Final Report for SW01-034

Assessment of Value Added Milk from Pasture-based Dairies

Project Type: Research and Education
Funds awarded in 2001: $78,000.00
Projected End Date: 12/31/2004
Matching Non-Federal Funds: $21,831.00
Region: Western
State: Utah
Principal Investigator:
Tilak Dhiman
Utah State University
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Project Information

Abstract:

Conjugated linoleic acid (CLA) is a potent anticarcinogenic compound. Milk fat is the richest source of CLA. Our research suggests that milk from pasture-based dairies was high in CLA. The CLA contents in milk were higher in summer than in winter months. The consumer acceptability and quality of CLA-enriched dairy products produced from cows grazing pasture was the same as from cows fed conserved forages and grains. Consumers were willing to pay more for the CLA-enriched dairy products. Dietary intake of CLA in adults living in Utah was 25% of the effective dose for cancer prevention.

Project Objectives:

Objective 1: To assess the year-round supply and value of CLA-enriched dairy products produced on pasture-based dairies.
Objective 2: To characterize physical, chemical, and sensory properties of CLA-enriched dairy products
Objective 3: To assess the market values of CLA-enriched milk, cheese, and butter.

Introduction:

Conjugated linoleic acid (CLA) has been intensively studied recently, mainly because of its potential in protecting against cancer, atherogenesis, and diabetes (Kritchevsky, 2000; Pariza et al., 2003). Major dietary sources of CLA are dairy products and other foods derived from ruminants. The cis-9, trans-11 isomer is the principle dietary form of CLA exhibiting biological activity, and accounts for 94% of total CLA in milk and dairy products. Conjugated linoleic acid originates from either ruminal biohydrogenation of C18:2 and C18:3 fatty acids or from endogenous synthesis in mammary tissues themselves. Endogenously, CLA is synthesized from trans-11 C18:1 vaccenic acid (TVA), another intermediate of ruminal biohydrogenation, via delta-9-desaturase (Griinari et al., 2000; Corl et al., 2001).
The normal concentration of cis-9 trans-11 isomer in milk from cows fed a typical dairy ration is about 0.38 g/100 g of total milk fat (Dhiman et al., 1999) and about 0.35% in beef lipids. It is currently estimated that the intake of the average human adult consuming western diets is only one-third to one-half of the amount of CLA that has been shown to reduce cancer in animal studies. For this reason, increasing the CLA content of milk and meat has the potential to raise the nutritive and therapeutic values of dairy products and meat.
The CLA content in milk and meat is affected by several factors, such as an animal’s breed, age, diet, and management factors related to feed supplements affecting the diet. Increasing the supply of precursors for CLA synthesis through nutritional manipulations, for example, inclusion of oils or extruded oil seeds increases the CLA content of milk (Dhiman et al., 2000). Cows grazing pasture had 500% higher CLA content in milk compared with cows fed typical dairy cow diets containing conserved forage and grain in a 50:50 ratio (2.2 vs 0.4% of CLA in milk fat; Dhiman et al., 1999). The higher CLA in milk from grass-fed cows means higher nutritive and therapeutic value. In the near term, dairy products naturally enriched with CLA will be value-added products that could enhance profitability and competitiveness of dairy producers. Questions such as the supply, quality, CLA content, and profitability of producing CLA-enriched products need to be addressed.

Research

Materials and methods:

