Conjugated Linoleic Acid Content of Beef Finished with Pasture

Final Report for LNC02-216

Project Type: Research and Education
Funds awarded in 2002: $97,533.00
Projected End Date: 12/31/2006
Matching Non-Federal Funds: $29,902.00
Region: North Central
State: Missouri
Project Coordinator:
Carol Lorenzen
University of Missouri
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Project Information

Summary:

Cattle were randomly assigned to one of four finishing regimens; pasture, pasture with grain supplement, pasture with grain supplement containing soyoil, and feedlot. Pasture inclusion produced higher levels (P < 0.05) of total CLA than the feedlot diet on an mg/g fat basis for cooked samples while maintaining acceptable eating quality. Meat from all finishing regimes was considered acceptable by consumers. Gains for pasture cattle were poor, partly due to late turnout. Profit potential exists for supplemented pasture systems, but is dependent on sound gains and grazing management and targeted marketing to consumers willing to pay a premium for CLA enhanced beef.

Introduction:

Conjugated linoleic acid (CLA) is a naturally occurring fatty acid found in ruminant animal fats. CLA is a product of ruminal biohydrogenation of polyunsaturated fatty acids (Kelly et al., 1998), and there is strong evidence that CLA has anticarcinogenic properties in laboratory animals (Ip, Scimeca, & Thompson, 1994) as well as be protective against heart disease, diabetes, and obesity (Sumeca and Miller, 2000; Weiss, Martz, & Lorenzen, 2004). The CLA content of beef has been characterized by previous researchers (Shantha, Crum, & Decker, 1994; Ma, Wierzbicki, Field, & Clandinin, 1999); however, these studies used small sample sizes and the tested beef was purchased from retail stores implying that the cattle producing the beef had been fed in a normal production scheme including a high-concentrate finishing diet. CLA content in grass fed cattle was greater in the Semimembranosus muscle compared to cattle on pasture and supplemented with grain (Shantha, Moody, & Tabeidi, 1997). French et al. (2000) reported a linear increase in CLA content with increased percentage of grass in the diet. While these studies indicate the likelihood that beef from pasture-fed or pasture-finished cattle will contain higher concentrations of CLA than feedlot cattle, small sample sizes and the limited selection of muscles for analysis prevent a firm conclusion.

Since beef is not consumed raw, cooking and other processing methods that may alter the original CLA content of the meat also deserve investigation. CLA content in cooked meat patties has been shown to increase on an mg/g of fat basis and mg/100 g of cooked meat basis (Shantha et al., 1994). In order for consumers to receive the health benefits of CLA from meat, there will need to be a maintained and/or elevated amount in the cooked product. In addition, muscles differ in fat concentration based on function and location within the body making it important to investigate more than one muscle.

References
French, P., Stanton, C., Lawless, F., O’Riordan, E. G., Monahan, F. J., Caffrey, P. J., & Moloney, A. P. 2000. Fatty acid composition, including conjugated linoleic acid, of intramuscular fat from steers offered grazed grass, grass silage, or concentrate-based diets. J. Anim. Sci. 78:2849-2855.

Ip, C., Scimeca, J. A., & Thompson, H. J.. 1994. Conjugated linoleic acid: a powerful anticarcinogen from animal fat sources. Cancer 74:1050-1054.

Kelly, M. L., Berry, J. R., Dwyer, D. A., Griinari, J. M., Chouinard, P. Y., Van Amburgh, M. E., & Bauman, D. E. 1998. Dietary fatty acid sources affect conjugated linoleic acid concentrations in milk from lactating dairy cows. J. Nutr. 128:881-885.

Ma, D. W. L., Wierzbicki, A. A., Field, C. J., & Clandinin, M. T. 1999. Conjugated linoleic acid in Canadian dairy and beef products. J. Agric. Food Chem. 47:1956-1960.

Shantha, N. C., Crum, A. D., & Decker, E. A.. 1994. Evaluation of conjugated linoleic acid concentrations in cooked beef. J. Agric. Food Chem. 42:1757-1760.

Shantha, N. C., Moody, W. G., & Tabeidi, Z.. 1997. Conjugated linoleic acid concentration in semi-membranosus muscle of grass- and grain-fed and zeranol-implanted beef cattle. J. Muscle Foods 8:105-110.

