasma prolactin concentration was low during cold exposure but, again, individual results were variable. 4. 5. These effects have been compared with those previously reported in other high-yielding species.

Composition and Yield of Goat Milk as Affected by Nutritional Manipulation

This report deals with the influence of quantity and nature of roughages and concentrates on milk yield and composition by goats producing 500 to 900kg milk per year, particularly the influence of crude fiber and crude protein. Forages with most voluntary intakes and milk yielding capabilities were legumes (alfalfa, red clover) and Italian ryegrass. Milk production was highest with green forages and hay pellets. Corn silage feeding reduced milk yields by 5 to 14% and hay of medium quality by 15 to 25%. Supplementary concentrates during midlactation increased intakes of dry matter and energy and milk production. Milk protein percentage was increased, but milk fat contents were lower. Increased intakes of energy raised percentages of palmitic acid and decreased carbon-18 acids. Low lipid contents (<1% of dry matter) in the total ration reduced milk production, fat percentages, and carbon-18 fatty acids in milk fat. Formaldehyde-treated oil-meals improved milk production. Concentrates at 400 g/kg milk instead of 200g improved milk production by 20 to 25% in early lactation and by 7.5% in midlactation. Because of persistency, the feeding plan giving most economic returns during the whole cycle of reproduction seems to be a medium 200 to 400g concentrates per day in late pregnancy and a high 300 to 400 g/kg milk during lactation.

Effects of Feeding Oleic Acid or Hydrogenated Vegetable Oils to Lactating Cows

In feeding trials to clarify the mechanism by which unsaturated oils depress milk fat percentage, oleic acid at 250 or 500ml per cow per day did not reduce milk fat percentage significantly. At 500ml these changes were significant (control, oleic): rumen acetate 61.6, 603%; rumen propionate 19.4, 21.0%; milk fat content of 18:1 trans fatty acid 3.0, 8.0%; and of 18:2 cis fatty acid 2.2, 1.4%.Feeding hydrogenated vegetable oil containing 13% trans acid at 454g per cow per day decreased slightly milk fat percentage and elevated plasma cholesterol 190 to 245 mg/100ml and 18:1 trans fatty acid in milk fat 4.2 to 6.2%. Hydrogenated vegetable oil containing 49% 18:1 trans acid at 454g daily decreased milk fat 3.9 to 3.1%. Milk fat triglycerides decreased in short chain fatty acids and increased in 18:1 trans 2.6 to 11.2%, 18:1 cis 22.9 to 29.0%, and 18:2 trans .2 to 1.8%. Milk phospholipids decreased 14.1 to 9.6% in 14:0 fatty acid and increased .3 to 3.1% in 18:1 trans and 20.5 to 31.4% in 18:1 cis. Blood cholesterol esters were increased 152 to 195 mg/100ml.The data lend support to the concept that trans acids or compounds produced in the rumen during their formation from polyunsaturated fatty acids are responsible for the milk fat depression from unsaturated oils.

Polyunsaturated Protected Lipid: Effect on Triglyceride Molecular Weight Distribution

Five lactating Holsteins were fed a polyunsaturated protected lipid supplement for 28 days. There were no significant changes in dry matter consumed or milk produced per cow per day. No changes in protein, solids-not-fat, and freezing point of the milk were significant.All cows increased from 22 to 34% in daily milk fat production. As expected, the fatty acid composition of the milk fat changed markedly during protected lipid feeding with increases in production of C4, C18:0, C18:l, C18:2, and C18:3 fatty acids. The production of triglyceride classes with 40, 52, and 54 fatty acid carbons also increased. Per day mammary production of the short chain fatty acids increased while the medium chain length fatty acid output decreased. This supports evidence by other researchers that two mechanisms of mammary synthesis are generating short and medium chain length fatty acids in milk fat.

The influence of the legume Leucaena leucocephala and formal-casein on the production and composition of milk from grazing cows

SummaryTwenty-four lactating Jersey cows, grazing a 3-week regrowth of nitrogen-fertilized Chloris gayana cv. Pioneer pastures selected a diet containing 18% crude protein and were given 0, 2 or 4 kg/day of fresh Leucaena leucocephala or 250 g/day of formal-casein. The effect of the treatments on milk production was measured in a 4 × 4 latin-square design experiment with experimental periods of 14 days.Mean milk yield of unsupplemented cows was 9·6 kg/day, 10·1 kg/day when cows were supplemented with formal-casein and 10·3 kg/day when fed 2 or 4 kg Leucaena/day. Yields of solids-not-fat, protein, casein, butterfat and short and medium-chain (C4–C16) fatty acids in milk fat were higher when cows were fed supplements (P &lt; 0·01). Intake of digestible organic matter was lowest on the unsupplemented diets although feed in excess of 40 kg D.M./cow/day was offered and cows had little difficulty harvesting feed with a mean bite size of 350 mg organic matter/bite and mean grazing time of 507 min/24 h.It was concluded that a tropical grass diet containing 18% crude protein was deficient in protein for lactating cows and that small quantities of the legume Leucaena can alleviate such a deficiency.