Objective 1: To assess the year-round supply and value of CLA-enriched dairy products produced on pasture-based dairies.
A large majority of the dairy cows (80-90%) in the United State are maintained in confinement and are fed diets containing conserved forages (hay and silage) and grains. There are some dairy operations where cows graze on pasture in the summer. Dairies that graze cows during the summer supplement some form of grain or a mixture of grains to minimize the loss in milk yield while on pasture. These dairies have to rely on conserved forage and grains during winter when pasture is not available. There are few dairies that graze cows in summer and feed only conserved forages in winter time with no grain supplementation. As mentioned earlier, diet and management practices related to diet influence the CLA content of milk. We investigated the year-round concentration of CLA in milk from four commercial dairy farms in Idaho and Utah for 2 years. Cows on these farms were either grazed or fed fresh cut green forage during the summer and conserved forages and grain during the winter time.
Profiles of dairy farms
Farm A: The number of milking cows on this farm ranged between 75-90 during the study. Cows were grazed during the summer (mid May through September) and supplemented with 7.0 kg/cow per day of flaked corn and barley mix (60:40). Grain was provided in equal portions in the parlor during each milking. Pasture contained a mixture of alfalfa (Medicago sativa), brome grass (Bromus commutatus), fescue (Festuca arundinacea), perennial ryegrass (Lolium perenne), and white clover (Trifolium repens). During winter months cows were fed oat hay, alfalfa hay, and alfalfa silage plus 7.0 kg/cow per day of flaked corn and barley mix (60:40).
Farm B: The number of milking cows on this farm ranged between 380-410 during the study. Cows were fed diets as total mixed ration (TMR) with no access to grazing during any time of the year. The TMR contained flaked corn, whole cottonseed, sugar beet pulp, wheat bran, oat grain, alfalfa silage, alfalfa hay, grass hay, and a mineral supplement. During summer months cows on this farm were fed fresh cut pasture grass (mix of meadow brome (Bromus commutatus) and fescue (Festuca arundinacea) at a level of 10% of the dietary DM.
Farm C: The number of milking cows on this farm ranged between 140-160 during the study. Cows were grazed during the summer and supplemented with 7.0 kg of grain mix /cow per day in two equal portions at each milking. Grain contained 60% flaked corn, 30% sugar beet pulp pellets, and 10% molasses. Pasture contained a mixture of fescue (Festuca arundinacea), brome grass (Bromus commutatus), perennial ryegrass (Lolium perenne), alfalfa (Medicago sativa), and white clover (Trifolium repens). During winter months cows were fed alfalfa and meadow hay in year 1 and alfalfa hay alone in year 2 along with 7 kg of grain mix /cow per day.
Farm D: The number of milking cows on this farm ranged between 450-500 during the study. This farm had a mixed production system with one-third of the cows grazing during summer months and supplemented with TMR. Other cows on the farm were fed TMR in the tie stall. The TMR contained steam flaked corn, whole cottonseed, distiller’s grain, alfalfa hay, corn silage, sugar beet pulp, and mineral and vitamin mixture.
Sampling and analysis:
Feed and bulk tank milk samples were collected every month from each farm over a period of 2 years. Milk samples from individual cows were collected twice a year from two consecutive milkings, once during the grazing season in July/August and once during winter in January/February. A minimum of 20 cows or 15% of the total milking cows, whichever was greater at the time of sampling, was selected for milk sampling. Feed and milk samples were analyzed for composition and fatty acid profile. Data were analyzed statistically using proc MIXED in a factorial structure. Farm, year, season, farm × year, farm × season, year × season, and farm × year × season were included in the model.

Objective 2: To characterize physical, chemical, and sensory properties of CLA-enriched dairy products.
Sensory attributes play a key role in determining consumer acceptability for dairy products. Consumer acceptability of synthetic CLA-enriched dairy products containing extremely high levels of CLA appears to be low, and it is unrealistic due to cost constraints (Campbell et al., 2003). Ramaswamy et al. (2001) studied the oxidized flavor scores of CLA-enriched milk and butter from cows fed fish oil, extruded soybeans, or their combination and found no difference between low- and high-CLA milk or butter. There is little information about the consumer acceptability and sensory attributes of CLA-enriched milk and cheese from cows grazing on pasture. While one objective of this study was to produce CLA-enriched milk and cheese, the study was primarily conducted to test the hypothesis that CLA-enriched milk and cheese from pasture-fed cows will be similar in consumer acceptability attributes and specific flavor characteristics to that of milk and cheese with low levels of CLA.

Two experiments were conducted to study the consumer acceptability attributes of CLA-enriched milk (Experiment 1) and cheese (Experiment 2) from cows grazing on pasture.

