Progress 10/01/99 to 09/30/04
Outputs
The following summary of the studies conducted as part of this project was provided in the previous progress report. Unsaturated vegetable oils containing primarily oleic acid and linoleic acid were added to the diet of lactating cows to obtain milk with greater amounts of unsaturated fatty acids and cis9,trans11-18:2, the anticarcinogenic isomer of conjugated linoleic acid (9/11CLA). The modified milk fat also contained greater amounts of trans11-18:1 (trans-vaccenic acid, TVA) than normal milk fat, but the ratio of TVA to 9/11CLA in milk fat was approximately two to one to three to one regardless of diet composition. In contrast, TVA in rumen fluid of lactating cows was 10-fold to 30-fold greater than that of 9/11CLA. To further evaluate interrelationships between trans-18:1 isomers and CLA isomers during biohydrogenation of dietary oleic acid, linoleic acid, and linolenic acid, effluent from automated continuous-culture fermenters was analyzed. Daily TVA output from
the fermenters was approximately 50-fold greater than 9/11CLA output when only forage (orchardgrass or clover) (50 grams of dry matter per day) was used as the substrate for fermentation. To reduce the amount of linolenic acid and increase the amounts of oleic acid and linoleic acid entering the fermenters, ground corn grain was substituted for a portion (0, 8, or 16 grams per day) of the forage. Output of TVA and 9/11CLA increased linearly (two-fold) in response to the increase in corn input, but the ratio of TVA to 9/11CLA remained relatively constant. Also in response to increasing to corn input, trans10-18:1 and trans10,cis12-18:2 (10/12CLA) outputs increased linearly (two-fold). Our recent studies indicated small quantities of 10/12CLA infused into the small intestine (lactating cows) or added to the diet (lactating mice) resulted in a 25 percent reduction in milk fat yield, because 10/12CLA is a potent inhibitor of de novo fatty acid synthesis. Although the amount of 10/12CLA
normally found in bovine milk fat was very low or not detectable, 10/12CLA concentration was increased substantially when we infused pure 10/12CLA into the intestine or added a mixture of 9/11CLA and 10/12CLA to the cow's diet. Addition of a CLA mixture to a cow's diet during early lactation may be a practical method for improving overall energy balance by reducing the amount of energy used for de novo fatty acid synthesis in the mammary gland. However, milk with enhanced 10/12CLA content may have undesirable long-term effects if consumed by children. We fed young, growing male and female mice small amounts (0.15 or 0.30 percent of the diet) of 10/12CLA for six weeks. Body fat content declined rather than increased with age, and liver weight increased significantly due to lipid accumulation.
Impacts
Dairy products are a primary source of the conjugated linoleic acid isomer (9/11CLA) known to suppress formation of several types of tumors, and diets of lactating dairy cows can be modified to enhance the 9/11CLA content of milk fat. However, feeding or management practices that increase the amount of a secondary CLA isomer (10/12CLA) in bovine milk may not be beneficial. Dietary 10/12CLA reduced the fat of milk produced by lactating mice, reduced the rate of body fat deposition in growing mice, and caused excessive hepatic lipid accumulation in growing mice.
Publications
- Loor, J. J., X. Lin, and J. H. Herbein. 2003. Effects of dietary cis9,trans11-18:2, trans10,cis12-18:2, or vaccenic acid (trans11-18:1) during lactation on body composition, tissue fatty acid profiles, and litter growth in mice. Br. J. Nutr. 90:1039-1048.
- Lin, X., J. J. Loor, and J. H. Herbein. 2004. Trans10,cis12-18:2 is a more potent inhibitor of de novo fatty acid synthesis and desaturation than cis9,trans11-18:2 in the mammary gland of lactating mice. J. Nutr. 134:1362-1368.
