Effects of feeding different linseed sources on omasal fatty acid flows and fatty acid profiles of plasma and milk fat in lactating dairy cows

The aim of this experiment was to study the effects of feeding different linseed sources on omasal fatty acid (FA) flows, and plasma and milk FA profiles in dairy cows. Four ruminally cannulated lactating Holstein-Friesian cows were assigned to 4 dietary treatments in a 4×4 Latin square design. Dietary treatments consisted of supplementing crushed linseed (CL), extruded whole linseed (EL), formaldehyde-treated linseed oil (FL) and linseed oil in combination with marine algae rich in docosahexaenoic acid (DL). Each period in the Latin square design lasted 21 d, with the first 16 d for adaptation. Omasal flow was estimated by the omasal sampling technique using Cr-EDTA, Yb-acetate, and acid detergent lignin as digesta flow markers. The average DM intake was 20.6 ± 2.5 kg/d, C18:3n-3 intake was 341 ± 51 g/d, and milk yield was 32.0 ± 4.6 kg/d. Milk fat yield was lower for the DL treatment (0.96 kg/d) compared with the other linseed treatments (CL, 1.36 kg/d; EL, 1.49 kg/d; FL, 1.54 kg/d). Omasal flow of C18:3n-3 was higher and C18:3n-3 biohydrogenation was lower for the EL treatment (33.8 g/d; 90.9%) compared with the CL (21.8 g/d; 94.0%), FL (15.5 g/d; 95.4%), and DL (4.6 g/d; 98.5%) treatments, whereas whole-tract digestibility of crude fat was lower for the EL treatment (64.8%) compared with the CL (71.3%), FL (78.5%), and DL (80.4%) treatments. The proportion of C18:3n-3 (g/100 g of FA) was higher for the FL treatment compared with the other treatments in plasma triacylglycerols (FL, 3.60; CL, 1.22; EL, 1.35; DL, 1.12) and milk fat (FL, 3.19; CL, 0.87; EL, 0.83; DL, 0.46). Omasal flow and proportion of C18:0 in plasma and milk fat were lower, whereas omasal flow and proportions of biohydrogenation intermediates in plasma and milk fat were higher for the DL treatment compared with the other linseed treatments. The results demonstrate that feeding EL did not result in a higher C18:3n-3 proportion in plasma and milk fat despite the higher omasal C18:3n-3 flow. This was related to the decreased total-tract digestibility of crude fat. Feeding FL resulted in a higher C18:3n-3 proportion in plasma and milk fat, although the omasal C18:3n-3 flow was similar or lower than for the CL and EL treatment, respectively. Feeding DL inhibited biohydrogenation of trans-11,cis-15-C18:2 to C18:0, as indicated by the increased omasal flows and proportions of biohydrogenation intermediates in plasma and milk fat.     

Composition and flavor of milk and butter from cows fed fish oil, extruded soybeans, or their combination.

Milk was collected from eight multiparous Holstein and four multiparous Brown Swiss cows that were distributed into four groups and arranged in a randomized complete block design with four 4-wk periods. The four treatments included a control diet of a 50:50 ratio of forage-to-concentrate; a fish oil diet of the control diet with 2% (on dry matter basis) added fat from menhaden fish oil; a fish oil with extruded soybean diet of the control diet with 1% (on dry matter basis) added fat from menhaden fish oil and 1% (on dry matter basis) added fat from extruded soybeans; and an extruded soybean diet of the control diet with 2% (on dry matter basis) added fat from extruded soybeans. Milk from cows fed control, fish oil, fish oil with extruded soybean, and extruded soybean diets contained 3.31, 2.58, 2.94, and 3.47% fat, respectively. Concentrations of conjugated linoleic acid in milk were highest in the fish oil (2.30 g/100 g of fatty acids) and fish oil with extruded soybean (2.17 g/100 g of fatty acids) diets compared with the control (0.56 g/100 g fatty acids) diet. Milk, cream, butter, and buttermilk from the fish oil, fish oil with extruded soybean, and extruded soybean diets had higher concentrations of transvaccenic acid and unsaturated fatty acids compared with the controls. Butter made from the extruded soybean diet was softest compared with all treatments. An experienced sensory panel found no flavor differences in milks or butters.     