Sumeca, J. A. & Miller, G. D. 2000. Potential health benefits of conjugated linoleic acid. J. Amer. College Nutr. 19:472-506.

Weiss, M. F., Martz, F. A., & Lorenzen, C. L. 2004. Conjugated linoleic acid: implicated mechanisms related to cancer, atherosclerosis, and obesity. Professional Animal Scientist 20:127-135.

Project Objectives:

1. Determine and compare the CLA content of pasture finished beef in the raw and cooked states.

2. Determine the effects of different grain supplementation regimes on CLA content of beef.

3. Determine the economic feasibility of pasture-finished beef for a niche market.

4. Develop educational materials for producers about the management tools and economics involved with increasing the CLA content beef through pasture finishing.

Cooperators

Click linked name(s) to expand
  • James Gerrish
  • Ingolf Gruen
  • Fred Martz
  • Kevin Moore

Research

Materials and methods:

Cattle Selection and Feeding

Forty-eight steers were obtained from Grassland Beef, Inc., a Missouri producer owned operation, and used in a Management-intensive Grazing (MiG) system at the University of Missouri Forage Systems Research Center (FSRC; Linneus, MO). Cattle were of the same age and biological type and age, British x Continental crosses, appropriate for pasture-based finishing. Steers were background grazed on pasture on a producer-cooperator farm to a weight of 363 to 385 kg, and then moved to finishing pastures at the FSRC. Target harvest weights were uniform for all treatments, 500 kg live weight with 0.76 cm carcass backfat.

Cattle were weighed two consecutive days at the beginning and end of the trial and each month while on feed. Prior to the start of the trial, all pasture cattle received only pasture. Grazing commenced on July 23 and continued until each group had reached target weights and backfat thickness or until adequate pasture was no longer available. Less than average rainfall resulted in pastures becoming limited in their ability to support extended grazing, and thus, the target weight and backfat thickness was not attained for some feeding regimen groups. Four feeding regimens were employed: 1) Pasture only, 2) Grain supplement (cracked corn and soyhulls) offered to 1.2% of body weight, 3) Soyoil supplement (cracked corndried distillers grains and soyhulls plus soyoil premix) offered to 1.2% of body weight, and 4) Feedlot ration (cracked corn and soyhulls) offered free choice in dry lot with a self feeder. There were two replications of six steers per replication for each feeding treatment. Two animals were removed from the study due to animal management issues.

The pasture used in this study was an 80-acre unit consisting of 24 permanent paddocks of approximately three acres. Paddocks were arranged such that stock water was available ad libitum in each paddock. Pastures were diverse cool season plant species mainly consisting of endophyte free tall fescue (Festuca arundinacea), orchardgrass (Dactylis glomerata), timothy (Phleum pratense), smooth bromegrass (Bromus inermis) with red clover (Trifolium pretense) as the principle legume with some birdsfoot trefoil (Lotus corniculatus). Pastures were approximately 30% legumes. Each replication group of steers was rotationally grazed on four replicated three acre pastures. The three acre pastures were further subdivided into strips to facilitate moving the steers to fresh pasture every 2 to 3 d.

Cattle were weighed at the end of the trial and penned overnight with water available at the FSRC. The next morning cattle were loaded and transported to the University of Missouri Meat Laboratory, approximately 170 km, for further processing.

Steak Preparation

Prior to processing the carcasses, USDA yield and quality grade factors (USDA, 1997) were collected to characterize the cattle. The following cuts were selected from each carcass: ribeye roll similar to IMPS #112A (NAMP, 1997; USDA, 1996), shoulder clod similar to IMPS #114 (NAMP, 1997; USDA, 1996), and inside round similar to IMPS #169 (NAMP, 1997; USDA, 1996) in order to test CLA content in the middle meats, chuck, and round. Subprimals were aged for 14 d and frozen until fabrication into steaks. Frozen subprimals were cut into 2.54 cm steaks in order to obtain the following muscles: Longissimus lumborum, Triceps brachii, and Semimembranosus. For each subprimal, one steak was analyzed raw and one steak was analyzed cooked.

Laboratory Analysis

All steaks were analyzed for moisture, fat, total fatty acids, and specific CLA isomers (cis-9, trans-11; trans-10, cis-12; Cis-cis-9, cis-11; trans-9, trans-11). Crude fat and moisture were determined using a CEM SMART Trac Moisture and Fat Analysis System (CEM Corporation, Matthews, NC). The SMART System utilizes microwave technology to determine moisture content of a meat sample. The SMART Trac NMR system utilizes nuclear magnetic resonance and directly measures fat content utilizing a signal-to-mass ratio.

