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W181: Modifying Milk Fat Composition for Improved Manufacturing Qualities and Consumer Acceptability

Annual/Termination Reports (SAES-422): [12/09/2002] [10/02/2003] [12/30/2004]

Date of Annual Report: 12/09/2002

Report Information:
  • Annual Meeting Dates: 01/07/02 to 01/08/02
  • Period the Report Covers: 01/2001 to 12/2001

    • Participants:
    Brief Summary of Minutes of Annual Meeting:
    http://www.ag.unr.edu/w181/Minutes/minutes2002.html

    Accomplishments:
    Accomplishments and Impacts:

    IMPACT STATEMENT

    Dairy products are an important source of vital nutrients in the human diet. We have increased understanding of methods for improving the health index of dairy products, demonstrated health benefits of vaccenic acid, learned that products from these methods are acceptable to consumers, and increased the marketability of dairy products.


    Objective 1: To identify and characterize important regulatory steps in fatty acid synthesis and
    desaturation and their positional distribution on glycerol in milk fat.

    In lactating dairy cows it was established that endogenous synthesis of milk fat CLA was possible. There was a 31% increase in milk fat CLA with abomasal infusion of trans-11 C18:1 fatty acid. Stearoyl-CoA desaturase enzyme was identified to be responsible for conversion of trans C18:1 to CLA in the mammary gland. It was shown that endogenous synthesis of CLA accounted for over 75% of the cis-9, trans-11 CLA found in milk.

    Research completed at Cornell University showed that there are differences in dairy cows, probably based on genetics, in ability to either extract CLA or make CLA for deposition into milk fat. The rank order of cows based on CLA concentration in milk fat did not change whether cows were fed a diet to enhance CLA synthesis or a diet that was designed to keep CLA synthesis in the cow low. The researchers used a C14:0 to C14:1 ratio to determine desaturation indices because all C14:1 originates from the delta-9 desaturase.

    It was found that the trans-10 cis-12 isomer of CLA reduces milk fat content and fat yield. Variation in trans 11 oleic acid may explain the trans 10, cis 12 effect on milk fat depression. Research completed at the Ohio State University suggests a dose response curve of lower milk fat yield with increasing concentrations of the trans 11, cis 12 isomer of CLA. Much of the decrease was due to a decrease in de novo synthesis. Several other isomers were involved, however, it is felt that the t10, c12 isomer is coordinating the change. When milk fat synthesis is decrease, it may lead to increased lipogenesis in adipose tissue.

    Research completed at the University of Minnesota is studying the fatty acid concentration of milk from high and low producing herds in the state. Data is being collected. University of Minnesota is also interested in determining what effects flavors in milk and certain peptides in milk to determine if flavors or peptides can be fed or selected for.

    Studies conducted at the University of Maryland were started to determine if concentrations trans isomers and CLA isomers in milk fat are correlated or independent. Ruminocentesis was used to determine concentrations of TVA and CLA in ruminal fluid and this was compared to milk concentrations. It was found that trnas, trans isomers may have been made during the processing of samples. There may actually be trans, trans isomers formed in the rumen, but it is not likely that they are absorbed.

    Objective 2: To quantify modification of milk fat composition by manipulating the diet of
    the cow.

    Studies were conducted to determine the influence of feeding various fat sources on fatty acid composition of various breeds of dairy cows. It was found that milk from Jersey cows was more saturated than milk from Holstein and Brown Swiss cows. Feeding supplemental fat reduced the fat globule size in milk.

    An interesting aspect of CLA is its relationship to diet-induced milk fat depression. Recent research results from the Cornell University suggest that it is trans-10 C18:1 fatty acid that is responsible for milk fat depression.

    Ann Fearon, Belfast University, presented Optimizing milk fat composition and an example of current technology practices. Dietary enhancement by feeding cows on pasture a supplement to increase unsaturated fatty acids allowed manufacturing and marketing of a naturally spreadable butter. Produced only in summer when animals are on pasture then stored. The primary criterion for increasing spreadability was increasing oleic acid content of milk fat.

    Research done at University of Utah compared breeds of dairy cattle for changes in fatty acids composition of milk fat. Data suggested that, if animals had been pastured, there would have been larger differences. When not pastured, animals had lower CLA concentrations in milk, but TVA concentrations were similar. Research on breed differences will also continue at the University of Arizona where Brown Swiss will be compared with Holstein cattle. There may be differences in these two breeds because Brown Swiss are thought to be less susceptible to milk fat depression.

    Research competed at Iowa State University was completed to determine the diversity of fatty acid composition in cow distinct dairy herds. Differences in cows were seen that seemed to be related to stage of lactation, parity, and genetics. The idea was that, if milk could be segregated from certain animals, products enhanced in unsaturated fatty acids or CLA concentrations could be manufactured. ISU also tried using NIR indices as potential rapid checks for the unsaturation (via the atherogenic index of milk fat) but accuracy was not adequate for good estimation. FTIR may provide a better answer.