Composition and properties of milk and butter from cows fed fish oil

A control diet and a fish oil diet were fed to 12 multiparous Holstein cows to determine how the incorporation of Menhaden fish oil in the diet would influence the fatty acid composition, especially the conjugated linoleic acid and transvaccenic acid, contents of milk and butter. The control diet consisted of a 50:50 ratio of forage to concentrate, and the fish oil diet consisted of the control diet with 2% (on a dry matter basis) added fish oil. Milk from cows fed the control diet contained higher average concentrations of milk fat (3.37%) compared with milk from cows fed the fish oil diet (2.29%). Milk from cows fed fish oil contained higher concentrations of conjugated linoleic acid, transvaccenic acid, and total unsaturated fatty acids (0.68 and 2.51; 1.42 and 6.28; and 30.47 and 41.71 g/100 g of fat, respectively). Butter made from the fish oil diet milk also had higher concentrations of conjugated linoleic acid, transvaccenic acid, and unsaturated fatty acids. Penetrometer readings indicated fish oil diet butters were softer at 4 and 20 degrees C than the control diet butters. Acid degree values were similar in the fish oil butters compared with the control butters. No significant difference was found in the flavor characteristics of milk and butter from cows fed the control and fish oil diets. Production of milk and butter with increased amounts of conjugated linoleic acid, transvaccenic acid, and other beneficial fatty acids may have a desirable impact on the health of consumers and lead to increased sales.     

Conjugated linoleic acid (CLA) content of milk from cows offered diets rich in linoleic and linolenic acid

Two experiments were conducted to determine the conjugated linoleic acid (CLA) content of milk from cows offered diets rich in linoleic and linolenic acid. In experiment 1, 36 cows were assigned to a control and five treatment groups. Cows in the control group received a diet containing 51% forage and 49% grain on a dry matter basis. In the treatment group, grain was partly replaced by either 18% raw cracked soybeans, 18% roasted cracked soybeans, 3.6% soybean oil, 2.2% linseed oil, or 4.4% linseed oil. Experimental diets were fed for 5 wk. Average CLA contents in milk fat from wk 2 through 5 were 0.39% in control and 0.37, 0.77, 2.10, 1.58, and 1.63% of total fatty acids in the raw soybean, roasted soybeans, soybean oil, 2.2% linseed oil, and 4.4% linseed oil treatments, respectively. In experiment 2, 36 cows were assigned to a control and 5 treatment groups. Cows in the control group received a diet containing 55% forage and 45% grain. In the treatment groups, grain was partly replaced by soybean oil at 0.5, 1.0, 2.0, 4.0, or by linseed oil at 1.0% of the dietary dry matter. Experimental diets were fed for 5 wk. Average CLA contents in milk fat from wk 2 through 5 were 0.50% in control and 0.75, 0.76, 1.45, 2.08, and 0.73% of total fatty acids in 0.5, 1.0, 2.0, 4.0 soybean oil and 1.0% linseed oil treatments, respectively. Diets rich in linoleic or linolenic acid can increase CLA content of milk when dietary oil is accessible to the rumen microorganisms.     

Fatty acid and triglyceride composition of milk fat from lactating Holstein cows in response to supplemental canola oil

The objective was to determine the influence of dietary lipid on total and sn-2 fatty acid composition and triglyceride structure of milk fat in lactating Holstein cows. Five primiparous Holstein cows surgically fitted with ruminal and duodenal cannulas were used in a 4 x 5 incomplete Latin square. All cows received a basal diet. Treatments consisted of a basal diet with no supplemental canola oil (control), basal diet with canola oil added to the concentrate portion of the diet to provide 1.6% fat, basal diet with 330 g of canola oil infused directly into the rumen, and basal diet with 330 g of canola oil infused directly into the abomasum. Canola oil treatments decreased palmitic acid and increased oleic acid content of milk fat compared with the control. Stearate was higher when canola oil was rumen available compared with control and abomasal infusion. Abomasal infusion increased linoleic and linoleic acids in milk fat compared with the other treatments. The sn-2 fatty acid composition reflected total fatty acid composition. All canola oil treatments reduced palmitic acid and increased oleic acid content at the sn-2 position. Changes in sn-2 composition reflect specificity of the acyl transferases and substrate concentration. Triglyceride composition reported as carbon number was altered by canola oil. Triglycerides in carbon number C50, C52, and C54 were increased while C32, C34, and C36 were decreased.     