For fatty acid profile and CLA analysis, lipids were extracted according to Hara and Radin (1978) using a solvent mixture of hexane and isoproponol (3:2 v/v). An aliquot of 2 g sample was extracted with 30 mL extraction solvent, which was washed with 25 mL sodium sulfate solution in a separatory funnel. The hexane layer was dried with anhydrous sodium sulfate and a 2 mL aliquot was combined with 1 mL of internal standard (1 mg/mL C17:0 methyl ester). The fatty acid profile and CLA content was determined using the alkaline methylation method of Shantha et al. (1994). The lipid extract was dried under nitrogen and transesterified using tetramethyl guanidine in methanol. The methyl esters were separated by gas chromatography (Perkin Elmer 8500) on a fused silica capillary column (Supelcowax 10, 60 m x 0.32 mm x 0.25 µm film, Supelco Inc, Bellefonte, PA) with a helium flow rate of 1.8 mL/min at 30 psi head pressure. Injector and FID temperatures were 250 ºC. The initial column temperature of 100 ºC was kept for 5 min, then ramped at 10 ºC /min to 225 ºC and held at that temperature for 30 min for a total run time of 47.5 min.

Prior to sample analysis, the method was validated by determining method accuracy and precision using CLA spiked meat imitation samples. Fatty acid methyl esters standards (C16:0, C16:1, C18:0, C18:1, C18:2, C18:3, C20:4, C20:5n-3 and C22:6n-3) and four standard CLA methyl ester isomers 9c,11c; 9c,11t; 10t, 12c and 9t, 11t (98% purity) (Matreya, Inc., Pleasant Gap, PA) were used to generate an internal standard curve, with C17:0 methyl ester as the internal standard, which was used for quantifying the various fatty acids and CLA isomers. Fatty acids, including CLA, were expressed as fatty acid methyl esters.

Steaks were cooked on a Farberware Open Hearth broiler (Bronx, NY). Internal temperatures were monitored with a copper constantan thermocouple inserted into the geometric center of each steak, and temperatures were monitored with a hand-held thermometer (Omega model HH21 microprocessors/thermometer; Omega Engineering Inc., Stanford, CT). Steaks were cooked to an internal temperature of 35°C, turned, and cooked to a final internal temperature of 70°C.

Warner-Bratzler Shear Force and Consumer Panel

Warner-Bratzler shear force was conducted according to AMSA (1995) guidelines. Briefly, steaks were cooked to a target endpoint temperature of 70 oC on a MagiKitch’n Conveyor Grill. After cooking, cuts were wrapped in Sam’s Choice® oxygen-permeable clear plastic wrap to reduce evaporation and cooled overnight under refrigeration (4 oC). Six 1.27 cm cores were removed parallel to the muscle fiber and sheared perpendicular to the muscle fiber. Shear force was measured using a United STM Smart-1 Test System SSTM-500 (United Calibration Corp., Huntington Beach, CA). Settings for the United Testing System were: force units – kg, linear units – mm, cycling – 1  70 mm, test speed – 250 mm/min, return speed – 500 mm/min, setup scales – CAP = 226.8. The shear force value of the cores was then averaged.

Panelists (n=87) were recruited from the Columbia, MO area from a list of consumers who had participated in previous meat consumer panels, posted flyers, and by word of mouth. Consumers were told that they would receive a five-dollar gift certificate for participation in the study. There were two consumer panel sessions were needed to achieve the desired number of panelists. Consumers were given verbal and written instructions on how to complete the ballot before the first sample was served. Consumers were asked to rate longissimus lumborum steaks for overall liking, liking of tenderness, liking of juiciness, and liking of flavor. Samples were rated on a nine-point category scale for liking where 1 = dislike extremely and 9 = like extremely. A subset of steaks were was chosen to be either Slight or Small marbling to minimize the effect of USDA quality grade (Smith et al., 1984) on consumer panel results. Duplicate treatment samples, for a total of eight samples, were served to consumers in a random order. Steaks were cooked to a target endpoint temperature of 70 oC on a MagiKitch’n Conveyor Grill. Steaks were then cut into 1 x 1 x 2.54 cm3 cubes and each consumer received two cubes of each sample. All samples were served warmed.