Dietary Lipid Metabolism in Lactating Dairy Cows

Effects of feeding an oil seed supplement treated with formalin upon lipid patterns of blood and synthesis of milk fat were evaluated. Percentages and yields of fatty acids of milk fat with chain lengths between 6 and 16 carbons were decreased while percentages and yields of stearate and linoleate were increased when the lipid supplement was fed. Calculations in cows fed control and supplement, 60% and 80%, respectively, of fatty acids of milk were derived from lipids of blood were supported by arterial-venous differences. Comparisons of the fatty acid compositions of triacylglycerol of plasma and milk fat suggested that triacylglycerol may not be the sole source of linoleate transferred from blood to milk fat. A preliminary evaluation of supplement effects upon lipoprotein patterns of serum indicated two peaks in the low density lipoprotein class and that the increase in total cholesterol of blood caused by feeding lipid supplement is due to increases in cholesterol content of the low density and high density lipoprotein classes.

Effects of Age, Diet and Lactation on Lipogenesis in Rat Adipose, Liver and Mammary Tissues

Four diets varying in safflower oil content from zero to 20% were used in a study of interactions among diet and physiological state. Increasing fat in the diet did not alter food intakes but decreased digestibility coefficients. Increasing safflower oil intake did not alter milk fat content in lactating rats but increased relative amounts of unsaturated fatty acids in milk fat. In liver and perirenal adipose tissues from young male and non-lactating female rats, low fat diets increased rates of lipogenesis from glucose in vitro and specific activities of enzymes whose functions are closely associated with lipogenesis. This adaptive hyperlipogenic response was not evident or was less prominent in aged or lactating rats. In the case of lactating rats it appears that lactation produces a marked reduction in adipose lipogenesis when low fat diets are fed. Reduced glyceride glycerol synthesis in lactating as compared to non-lactating rat adipose coupled with reduced fatty acid synthesis and in increased lipolysis indicated a shift in adipose function in the direction of increased fat mobilization as would be supportive of lactation. Only minor diet effects upon mammary enzyme patterns and rates of in vitro lipogenesis were observed.

Effects of Long Supplementation with Lipids on Lacting Dairy Cows

Effects of long term feeding of large amounts of an oil seed supplement treated with formalin upon metabolite patterns in blood of the dairy cow, milk composition, and general performance were studied. Cholesterol and cholesterol esters in plasma rose to 1000 mg/100ml at peak lactation when lipid intakes were declined in later lactation. High concentrations of cholesterol did not induce hemolytic anema. Concentrations of nonesterified fatty acid in serum peaked at 700 microequivalents per liter when lipid intakes were greatest and declined thereafter. The pattern of triacylglycerol concentrations in plasma seemed to reflect both lipid intake and mammary uptake. No changes in blood hematocrite, hemoglobin content, plasma protein, amino acid nitrogen, urea glucose, aspartate aminotransferase, or creatine phosphokinase were noted, excepting a temporary decrease in urea concentrations when initiating feeding of the supplement. Milk protein and lactose contents were unaffected by the supplement while percentage of milk fat was increased. Since the supplement was high in linoleate, a major increase was in percentage of this fatty acid in milk fat. Changes in the fatty acid pattern in milk fat adjusted rapidly to the change in diet and remained constant thereafter. There was indication that the supplement increased lactational performance during early lactation. This apparent advantage was more than offset by a subsequent depression in milk yields and shortcoming of lactation in several cows under the ad lib feeding regime. if high lipid supplements are to be used in practice, research on appropriate feeding regimes is required.