Fish oil and extruded soybeans fed in combination increase conjugated linoleic acids in milk of dairy cows more than when fed separately

Eight multiparous Holstein and four multiparous Brown Swiss (78 +/- 43 DIM) cows were used in a 4 x 4 Latin square with 28-d periods to evaluate if feeding fish oil with a source of linoleic acid (extruded soybeans) would stimulate additional amounts of conjugated linoleic acid in milk. Four treatments consisted of a control diet with a 50:50 ratio of forage to concentrate (DM basis), a control diet with 2% added fat from either menhaden fish oil or extruded soybeans, or a combination of fish oil and extruded soybeans each adding 1% fat. DM intake (24.3, 21.6, 24.5, and 22.5 kg/d, for control, fish oil, extruded soybeans, and combination diets, respectively), milk production (32.1, 29.1,34.6, and 31.1 kg/d), and milk fat content (3.51, 2.79, 3.27, and 3.14%) were lower for cows that consumed either fish oil-containing diet, especially the 2% fish oil diet. The proportion of n-3 fatty acids in milk fat increased similarly among all three fat-supplemented diets. Concentrations of transvaccenic acid (1.00, 4.16, 2.17, and 3.51 g/100 g of fatty acids) and cis-9, trans-11 conjugated linoleic acid (0.60, 2.03, 1.16, and 1.82 g/100 g of fatty acids) in milk fat increased more with fish oil than with extruded soybeans. When fed the combination diet, these fatty acids were approximately 50% higher than expected for Holsteins, whereas concentrations were similar for Brown Swiss compared with feeding each fat source separately. These data indicated that fish oil modifies ruminal or systemic functions, stimulating increased conversion of linoleic acid into transvaccenic and conjugated linoleic acids.     

Flaxseed supplementation improves fatty acid profile of cow milk

The objective of the study was to determine the effects of adding flaxseed or fish oil to the diet on the milk fatty acid profile of cows. The experiment was conducted in the summer of 2006 and involved 24 Friesian cows that were divided into 3 groups of 8 animals according to different type of fat supplementation: a traditional diet with no fat supplementation, a diet supplemented with whole flaxseed, and a diet supplemented with fish oil. Results suggested that whole flaxseed supplementation positively affects the milk fatty acid profile during summer. In particular, milk from cows receiving flaxseed supplementation showed a decrease in saturated fatty acid, an increase in monounsaturated fatty acid, and, together with the milk from fish oil-supplemented cows, an increase in polyunsaturated fatty acid content compared with milk from control cows. As expected, both fish oil and flaxseed supplementation increased the content of n-3 polyunsaturated fatty acids in milk fat. The increased dietary intake of C18:3 in flaxseed-supplemented cows resulted in increased levels of milk C18:1 trans-11 and increased conjugated linoleic acid C18:2 cis-9,trans-11 by Δ⁹-desaturase activity. Milk from flaxseed-supplemented cows together with the high conjugated linoleic acid content was characterized by low atherogenic and thrombogenic indices, suggesting that its use has less detrimental effects concerning the atherosclerosis and coronary thrombosis risk associated with the consumption of milk and dairy products. In conclusion, flaxseed supplementation improves composition and nutritional properties of milk from cows milked during times of high ambient temperature.     

Influence of dietary fish oil on conjugated linoleic acid and other fatty acids in milk fat from lactating dairy cows

Lactating cows were fed menhaden fish oil to elevate concentrations of conjugated linoleic acid, transvaccenic acid, and n-3 fatty acids in milk. Twelve multiparous Holstein cows at 48+/-11 DIM were assigned randomly to a replicated 4 x 4 Latin square. Each treatment period was 35 d in length, with data collected d 15 to 35 of each period. On a dry matter (DM) basis, diets contained 25% corn silage, 25% alfalfa hay, and 50% of the respective concentrate mix. Fish oil was supplemented at 0, 1, 2, and 3% of ration DM. Linear decreases were observed for DM intake (28.8, 28.5, 23.4, and 20.4 kg/d) and milk fat (2.99, 2.79, 2.37, and 2.30%) for 0 to 3% dietary fish oil, respectively. Milk yield (31.7, 34.2, 32.3, and 27.4 kg/d) increased as dietary fish oil increased from 0 to 1% but decreased linearly from 1 to 3% dietary fish oil. Milk protein percentages (3.17, 3.19, 3.21, and 3.17) were similar for all treatments. When the 2% fish oil diet was fed, concentrations of conjugated linoleic acid and transvaccenic acid in milk fat increased to 356% (to 2.2 g/ 100 g of total fatty acids) and 502% (to 6.1 g/100 g), respectively, of amounts when 0% fish oil was fed. There were no additional increases in these fatty acids when cows were fed 3% fish oil. The n-3 fatty acids increased from a trace to over 1 g/100 g of milk fatty acids, when the 3% fish oil diet was fed. Fish oil supplementation to diets of dairy cows increased the conjugated linoleic acid, transvaccenic acid, and n-3 fatty acids in milk.     