Experiment 1:
Fifteen Holstein cows were assigned to one of three treatments. Cows were fed either a TMR containing 51% forage and 49% concentrate (TMR), grazed on pasture (PS), or grazed on pasture and supplemented with 3.2 kg/cow per day of a grain mix (PES). The total mixed ration in TMR contained on a DM basis: 23.6% alfalfa hay, 27.8% corn silage, 10.7% steam-flaked corn, 19.3% commodity grain mix, 8.1% whole linted cottonseed, 2.1% soybean meal, 6.3% sugar beet pulp, 0.2% custom yeast mix, 1.2% molasses, and 0.8% fat. The grain mix fed in PES contained 75% full-fat extruded soybeans, 10% dry ground corn, 10% dried sugar beet pulp, and 5% molasses on a DM basis. Experimental duration was 6 weeks, and measurements were made during the last 3 weeks. All cows were grazed together under intensive rotational grazing management. To feed the grain mix, cows in PES were brought to individual tie-stalls for 15 min after each milking before turning out onto pasture. Feed, pasture grass, and milk samples were collected weekly and analyzed for composition and fatty acid profile.
Milk collected during weeks 4, 5, and 6 was pasteurized at 72ºC for 15 sec, homogenized using a Gaulin model CGC 2-stage homogenizer, and used for taste panel evaluation. Sensory evaluation of milk was conducted within 72 h of procurement and 36 h of processing the milk.

Experiment 2
Eighteen Holstein cows were assigned to TMR, PS, and PES treatments similar to Experiment 1, except that cows in PES were fed only 2.5 kg of full-fat extruded soybeans/cow per day instead of the grain mix. This change in Experiment 2 was made to feed more C18:2 fatty acid through full-fat extruded soybeans than in Experiment 1. Cow management, feeding practices, experimental duration, feed sampling, and milk sampling procedures were the same as described in experiment 1. Cheddar cheese was manufactured from milk collected in this experiment and used for FA analysis and consumer acceptability evaluation. Cheese was manufactured in four different sessions. A total of 12 batches (14-kg each batch) of cheeses (4 /treatment) was made over a period of 16 days from weeks 4 through 6 of the experiment. Cheese was prepared using the basic small-scale manufacturing procedure of Kosikowski and Mistry (1997). Cheese blocks were vacuum-packaged and refrigerated at 4ºC until evaluation by an open panel of consumers after 40 days. After open-panel evaluation, cheese was frozen at -20ºC for 6 months before conducting the trained-panel evaluation. Milk and cheese samples were analyzed for fatty acid profile.

Sensory evaluation of milk and cheese
Refrigerated fluid milk was evaluated by an open panel of consumers. Panelists consisted of men and women ages 24-60 who were regular consumers of fluid milk and cheese. The evaluation was conducted in individual booths under fluorescent white light by 62, 86, and 92 judges, respectively. Judges were asked to rate each sample independently for color, mouth-feel, flavor, and overall quality on a continuous 9-point hedonic scale (where 9 = like extremely, 5 = neither like nor dislike, and 1 = dislike extremely).
An open panel of consumers evaluated each batch of cheese for color, flavor, texture, and overall quality on a continuous 9-point hedonic scale. Evaluation was conducted in 3 different sessions with 78, 83, and 73 consumers, respectively, in each session. Cheese (15-g) held at room temperature was served in plastic cups. Testing conditions were similar to those described previously for milk evaluation.
A trained panel of experts evaluated the fluid milk and Cheddar cheese for color, overall quality, and specific flavors on a score card patterned after the American Dairy Science Association scoring guide. Eight judges were selected from a group of people who had been regularly exposed to training and judging a variety of dairy products, including fluid milk. The sensory testing scale used was a continuous 10-point scale for flavor characteristics with 10 = highly pronounced, 7 = moderate, 5 = slight, 3 = barely perceptible, and 1 = none. For color and overall quality, a 9-point scale was used with 9 being best in color and overall quality, 5 being average, and 1 being undesirable color and unfit for sale.
All statistical analysis was performed using the statistical procedures of SAS (1999-2000).