    Objective 3: To characterize the effects of modified milk fats on physical, chemical,
    manufacturing, and sensory properties of dairy products.

    Sphingomyelin is a phospholipid referred to as tumor suppressor lipid. Milk is a major source of sphingomyelin in the human diet. Studies conducted at the University of Illinois showed that Sphingomyelin was more concentrated in Holstein milk fat than Jersey milk fat.

    Consumer testing done at two sites in the United States by Land OLakes on pilot samples of spreadable butter. Consumers suggested that they liked the concept but were not willing to pay a premium for the product. Consumer testing completed by University of Kentucky, however, suggested that consumers would purchase a CLA enhanced products (milk and cheese) based on health claims. The CLA enhancement was accomplished by feeding fish oil.

    COLLABORATIVE WORK
    Linkages between researchers

    1. Health aspects of vaccinic acid are being demonstrated by collaborations done with Dairy Management, Inc. (DMI) and University of Helsinki
    2. University of Illinois and University of Reading, Dept. of Agriculture, UK.
    3. Cornell University is collaborating with University of Helsinki, Finland; University Cagliari, Italy; INRA France; University of Laval, Canada; University of Illinois; Roswell Park Cancer Institute, Buffalo; University of Sao Paulo, Brazil; University of Idaho; Natural lipids, Norway; ARS/USDA; ARO Israel; Purdue University, Land OLakes, Webster City, Iowa.
    4. Utah State University and Western Dairy Center, Logan, Utah
    5. Department of Dairy Science and Food Science and Technology, Virginia Polytechnic Institute and State University.
    6. Iowa State University, Ames, Iowa and Land O‘Lakes, Webster City, Iowa.
    7. University of Belfast representative visited with W-181 group to share experiences with commercialization of fatty acid modified butters in Ireland.

    Impact Statements:
    Last Modified: unknown

    Date of Annual Report: 10/02/2003

    Report Information:
  • Annual Meeting Dates: 01/06/03 to 01/07/03
  • Period the Report Covers: 01/2002 to 12/2002

    • Participants:
    Brief Summary of Minutes of Annual Meeting:
    Report from Henry Tyrrell, representative of CSREES

    Tyrrell provided an update on agricultural issues in Congress. He described the regional project system to us and reminded us that 25% of Hatch allocations are used to fund approved regional projects. Of these regional funds, greater than 90% are used for salaries. Approximate allocation toward disciplines is > 4X for human research, 4X for animal science research, 2X for plant science research, and X for social science research. Tyrrell announced to everyones chagrin that this meeting will be the last time he attends because of his impending retirement. He plans to move south of D.C.perhaps Florida or Alabama. Tyrrell announced that colleagues Bill Wagner and Dick Frahm also are retiring from CSREES and that Gary Cromwell of the University of Kentucky will fill in to about 25% of his time. The group had an extended discussion about future leadership in the CSREES, the NRI competitive grants program, and the land grant system.

    Monday, January 6, 2003

    Chair Bev Teter called the meeting to order at 8:25 a.m. Each attendee introduced herself or himself. Ron Pardini, our administrative advisor, gave us a genuine welcome to the University of Nevada. He expressed concern about the poor attendance, and some of the reasons such as late approval of the meeting were discussed. Pardini reminded us that our project expires in September of 2004. Therefore, we were encouraged to initiate discussions of objectives for the renewal project. He encouraged us to put more emphasis on impacts, what has been done, and why we work together. To meet our renewal deadline, we need to have a rewrite completed by March 2004, which is the scheduled meeting of the Western Regional Directors.

    The minutes of the 2002 annual meeting were approved with minor changes in spelling.

    Station Reports

    Jeff Firkins (Clemson University): Objective 1

    Firkins has been studying biohydrogenation in the rumen. Specifically, he has studied the reduction and isomerization of elaidic (and oleic acids) to monoenoic acids and stearic acid. Additionally, he and his colleagues have studied the biohydrogenation of linoleamide and its effects on linoleic acid concentration in duodenal contents of sheep. Other studies were a comparison of amide and calcium salt derivatives of linoleic acid on linoleic acid concentration in digesta, blood, and milk of Holstein cows.

    Don Beitz (Iowa State University): Objective 2 and 3

    Beitz and his colleagues have studied the response of cows that produce a more saturated fat and those that produce a more unsaturated fat to diets rich in polyunsaturated fatty acids. They used fish oil and soy oil in roasted soybeans as the source of supplemental fat and studied the properties of butter prepared from the resulting different milks. The bottom line of their research is that natural variation and nutritional manipulation of fatty acid composition of bovine milk provides the possibility of selecting or causing cows to produce a more healthful milk that produces a more spreadable butter.