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Progress 10/01/02 to 09/30/03
Outputs
In our previous studies, unsaturated vegetable oils containing primarily oleic acid and linoleic acid were added to the diet of lactating cows to obtain milk with greater amounts of unsaturated fatty acids and cis9,trans11-18:2, the anticarcinogenic isomer of conjugated linoleic acid (9/11CLA). The modified milk fat also contained greater amounts of trans11-18:1 (trans-vaccenic acid, TVA) than normal milk fat, but the ratio of TVA to 9/11CLA in milk fat was approximately two to one to three to one regardless of diet composition. In contrast, TVA in rumen fluid of lactating cows was 10-fold to 30-fold greater than that of 9/11CLA. To further evaluate interrelationships between trans-18:1 isomers and CLA isomers during biohydrogenation of dietary oleic acid, linoleic acid, and linolenic acid, effluent from automated continuous-culture fermenters was analyzed. Daily TVA output from the fermenters was approximately 50-fold greater than 9/11CLA output when only forage
(orchardgrass or clover) (50 grams of dry matter per day) was used as the substrate for fermentation. To reduce the amount of linolenic acid and increase the amounts of oleic acid and linoleic acid entering the fermenters, ground corn grain was substituted for a portion (0, 8, or 16 grams per day) of the forage. Output of TVA and 9/11CLA increased linearly (two-fold) in response to the increase in corn input, but the ratio of TVA to 9/11CLA remained relatively constant. Also in response to increasing to corn input, trans10-18:1 and trans10,cis12-18:2 (10/12CLA) outputs increased linearly (two-fold). Our recent studies indicated small quantities of 10/12CLA infused into the small intestine (lactating cows) or added to the diet (lactating mice) resulted in a 25 percent reduction in milk fat yield, because 10/12CLA is a potent inhibitor of de novo fatty acid synthesis. Although the amount of 10/12CLA normally found in bovine milk fat was very low or not detectable, 10/12CLA concentration
was increased substantially when we infused pure 10/12CLA into the intestine or added a mixture of 9/11CLA and 10/12CLA to the cow's diet. Addition of a CLA mixture to a cow's diet during early lactation may be a practical method for improving overall energy balance by reducing the amount of energy used for de novo fatty acid synthesis in the mammary gland. However, milk with enhanced 10/12CLA content may have undesirable long-term effects if consumed by children. We fed young, growing male and female mice small amounts (0.15 or 0.30 percent of the diet) of 10/12CLA for six weeks. Body fat content declined rather than increased with age, and liver weight increased significantly due to lipid accumulation.
Impacts
Dairy products are a primary source of the conjugated linoleic acid isomer (9/11CLA) known to suppress formation of several types of tumors, and diets of lactating dairy cows can be modified to enhance the 9/11CLA content of milk fat. However, feeding or management practices that increase the amount of a secondary CLA isomer (10/12CLA) in bovine milk should be avoided. Dietary 10/12CLA reduced the fat content of milk produced by lactating mice, reduced the rate of body fat deposition in growing mice, and caused excessive hepatic lipid accumulation in growing mice.
Publications
- Loor, J. J., A. B. P. A. Bandara, and J. H. Herbein. 2002. Characterization of 18:1 and 18:2 isomers produced during microbial biohydrogenation of unsaturated fatty acids from canola and soybean oil in the rumen of lactating cows. J. Anim. Physiol. & Anim. Nutr. 86:422-432.
- Loor, J. J. and J. H. Herbein. 2003. Dietary canola or soybean oil with two levels of conjugated linoleic acids (CLA) alter profiles of 18:1 and 18:2 isomers in blood plasma and milk fat from dairy cows. Anim. Feed Sci. & Tech. 103:63-83.
- Viswanadha, S., W.A. Wark, and J. H. Herbein. 2003. Trans10,cis12-conjugated linoleic acid (CLA) decreases stearoyl CoA desaturase gene expression in adipose tissue and alters fatty acid profile of muscle and liver in mice. FASEB J. (Late-Breaking Abstracts) 17(5):67.
- Gonzalez, S., S. E. Duncan, S. F. O'Keefe, S. S. Sumner, and J. H. Herbein. 2003. Oxidation and textural characteristics of butter and ice cream with modified fatty acid profiles. J. Dairy Sci. 86:70-77.
- Loor, J. J., W. H. Hoover, T. K. Miller-Webster, J. H. Herbein, and C. E. Polan. 2003. Biohydrogenation of unsaturated fatty acids in continuous culture fermenters during digestion of orchardgrass or red clover with three levels of ground corn supplementation. J. Anim. Sci. 81:1611-1627.
- Loor, J. J. and J. H. Herbein. 2003. Reduced fatty acid synthesis and desaturation due to exogenous trans10,cis12-CLA in cows fed oleic or linoleic oil. J. Dairy Sci. 86:1354-1369.
- Loor, J. J., F. D. Soriano, X. Lin, J. H. Herbein, and C. E. Polan. 2003. Grazing allowance after the morning or afternoon milking for lactating cows fed a total mixed ration (TMR) enhances trans11-18:1 and cis9,trans11-18:2 (rumenic acid) in milk fat to different extents. Anim. Feed Sci. & Tech. 109:105-119.