Objective 3: To assess the market values of CLA-enriched milk, cheese, and butter.
Functional foods offer health benefits above and beyond basic nutritional value. High-CLA dairy products will not be commercially viable unless consumers are willing to pay a premium for the additional costs of enhancing CLA levels in milk. Cows grazing on pasture have higher levels of CLA and TVA in milk, but total milk production drops when cows are on pasture compared to when cows are fed conserved forages and grains. Recently, Maynard and Franklin (2003) published a research report on sensory evaluation and willingness to pay for the cancer-fighting attributes of high-CLA dairy products. The method used was contingent valuation measures that estimate the willingness to pay for a non-market good by creating a hypothetical market for a particular good. Participants first read a brief description of cancer fighting benefits of CLA and how CLA levels could be raised in dairy products. The hypothetical scenario is then presented as “regular” and “cancer fighting” dairy products, both products are available in the market and they tasted the same, and are identical in every other respect except price. Participants (n= 103) responded by indicating how much more they would pay for “cancer fighting” dairy products above the price of “regular” dairy products. On average, respondents indicated willingness to pay $0.11 per liter more for high-CLA milk, $0.38 per pound more for high-CLA butter, and $0.15 per 224 g cup more for high-CLA yogurt. At an average production level of 7711kg /cow per year, estimated additional costs of producing high CLA milk are $0.03 per gallon (Maynard and Franklin, 2003). Results from this study suggest that profit potential exists for producers serving niche markets via small-scale processing ventures. Some respondents in this study commented that their willingness to pay was contingent upon the medical community’s support of CLA as an anticancer agent, highlighting the relevance of ongoing CLA research on human health benefits.
In objective 3 we decided to take research one step further from the study reported by Maynard and Franklin (2003). We determined the distribution of CLA in the food supply, and estimated intake from dairy and beef products in the diet of men and women 50 years of age or older living in Utah. The prevalence of heart disease, cancer, and osteoporosis is lower in Utah than the national average, while diabetes rates are higher.
A population-based survey of 485 men and 522 women aged 50 and above living in Utah was conducted using a mailed questionnaire and a validated food frequency questionnaire. Respondents were questioned as to their intake of meat and dairy products. The survey was patterned after National Health and Nutrition Survey III. Respondents were selected by accessed random sample using Utah Driver’s License records. Mean age of men and women respondents was 68.3±11.8 and 66.4±11.7, respectively. Body mass index of men and women was 27.2±5.1 and 27.2±5.8, respectively. Statistical analysis was conducted separately for men and women and for age groups 50-64 and 65+ years old. Highest consumption among dairy products was of hard cheeses followed by milk, ice cream, cottage cheese, butter, yogurt, hot chocolate, frozen yogurt, and cream cheese.
To obtain an accurate sampling of the meat and dairy products that these respondents consumed, a random sampling table was designed in which 50 different stores were selected. Seven samples, three beef and/or lamb products and four dairy products, were randomly designated for collection from each store. Dairy, beef, and lamb products were chosen to be sampled because they contain the greatest amounts of CLA. A total of 120 samples were collected and analyzed for fatty acid profile including CLA using the method described by Chouinard et al. (1999). Conjugated linoleic acid intake of respondents was calculated by multiplying the CLA content of foods by average total fatty acids intake measurements from the above Nutritional Survey.