Short communication: Consumer evaluation of milk high in conjugated linoleic acid

A consumer evaluation was undertaken to determine whether there were differences in the acceptability of milk from cows fed a control or a fish oil diet. The two treatments included a control diet of a 50:50 ratio of forage-to-concentrate and fish oil added to the control diet with 2% (on dry matter basis) added fat from menhaden fish oil. Milk from cows fed the control or fish oil diet contained 3.31 and 2.58% fat and 0.56 and 2.30 g of total conjugated linoleic acid/100 g of fatty acids, respectively. Consumer evaluation of control and fish oil milks found no difference in acceptability.     

Addition of protected and unprotected fish oil to diets for dairy cows. I. Effects on the yield,composition and taste of milk

Thirty Holstein cows in mid-lactation (158+/-20 DIM) were given a total mixed ration based on grass silage, maize silage and rolled barley. After a preliminary period of 1 week, this diet was supplemented with nothing (control), unprotected fish oil (3.7% of dry matter, DM), or two levels of glutaraldehyde-protected microcapsules of fish oil (1.5% and 3.0% of DM, respectively). Unprotected and protected supplements contained, respectively, 74% and 58% of DM as lipids. Cows given the unprotected supplement reduced their feed intake by > 25%. Consequently, these cows lost body weight and produced less milk. DM intake, body weight, and milk yield were unaffected by protected fish oil. Fish oil reduced both milk fat and protein percentages, and decreased the proportion of short-chain fatty acids, stearic, and oleic acids in milk fat. Milk trans C18:1 fatty acids increased in cows given both unprotected and protected fish oil. Milk fat content of very-long-chain n3 polyunsaturated fatty acids, including C20:5 and C22:6, increased with fish oil in the diet. Accordingly, the peroxide index increased and a taste panel was able to detect unusual taste in milk from cows consuming the higher level of protected fish oil and disliked the milk from cows given unprotected fish oil. In conclusion, when lactating cows consumed fish oil, milk concentration of long-chain n3 fatty acids increased and mammary de novo synthesis of fatty acids decreased, but milk yield and milk protein content were reduced, and the milk was more susceptible to oxidation and its taste was adversely affected.     

Digestion,milk production,milk composition,and blood composition of dairy cows fed formaldehyde treated flaxseed or sunflower seed

Forty midlactation Holstein cows averaging 635 kg of body weight (SE = 8) were allotted at wk 25 of lactation to ten groups of four cows blocked for similar calving dates to determine the effects of formaldehyde treatment of flaxseed and sunflower seed on fatty acid composition of blood and milk, milk yield, feed intake, and apparent digestibility. Cows were fed a total mixed diet based on grass silage and supplements for ad libitum intake over a 10-wk period. Cows within each block were assigned to one of the four isonitrogenous supplements based on either untreated whole flaxseed, formaldehyde-treated whole flaxseed, untreated whole sunflower seed, or formaldehyde-treated whole sunflower seed. Cows fed whole flaxseed compared with sunflower seed maintained greater dry matter (DM) intake (20.3 vs. 18.9 kg/d). Intake of DM, expressed as a percentage of body weight, was increased by adding formaldehyde to oilseeds (3.24 vs. 2.98%). Milk production was similar for cows fed flaxseed and those fed sunflower. Formaldehyde treatment of flaxseed and sunflower seed increased milk production by an average of 2.65 kg/d. Efficiency of fat-corrected milk yield per kilogram of DM intake was increased by formaldehyde treatment (1.31 vs. 1.21), and it was greater with sunflower seed than with flaxseed (1.33 vs.1.21). Protein concentration in milk was greater for cows fed flaxseed (3.38%) compared with those fed sunflower seed (3.21%) and formaldehyde had no effect. Apparent digestibility of DM was not affected by type of seed but it was greater for cows fed formaldehyde-treated seeds. Cows fed formaldehyde-treated flaxseed had the greatest apparent digestibilities of acid detergent and neutral detergent fiber compared with those fed the other diets. Apparent digestibilities of fatty acids were greater for sunflower seed than for flaxseed-based diets. In general, formaldehyde treatment had limited effect on milk fatty acid composition, suggesting that formaldehyde was not very effective in protecting polyunsaturated fatty acids against ruminal biohydrogenation. Feeding flaxseed resulted in the lowest omega 6 to omega 3 fatty acid ratio. The data suggest that both flaxseed and sunflower seed are acceptable fat sources for midlactating cows and that flaxseed increases milk protein percentage compared to sunflower seed.     