    Cindie Luhman and Paul Porter (Land OLakes/Farmland): Objective 3

    Luhman and Porter reported on research in which they were studying the effect of different dietary fats (proprietary protection) on fatty acid composition including the different trans fatty acids of milk and the spreadability of butter. They noted that spreadability of butter is not only dependent on the percentage of unsaturated fatty acids in the milk fat but also dependent on the location of the unsaturated fatty acids on the glycerol moiety of the triacylglycerol. They also studied the use of Fourier transform infrared (FTIR) spectroscopy to estimate degree of unsaturation of milk fat quickly and accurately.

    David Schingoethe and Amer Abughazaleh (South Dakota State University): Objective 2

    Schingoethe and Abughazaleh determined that optimal concentrations of trans-vaccenic acid (TVA) and conjugated linoleic acid (CLA) in the rumen for maximal CLA in milk can be obtained with as little as 0.33% fish oil in a diet that contains supplemental extruded soybeans. Fish oil is thought to inhibit the ruminal hydrogenate of TVA to stearate. Also, TVA and CLA content was increased most when the supplemental fat in addition to the fish oil was rich in linoleic acid. The greater CLA because of fish oil is likely the result of increased supply of TVA at the mammary gland. In another study of cheese yield from Holstein and Brown Swiss milks, the Brown Swiss milk yielded greater amounts of cheese per milk volume. Also, curd formation required less time and the curd was firmer from the Brown Swiss milk.

    Bev Teter (University of Maryland): Objective 2

    Teter and her colleagues continued to study the transfer of dietary CLA and other trans fatty acids as calcium salts to the myriad of isomers of CLA in milk fat. They observed a significant milk fat depression (0.85%) when cows were fed daily 100/g of CLA as a calcium salt. Another focus has been to use mice as models for the metabolic effect of dietary CLA. They observed that trans 10, cis 12 CLA increases heat production and that the CLA seemed to increase the volume of peroxisomes and total lipid in liver.

    Renewal of Project

    The group discussed the fact that our project requires renewal during early 2004. These items were put forth for consideration.
    1. The renewal project should include a greater emphasis on extension of research to clientele. Thus, we need to include more extension people to join the group.
    2. These emerging dairy issues were stated for consideration in the renewal:
    ‘ Increase manufacturing focus.
    ‘ Increase integration of nutrition and product quality.
    ‘ Consider spreadability of butter to price of the product.
    ‘ Emphasize cheese yieldthis quality of milk seems to be a stimulus for the selection of Jersey cows for milk production.
    ‘ Study factors that control cheese quality because inconsistency in quality of cheddar cheese remains a challenge.
    ‘ Continue to study factors that influence shelf life of dairy products.
    3. Development of a symposium that integrates milk production practices with qualities of common dairy foods. Such a symposium could include topics related to:
    ‘ Nutrition of cow and milk fat composition.
    ‘ Production and value of whey and its products.
    ‘ Regulation of protein composition and concentration in milk.
    ‘ Mechanism of milk fat synthesis, including role of peroxisomes and mitochondria.
    ‘ Influence of dairy products on human health.
    4. Are objectives of current project appropriate for renewal project. A consensus was that more emphases on studies in improve health-promoting properties of dairy foods should be developed.
    5. Ron Pardini reminded us that the web site of should be used for electronic proposal writing.

    Seminar by Ron Pardini

    The group had the privilege to learn about the successful research program of Ron Pardini on the nutritional intervention with fat rich in omega-3 fatty acids for treatment of cancer. He has been studying the effect of different fatty acids on growth of a model cancer cell culture. One finding that seems very promising for adoption is the inhibition of cancer cell growth by docosahexaenoic acid (DHA). He presented a testimonial of his neighbor friend that amazed all of us. The neighbor had a type of terminal cancer reversed by use of DHA supplements without the use of the usual chemotherapeutic protocol. He mentioned other testimonials of friends and relatives who died or are suffering from cancer who use(d) supplemental DHA or fish oil to slow growth of cancer. Many of us were left with the thoughts of reinitiating the practice of taking our cod liver oil supplement with breakfast for benefits to personal health.

    Impacts of W-181 Research

    The group initiated discussion of developing a list of impacts or findings from W-181 regional research. We request that each member of the regional project assist the writing team (Bev Teter, Tom Jenkins, and Don Beitz) in developing this list. Henry Tyrrell will send the previous five annual reports and minutes to the writing team for summarization. As a starter, these impacts were voiced:
    1. Nutritional manipulation can impact CLA content of milk.
    2. Nutritional manipulation can increase oleic acid content and decrease saturated fatty acid content of milk.
    3. Fatty acid content of milk fat is regulated partly by genetic mechanisms.
    4. Milk from cows of different breeds differ in CLA content.
    5. Feeding fish oil at low dosages does not have negative effects on taste of dairy foods.
    6. CLA-enriched butter has anticancer effects.
    7. Diet can be manipulated to alter melting point and spreadability of butter.
    8. FTIR spectroscopy may be a tool to relatively quickly estimate degree of unsaturation of milk fat.
    9. Trans-vaccenic acid is a precursor of CLA.
    10. Feeding CLA may have positive impact on cows in negative energy balance by causing milk fat depression.
    11. Pasture feeding increases CLA content of milk.