Research results and discussion:

Objective 1
Commercial dairies that grazed cows during summer and supplemented with grain mix produced milk with 60% or more milk fat CLA and TVA contents on a year-round basis compared with the dairy that fed 10% of diet DM as fresh cut pasture. Similarly, the dairy that grazed one-third of its cows during summer and supplemented with TMR produced 30% or more CLA and TVA in milk compared with the dairy that fed 10% of dry matter as fresh cut forage. Milk fat content of CLA and TVA was 150-200% more during summer compared with winter across all farms. Although individual cow milk samples varied from 0.16 to 2.22% in milk fat CLA contents, 89% of the cows had CLA contents between 0.3 and 1.0%, indicating that only a small proportion of cows in the population were at either end of the curve. Individual cow variation was larger in dairies that had cows grazing in the summer compared with dairies that either did not graze or grazed only one-third of their cows. Variation was larger in summer than in winter. The range in bulk-tank milk CLA content was smaller than in individual cow milk samples, ranging from 0.27 to 1.35% of milk fat. Cows in farms A and C produced similar or higher amounts of milk fat CLA on a daily basis even though their milk yield was lowest among the dairies. Concentration and supply of CLA and TVA were highest from June through September and lowest from February through April, which should be the months for targeting the improvement of the CLA and TVA content of milk.

Objective 2
Average CLA contents (g/100 g of fatty acid methyl esters) were 0.52, 1.63, and 1.69 in milk and 0.47, 1.47, and 1.46 in cheese from cows in TMR, PS, and PES treatments, respectively. Supplementation of C18:2 fatty acid (linoleic acid) in the form of full-fat extruded soybeans to cows grazing on pasture did not increase CLA content in milk compared to grazing on pasture alone. Open and trained sensory panel evaluations of milk and cheese showed no differences among treatments for any of the attributes, except that the trained panel detected more barny flavor in milk from PS and PES compared with milk from TMR. Results from the current study suggest that consumer acceptability attributes of CLA-enriched milk and cheese from cows grazing on pasture were similar to milk and cheese with normal levels of CLA from cows fed a conventional diet containing conserved forages and grain.
CLA Intake from Dairy Products
Based on appropriate extrapolation of data from animals to humans, an adult human would require 0.72-0.80 g of CLA/d to inhibit tumor growth (Parrish et al., 2003; Watkins and Li, 2003). Based on fat and CLA contents of milk in this study, 500 ml of milk from TMR, PS, and PES treatments would provide 0.07, 0.25, and 0.26 g of CLA. Using CLA contents of cheese in the current study and a fat content of 32% (Shantha et al., 1995), 100 g of cheese from TMR, PS, and PES treatments would provide 0.13, 0.40, and 0.40 g of CLA. A person consuming 500 ml of milk and 100 g of cheese daily from cows in the TMR treatment would only be consuming about one-third of the estimated requirement for humans. However consuming similar amounts of milk and cheese from cows in PS or PES will provide CLA close to the requirements.
In addition, there is a potential for higher levels of TVA in CLA-enriched dairy products to be converted to CLA in human tissues (Turpeinen, 2002), further increasing the supply of CLA that could be obtained from enriched products. Clearly, if the objective is to achieve health benefits from CLA, it is practical to consume CLA-enriched milk and cheese.

Objective 3
Daily fatty acid consumption of combined men and women was milk = 5.61 g, cheese = 6.70 g, meat = 8.76 g and other dairy products = 15.1 g. The average CLA content of milk, cheese, meat and other dairy products was 0.52, 0.54, 0.31, and 0.58 % of total fatty acids. The average CLA intake from dairy and meat products was 0.178 g/day. Based on appropriate extrapolation of data from animals to humans, an adult human would require 0.72-0.80 g of CLA/day to inhibit tumor growth (Parrish et al., 2003; Watkins and Li, 2003). Our data clearly suggest that intake of CLA in our population was only 25% of the dose that has been shown to be effective for cancer prevention.

Overall results and milestone summary (Objectives 1-3)
Results from our research suggest that milk from pasture-based dairies was high in CLA. The CLA contents in milk were higher in summer months than in winter months. The consumer acceptability characteristics (flavor, taste, texture, color, and overall quality) of CLA-enriched milk and cheese produced from cows grazing on pasture was the same as milk and cheese from cows fed conserved forages and grains (conventional diets). The higher CLA in milk from grass-fed cows means higher nutritive and therapeutic value. Consumers are willing to pay a premium price for the CLA enriched products. Consumption of CLA from dairy and meat products in a sample of the Utah adult population (50 years or above) was 25% of the dose that has been shown to be effective for cancer prevention in animal models.