Statistical Analysis

Statistical analyses were performed using GLM procedures of SAS (SAS Institute Inc., Cary, NC). Carcass and consumer panel data were analyzed as a completely randomized design for treatment effects. Fat content, Warner-Bratzler shear force, and fatty acids were analyzed as a split plot design with feeding regime and animal within feeding regime as whole plots and muscle and feeding regime by muscle as sub plots. Previously published research has demonstrated the effects of cooking on fat percentage (Harris et al., 1992) and fatty acid content (Cannell et al., 1989; Smith et al., 1989; Duckett and Wagner, 1998); therefore, cooked and raw samples were analyzed separately. LSMEANS were generated and separated using least significant differences.

References

AMSA. 1995. Research guidelines for cookery, sensory evaluation and instrumental tenderness measurements of fresh meat. American Meat Science Association in cooperation with National Live Stock and Meat Board. Chicago, IL.

Cannell, L. E., Savell, J. W., Smith, S. B., Cross, H. R., & St John, L. C. 1989. Fatty acid composition and caloric value of ground beef containing low levels of fat. J. Food Sci. 54:1163-1168.

Duckett, S. K., & Wagner, D. G. 1998. Effect of cooking on the fatty acid composition of beef intramuscular lipid. J. Food Comp. Anal. 11:357-362.

Hara, A., & Radin, N.S. 1978. Lipid extraction of tissues with a low-toxicity solvent. Anal. Biochem. 90:420-426.

Harris, K. B., Haberson, T. J., Savell, J. W., Cross, H. R., & Smith, S. B.. 1992. Influence of quality grade, external fat level, and degree of doneness on beef steak fatty acids. J. Food Comp. Anal. 5:84-89.

NAMP. 1997. The Meat Buyers Guide (4th Ed.). National Association of Meat Purveyors, Reston, VA.

Shantha, N. C., Crum, A. D., & Decker, E. A.. 1994. Evaluation of conjugated linoleic acid concentrations in cooked beef. J. Agric. Food Chem. 42:1757-1760.

Smith, D. R., Savell, J. W., Smith, S. B., & Cross, H. R.. 1989. Fatty acid and proximate composition of raw and cooked retail cuts from beef trimmed to different external fat levels. Meat Sci. 26:295-311.

Smith, G. C., Carpenter, Z. L., Cross, H. R., Murphey, C. E., Abraham, H. C., Savell, J. W., Davis, G. W., Berry, B. W., & Parrish, Jr., F. C. 1984. Relationship of USDA marbling groups to palatability of cooked beef. J. Food Quality. 7:289-308.

USDA. 1996. Institutional Meat Purchase Specifications for Fresh Beef Products. Agric. Marketing Serv., USDA, Washington, DC.

USDA. 1997. Official United States Standards for Grades of Beef Carcasses. Agric. Marketing Serv., USDA, Washington, DC.

Research results and discussion:

Grazing commenced on July 23 and continued until each group had reached target weights and backfat thickness or until adequate pasture was no longer available. Four feeding treatments were employed: 1) Pasture only, 2) Grain supplement (cracked corn and soyhulls) offered to 1.2% of body weight, 3) Soyoil supplement (cracked corn and soyhulls plus soyoil premix) offered to 1.2% of body weight, and 4) Feedlot ration (cracked corn and soyhulls) offered free choice in dry lot with a self feeder.

Pastures were diverse cool season plant species mainly consisting of endophyte free tall fescue (Festuca arundinacea) , orchardgrass (Dactylis glomerata), timothy (Phleum pratense), smooth bromegrass (Bromus inermis) with red clover (Trifolium pretense) as the principle legume with some birdsfoot trefoil (Lotus corniculatus). Pastures were approximately 30% legumes.

The entire grazing period for this study was from July 23 to December 3, 2002. Rainfall during the period was very low with less than 1.0 in per month occurring in June, September, October, and November. About 1.5 in of rainfall occurred in July as several small events and 3.0 in of rain fell during a 5-day period in August. Because of this extreme drought situation, pasture condition was very poor throughout the study. Estimated forage availability was 730 lb DM/acre at the beginning of the trial. The only period when forage availability exceeded this level was a 3-week period from late August to mid-September following the mid-August rainfall when available forage reached levels near 1096 lb DM/acre.