    W-181 Meeting at 2003 ADSA/ASAS

    Tom Jenkins will coordinate a meeting time of W-181 members in Phoenix to continue discussion of the W-181 renewal.

    2004 Meeting of W-181 Committee

    The group selected Thursday January 8 (8 a.m.  5 p.m.) and Friday January 9 (8 a.m.  12 noon) as the meeting time for the 2004 annual meeting of the W-181 committee. Ron Pardini agreed to host the committee again in Reno, NV.

    Committee Member Responsibilities

    Don Beitz agreed to prepare the minutes of the 2003 meeting. Bev Teter will prepare the annual report. Sharon Franklin will be asked and has agreed to serve as secretary at the 2004 annual meeting. To each of you members, if you have not yet provided an annual report for 2003, please send the report to Bev Teter at your earliest convenience for inclusion in the 2003 annual report.

    Accomplishments:
    Objective 1. To identify and characterize important regulatory steps in fatty acid synthesis and desaturation and their positional distribution on glycerol in milk fat.

    Several studies have indicated that the synthesis of short chain fatty acids is inhibited by diets and diet supplements that increase the amounts of trans monoenes and CLA fatty acids. Studies have been conducted in mice, rats, goats, and cows. Some studies are still in progress but in those that are finished, the abundances of mRNA for fatty acid synthase (FAS) and acetyl-CoA Carboxylase (ACC) enzymes were decreased under these conditions. Mechanisms of these changes are not yet known but there is evidence that at the cellular level they involve the SREBP family of transcription factors. In both cows and mice increased liver triglyceride and liver weight (mice) has been noted with consumption of CLA, especially the trans-10, cis-12-CLA isomer. Continuing studies are examining stearoyl-CoA desaturase (SCD) in liver and adipose. Another study in mice is examining the effect of trans-10, cis-12-CLA on the SCD activities in adipose tissue. Additional tissue culture studies are underway to determine CPT-1 mRNA and PPARa mRNA expression in response to trans-10, cis-12-CLA. Conversely, a study using adult post-prandial Wistar rats showed that trans-10, cis-12 CLA increased the lipogenic activities in perirenal and epididymal adipose tissues as well as increasing the plasma non-esterified fatty acids, and ketogenesis but decreased other plasma lipids. On the other hand, the cis-9, trans-11-CLA decreased plasma cholesterol. In this study CLA did not alter organ weight, protein content or protein synthesis rates in liver or intestine. Muscle protein synthesis was stimulated by the trans-10, cis-12-CLA isomer. It appears that there may be major species differences in CLA metabolism in mammals.

    The French group has shown that the trans-10-18: 1 isomer was better related to the milk fat decrease in cows fed diets rich in cereals than the trans-10, cis-12 CLA.

    Human subjects are being used to evaluate the metabolic rate and RQ during rest and exercise after ingestion of 10/12 CLA.

    There have been several studies looking at the effects of CLA dietary supplementation or diet modifications on the desaturation index of milk fats by comparing the ratios of saturate to monounsaturate carbon number pairs. The results from different research groups have been mixed - some have seen effects while others have not. The variation among cows in content of CLA and CLA-desaturase index is 3 fold but over a 12-week period the index is maintained even when cows are shifted between diets.

    A recent study of feeding cottonseed in conjunction with iron sulfate demonstrated that the intake of dry matter and milk yield decreased linearly with the addition of iron sulfate but it did lower plasma gossypol levels. Examination of the total fatty acids in triglycerides and the sn-2 fatty acids found small differences. Fatty acid composition of milk fat triglycerides and phospholipid did not differ greatly.

    The most consistently observed and perhaps the most important observation for human health and nutrition is the observation that most of the CLA appearing in cows milk is made in the gland from the trans-11-18: 1, vaccenic acid, produced in the rumen. This fatty acid transfers readily to the mammary gland and is desaturated to the cis-9, trans-11 CLA that has been shown to be protective for mammary cancer in the mouse model. The trans-7, cis-9-CLA isomer is formed in the same manner. Vaccenic acid (trans-9-18: 1) has recently been shown to be protective for mammary tumors in a rat model when provided in a triglyceride. This may be due to the formation of the cis-9, trans-11 CLA as observed in cow milk. The apparent transfer of the preformed CLA from the rumen is of a smaller order of magnitude compared to that formed in the gland.



    Objective 2. To quantify modification of milk fat composition by manipulating the diet of the cow.