- Loor, J. J., X. Lin, and J. H. Herbein. 2003. Effects of dietary cis9,trans11-18:2, trans10,cis12-18:2, or vaccenic acid (trans11-18:1) during lactation on body composition, tissue fatty acid profiles, and litter growth in mice. Br. J. Nutr. 90:(In Press).
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Progress 10/01/01 to 09/30/02
Outputs
The lipids in preserved forages and grains typically fed to dairy cows contain polyunsaturated 18-carbon fatty acids, primarily linoleic acid (18:2) and lesser amounts of linolenic acid (18:3). Anaerobic bacteria in the rumen completely hydrogenate most of the polyunsaturated fatty acids. Thus, the primary fatty acid leaving the rumen for absorption in the small intestine is stearic acid (18:0). However, small quantities of fatty acid intermediates in the hydrogenation pathways also flow from the rumen to the small intestine for absorption and transport via blood to the mammary gland for incorporation into milk fat. Although the primary intermediate is trans-vaccenic acid (trans11-18:1) (TVA), small amounts of other intermediates also are found in blood lipids and milk fat. These include several conjugated linoleic acid isomers, primarily (cis9,trans11-18:2) (9/11CLA). In mammalian tissues, stearoyl-CoA desaturase (SCD) adds a cis-double bond at the number 9 carbon of
TVA to yield 9/11CLA. When we fed lactating mice diets containing TVA, but not 9/11CLA, the amount of 9/11CLA in their tissues and milk was proportional to TVA intake. Due to the documented anticarcinogenic properties of 9/11CLA, optimal SCD activity in the bovine mammary gland is desirable. Our in vitro studies with mouse and bovine mammary cell cultures indicated SCD transcription was reduced approximately 60 percent when 9/11CLA was added to the culture medium of mouse cells. However, SCD transcription in bovine mammary cells was not reduced. Thus, synthesis of the SCD enzyme in bovine mammary gland may not be inhibited by accumulation of 9/11CLA, the product of the SCD reaction. The amounts of TVA and 9/11CLA in bovine milk fat were enhanced by addition of vegetable oils or oil seeds, such as canola or soybean, to the diets of lactating cows. Several of these studies included analyses to determine fatty acid profiles in lipid fractions of blood plasma: phospholipids, cholesterol
esters, triglycerides, and free fatty acids. Whereas the majority of the TVA in plasma was associated with the triglycerides fraction, most of the 9/11CLA was in phospholipids. Concentrations of TVA and 9/11CLA in blood were highly correlated with their concentrations in milk fat. Our studies also included grazing cows consuming pasture (orchardgrass and clover). The primary fatty acid in the fresh pasture was 18:3. Compared with cows fed a diet containing preserved forages and grains, pasture-fed cows had elevated yields of TVA and 9/11CLA in their milk fat. In addition, their milk fat contained substantial amounts of trans11,cis15-18:2, an intermediate in the pathway for hydrogenation of 18:3 to TVA and 18:0 in the rumen. Subsequent in vitro studies indicated trans11,cis15-18:2 accounted for up to 15 percent of total fatty acid outflow from fermentations of fresh pasture.
Impacts
Dairy cattle diets can be modified to enhance the concentration of trans-vaccenic acid (TVA) in fluid milk and dairy products. Because TVA is converted to an anticarcinogenic isomer of conjugated linoleic acid (CLA) via an enzyme reaction in tissues of humans, dairy products with enhanced TVA content may be beneficial to the health of consumers.
Publications
- Loor, J. J. and J. H. Herbein. 2001. Alterations in blood plasma and milk fatty acid profiles of lactating Holstein cows in response to ruminal infusion of a conjugated linoleic acid mixture. Anim. Res. 50:463-476.
- Loor, J. J., J. H. Herbein, and C. E. Polan. 2002. Trans 18:1 and 18:2 isomers in blood plasma and milk fat of grazing cows fed grain supplement containing solvent-extracted or mechanically-extracted soybean meal. J. Dairy Sci. 85:1197-1207.
- Loor, J. J., J. H. Herbein, and T. C. Jenkins. 2002. Nutrient digestion, biohydrogenation, and fatty acid profiles in blood plasma and milk fat from lactating Holstein cows fed canola oil or canolamide. Anim. Feed Sci. & Tech. 97:65-82.
- Loor, J. J., X. Lin, and J. H. Herbein. 2002. Dietary trans-11-18:1 increases cis-9,trans-11-18:2 concentration in tissues of lactating mice and their suckling pups. Reprod. Nutr. Dev. 42:85-99.