Comparative study of triacylglycerol fatty acids in milk fat from two leporidae species: rabbit ( oryctolagus cuniculus) and hare ( Lepus europaeus)

1. 1. Fatty-acid composition of hare milk triacylglycerols markedly differed from that of rabbit milk and was essentially characterized by a 2.1 times lower concentration of medium-chain fatty-acids (M.C.F.A.). 2. 2. Consequently, very high levels (>70 moles %) of M.C.F.A., previously reported for rabbit milk, cannot be considered as a general characteristic of the Leporidae. 3. 3. General tendencies recorded for intramolecular fatty acid distribution in hare milk triacylglycerols agreed with those reported for other animal species.

The response of dairy cows grazing a nitrogen fertilized grass pasture to a supplement of protected casein

SummaryTwenty-one Jersey cows in their 6th–8th week of lactation grazed Chloris gayana pastures fertilized with nitrogen and were treated in three ways, no casein (control), casein (1 kg/cow/day) or formal-casein (1 kg/cow/day) in seven 3 x 3 Latin squares to measure the effect of protein protection on milk yield and milk composition. Additional animals fitted with oesophageal and rumen fistulae were used to determine composition of the diet selected and rumen characteristics on three treatments.Cows ingested herbage containing 20% crude protein with a protein solubility of 40%. The untreated casein supplement increased milk yield by 3%, fat 5% and protein 2·4%. Formal-casein produced 20% (3·3 kg/day) more milk than the control, a 13% higher yield of butterfat and 27% more protein. Rumen ammonia concentrations in the afternoon were similar for the control and formal-casein supplemented cows (21 and 23mg/100ml) but significantly higher when casein was fed (74 mg/100 ml) indicating extensive deamination of the untreated protein.Yields of C4–C16 fatty acids in milk fat were 8 and 21% higher for the casein and formal-casein treatments than for the controls, which together with the higher live weight of formal-casein supplemented cows indicated that the milk yield response to the protein supplements was mainly due to a higher daily intake of herbage.

Studies on lipid digestion in the preruminant calf. 2. A comparison of the products of lipolysis of milk fat by salivary and pancreatic lipases in vitro.

1. A comparison has been made of the products of lipolysis of the fat in cow's milk by salivary and pancreatic lipases (EC 3-1-1-3) from a preruminant calf. 2. It was confirmed that salivary lipase releases short-chain acids preferentially, particularly butyric and caproic acids. This was not only true initially but also as the course of lipolysis progressed. Even after 60 min incubation the longer-chain acids were only released to about one-twentieth of the extent of butyric acid. 3. Although pancreatic lipase also initially released proportionately more butyric acid than other fatty acids, within 30 min the longer-chain acids were released to about half the extent of butyric acid. 4. Since the over-all extent of lipolysis by salivary lipase was limited by its inability to release long-chain acids, the release of these acids (which comprise two-thirds of the total fatty acids of milk fat) in the calf is likely to be dependent on the subsequent action of pancreatic lipase. 5. The release of fatty acids by pancreatic lipase was enhanced by pre-incubating milk fat with salivary lipase.

Short-term effects of herbage allowance on milk production, milk composition and grazing time of cows grazing nitrogen-fertilized tropical grass pasture

The short-term effects of varying the quantities of herbage allocated (15, 25, 35, 55 kg DM cow-1, day-1) to lactating Jersey cows strip grazing 3-week regrowths of nitrogen-fertilized Panicum maximum cv. Gatton panic pastures, upon the diet selected, milk production, milk and milk fat composition and grazing time, were measured. Sixteen cows were used in a latin-square design with experimental periods of 1 4 days. With increasing herbage allowance milk yields rose, averaging 8.9, 9.9, 10.4 and 10.6 kg milk cow-1, day-1 respectively. A lower solids-not-fat percentage in milk from cows receiving 15 kg DM cow-1, day-1 and a lower percentage protein from cows receiving 15 and 25 kg DM cow-1 day-1 indicated a lower intake of digestible energy by cows at these lower herbage allowances. Molar percentages of short-chain fatty acids in milkfat (C6, C8, C10, C14) increased linearly and oleic acid (C18:1) decreased linearly as herbage allowance increased, showing that a higher proportion of the milk fat was coming from energy in the feed and a smaller proportion from body reserves. Cows selectively grazed leaf from the uppermost layers of the swards. As herbage allowance was restricted, a higher proportion of pasture was eaten and this came mainly from pasture growing 10 cm or more above ground level. Total time spent grazing was similar for all herbage allowances but the proportion of night grazing was consistently lower at the higher intensities of grazing.

Distribution of isomeric octadecenoic fatty acids in milk fat.