    Much of the effort during this period of the W-181 project has been devoted to defining the dietary conditions that lead to the desired production of milk fat of certain composition. This desired composition varied among research groups and was modified in several ways. Some groups were seeking to decrease saturated fatty acids or to increase polyunsaturated fatty acids. Some groups were interested in decreasing total milk fat and others worked to increase CLA or other fatty acids deemed important in human nutrition such as omega-3 isomers.

    The diets have been modified using many different schemes. Some have included the addition of vegetable oils, fish oils, rumen protected salts, or high oil containing grains or combinations of these treatments. In addition there have been studies with pasture feeding both cows and steers to increase the CLA content of the milk or meat. Some studies have included post-rumen infusions to exclude rumen modification of the diet supplements.

    It has been shown that diets high in concentrate and lower in forage lead to higher levels of trans (tFA) and CLA fatty acids. These diets also decrease milk fat. Buffering such diets alleviates the milk fat depression. Addition of oils to these diets increases the levels of tFA and CLA. The combination of a high linoleic fat source with fish oil leads to even higher levels of the tFA and CLA isomers. The form of the forage and method of lipid feeding have also been studied. It was found that feeding a soy oil/wheat mill mixture after milking lead to higher levels of CLA than when the soy oil/wheat mill mixture was part of the TMR. The type of forage has been shown to affect the production of trans-10-18: 1 fatty acid production. In the dairy goat is was observed that the of trans-10-18: 1 was higher in the milk when the goats were fed a corn silage-based diet as opposed to a diet which was alfalfa hay based. Pasture feeding cows leads to high levels of CLA but the addition of feed sources rich in linoleic acid does not increase the CLA levels beyond only pasture feeding.

    There has been a large number of studies in which calcium salts of fatty acids are fed in order to rumen protect the fatty acids. Calcium salts of palm fatty acids are used to increase milk fat production and polyunsaturated fatty acids are being investigated to improve fertility. Salts of both tFA and CLA have been fed to reduce milk fat and/or to increase the levels of CLA in the milk. It has been shown that the effects lasted during a 20-week study with no adverse effects on the cow well-being or subsequent pregnancy.

    Studies examining the effect of supplemental fat types on the reproductive performance of lactating dairy cows have be done using calcium salt products containing fish oils or polyunsaturated vegetable oils. Some of these studies are still in progress.

    A number of our member groups have been using in vitro rumen fermentation to study modification of feed components. This is a technique, which allows more detailed study of the processes involved in rumen modification of feedstuffs. Products and intermediates can be isolated and studied and quantitative comparisons made since there is not a flow into or out of the fermentation vessel unless it is designed to be sampled. One study based on gas chromatograph-mass spectrometry has shown that incubation of 13C labeled Elaidic acid (trans-9-18: 1) for 48 hours resulted in the formation of all trans-18: 1 isomers from delta position 6 through 16. Furthermore 5 to 10% of the Elaidic acid was converted to cis-9- and cis-11-18: 1. If the starting fatty acid was oleic acid the range of trans isomers was also seen. It was also determined that oleamide and linoleamide was less biohydrogenated than the parent acids.

    Impact Statements:
    1. The research of this committee has produced insights into milk fat production and methods to alter milk fat amount and composition by simple dietary means. Based on the work of individual researchers and collaboration among member research groups, knowledge has been developed that should allow milk fat to be tailored in composition to meet market demands for improved fatty acid composition and milk fat levels.
    2. It has been demonstrated that nutritional manipulation can increase oleic acid content and decrease saturated fat content of cow milk. It can decrease milk fat production and thus have a positive impact on early lactation cows in negative energy balance. Allowing cows to pasture feed increases the CLA content of milk as does manipulating the fat content of the diet with grains, fish oils and calcium salt supplements.
    3. In addition, the mechanisms at a cellular level are being examined to provide clues to additional regulation that may be possible by targeting specific enzymes relating to milk fat production. Increasing the vaccenic acid content from the diet leads to increased cis-9, trans-11 CLA in the milk due to the action of the delta-9 desaturase enzyme. Work is proceeding to identify fatty acids, which regulate genes that are important in milk fat production, and to examine genetic influences in diffe
    4. Based on evidence from studies indicating that certain conjugated linoleic acids (CLA) are protective in animal models for some cancers, the ability to increase these in milk fat holds promise for improvement of human health. Other CLA isomers are shown to lead to decreased body weight and increased lean muscle mass in animal models. Milk and ruminant animal products are the major natural source of this class of fatty acids. Pilot plant studies have shown that products such as butter, cheese,
    Last Modified: unknown

    Date of Annual Report: 12/30/2004

    Report Information:
  • Annual Meeting Dates: 01/08/03 to 01/09/03
  • Period the Report Covers: 01/2003 to 12/2003

    • Participants:
    Brief Summary of Minutes of Annual Meeting:
    Ron Pardini led a discussion of procedures for renewal of the W-181 project that is scheduled to terminate in September of 2004. He emphasized the inclusion of strong statements on impact and extension activities. T. Jenkins was elected to provide leadership to the renewal application.