REFERENCES
Bauman, D. E., L. H. Baumgard, B. A. Corl, and J. M. Griinari. (1999). Biosynthesis of conjugated linoleic acid in ruminants. Proc. Am. Soc. Anim. Sci., pp. 1-15.
Campbell, W., M. A. Drake, and D. K. Larick. 2003. The impact of fortification with conjugated linoleic acid (CLA) on the quality of fluid milk. J. Dairy Sci. 86:43-51.
Chouinard, P. Y., L. Corneau, D. M. Barbano, L. E. Metzger, and D. E. Bauman. (1999). Conjugated linoleic acids alter milk fatty acid composition and inhibit milk fat secretion in dairy cows. J. Nutr., 129:1579-1584.
Corl, B. A., L. H. Baumgard, D. A. Dwyer, J. M. Griinari, B. S. Phillips, and D. E. Bauman. (2001). The role of delta(9)-destaurase in the production of cis-9, trans-11 CLA. J. Nutr. Biochem., 12:622-630.
Dhiman, T. R., G. R. Anand, L. D. Satter, M. W. Pariza. 1999. Conjugated linoleic acid content of milk from cows fed different diets, J. Dairy Sci. 82:2146-2156.
Dhiman, T. R., L. D. Satter, M. W. Pariza, M. P. Galli, K. Albright, and M. X. Tolasa. (2000). Conjugated linoleic acid (CLA) content of milk from cows offered diets rich in linoleic and linolenic acid. J. Dairy Sci., 83:1016-1027.
Griinari, J. M., B. A. Corl, S. H. Lacy, P. Y. Chouinard, K.V.V. Nurmela, and D. E. Bauman. (2000). Conjugated linoleic acid is synthesized endogenously in lactating dairy cows by delta (9)-destaurase. J. Nutr., 30:2285-2291.
Kosikowski, F. V. and V. V. Mistry. 1997. Cheese and Fermented Milk Foods. Vol. II. F. V. Kosikowski L. L. C., Great Falls, VA.
Kritchevsky, D. (2000). Antimutagenic and some other effects of conjugated linoleic acid. Br. J. Nutr., 83: 459-465.
Maynard, L. J. and S. T. Franklin. 2003. Functional foods as a value-added strategy: the commercial potential of “cancer-fighting” dairy products. Rev. Agri. Econ. 25:316-331.
Pariza, M. W., Y. Park, X. Xu, J. Ntambi, and K. Kang. (2003). Speculation on the mechanisms of action of conjugated linoleic acid. In: Sebedio, J., Christei, W. W., and Adolf, R. (Eds.), Advances in Conjugated Linoleic Acid Research. Vol. 2, pp. 251-266. Champaign, IL: AOCS Press.
Parrish, F. C., Jr., B. R. Wiegand, D. C. Beitz, D. U. Ahn, M. Du, and A. H. Trenkle. 2003. Use of dietary CLA to improve composition and quality of animal-derived foods. Pages 189-217 in Advances in Conjugated Linoleic Acid Research. Vol. II. J. L. Sebebio, W. W. Christie, and R. Adlof, eds. AOCS Press, Champaign, IL.
Ramaswamy, N., R. J. Baer, D. J. Schingoethe, A. R. Hippen, K. M. Kasperson, and L. A. Whitlock. 2001. Composition and flavor of milk and butter from cows fed fish oil, extruded soybeans, or their combination. J. Dairy Sci. 84:2144-2151.
SAS. 1999-2000. SAS/STAT User’s Guide (Release 8.1), SAS Inst. Inc., Cary, NC.
Shantha, N. C., L. N. Ram, J. O’Leary, C. L. Hicks, and E. A. Decker. 1995. Conjugated linoleic acid concentrations in dairy products as affected by processing and storage. J. Food Sci. 60:695-697.
Turpeinen, A. M., M. Mutanen, A. Aro, I. Salminen, S. Basu, D. L. Palmquist, and J. M. Griinari, J. M. (2002). Bioconversion of vaccenic acid to conjugated linoleic acid in humans. Am. J. Clin. Nutr., 76:504-510.
Watkins, B. A. and Y. Li. 2003. CLA in functional food: enrichment of animal products. Pages 174-188 in Advances in Conjugated Linoleic Acid Research. Vol. II. J. L. Sebebio, W. W. Christie, and R. Adlof, eds. AOCS Press, Champaign, IL.