- Loor, J. J., L. E. Quinlan, A. Bandara, and J. H. Herbein. 2002. Distribution of trans-vaccenic acid and cis9,trans11-conjugated linoleic acid (rumenic acid) in blood plasma lipid fractions and secretion in milk fat of Jersey cows fed canola or soybean oil. Anim. Res. 51:119-134.
- Loor, J. J. and J. H. Herbein. 2002. Reduced fatty acid synthesis and desaturation due to exogenous trans10,cis12-CLA in cows fed oleic or linoleic oil. J. Dairy Sci. 85:(In Press).
- Gonzalez, S., S. E. Duncan, S. F. O'Keefe, S. S. Sumner, and J. H. Herbein. 2002. Oxidation and textural characteristics of butter and ice cream with modified fatty acid profiles. J. Dairy Sci. 85:(In Press).
- Loor, J. J., A. B. P. A. Bandara, and J. H. Herbein. 2002. Characterization of 18:1 and 18:2 isomers produced during microbial biohydrogenation of unsaturated fatty acids from canola and soybean oil in the rumen of lactating cows. J. Anim. Physiol. Anim. Nutr. 86:(In Press).
- Carlson, B., M. S. Laubach, W. L. Keller, J. W. Schroeder, J. H. Herbein, and C. S. Park. 2002. Effect of sunflower seed inclusion on conjugated linoleic acid concentrations in milk fat of Holstein cows. J. Dairy Sci. 85(Suppl. 1):196.
- Shafer, B. D., F. W. Thye, J. H. Herbein, S. E. Duncan, and C. P. Earthman. 2002. Concentrations of conjugated linoleic acid (CLA) isomers in human plasma reflect intake of dairy products with enhanced c9,t11-CLA or t10,c12-CLA content. FASEB J. 16(4):A635.
- Viswanadha, S., W. A. Wark, and J. H. Herbein. 2002. Dietary t10,c12-conjugated linoleic acid alters adipose tissue fatty acid profile in adult mice fed trans-vaccenic acid. FASEB J. 16(4):A633.
- Viswanadha, S., W. A. Wark, J. J. Loor, and J. H. Herbein. 2002. Alterations in tissue weights and carcass composition of growing mice fed diets containing 0, 0.15, or 0.30 percent t10,c12-conjugated linoleic acid. FASEB J. 16(4):A1025.
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Progress 10/01/00 to 09/30/01
Outputs
The primary 18-carbon polyunsaturated fatty acids in forages and grains typically fed to dairy cows are linoleic acid (18:2) and linolenic acid (18:3). Small amounts of the monounsaturated fatty acid, oleic acid (18:1), also are present in typical feeds. Anaerobic bacteria in the cow's rumen hydrogenate unsaturated fatty acids. Thus, the primary fatty acid leaving the rumen for absorption in the small intestine is stearic acid (18:0), but there are small quantities of many intermediates in the hydrogenation pathway that flow from the rumen to the small intestine for absorption and transport via blood to the mammary gland for incorporation into milk fat. The primary intermediate is trans-vaccenic acid (trans-11-18:1) (TVA), but small amounts of other hydrogenation intermediates also are found in milk fat. These include conjugated linoleic acid isomers, primarily (cis-9,trans-11-18:2) (9/11CLA). In the mammary gland, TVA can be desaturated at the number 9 carbon to form
9/11CLA. Due to the known anticarcinogenic properties of 9/11CLA, optimal enzymatic conversion of TVA to 9/11CLA in the bovine mammary gland is desirable. Tissues of other mammals, including the human, also can convert TVA to 9/11CLA. Feeding vegetable oils or oil seeds, such as canola seed, enhanced the amounts of TVA and 9/11CLA in bovine milk fat. In addition, desirable fatty acids in the oil, such as oleic acid and linoleic acid, were incorporated into milk fat, because their concentration in the diet was high enough to escape the hydrogenation process in the rumen. Milk fat modified by feeding high-oleic acid or high-linoleic acid oil was used to make butter and ice cream. In addition to enhanced TVA and 9/11CLA content, the modified milk fat contained a higher ratio of unsaturated to saturated fatty acids. The texture of butter made with modified milk fat was softer (more desirable) than typical butter at refrigerator temperature. Modified milk fat also was used to make butter
and yogurt for a study with human subjects. The modified milk fat or control milk fat in the dairy products they consumed accounted for 17 percent of their total caloric intake. Within two weeks, concentration of 9/11CLA in the blood plasma of the human subjects was proportional to the 9/11CLA content of the milk fat they consumed.