    Gary Cromwell, USDA-CSREES representative and professor of animal science at the University of Kentucky, introduced himself and provided information on the development of the USDA budget and structure of CSREES within the USDA.

    Chris Reynolds of Ohio State University was approved as a new member of the Committee.

    Don Beitz agreed to organize a social event at the 2004 ADSA/ASAS/PSA meeting in St. Louis to honor H. Tyrrell for his many years of service to W-181 and other USDA regional committees.

    Cindie Luhman reviewed the development of the Longview Animal Nutrition Center in the St. Louis area of which Cindie is director.

    The Committee voted to have the 2005 meeting in Reno again and selected January 8 and 9 as the dates. Other sites may be considered in the future. Sharon Franklin will serve as chair and Vivek Fellner as secretary for the 2005 meeting.

    At the request of the Committee, Ron Pardini gave an update on his research activities on prevention of cancer development by omega-three fatty acids. The Committee thanked him for again graciously hosting the meeting in Nevada.

    Ed DePeters agreed to investigate the possibility of developing a symposium at a future meeting of ADSA to honor Don Palmquist.

    Accomplishments:
    Station Reports

    Don Beitz (Iowa State University): Objective 2

    On farm demonstrations were conducted with organic farms (50  100 cow operations) to assess the CLA concentrations in milk from pastured and conventionally fed dairy cattle. Collected feed and milk samples from farms to analyze CLA.

    Fatty acid composition of milk and feed was analyzed and milk production and feed intake were determined. Information was presented regarding linoleic and linolenic acid concentrations of feed for Iowa and Wisconsin farmers. Atherogenic indexes and n3/n6 fatty acid ratios in milk were compared. Pasture feeding increased CLA content in milk at least 2 fold. Producer who fed oat pasture had the highest CLA and TVA but also were feeding Dutch Belted cattle. Tilak Dhiman indicated that milk from Dutch Belted cattle have higher CLA concentrations compared with milk from Holsteins.

    Vivek Fellner (North Carolina State University): Objective 2

    Comparative assessment of dietary calcium salts of fatty acids on milk production and fatty acid composition of the milk was conducted. Different commercially available calcium salts of fatty acids were tested. Other studies involved the effect on fermentation of calcium propionate (long-chain and VFA profiles) in mixed ruminal cultures.

    Bev Teter (University of Maryland): Objective 1

    Results on the effects of dietary calcium salts of CLA and other trans fatty acids (e.g., trans-18:1) on fatty acid composition of milk fat was evaluated.

    Tom Jenkins (Clemson University): Objective 1

    Results of ruminal biohydrogenation of amides and calcium salts of long-chain fatty acids in the rumen of Holstein cows were presented. Omasal flow of C18 fatty acids was quantified. Biohydrogenation of DHA and EPA by cultures of mixed ruminal microorganisms were reported.

    James Drackley (University of Illinois): Objectives 1 and 2

    Previous research on postruminal effects of different profiles of long-chain fatty acids was reviewed. Recent research was to determine effects of amount of abomasally infused fatty acids on esterification (TG vs FFA) and saturation of various components of milk fat. Severe diarrhea begins to occur at about 450 g/d of infused FFA. Diarrhea occurred with linoleic acid but not oleic acid. Total tract fatty acid digestibility was decreased by FFA.

    David Schingoethe (South Dakota State University): Objective 2

    Long-term production of CLA by feeding 0.5% fish meal and 2% soybean oil was evaluated. CLA and TVA of milk peaked after 3 to 4 weeks but plateaued after that. A second study investigated feeding linoleic acid from linseed oil. Dave also presented a potential letter to the Editor of the Journal of Dairy Science regarding terminology for C18:2 cis-9, trans-11 and C18:1 trans-11. It was suggested that the terms rumenic acid and vaccenic acid, respectively, should be used or that n-7 fatty acids should be used to describe the group of fatty acids. This terminology would differentiate specific CLA from ruminants and prevent negative connotations associated with use of trans fatty acids. The committee suggested sending the letter to editors of Lipids and Journal of Nutrition as well.

    Tilak Dhiman (Utah State University): Objective 2

    Three experiments were conducted to determine when fatty acids reach peak under pasture feeding conditions. Pasture was fed for approximately 30 d without a transition period from TMR to pasture. Three wk of pasture feeding were required to maximize CLA and TVA. The concentrations of CLA and TVA decreased to baseline levels when cows returned to TMR diets. Production dropped to almost half. For the second experiment, cows were transitioned during the first wk on pasture. The cows still experienced large decrease in milk yield. CLA was maximized at 27 days and reached approximately 2% of fatty acids. For experiment 3, rumen protected CLA was fed prior to and following parturition. Concentrations of serum BHBA and NEFA increased when cows were fed CLA.