Research conclusions:

The results from this research documented the CLA content of milk from farms that graze cows or fed fresh cut forage during the summer and conserved forages and/or grains during the winter months. The CLA content of milk varied between farms depending on the production systems. The CLA in milk from individual cows varied from 0.16 to 2.22% in milk fat CLA content, and 89% of the cows had milk fat CLA content between 0.3 and 1.0%. Our research also demonstrated that consumer acceptability and overall quality of CLA-enriched dairy products was comparable to conventional dairy products. Additionally results from our research suggest that the CLA intake in adult population living in Utah was only 25% of the dose that has been shown to be effective for cancer prevention.
The information was disseminated to producers and dairy extension specialists. It is difficult to asses the market impact of this research with the limited information collected, however, the results of this research will be useful in calculating year-round supply of CLA-enriched dairy products. The results of this study are useful for marketing CLA-enriched dairy products with a claim of comparable consumer acceptability and need for human consumption to prevent cancers. This research will generate interest in graziers wanting to have their cows consuming more green grass than conserved forages and grains inside the barn and establishing a niche market for CLA-enriched dairy products. Positive health effects of grass-based dairy products will increase the overall consumption of dairy products and farm profitability.

Participation Summary

Educational & Outreach Activities

Participation Summary

Education/outreach description:

PUBLICATIONS
Khanal, R. C., T. R. Dhiman, A. L. Ure, C. P. Brennand, R. L. Boman, and D. J. McMahon. 2005. Consumer acceptability of conjugated linoleic acid-enriched milk and Cheddar Cheese from cows grazing on pasture. In press J. Dairy Sci.
Dhiman, T. R., S. Nam, and A. L. Ure. 2005. Factors affecting conjugated linoleic acid content of milk and meat. In press Critical Rev. in Food Sci. Nutr.
Khanal, R.C. 2004. Dietary influence on conjugated linoleic acid content of milk and consumer acceptability of milk and cheese naturally enriched with conjugated linoleic acid. Ph.D. Dissertation, Animal, Dairy and Veterinary Sciences, Utah State University.
Khanal, R. C. and T. R. Dhiman. 2004. Milk fat conjugated linoleic acid in selected commercial dairies of Utah and Idaho. J. Dairy Sci. 87 (Suppl. 1):335.
Aguiar, G., T. R. Dhiman, A. L. Ure, S. F. Porter, and L. L. Jeffs. 2004. Changes in milk fatty acids during transition of dairy cows from diet based on conserved forages and grain to pasture. J. Dairy Sci. 87 (Suppl. 1):341.
Dhiman, T. R. 2004. Potential human health benefits of forage based milk and meat. Proceedings American Association for the Advancement of Science, Pacific Div. Vol. 23:47 (Abstract).
Neelam Kewalramani, T. R. Dhiman and Harjit Kaur. 2003. Factors affecting conjugated linoleic acid content of milk – A Review. Anim. Nutr. Feed Technol. 3:91-105.
Khanal, R. C., T. R. Dhiman, and R. L. Boman. 2003. Influence of turning cows out to the pasture on fatty acid profile of milk. J. Dairy Sci. 86 (Suppl. 1):356.
Khanal, R. C., T. R. Dhiman, D. J. McMahon, and R. L. Boman. 2002. Influence of diet on conjugated linoleic acid content of milk, cheese and blood serum. J. Dairy Sci. 85(Suppl. 1):142.