Impacts
Dairy products are a primary source of conjugated linoleic acid (9/11CLA), which may be beneficial to human health by suppressing tumor formation. Supplementing the cow's diet with vegetable oils modifies the fatty acid profile of milk fat in a manner that benefits human health. Modified milk fat has enhanced 9/11CLA content, and also provides physical characteristics desired by consumers.
Publications
- Gonzalez, S. 2001. Oxidation and textural characteristics of butter and ice cream with modified fatty acid profiles. M.S. Thesis. Virginia Polytechnic Institute & State University. 84 pages.
- Gonzalez, S., Duncan, S. E., Sumner, S. S., O'Keefe, S. F., and Herbein, J. H. 2001. Evaluation of quality properties of butter and ice cream with a high content of linoleic acid and oleic acid. J. Dairy Sci. 84(Suppl. 1):5.
- Handegard, J. D., Carlson, D. B., Laubach, M. S., Schimek, D. E., Keller, W. L., Schroeder, J. W., Park, C. S., and Herbein, J. H. 2001. Influence of feeding canola seed on lactation performance and conjugated linoleic acid concentration in milk fat of lactating cows. J. Dairy Sci. 84(Suppl. 1):353.
- Jayan, G. C., and Herbein, J. H. 2000. Healthier dairy fat using trans-vaccenic acid. Nutrition & Food Science 30(6):304-309.
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Progress 10/01/99 to 09/30/00
Outputs
Linoleic (18:2) acid and linolenic (18:3) acid, the major polyunsaturated fatty acids in dietary forages and grains in typical diets for dairy cows, are hydrogenated in the rumen. The primary intermediates in the hydrogenation pathway include a conjugated linoleic isomer (cis-9,trans-11-18:2) (9/11CLA) and trans-vaccenic acid (trans-11-18:1) (TVA). However, synthesis of secondary intermediates, such as trans-10,cis-12-18:2 (10/12-CLA) and trans-10-18:1, may increase as the amount of grain in the diet is increased. To evaluate this possibility, corn grain was substituted for portions of the forage (orchardgrass or clover) that served as the primary fermentation substrate in continuous-culture fermenters. When no grain was included in the fermentation, TVA was the primary trans-18:1 isomer in the fermenter effluent, and it accounted for 16 percent of total fatty acids. The primary CLA isomer in the effluent was 9/11CLA (40 percent of total CLA), but it accounted for
less than 1 percent of total fatty acids. Replacing forage with increasing amounts of corn grain resulted in a linear increase in the concentration of trans-10-18:1 in the effluent. Regardless of amount of corn grain added, however, 10/12CLA consistently accounted for 8 percent of total CLA. Thus, corn grain addition created conditions favorable for accumulation of trans-10 18:1 in the rumen. The CLA isomers and the trans-18:1 isomers produced in the rumen can be absorbed by the digestive tract and transported via blood to the mammary gland. In the mammary gland, TVA can be desaturated at the number 9 carbon to form 9/11CLA. Due to the anticarcinogenic properties of 9/11CLA, enzymatic conversion of TVA to 9/11CLA in the bovine mammary gland is desirable. The trans-10 isomer of 18:1, however, is not desaturated in the mammary gland and may cause inhibition of milk fat synthesis. Our previous studies also demonstrated a potent inhibition of body and milk fat synthesis by 10/12CLA. Thus,
the trans double bond at the number 10 carbon of 18-carbon fatty acids may be responsible for inhibition of fat synthesis. Synthetic CLA supplements containing 10/12CLA are sold in health food stores as promoters of lean body mass accretion and inhibitors of fat accretion. We infused pure isomers of 9/11CLA or 10/12CLA into the small intestine of lactating cows to enhance the 9/11CLA or 10/12CLA content of their milk fat. The 9/11CLA infusion had no effect on milk fat output during infusion, but milk fat output decreased by 29 percent during 10/12CLA infusion. In addition, concentration of 9/11CLA in milk fat decreased by nearly 50 percent when 10/12CLA was infused. This effect is consistent with inhibition of the enzyme that desaturates TVA to form 9/11CLA. Exogenous 10/12CLA represented only 0.08 percent of daily feed intake by the cows. Given that a small amount of 10/12CLA caused a substantial decrease in fat synthesis and fatty acid desaturation in the mammary gland, 10/12CLA may
be beneficial as a dietary supplement for regulating synthesis or composition of fat in growing or lactating animals.
Impacts
Bovine milk fat contains several isomers of conjugated linoleic acid (CLA). The primary isomer has anticarcinogenic properties. In contrast, a secondary isomer (trans10,cis12-CLA) reduces fat synthesis and fatty acid desaturation in tissues. Thus, trans10,cis12-CLA may offer opportunities for regulating rate of fat deposition in humans or in animals fed for meat production.