    Sharon Franklin (University of Kentucky): Objective 2

    The objectives of the study were to evaluate the effects of long-term feeding of menhaden fish oil on milk production and composition, body weight and condition, and feed intake. Preliminary data were presented for feed intake during the dry period and production parameters during lactation.

    Ed DePeters (University of California-Davis): Objective 2

    Data were presented from a study that evaluated the effects of method of lipid supplementation and physical form of the forage on the fatty acid composition of milk fat. Another study is in progress that evaluates the effects of feeding calcium salts differing in fatty acid composition on lactation and reproductive performance of high producing Holstein cows.

    Mark McGuire (University of Idaho): Objective 2

    Research was presented regarding the possible interaction of body composition and CLA on milk fat synthesis in rats. Previous research had not demonstrated milk fat depression in rats as in lactating women. In women, milk fat depression seems related to body composition. Women with low body fat had milk fat depression and women with higher body fat did not experience milk fat depression. Therefore, lean and normal (obese) rats were fed 10,12 CLA, and milk composition and litter growth were evaluated. Data were presented regarding milk fat percentage.

    Accomplishments

    Objective 1. To identify and characterize important regulatory steps in fatty acid synthesis and desaturation and their positional distribution on glycerol in milk fat.

    1. Mixtures of saturated free fatty acids and highly digestible when they can associate with digesta particles (IL). 2. Unsaturated fatty acids given at 500 g/d to cows postruminally were absorbed poorly and resulted in diarrhea and off-fed conditions (IL). 3. Endogenous synthesis via D9-desaturase is the major source of milk fat cis-9, trans-11 and trans-7, cis-9 CLA (NY). 4. Variation among cows in milk fat content of CLA and CLA-desaturase index is 3-fold (NY). 5. Effect of breed, stage of lactation and parity on milk fat CLA content and CLA desaturase index are minimal (NY). 6. Mechanism where milk fat synthesis is reduced with diet-induced MFD or with trans-10, cis-12 CLA treatment involves a coordinated reduction in expression of genes for key enzymes (NY). 7. Mechanism for milk fat depression at the cellular level appears to involve the SREBP family of transcription factors (NY). 8. Vaccenic acid is anticarcinogenic in a biomedical model of breast cancer (NY). 9. Reduction in milk fat content and milk fat yield from feeding rumen-protected CLA (Ca-salts) is maintained (NY). 10. Developed method of analyzing the geometry of mixed double bonds in CLA isomers was developed (NY). 11. Established that trans-8, cis-10 and cis-11, trans-13 CLA have no effect on milk fat (NY).

    Objective 2. To quantify modification of milk fat composition by manipulating the diet of the cow.