Abomasal or ruminal administration of flax oil and hulls on milk production, digestibility, and milk fatty acid profile of dairy cows

Four ruminally fistulated primiparous lactating Holstein cows were assigned to a 4 × 4 Latin square design to determine the effects of the site of administration (rumen or abomasum) of flax oil and flax hulls on diet digestibility and milk fatty acid profile of dairy cows. The treatments were 1) oil and hulls administered in the rumen and abomasal infusion of water (RUM/RUM), 2) oil and hulls infused in the abomasum (ABO/ABO), 3) oil administered in the rumen and hulls infused in the abomasum (RUM/ABO), and 4) oil infused in the abomasum and hulls placed in the rumen (ABO/RUM). Cows on the ABO/ABO and RUM/RUM treatments had the highest and lowest amounts of basal dry matter eaten, respectively. Higher dry matter digestibility was obtained when flax oil bypassed the rumen (ABO/ABO and ABO/RUM) compared with when flax oil was administered directly in the rumen (RUM/ABO and RUM/RUM). Apparent digestibility of ether extract was higher when flax hulls were administered in the rumen (RUM/RUM and ABO/RUM) compared with when flax hulls were infused in the abomasum (ABO/ABO and RUM/ABO). The lowest digestibility of acid detergent fiber and neutral detergent fiber was obtained when both flax products were added in the rumen, which may be attributed to the high amount of oil present in the rumen (7.8% of total dry matter input). The lowest yield of 4% fat-corrected milk was obtained for cows on the RUM/RUM treatment, probably as a result of lower dry matter intake and digestibility of fiber. Milk concentrations of protein, fat, total solids, and lactose were similar among treatments. Administration of oil and hulls in the rumen resulted in the highest concentrations of intermediate products of biohydrogenation and total trans fatty acids in milk fat compared with the other treatments. All ratios of n-6 to n-3 fatty acids in milk fat were lower than the 4 to 1 ratio recommended to improve human health. These results suggest that the presence of both flax oil and flax hulls in the rumen decreases 4% fat-corrected milk yield and digestibility but provides a desirable fatty acid profile of milk to enhance consumers’ health.     

Conjugated linoleic acid content of milk from cows fed different diets.

Conjugated linoleic acid in milk was determined from cows fed different diets. In Experiment 1, cows were fed either normal or high oil corn and corn silage. Conjugated linoleic acid was 3.8 and 3.9 mg/g of milk fatty acids in normal and high oil treatments, respectively. In Experiment 2, cows consumed one-third, two-thirds, or their entire feed from a permanent pasture. Alfalfa hay and concentrates supplied the balance of feed for the one-third and two-third pasture treatments. Conjugated linoleic acid was 8.9, 14.3, and 22.1 mg/g of milk fatty acids in the one-third, two-third, and all pasture treatments, respectively. Cows grazing pasture and receiving no supplemental feed had 500% more conjugated linoleic acid in milk fat than cows fed typical dairy diets (Experiment 1). In Experiment 3, cows were fed either a control diet containing 55% alfalfa silage and 45% grain, or similar diets supplemented with 3% fish meal, or 250 g of monensin/cow/per day, or fish meal and monensin together. Conjugated linoleic acid was 5.3, 8.6, 6.8, and 8.9 mg/g of milk fatty acids in the control, fish meal, monensin, and fish meal plus monensin treatments, respectively. In Experiment 4, cows were fed either finely chopped alfalfa hay (Treatment 1), or coarsely chopped alfalfa hay (Treatment 2) in a 50% forage and 50% grain diet, or 66.6% grass hay and 33.4% grain (Treatment 3), or 98.2% grass hay (Treatment 4). Conjugated linoleic acid was 7.3, 8.3, 9.0, and 7.9 mg/g of milk fatty acids in treatments 1 through 4, respectively.     