INVITED SCHOLARLY PRESENTATIONS
2004
 Presentation “CLA content of milk and meat from grass based systems” at the 24th Annual Ecological Farming Conference held at Asilomar Conference Center, Pacific Grove, CA on January 21-24, 2004.
 Keynote speaker presentation at the Northeast Grasstravaganza Conference – 2004 sponsored by the Central New York RC&D Project Inc. and USDA-NRCS. Conference was held at Binghamton, New York during February 27-28, 2004. Title of the presentation was “Health benefits of grass based milk and meat.”
 Presentation at the 1st Annual American Grassfed Association Conference, Topeka, Kansas, March 5-6, 2004. Title of the presentation was “Health benefits of grass based milk and meat.”
 Presentation at the Annual meeting of American Association for the Advancement of Science, Pacific Division held at the Utah State University, Logan from June 13-17, 2004. Title: “Potential human health benefits of forage based milk and meat.”
 Presentation at the Organic Pastured Dairy Farm Rotational Grazing Pasture Walk & Educational Program held at Fowler, Michigan on July 14, 2004. Program organized by the Bio-Systems Soil Testing and Consulting Services and University of Michigan.
 Presentation at the “Power of Animal Nutrition and Human Nutrition” – A workshop and tour organized by the University of Nebraska, Cooperative Extension Service, Knox County, Center, NE on July 15-16, 2004.
 Presentation at the Alabama Grazefest – 2004 organized by the U.S. Grassfed Society, September 11-12, 2004, Montgomery, Alabama. Title of the presentation was “Health benefits of grass based milk and meat.”
2003
 Presentation at the Seventh Annual Vermont Grazing Conference “ Innovations in grass farming” organized by the Vermont Grass Farmers Association and University of Vermont Center for Sustainable Agriculture, 63 Carrigan Drive, Burlington, VT 05405, held at the Vermont Technical College, Randolph, Vermont on January 25, 2003
 Presentation at the 11th Annual Wisconsin Grazing Conference, “Grazing towards a Greener Tomorrow” organized by the GrassWorks, Inc. 210 River Drive, Wausau, WI 54403, held at the Holiday Inn, Stevens Point, WI from February 16-18, 2003.
 Presentation at the Natural Resources Conservation Service, Short Course “Health benefits of grass based milk and meat” at the Department of Department of Rangeland Resources, Utah State University, July 2003.

Project Outcomes

Project outcomes:

Incorporating green grass or pasture into dairy production systems increases the CLA content of milk. Consumers are willing to pay a premium of $0.41 per gallon for CLA-enriched milk compared to conventional milk. Health-conscious consumers will probably pay more for CLA-enriched dairy products. Anecdotal evidence of actual willingness to pay comes from a brief test market for the professionally processed high-CLA cheese. High-CLA cheese was priced at $5.50 per pound compared to $2.50 for conventional cheese. Results from a study conducted at the University of Wisconsin suggested that cost of producing milk from pasture based systems is $1.30/cwt cheaper than the conventional way. If future studies in humans support the health benefit of CLA-enriched dairy products, then pasture-based systems will produce a product with greater profit.

Farmer Adoption

 A web page for “Conjugated linoleic acid” was developed. The address for the website is: http://www.usu.edu/trdhiman/publication.html
 We are posting our CLA research on this site as it is being published in refereed journals. Research was also distributed to the participating and other dairy producers.
 The PI is analyzing about 400 samples of milk and meat products per year for fatty acids including CLA and omega fatty acids from producers across the country.
 Invitational talks that PI has given across the country and increasing number of samples received in PI’s laboratory for CLA analysis clearly suggest that our research has made its way to the small family farms.

Recommendations:

Areas needing additional study

 More studies are needed to demonstrate the health benefits of CLA and CLA enriched foods in humans.
 Research in the area of other bioactive compounds present in milk and meat from grass-based systems will help improve the nutritional and therapeutic value of grass-based milk and meat as well as farm profitability.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.