    1. Differences in linoleic acid and linolenic acid concentrations were observed between feeds. More than 50% of the fatty acids in grass-legume pastures is linolenic acid but the percentage is lower in predominantly legume pastures. More than 50% of the fatty acids in corn silage, cereal grains and corn-based concentrates, and raw and processed soybeans is linoleic acid (IA). 2. The average initial (before pasture) milk CLA concentration of northeast Iowa farms was 0.35 g/100g and that of the southwest Wisconsin farms was 0.27 g/100 g of the total fatty acids. Among the northeast Iowa farms, Farm A had the highest CLA concentrations, 1.00 g/100 g and 1.29 g/100 g of the total fatty acids in May and June, respectively. Among the southwest Wisconsin farms, Farm H, F, and G had the highest CLA concentrations. Intensive grazing of grass-legume pasture and less feeding of concentrates resulted in increased concentration of CLA (IA). 3. Atherogenic indices ranged from 2.12 to 3.27 among northeast Iowa farms and from 3.00 to 3.78 among southwest Wisconsin farms (lower value is considered to be healthier) (IA). 4. Omega-3 to omega-6 fatty acid ratios of milk ranged from 0.24 to 0.69 among northeast Iowa farms and from 0.40 to 0.53 among southwest Wisconsin farms (IA). 5. Farms (Farms B, C, and D) that have consistently fed soybeans produced milk with higher linoleic acid concentration, a desirable component for making butter (IA). 6. Preliminary data analysis (using GeneSpring) demonstrated clear increases over time in the expression (fold-change expressed as tissue/universal control) of genes with known or unknown functions associated with metabolism that accompanies copious milk synthesis. Large fold-changes in mRNA expression were detected between -14 and +14 d for stearoyl-CoA desaturase, xanthine dehydrogenase, fatty acid binding proteins-3 and -5, fatty acyl-CoA ligase-2, transport proteins (ABCG2, ABCA1, TAP1), GLUT1, IGFBP3, Lipin-1, SPP1, kinases (Janus, pyruvate dehydrogenase-4, myosin light-chain), PPAR-g, aminoacyl tRNA synthases, leucine aminopeptidase, and b-1, 4 galactosyl transferase. Expression of immunoglobulin lambda and kappa also were markedly upregualted by d 14 postpartum. Results demonstrate the power of microarrays to study patterns of gene expression in the bovine mammary gland (IL). 7. Converting fatty acids in soybean oil to calcium salts or amides did not alter biohydrogenation of unsaturated fatty acids in the rumen (SC). 8. Both the prilled and VF100® fat sources depressed dry matter intake when included in diets with total fat content of 8%. A depression of intake was not observed for the VF200® fat source. Lower intakes resulted in reduced milk yields for both the prilled and VF100®. In contrast, VF200® resulted in the highest milk production. The VF100® and VF200® fat supplements remained relatively inert in the rumen, resulting in an increased passage of the unsaturated linoleic acid into milk. The VF100® resulted in a higher trans-fatty acid production that lowered milk fat percentage. VF200® is relatively inert in the rumen and can be included in diets already high in fat content. The VF200® fat supplement supported high milk yields and improved milk fatty acid composition, which is consistent with enhanced health benefits (NC). 9. Adding calcium propionate to mixed cultures of rumen microorganisms increased CLA production (NC). 10. Yields of 9, 11-CLA and TVA in milk fat are increased by feeding a blend of fishmeal and extruded soybeans (SD). 11. Maximal CLA concentration was achieved by giving cows at least 23 days of pasture with no supplemental grain (UT). 12. Milk from cows grazing on pasture had double the alpha-tocopherol content than that from cows fed conserved forages and grains (UT). 13. Supplementing CLA to cows had no effect on feed DM intake during pre-calving, but there was a tendency for lower feed intake post calving (1-10 wk). Cows supplemented with CLA had lower fat content in milk and produced less energy corrected milk compared with cows in control diet. Supplementing CLA had no effect on CLA content of milk. Cows supplemented with CLA had higher levels of BHBA and NEFA in blood serum compared with cows receiving no CLA, suggesting body fat mobilization during early lactation (UT). 14. A rumen protection delivery system was developed and has been submitted for patent approval. Initially the complex was used to protect polyunsaturated fatty acids from rumen biohydrogenation. The complex was successful in increasing the polyunsaturated fatty acid content of milk fat when fed as part of the total mixed ration (CA). 15. Feeding calcium salts of either trans C-18:1 and of CLA increased 9, 11-CLA in milk fat; 7,9-CLA was increased only by Ca-tFA treatment; 10,12-CLA was increased by Ca-CLA treatment (MD). 16. Decreased milk fat percentage was caused by trans monoenoic fatty acids (MD). 17. Dietary restriction attenuates the milk fat depressing effect of trans-10, cis-12 CLA in rats (ID). 18. Dietary CLA causes milk fat depression, but a greater dose is required in early than in later lactation (AZ).

    Objective 3. To characterize the effects of modified milk fats on physical, chemical, manufacturing, and sensory properties of dairy products.

    None were reported this year.

    Impact Statements:
    1. The year round assessment of milk CLA concentration indicates that CLA concentration is highest (2-4 fold) during the grazing months and lowest during the nongrazing time of the year. Also, the data support the hypothesis that milk CLA concentration under actual farm conditions is highly affected by the grazing intensity of cows. Intensive grazing results in higher CLA concentration in the milk presumably because of higher linolenic acid content in pasture grasses, which could be degraded t
    2. Preliminary research demonstrated the power of microarrays to study patterns of gene expression in the bovine mammary gland.
    3. Biohydrogenation of unsaturated fatty acids in the rumen in not altered by converting then to calcium salts or amides.
    4. Yields of cis-9, trans-11 CLA and TVA in milk fat can be increased by feeding a blend of fish meal and extruded soybeans. That increase occurs rapidly, peaks out quite high within three weeks, but is relatively constant after 5 weeks on the diet.
    5. If method of lipid supplementation or forage particle size can be manipulated to modify milk fatty acid composition e.g. CLA, practical management programs can be developed for use on dairy farms to enhance the nutritional value of milk fat. These management programs may modify milk fat composition similar to what is obtain with grazing dairy cows. If the fatty acid composition of the dietary lipid supplement can be used to improve health during the transition period and reproductive perfo
    6. Unsaturated fatty acids having important nutritional and marketing benefits for milk products are destroyed by bacteria in the rumen of cows before reaching the mammary gland. These studies demonstrate that conversion of an unsaturated fatty acid to either a calcium salt or an amide reduced their metabolism by ruminal bacteria. The protection from bacterial destruction is greater for oleic acid than for linoleic acid. Also, the metabolism of fish oil fatty acids by ruminal bacteria is cons
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