Milk composition, milk fatty acid profile, digestion, and ruminal fermentation in dairy cows fed whole flaxseed and calcium salts of flaxseed oil

Four ruminally lactating Holstein cows averaging 602 ± 25 kg of body weight and 64 ± 6 d in milk at the beginning of the experiment were randomly assigned to a 4 × 4 Latin square design to determine the effects of feeding whole flaxseed and calcium salts of flaxseed oil on dry matter intake, digestibility, ruminal fermentation, milk production and composition, and milk fatty acid profile. The treatments were a control with no flaxseed products (CON) or a diet (on a dry matter basis) of 4.2% whole flaxseed (FLA), 1.9% calcium salts of flaxseed oil (SAL), or 2.3% whole flaxseed and 0.8% calcium salts of flaxseed oil (MIX). The 4 isonitrogenous and isoenergetic diets were fed for ad libitum intake. Experimental periods consisted of 21 d of diet adaptation and 7 d of data collection and sampling. Dry matter intake, digestibility, milk production, and milk concentrations of protein, lactose, urea N, and total solids did not differ among treatments. Ruminal pH was reduced for cows fed the CON diet compared with those fed the SAL diet. Propionate proportion was higher in ruminal fluid of cows fed CON than in that of those fed SAL, and cows fed the SAL and CON diets had ruminal propionate concentrations similar to those of cows fed the FLA and MIX diets. Butyrate concentration was numerically higher for cows fed the SAL diet compared with those fed the FLA diet. Milk fat concentration was lower for cows fed SAL than for those fed CON, and there was no difference between cows fed CON and those fed FLA and MIX. Milk yields of protein, fat, lactose, and total solids were similar among treatments. Concentrations of cis-9 18:1 and of intermediates of ruminal biohydrogenation of fatty acids such as trans-9 18:1 were higher in milk fat of cows fed SAL and MIX than for those fed the CON diet. Concentration of rumenic acid (cis-9, trans-11 18:2) in milk fat was increased by 63% when feeding SAL compared with FLA. Concentration of α-linolenic acid was higher in milk fat of cows fed SAL and MIX than in milk of cows fed CON (75 and 61%, respectively), whereas there was no difference between FLA and CON. Flaxseed products (FLA, SAL, and MIX diets) decreased the n-6 to n-3 fatty acid ratio in milk fat. Results confirm that flax products supplying 0.7 to 1.4% supplemental fat in the diet can slightly improve the nutritive value of milk fat for better human health.     

Effects of different forms of canola oil fatty acids plus canola meal on milk composition and physical properties of butter

Twenty multiparous Holstein cows were used in a 16-wk trial. A block of 10 cows received a control diet, based on corn silage, and the other block of 10 cows successively received four diets with 1) an extruded blend of canola meal and canola seeds, 2) canola meal and whole canola seeds, 3) canola meal and ground canola seeds, or 4) canola meal and calcium salts of canola oil fatty acids. Canola fat represented about 2% of dietary dry matter. Compared to control cows, treated cows had similar dry matter intake, milk production, and daily milk output of true protein or fat. Protein contents of milk was decreased by all treatments, with a lower effect of extruded or whole canola seeds. Milk fat contents was lowered by all treatments, extruded seeds and calcium salts resulting in most important effects. All treatments lowered the percentage of fatty acids with 12 to 16 carbons in milk fat, increased C18:0 and cis-C18:1 percentages, and the proportion of liquid fat in butter between 0 and 12 degrees C. Calcium salts and, to a lesser extent extruded seeds, resulted in most important improvements of milk fatty acid profile and butter softness, whereas whole seeds had low effects.     