Milk fat octadecenoic acids were isolated by preparative gas-liquid chromatography of their methyl esters and separated into cis and trans isomers by argentation thin-layer chromatography. The distribution of the double bonds in the two fractions was determined by reductive ozonolysis. Cis octadecenoic acids had double bonds in positions 6 to 14. The cis-9 isomer was the most abundant isomer representing approximately 95% of the total. Trans octadecenoic acids had double bonds in positions 6 to 16, the predominant isomer being trans-11 octadecenoic acid. Data illustrating the range of variation in the distribution of positional isomers of octadecenoic acid for herd milk fat and butter are presented. There was no obvious seasonal variation in the distribution pattern. Fat from perirenal and subcutaneous adipose tissue of a dairy cow had composition similar to that of butter samples.

Effects of Abomasal Infusions of Safflower Oil or Elaidic Acid on Blood Lipids and Milk Fat in Dairy Cows

In each of three trials with abomasally-fistulated lactating Holstein cows, we compared control rations to the same ration plus abomasal infusion of safflower oil or elaidic acid. In Trial 1, 250ml safflower oil were infused over 4h daily for 3 wk. Trial 2 involved infusing 500ml safflower oil over 4h daily for 1 wk. In Trial 3 elaidic acid was infused daily for 1 wk.Infusion of safflower oil in Trial 1 increased milk fat percentage and proportion of 18-carbon polyunsaturated fatty acids in the milk fat. Proportions of myristic, palmitic, stearic, and oleic fatty acids of milk fat decreased. Blood ketones and free fatty acids and cholesterol of plasma were increased by the oil infusion.In Trial 2 the 1-wk infusion of safflower oil did not affect milk fat yield or percentage. The infusion increased the proportion of polyunsaturated 18-carbon fatty acids in the milk fat and decreased myristate, palmitate, and stearate. An increase in plasma free fatty acid was small but significant. Triglycerides, cholesterol, glucose, ketones, and acetate were not affected by the infusion. Intake of hay was depressed by this infusion rate.In Trial 3, infusion of elaidic acid had no effect on milk fat yield or percentage. Blood or plasma lipids did not change.

Synthesis of milk fat from beta-hydroxybutyrate and acetate in lactating goats.

SummaryThe relative importance of β-hydroxybutyric acid (BHBA) and acetate as precursors for milk-fat synthesis was studied in lactating goats by infusing separately tracer quantities of [3−14C]DL-BHBA and [1−14C]acetate into the jugular vein, and [1−14C]butyrate into the portal vein. The concentrations and specific radioactivities of blood plasma constituents, the yields and specific radioactivities of individual milk fatty acids and the relative radioactivities of individual carbon atoms of milk fatty acids were determined.The infusion of [1−14C]butyrate resulted in the appearance of labelled BHBA in the blood plasma which behaved almost identically with infused [14C]BHBA as a precursor for milk fatty acids.The relative radioactivity of carbon atoms of the fatty acids of milk fat following the infusions provided direct evidence that BHBA had provided an intact 4-carbon unit at the methyl end of each fatty-acid chain. Acetate provided 2-carbon units both for the elongation of the 4-carbon units and for completede novosynthesis. BHBA also provided 2-carbon units which behaved in a similar fashion to those from acetate.Acetate and BHBA together accounted for all of the C4–C12acids of milk fat, about 75% of the C14, 45% of the C16and 10% of the C18.The total contributions of the various precursors to the fatty acids of milk fat were: acetate 42%, BHBA 9·4% and other plasma precursors (by difference) 48·6%.

Milk yield and composition of milk and blood as indicators of energy intake by Jersey cows

Jersey cows were used in a change-over design to examine the effect of three levels of energy intake (lucerne hay at 100, 75 and 50% ad lib.) on milk yield, milk composition, fatty acid composition of milk fat, and blood metabolites (non-esterified fatty acids, glucose and total ketones) to determine which measurement was the most accurate indicator of intake of energy. Milk yields averaged 9.9, 8.7 and 7.2 kg/cow/day with relative intakes of 100, 75 and 50% of ad lib. When energy was restricted the proportion of C4–C16 fatty acids in milk fat decreased (72, 69 and 59%), while the proportion of oleic acid increased (15, 18 and 26%). These changes occurred within approximately 6 days on new energy levels. Fore milk and strippings had similar fatty acid proportions. Restriction of energy reduced the solids not fat, protein and casein contents of milk, and increased its butter fat percentage. Non-esterifred fatty acid levels in blood plasma increased with restriction of feed (348, 528 and 579 µ-equiv./l). Glucose and ketone bodies of blood averaged 58 mg/100 ml and 9.1 mg/100 mi respectively, and did not vary between treatments. It is concluded that milk production is the most sensitive indicator of the intake of digestible energy where change-over designs are used. However, when individual animal variation is not removed in the analysis, the intake of energy is most closely correlated with the fatty acid composition of milk fat (r = 0.73 and –0.74 for C4–C16 acids and oleic acid respectively). Significant correlations with the protein to fat and casein to fat ratios of milk were also measured (r = 0.64 and 0.63 respectively). There was a poor relationship between energy intake and blood composition (r = –0.25 for non-esterified fatty acid content).