The level of forage available was less than 713 lb DM/acre at other periods during the study which may have led to less than optimal pasture voluntary intake. The respective ADG for the trial was 3.5, 1.7, 2.0, and 1.1 1bs/d for feedlot, grain, soyoil, and pasture rations, respectively. Based on experience (Martz, Gerrish, Belyea, & Tate, 1999), we estimate that the gains observed on the pasture-based treatments were at least 0.4 lbs/d lower than normally observed due to drought conditions.

Cattle finished on the feedlot ration were fatter (P < 0.05) than cattle finished on the other feeding regimes as evidenced by heavier carcass weights, increased fat thickness, higher percentage of kidney, pelvic and heart fat, and higher USDA yield and quality grade scores. In addition, cattle finished on the feedlot ration were more muscular (P < 0.05) as evidenced by larger ribeye areas. Pasture finished cattle had the lightest carcass weights and lowest percentage of kidney, pelvic and heart fat (P < 0.05). Mandell, Buchanan-Smith, & Campbell (1998) also reported that grain finished cattle were higher in measures of fatness and muscling than forage finished cattle. Even though feedlot finished cattle had the highest mean USDA quality grade (P < 0.05), mean USDA quality grades of cattle from the other feeding regimes were considered to be acceptable. Drought conditions and poor pasture conditions probably contributed to the lack of uniform finish on the pasture finished treatments. Supplementation appeared to increase the amount of finish for cattle finished on pasture but the increase was not enough to elevate these cattle into higher carcass quality grades. Warner-Bratzler shear force values were not affected (P > 0.05) by feeding regime. However, Warner-Brazler shear force values were lower (P < 0.05) for LD (6.0 lbs) than SM or TB (both 6.8 lbs). All shear force values were below the 10.0 lbs threshold to be considered slightly tough and would be considered tender by consumers. In the raw state, meat from cattle finished on the soyoil diet was higher (P < 0.05) total CLA on a mg/g sample basis than the other feeding regimes. On a mg/g fat basis, meat from cattle finished on the soyoil diet was the highest (P < 0.05) in total CLA followed by the pasture diet with meat from cattle finished in the feedlot or grain supplements on pasture having the lowest (P < 0.05) total CLA. Diet has been shown to affect the CLA content in fat depots (Madron et al., 2002). Fat from pasture finished cattle have been reported to have higher total CLA contents than grain fed cattle (Steen and Porter, 2003; Poulson et al., 2004; Realini et al., 2004). CLA contents of raw meat on a mg/g fat basis from the feedlot and grain supplement diets were similar to those reported by Shantha et al. (1994); these two diets most closely reflect commercial finishing procedures. However, CLA content of meat from cattle finished on the pasture and grain supplement diets were higher than the values reported by Shantha et al. (1994); the inclusion of soyhulls in the grain supplement used in the current study may explain the higher CLA content. Values reported for total CLA by Ma et al. (1999) on a mg/g fat and a mg/g sample basis were lower than the values reported in the present study. In agreement with the soyoil inclusion in the present study, Mir et al. (2002) reported higher CLA levels when sunflower oil was included in the diet. Both soyoil and sunflower oil contain high amounts of linoleic acid which can be converted to CLA through ruminal biohydrogenation. On a mg/g fat basis, meat from cattle finished on the soyoil diet had the highest (P < 05) level of total CLA followed by the soyhull and pasture diets with meat from cattle finished on the feedlot diet having the lowest (P < 0.05). Total CLA values on a mg/g fat basis in the cooked state are similar to those reported by Shantha et al. (1994) and Ma et al. (1999) for meat from feedlot, grain supplement, and pasture feeding regimes with values for meat from the soyoil diet being higher. Data from this study indicate that in the cooked state or as meat is consumed, the inclusion of pasture in the diet will increase the total CLA content of the meat when cattle are finished to a constant fat endpoint. Ma et al. (1999) reported similar levels for total CLA content on a mg/g sample basis as the values reported in this study. Shantha et al. (1994) reported levels of CLA content on a mg/g sample basis that were much higher, approximately twice as high, for cooked ground beef patties than the levels reported in this study. The fat content differences between the samples used in the studies are probably responsible for these differences. In the raw state, TB was highest (P < 0.05) in total CLA on a mg/g sample basis compared to the other two muscles. Values reported in the present study for total CLA on a mg/g fat basis in the raw and cooked states are similar to the high end of the range reported by Shantha et al. (1994) and Ma et al. (1999) for different steaks. On a mg/g sample basis in the cooked state, Ma et al. (1999) reported similar values for total CLA content to the present study. However, Shantha et al. (1994) reported much higher CLA contents for ground beef than the present study. Differences in fat contents between the present study and Shantha et al. (1994) may explain the differences in CLA contents. Muscle by feeding regime interactions (P < 0.05) for CLA content existed in the cooked state for total CLA on a mg/g sample basis. Panelists (n =87) were recruited from the Columbia, MO area. Consumers were asked to rate longissimus lumborum steaks for overall liking, liking of tenderness, liking of juiciness, and liking of flavor. Samples were rated on a nine-point category scale for liking where 1 = dislike extremely and 9 = like extremely. A subset of steaks was chosen to be either Slight or Small marbling to minimize the effect of USDA quality grade on consumer panel results. Consumers rated meat from the feedlot diet highest (P < 0.05) for overall like, liking of flavor, and liking of juiciness. No differences (P > 0.05) were detected between the other three feeding regimes for these attributes. Consumers did not discriminate (P > 0.05) with their ratings for liking of tenderness. It is important to note that on a 9-point scale any rating above a 5.0 indicates that the attribute was found to be acceptable. Therefore, all meat from the consumer panel was found to be acceptable regardless of feeding regime.