Publications
- Loor, J. J. and Herbein, J. H. 2000. Exogenous trans-10, cis-12-18:2 reduces de novo synthesis and desaturation of milk fatty acids in cows fed diets supplemented with high-oleic or high-linoleic oil. J. Dairy Sci. 83 (Suppl. 1):162.
- Loor, J. J., Hoover, W. H., Miller-Webster, T. K., Polan, C. E., Wark, W. A., and Herbein, J. H. 2000. Biohydrogenation of unsaturated fatty acids in continuous culture fermenters fed orchargrass or clover with three levels of ground corn supplementation. J. Dairy Sci. 83 (Suppl. 1):276.
- Herbein, J. H., Loor, J. J., and Wark, W. A. 2000. Conjugated linoleic acids - An opportunity for pasture-based dairy farms? Proceedings from the Mid-Atlantic Dairy Grazing Field Day, Abingdon, VA. pp.16-20.
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Progress 10/01/98 to 09/30/99
Outputs
Modified bovine milk fat, which contains a higher ratio of unsaturated to saturated fatty acids compared to normal milk fat, was produced by feeding a typical diet containing silage and grain (TMR) supplemented with vegetable oils or allowing cows to graze pasture as their only source of forage. When compared with normal milk fat from cows fed a TMR, fat-modified milk also contained greater concentrations of trans-vaccenic acid (trans-11 18:1) (TVA) and the anticarcinogenic isomer (cis-9,trans-11 18:2) of conjugated linoleic acid (CLA). However, TVA and CLA concentrations in modified milk fat were two-fold greater when cows were fed pasture compared with a TMR supplemented with vegetable oil. To determine whether TVA and CLA content of milk fat from pasture-fed cows could be increased further, the solvent-extracted soybean meal in their daily grain supplement was replaced with soybean meal processed by mechanical extraction. Mechanically extracted meal contained 40
percent more unsaturated oil, which caused total unsaturated fatty acids, TVA, and CLA in milk fat of pasture-fed cows to increase by 10, 20, and 28 percent, respectively. The increase in TVA and CLA content of milk fat reflected enhanced production of TVA and CLA as intermediates in the pathways for hydrogenation of the linoleic acid (18:2) in the rumen due to additional intake of soybean oil. The major fatty acid in pasture, however, is linolenic acid (18:3), which yields TVA, but not CLA, as the primary intermediate during hydrogenation in the rumen. Large amounts of TVA, but little CLA, were found when we analyzed the effluent from a continuous in vitro fermentation of fresh pasture grasses. Also, supplemental CLA in the rumen, whether supplied via the diet or by continuous infusion, resulted in elevated TVA in milk fat. Thus, rapid hydrogenation of CLA to TVA in the rumen and the lack of a source of CLA resulting from 18:3 hydrogenation in the rumen suggest some of the CLA in
milk fat must be derived from one or more endogenous sources. The most likely source is enzymatic conversion of TVA to CLA by addition of a cis double bond at the ninth carbon of the 18-carbon fatty acid. Lactating mice were fed a diet containing TVA to confirm that liver and mammary gland have substantial capacities to convert dietary TVA to CLA. Current research supports suggestions that fat-modified dairy products be classified as functional foods, because the CLA contained in such products may provide beneficial influences on human health beyond their simple nutritive value. The enhanced TVA content of modified bovine milk fat may be an additional benefit to human health, because it can be easily converted to CLA.
Impacts
Dairy products containing modified bovine milk fat can be beneficial for human health due to their lower saturated fatty acid content and greater conjugated linoleic acid content. In addition, the trans-vaccenic acid in modified milk fat can be converted to conjugated linoleic acid, an anticarcinogenic factor, in body tissues after consumption.
Publications
- Loor, J. J., Lin, X., and Herbein, J. H. 1999. Desaturation of dietary trans-vaccenic acid to conjugated linoleic acid in the lactating mouse. FASEB J.13(5):A901.
- Loor, J. J., Herbein, J. H., Daubert, J. L., Wark, W. A., Lin, X., and Polan, C. E. 1999. Conjugated linoleic acid in blood plasma and milk of intensively grazed Holstein cows fed solvent extracted or mechanically extracted soybean meal. J. Dairy Sci. 82(Suppl. 1):83.
- Loor, J. J. and Herbein, J. H. 1999. Cis and trans isomers of 18:1 and 18:2 in milk fat of Holstein cows fed canola and(or) soybean oil in combination with conjugated linoleic acid. J. Dairy Sci. 82(Suppl. 1):83.