Sources of variation in the fatty acid composition of milk fat from monozygous twin cattle housed indoors

Abstract Some sources of variation in milk fat fatty acid compositions of monozygous twin cattle housed indoors are described. Differences in fatty acid proportions between night and morning milkings accounted for less than 8% of total observed variation in all acids except butyric; differences between 3 consecutive days for up to 21% of the variance in some acids; and differences between the six cows for up to 46% of the total variance. Significant (P < 0.05) differences between individual members of twin sets were observed in the proportions of most fatty acids. These sources of variation are discussed in relation to the design of short-term twin experiments where fat compositions are determined.

Relationships between milk and milk fat composition and trans-lactation changes in mammary gland enzyme activities in grazing cattle.

Ohanges in milk and milk fat composition during complete lactations of four grazing cows are described. Correlations among the proportions of pairs of milk fat fatty acids were interpreted to indicate that fatty acids were of three groups-those reaching the gland preformed as blood lipids, those synthesized de novo in the gland, and a fraction, chiefly palmitic' acid, derived from both sources. The pro-portions of all groups of acids varied in an erratic manner compared with steady changes observed in other studies with cows on controlled feeding.

Effect of Feeding Soybeans or Formaldehyde-Treated Soybeans on Lipid Metabolism in Ruminants

Three lactating fistulated goats were used in a 3×3 Latin Square design comparing control, formalin-treated, and untreated soybean rations. The concentrate-to-roughage ratio was 2:1.Milk yield was depressed (P<.05) in the formalin-treated soybean group. Long chain unsaturated milk fat fatty acids increased in both soybean treatments compared to controls with no significant difference between treated and untreated beans. Rumen pH and total protozoa counts were lower on the goats fed formaldehyde-treated beans. Total rumen lipids were elevated over controls in both treatments. Unsaturated 18 carbon fatty acids in the rumen lipids were higher with the treated soybeans compared to the untreated beans, suggesting some protection of the soybean lipids from hydrogenation. The inclusion of soybeans appeared to depress butyrate production and significantly increase propionate production in the rumen. Circulating blood acetate was depressed (P<.05) with the formaldehyde treatment. Plasma and fecal lipid levels and milk fatty acids suggested that the soybean lipids were being utilized in both treatments but with no distinct advantage for the treated soybeans.

The influence of ruminal infusion of volatile fatty acids on milk yield and composition and on energy utilization by lactating cows.

1. In an experiment of 3 x 3 latin square design, four lactating Holstein cows were given a basal ration designed to induce low percentages of milk fat. The treatments were (I) basal ration, a pelleted mixture of lucerne hay (20%) and concentrates (80%), with 40 l. of water infused intraruminally, (2) basal ration with acetic acid substituted for 15.4% of the metabolizable energy (ME) and (3) propionic acid substituted for 15.4% of the ME. In the last 3 weeks of the 6-week experimental period respiration trials were carried out in an open-circuit indirect calorimeter. The levels of feeding offered in the three periods were 325, 275 and 225 kcal ME/kg body-weight0.75in periods 1, 2 and 3 respectively.2. No differences were detected in the utilization of the energy of acetic and propionic acids, but there were differences in the partition of energy into milk or body tissues; with acetic acid infusion more energy was secreted as milk and with propionic acid infusion more was deposited in body tissue.3. There was an increase in milk fat percentage with acetic acid infusion, but not complete recovery to normal. The milk fat percentages were 1.96, 2.58 and 1.92 for treatments 1, 2 and 3 respectively. Acetic acid infusion caused increases in the C12, C14 and C16 fatty acids of milk fat and decreased the proportion of C18:1 fatty acids.4. It is suggested that the low percentages of milk fat found when cows are given concen- trates could result from a decreased extent of fermentation in the rumen, allowing a greater proportion of the starch consumed to be absorbed as glucose in the small intestine.