In summary, the amount of CLA in cooked meat can be increased by the inclusion of pasture, with or without grain supplementation, in the finishing diet compared to conventional feedlot diets. Pasture inclusion in the finishing diet was not detrimental to the eating quality of beef. Although feeding regime was able to increase the CLA content in cooked beef, it is important to note that at the levels of CLA achieved in this study one serving of beef per day would not be sufficient to achieve a dietary intake of CLA that has been shown to be beneficial in animal and human trials.

References
Ma, D. W. L., Wierzbicki, A. A., Field, C. J., & Clandinin, M. T. 1999. Conjugated linoleic acid in Canadian dairy and beef products. J. Agric. Food Chem. 47:1956-1960.

Mandell, I. B., Buchanan-Smith, J. G., & Campbell, C. P. 1998. Effects of forage vs. grain feeding on carcass characteristics, fatty acid composition, and beef quality on Limousin-cross steers when time on feed is controlled. J. Anim. Sci. 76:2619-2630.

Madron, M. S., Peterson, D. G., Dwyer, D. A., Corl, B. A., Baumgard, L. H., Beerman, D. H., & Bauman, D. E. 2002. Effect of extruded full-fat soybeans on conjugated linoleic acid content of intramuscular, intermusclular, and subcutaneous fat in beef steers. J. Anim. Sci. 80:1135-1143.

Martz, F. A., Gerrish, J., Belyea, R., & Tate, V.. 1999. Nutrient content, dry matter, and species composition of cool-season pasture with management-intensive grazing. J. Dairy Sci. 82:1538-1544.

Mir, P. S., Mir, Z., Kuber, P. S., Gaskins, C. T., Martin, E. L., Dodson, M. V., Elias Calles, J. A., Johnson, K. A., Busboom, J. R., Woods, A. J., Pittengers, G. J., & Reeves, J. J. 2002. Growth, carcass characteristics, muscle conjugated linoleic acid (CLA) content, and response to intravenous glucose challenge in high percentage Wagyu, Wagyu x Limousin, and Limousin steers fed sunflower oil-containing diets. J. Anim. Sci. 80:2996-3004.

Poulson, C. S., Dhiman, T. R., Ure, A. L., Cornforth, D., & Olson, K. C. 2004. Conjugated linoleic acid content of beef from cattle fed diets containing high grain, CLA, or raised on forages. Livestock Production Sci. 91:117-128.

Realini, C. E., Duckett, S. K., & Windham, W. R. 2004. Effect of vitamin C addition to ground beef from grass-fed or grain-fed sources on color and lipid stability, and prediction of fatty acid composition by near-infrared reflectance analysis. Meat Sci. 68:35-43.

Shantha, N. C., Crum, A. D., & Decker, E. A.. 1994. Evaluation of conjugated linoleic acid concentrations in cooked beef. J. Agric. Food Chem. 42:1757-1760.