Effect of supplementation with calcium salts of fish oil on n-3 fatty acids in milk fat

Enrichment of milk fat with n-3 fatty acids, in particular eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), may be advantageous because of their beneficial effects on human health. In addition, these fatty acids play an important role in reproductive processes in dairy cows. Our objective was to evaluate the protection of EPA and DHA against rumen biohydrogenation provided by Ca salts of fish oil. Four Holstein cows were assigned in a Latin square design to the following treatments: 1) ruminal infusion of Ca salts of fish oil and palm fatty acid distillate low dose (CaFO-1), 2) ruminal infusion of Ca salts of fish oil and palm fatty acid distillate high dose (CaFO-2), 3) ruminal infusion of fish oil high dose (RFO), and 4) abomasal infusion of fish oil high dose (AFO). The high dose of fish oil provided ∼16 and ∼21 g/d of EPA and DHA, respectively, whereas the low dose (CaFO-1) provided 50% of these amounts. A 10-d pretreatment period was used as a baseline, followed by 9-d treatment periods with interceding intervals of 10 d. Supplements were infused every 6 h, milk samples were taken the last 3 d, and plasma samples were collected the last day of baseline and treatment periods. Milk fat content of EPA and DHA were 5 to 6 times greater with AFO, but did not differ among other treatments. Milk and milk protein yield were unaffected by treatment, but milk fat yield and DM intake were reduced by 20 and 15%, respectively, by RFO. Overall, results indicate rumen biohydrogenation of long chain n-3 fatty acids was extensive, averaging >85% for EPA and >75% for DHA for the Ca salts and unprotected fish oil supplements. Thus, Ca salts of fish oil offered no protection against the biohydrogenation of EPA and DHA beyond that observed with unprotected fish oil; however, the Ca salts did provide rumen inertness by preventing the negative effects on DM intake and milk fat yield observed with unprotected fish oil.     

Effect of feeding oilseed supplements to dairy cows on ruminal and milk fatty acid composition

The objective of this study was to compare the effects of oilseed‐based supplements, rapeseed and linseed, against a barley‐based control, on the fatty acid composition, and subsequent solid fat ratio, of the milk fat from dairy cows. In addition, as a means of understanding the digestive processes which influence the milk fat composition, ruminal extracts were collected from the cows and analysed for fatty acid composition. Four lactating dairy cows each fitted with a rumen fistula were provided with silage and one of four concentrate diets. The main constituent of the concentrate supplements was either rapeseed (ground or unground), linseed (unground) or a barley control. The diets were offered in accordance with a 4 × 4 Latin square arrangement. The oilseed‐supplemented concentrates provided the cows with 620–640 g fatty acids day^?1. Experimental treatments were provided to the cows for 2 weeks, after which ruminal extracts were collected over a 24 h period and a milk sample was taken. All extracts were analysed for fatty acid composition. The diets fed influenced the long‐chain fatty acid composition of the ruminal extracts and milk fat. The proportion of C18:1n‐9 in the ruminal extracts increased from 202–224 to 282–321 g kg^?1 of the total fatty acids when the cows were provided with the rapeseed‐based diets. The linseed‐based diet increased the C18:1n‐9 proportion of the ruminal extracts from 164 to 218 g kg^?1 of the total fatty acids. Both rapeseed‐based diets also resulted in a higher proportion of C18:0 in the ruminal extract, possibly owing to biohydrogenation of the dietary fatty acids. This proportion of C18:0 in the ruminal extract was lowest immediately after feeding, increasing to a maximum 4–6 h later. Both rapeseed‐based concentrates increased the proportion of C18:1n‐9 in the milk fat to approximately 300 g kg^?1 of the total fatty acids as compared with 214 g kg^?1 for the control. The proportion of C18:1n‐9 in the milk fat from the cows offered the linseed‐based concentrate was 246 g kg^?1 of the total fatty acids. There were also significant decreases in the proportions of C16:0 in the milk fat from the cows offered all oilseed‐based concentrates. There was no difference between the fatty acid compositions of the milk fats from the cows fed the ground or unground rapeseed‐based supplements. The oilseed‐based supplements also resulted in significant decreases in the solid fat content of the milk fat at temperatures ranging from 0 to 35 °C, which would be indicative of a softer, more spreadable butter. © 2002 Society of Chemical Industry     

Effects of supplementation of dairy cattle with fish oil on silage intake, milk yield and milk composition