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Progress 10/01/97 to 09/30/98
Outputs
Our previous studies indicated fatty acid composition of bovine milk is altered in a manner beneficial to human health when flows of oleic acid, trans-vaccenic acid (TVA) and conjugated linoleic acid (CLA) from the rumen to the intestine of the dairy cow are increased. When infused into the abomasum, fed as a supplement, or fed as an acyl amide, oils with a high oleic acid content increased the ratio of unsaturated to saturated fatty acids in milk from 0.3 to approximately 0.6. The decrease in saturated fatty acid content of milk fat was attributed to inhibition of lipogenic enzymes, because oleic acid reduced acetyl-CoA carboxylase and fatty acid synthase activities and mRNA abundance in bovine mammary cell cultures. However, compared with oleic acid, TVA and CLA caused greater inhibition of the lipogenic enzymes. Concentrations of TVA and CLA in milk fat are elevated when dairy cattle are grazing pasture in addition to or in place of a total-mixed-diet (TMD). To
evaluate the relationships between saturated fatty acid content of milk fat and pasture intake, cows were fed a TMD only, TMD plus access to pasture in the morning (0300 to 1100 h), or TMD plus access to pasture in the afternoon (1500 to 2200 h.). Although cows reduced their TMD intake when fed pasture in the morning or afternoon, their milk yield and composition were similar to cows fed TMD only. Overall, pasture intake reduced the percentage of saturated milk fatty acids with 8 to 16 carbons, but increased the percentages of oleic acid, linolenic acid, TVA, and CLA. Palmitic acid concentration, however, was lower in milk from cows fed pasture in the afternoon rather than the morning, whereas concentrations of TVA and CLA were higher. Thus, the rate of saturated fatty acid synthesis in the mammary gland decreased as uptake of CLA and TVA increased. Studies conducted as part of this project have identified dietary and metabolic factors that can be used to regulate mammary gland lipid
metabolism, thus allowing modification of bovine milk fat composition in a manner that may substantially improve acceptance by health-conscious consumers.
Impacts
(N/A)
Publications
- Loor, J. J. 1997. Postruminal flow, digestibility, and utilization of fatty acyl amides or conjugated linoleic acid for milk fat synthesis by lactating Holstein cows. M.S. Thesis, Virginia Polytechnic Institute and State University, Blacksburg. 115 pp.
- Bandara, A. B. P. A. 1997. Modifying fatty acid composition of bovine milk by abomasal infusion or dietary supplementation of seed oils or fish oil. Ph.D. Dissertation, Virginia Polytechnic Institute and State University, Blacksburg. 132 pp.
- Herbein, J. H. 1998. Alterations in bovine milk fatty acid content in response to flow of cis and trans isomers of octadecenoic and octadienoic acids from the rumen. Abstracts of the 89th American Oil Chemists Society Annual Meeting. Page 61.
- Herbein, J. H. 1998. Enhancing the intrinsic value of milk through dairy herd management practices. J. Dairy Sci. 81(Suppl. 1): 16.
- Loor, J. J. and Herbein, J. H. 1998. Exogenous conjugated linoleic acid isomers reduce bovine milk fat concentration and yield by inhibiting de novo fatty acid synthesis. J. Nutr. 128 (in press).
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Progress 10/01/96 to 09/30/97
Outputs
Diets containing no supplemental oil (control) or high-oleic canola oil, soybean oil, or equal amounts of canola oil and soybean oil at 3.5 percent of dry matter were fed to lactating Jersey cows for five weeks to obtain milk with a greater percentage of unsaturated fatty acids and lower percentages of palmitic acid and medium-chain fatty acids (MCFA). Feed intake, milk yield, and milk composition were not affected by dietary treatment. When compared to cows fed canola oil, milk fat produced by cows fed soybean oil had greater percentages of trans-vaccenic acid (considered to be a hypercholesterolemic agent in human diets), linoleic acid, and conjugated linoleic acid (CLA) (shown to be anticarcinogenic). Percentages of MCFA and palmitic acid in milk fat were lowered to the same extent by feeding canola oil or soybean oil when compared with cows fed the control diet, but percentages of stearic acid and oleic acid were greatest when cows were fed canola oil. Also, when
compared with the control group, feeding canola oil allowed production of milk with a greater percentage of CLA without altering the amount of trans-vaccenic acid. Thus, with respect to modification of milk fat to benefit human health, cows fed high-oleic canola oil produced greater amounts of desirable (stearic acid, oleic acid, and CLA) fatty acids and lower amounts (MCFA and palmitic acid) or similar amounts (trans-vaccenic) of undesirable fatty acids. Ten liters of milk were processed in the first, second, and fourth weeks of the five-week study to prepare 10 percent cream for evaluation of sensory characteristics by a panel previously trained to detect off-flavors. The 10 percent creams from all dietary treatments were considered to be within specifications for quality standards. In addition, coffee creams prepared at each of the sampling times for all treatments provided adequate whitening and were stable when heated. Thus, dietary oils with high (greater than 80 percent) oleic
acid content improved the fatty acid profile of bovine milk with respect to human health without changing manufacturing characteristics or acceptability of the milk products. Consumer awareness of fluid milk and milk products with an improved fatty acid profile may create a demand for these value-added products in the marketplace.