Steen, R. W. J. & Porter, M. G. 2003. The effects of high-concentrate diets and pasture on the concentration of conjugated linoleic acid in beef muscle and subcutaneous fat. Grass and Forage Sci. 58:50-57.

Research conclusions:

A workshop was held in the fall of 2005 and aimed at livestock producers interested in pasture finished beef programs. Fifty of the participants completed surveys. The demographics of the participants were as follow: average cow herd size = 113, average acres of pasture = 354, and 37.5% of the participants finished beef on pasture at that time. At the end of the workshop, 62% of the participants indicated they had a high level of interest in pasture finishing of beef.

The workshop consisted of five formal talks with proceedings from each talk and panel discussion with all of the speakers participating. A producer collaborator on the project, John Woods, presented his perspectives of pasture finishing. In general, the information presented contained approximately 50% new materia and was seen as somewhat helpful to participant's operations.

Economic Analysis

One of the components of our research was to survey a group of beef consumers who made up the taste panel evaluating the beef from the animals in the study. Demographical information was collected from the panelists. A couple of interesting points from that data were that over half of the participants had not heard of conjugated linoleic acid (CLA) prior to that evening. Yet these were all regular consumers of beef. The primary reason given for eating beef was taste, followed by nutrition.

At the start of the evening, panelists were surveyed about their willingness to pay for CLA enhanced beef. Given a reference price of $6.99/lb for beef rib eye steak, they were asked how much they would pay for beef labeled as “CLA enhanced.” Prior to any information being provided about CLA, the 87 panelists gave an average price for CLA enhanced beef of $7.16/lb including 32 who valued the CLA enhanced beef above $6.99/lb (their average was $7.55/lb). Participants were asked the same question later in the study, after being provided education on CLA and its potential health benefits. After this information on CLA was delivered, panelists’ average value for CLA enhanced beef rose to $7.56/lb, and 70 individuals placed the value above the $6.99/lb for typical grocery store commodity beef (the average for the 70 was $7.71/lb).

Survey participants also sampled the beef from the four treatments (pasture only, pasture and soy hulls, pasture and soy oil, and feedlot). First they were asked to rate the samples “blind” and before they were given the CLA education presentation. After the CLA talk, they were again asked to sample and rate the beef from the treatments, this time knowing which treatments the samples came from. Prior to the informative CLA presentation, and tasting samples “blind,” panelists gave the greatest value to the feedlot beef. But after the consumers were given some education about CLA, and when they knew which treatments the beef samples came from, their preferences changed. Beef from the pasture-based treatments were all valued above the feedlot treatment, with pasture with soy oil supplementation receiving the highest value. More people were willing to pay above $6.99/lb for the pasture-based treatments, and the average premiums for just those consumers pushed the value of the supplemented pasture beef above $8.00/lb. These data highlight the importance of consumer education about CLA and beef production practices if pasture-based finished beef is going to capture any premium price in the marketplace. It appears that product differentiation is essential to making pasture-based beef products competitively priced. This in turn suggests the need for targeted marketing strategies and added costs for advertising, promotion and consumer education, and identity preserved products which are “branded” and possibly direct marketed.

Another component of the research project was to calculate costs and returns of the various production systems (i.e. treatments). The main focus was on feed costs and the potential revenues from the animals. Average prices for the years 2000-2004 were used to give an idea of “representative” or average costs and returns. Since the project got a late start (i.e. the cattle were placed on pasture much later than would be typical), both actual gains and gains hypothesized with a 65 day earlier start on pasture were used in the projections of revenues. Average market prices for the carcasses were used for one measure of income, reflecting the grade and yield for each animal within each treatment. But since the pasture-based treatment animals failed to reach acceptable levels of finish, in large part due to the late turnout date, a hypothesized heavier carcass (72 lbs heavier) was also used in some calculations to project a more typical level of performance and revenue.

Feed costs per pound of gain were lowest for the feedlot, partially due to the lack of grazing gains due to the late turnout. Supplementation on pasture improved average daily gains (ADG) but also added to the feed cost per pound of gain. With an assumed 65 day earlier pasture turnout date, annual pasture costs (and feedlot costs) don’t change, but supplementation costs (i.e. days) go up. Overall feed costs would fall for the pasture treatment, leaving it as the lowest cost, while the soy hulls and feedlot treatments would have about the same feed costs per pound of gain, and the soy oil treatment would be a few cents higher.