The effects of level of fish oil inclusion in the diet on grass silage intake, and milk yield and composition of dairy cows offered either 5 or 10 kg concentrates/d were evaluated in a ten treatment, partly balanced, changeover design experiment involving 50 cows in early lactation. Concentrates were prepared to provide 0, 150, 300 or 450 g fish oil/cow per d or 300 g fish oil/cow per d from a premix when each animal was offered 5 kg/d. The fish oil was predominantly from herring and mackerel caught in the North Atlantic while the fish oil premix was obtained from a commercial source and used palm kernel expeller as a carrier. Increasing fish oil supplementation decreased silage dry matter intake and the concentrations of milk fat and protein, and increased milk yield and diet digestibility. There were significant interactions between concentrate feed level and level of fish oil for silage intake and milk yield. Other than for the concentrations of milk fat and protein, and 20:4n-6 fatty acids, the source of fish oil did not affect forage intake or animal performance. Fish oil supplementation also decreased the concentrations of milk protein by 0.9 g/kg for each 100 g increase in fish oil supplementation, the depression being similar at each level of concentrate feeding. Supplementing the feed of dairy cows with 450 g fish oil/cow per d decreased the concentration of milk fat by 15 g/kg. This study also showed that feeding dairy cattle with fish oil is an efficient method of increasing eicosapentaenoic acid in the human diet through transfer into milk.     

Increasing omega fatty acid content in cow's milk through diet manipulation: Effect on milk flavor

Milk with an increased content of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and conjugated linoleic acid (CLA) was obtained by incorporating fish oil into the feed of cows. The 4 feed treatments used were a control diet of 57% forage and 43% concentrate mix with EnerGII fat supplement at 1.65% of dietary DM, or EnerGII in the basal diet was partially replaced with 1) 0.21% partially ruminally inert calcium salts of 71% fish oil given at 0.41% of DM; 2) 0.41% inert calcium salts of 71% fish oil given at 0.83% of DM; or 3) 0.83% inert calcium salts of 43% fish oil given at 0.83% of DM. The cows were milked after 5 and 8 wk and the EPA, DHA, and CLA contents in the pasteurized whole milk were determined. The presence of off-flavors in the milk was investigated after 3 and 10 d of storage. Twelve judges were trained to evaluate the presence of grassy, fishy, oily, oxidized, and rancid off-flavors. Although levels of EPA, DHA, vaccenic acid, and CLA increased for all 4 treatments, a trained sensory panel detected no difference in milk flavor between treatments and the control, with little or no intensity of off-flavors. Results suggest that feeding fish oil and EnerGII at varying levels enhanced CLA, EPA, DHA, and total n-3 fatty acids in milk over the length of the experiment without negatively affecting milk flavor. This creates the potential for a more marketable and healthful product.     

Milk production and composition from cows fed high oil or conventional corn at two forage concentrations

Twelve multiparous Holstein cows (63 +/- 24 d in milk) were used in a replicated 4 x 4 Latin square with 28-d periods to evaluate conventional and high oil corn grains when fed at two different forage-to-concentrate ratios. Dietary treatments consisted of conventional or high oil corn supplementing a diet with a 25:25:50 mixture of corn silage: alfalfa: concentrate mix, or a high forage diet with a 30:30:40 mixture of corn silage: alfalfa: concentrate mix. Dry matter intake (28.1, 28.7, 26.9, and 26.2 kg/d for normal diets with conventional and high oil corn, and high forage diets with conventional and high oil corn, respectively) and milk yields (36.8, 37.2, 35.5, and 35.2 kg/d) were similar for conventional and high oil corn diets and were lower with the high forage diet, regardless of corn source. Milk fat concentrations were greater when cows were fed diets containing 60% forage (4.03 vs. 3.88%, for the 60 and 50% forages, respectively), but milk protein concentrations were not affected by forage content. Corn source did not affect milk fat or protein concentrations. Long-chain fatty acid concentrations, unsaturated fatty acid concentrations, and total 18:1 fatty acid concentrations were greater when cows were fed high oil corn but were unaffected by forage content of the diet. Concentrations of transvaccenic acid (0.58, 0.81, 0.62, and 0.69 g/100 g of fatty acids) and cis-9, trans-11 conjugated linoleic acid (0.28, 0.39, 0.32, and 0.33 g/100 g of fatty acids) were greater when cows were fed high oil compared with conventional corn when fed 50% forage but were similar for both corn sources at 60% forage. Total n-3 fatty acids were not affected by corn source or forage content. High forage diets decreased milk production and increased milk fat concentration. Feeding high oil corn increased concentrations of long-chain, unsaturated, transvaccenic, and conjugated linoleic fatty acids in milk; however, production of transvaccenic and conjugated linoleic acids were attenuated by high forage diet.