Impacts
(N/A)
Publications
- RODRIGUEZ, L.A., STALLINGS, C.C., HERBEIN, J.H., and MCGILLIARD, M.L. 1997. Effect of degradability of dietary protein and fat on ruminal, blood, and milk components of Jersey and Holstein cows. J. Dairy Sci. 80:353-363.
- BANDARA, A.B.P.A. and HERBEIN, J.H. 1997. Oleic acid content of milk in response to abomasal infusion of canola oil, olive oil, or high-oleic sunflower oil on Holstein and Jersey cows. J. Dairy Sci. 80(Suppl. 1):242.
- LOOR, J.J., HERBEIN, J.H., and JENKINS, T.C. 1997. Alterations in milk fatty acid content due to feeding canola oil and(or) canolamide to Holstein cows. J. Dairy Sci. 80(Suppl. 1):164.
- LOOR, J.J. and HERBEIN, J.H. 1997. Secretion of cis-9,trans-11-18:2 in milk fat of Holstein cows in response to infusion of conjugated linoleic acid into the abomasum. J. Dairy Sci. 80(Suppl. 1):164.
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Progress 10/01/95 to 09/30/96
Outputs
The potential for altering bovine milk fatty acid composition was evaluated using in vitro and in vivo methods. Cultured bovine mammary cells were supplemented with 0, 12.5, 25, 50, or 100 uM oleic, linoleic, linolenic, or conjugated linoleic acid (CLA). Unsaturated fatty acids were incorporated in proportion to their concentration in the media. Rate of de novo synthesis of saturated fatty acids declined as uptake of unsaturated fatty acids increased. In vivo studies were conducted to verify the in vitro responses. Lactating Holstein cows were fed supplemented oleic acid as high-oleic-canola oil (HOCA) or HOCA reacted with ethanolamine to form fatty acyl amides, which are resistant to biohydrogenation in the rumen. Regardless of the dietary form of oleic acid, concentrations of all saturated fatty acids synthesized by the mammary gland were lower and concentration of oleic acid in milk was higher when compared to cows fed the control diet. When cows were fed HOCO,
concentrations of trans fatty acids also were higher in milk. Responses to linoleic acid isomers were determined by infusing 200 g of linoleic acid or 100 g linoleic plus 100 g CLA into the abomasum of lactating cows over 24 hours. Saturated fatty acids declined and linoleic acid increased in milk. However, during CLA infusion, oleic acid declined in milk as stearic acid increased, suggesting inhibition of stearoyl CoA desaturase due to increasing CLA.
Impacts
(N/A)
Publications
- BANDARA, A.B.P.A. and HERBEIN, J. H. and DUNCAN, S.
- E., 1996, Enhancement of oleic and linoleic acid content of milk by abomasal dinfusion of seed oils or fish oil in Jersey cows, J. Dairy Sci. 79(Suppl. 1):230.
- BAUGHMAN, C. E., 1996, Influence of in vitro elaidic acid or trans-vaccenic aciduptake and lactogenic hormone stimulation on fatty acid content of mouse mammary cells, M.S. Thesis.
- ELLING, J. L. and DUNCAN, S. E. and KEENAN, T. W. and EIGEL, W. N. and BOLING, J., 1996, Composition and microscopy of reformed creams from reduced-cholesterol butteroil, J. Food Sci. 61(1):48.
- ELLING, J. L. and DUNCAN, S. E., 1996, Physical properties of 20% milk fat reformulated creams manufactured from cholesterol-reduced butteroil, J. Food Sci. 61(2):375.
- RODRIGUEZ, L. A. and STALLINGS, C. C. and HERBEIN, J. H. and MCGILLIARD, M.
- L., 1996, Effect of degradability of dietary protein and fat on ruminal, blood and milk components of Jersey and Holstein cows, J. Dairy Sci. 79:(In Press).
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