Actual revenue favored the feedlot group, as they did reach an acceptable level of finish and graded well. The pasture-based treatments suffered a loss of revenue due to lighter weight carcasses that did not grade or yield well. Adding the hypothesized premium for each treatment (based on the panelists survey responses), helped narrow the gap between the feedlot treatment revenues and the supplemented pasture treatments, but the pasture only treatment gross revenues were still much below the other treatments. With the hypothesized price premiums (especially for pasture-based cattle) and an assumed earlier turnout date resulting in 72 pound heavier carcasses for the pasture-based treatments (and thus similar grade and yield as for the feedlot treatment), gross revenues for the supplemented pasture and feedlot treatments are very similar. Pasture only cattle would still have substantially lower revenue.

When average carcass prices were used in budgets with estimated total costs to calculate net incomes for the various treatments, only the feedlot treatment was profitable. If the potential consumer price premiums are added to the treatment revenues, then the supplemented pasture treatments improve their bottom lines to slightly negative for the soy hulls (-$11.17/head) and slightly positive ($8.07/head) for the soy oil treatment. If the assumed performance of 65 more grazing days is added (along with the price premiums), then the soy oil treatment is the most profitable followed by the soy hulls and feedlot treatments. The pasture only treatment still suffers a significant loss even under these assumptions.

Pasture-based finishing of cattle has many benefits. It produces a healthy and lower cost beef using more forages and less harvested feedstuffs. The beef is consumer acceptable to the general populous, and preferred by some consumers due to the potential health benefits of CLA and the preferences some consumers have towards method of production. It also provides beef consumers with another choice of product. Pasture-based finishing can reduce the potential pollution problems of confined and concentrated animal feeding operations. It also provides a healthy environment for the animal.

For beef producers to make a profit raising pasture-finished cattle there are many important factors which must be managed. Of course cattle performance and the associated grazing management must be good. Grass-finished cattle take longer to reach slaughter weights, and variability is greater. Less of the feeding environment is under the control of the manager (i.e. pasture productivity versus corn supply and prices), further increasing the risk. Marketing is also critical. To capture the consumer segment that is looking for this type of beef, and also to reap the potential price premiums, extra cost and effort in marketing will be needed. It takes a dedicated and top-notch producer to make pasture-based beef finishing a successful enterprise. But for some the rewards are worth the extra effort required.

Farmer Adoption

A major problem for farmers is the low profit margins available for farm produce, especially corn and soybeans. One scenario of answers to this problem is to change enterprises and grow products that will bring premium prices in the market place. Thus pasture finished beef appears to fit such a model and these research findings support these needed changes on the farm. We can speculate that farmers are hesitant to change or expand enterprises because of a lack of confidence that the new enterprise and/or system will be successful and profitable. Our findings will help bolster confidence in pasture finishing among farmers.

Participation Summary

Educational & Outreach Activities

Participation Summary:

Education/outreach description:
Publications

C. L. Lorenzen, J. W. Golden, F. A. Martz, I. U. Gruen, J. R. Gerrish, and K. C. Moore. 2004. Conjugated linoleic acid content of ribeye steaks from beef finished on pasture. J. Anim. Sci. 82(Supp. 2):28(Abstr.).

E. S. Blake, J. W. Golden, F. A. Martz, I. U. Gruen, K. C. Moore, J. R. Gerrish, and C. L. Lorenzen. 2004. Conjugated linoleic acid content of beef differs by feeding regime and muscle. 57th Recp. Meat Conf. Proc. Abstract 10.

C. L. Lorenzen, J. W. Golden, F. A. Martz, I. U. Gruen, M. R. Ellersieck, J. R. Gerrish, and K. C. Moore. 2007. Conjugated linoleic acid content of beef varies by feeding regime and muscle. Meat Sci. 75:159-167.

Project Outcomes

Recommendations:

Areas needing additional study

  • The effect of feed grain byproducts (Dried Distillers Grain/Solubles, Distillers Grain Solubles, Soy Hulls, etc.) on beef quality from pasture finishing systems.

    Improved methods for increased rate of gain in pasture finishing systems.

    Relationship of Vaccenic Acid levels in pasture finishing rations to final Conjugated Linoleic Acid levels in finished beef.

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.