Nutrient Density of Beef From Longhorn Cattle

A Final Report To
The Texas Longhorn Breeders Association of America

Dr. Jerry R. Gillespie, DVM. PhD • Chairman TLBAA Breed Research Committee
College of Veterinary Medicine, Veterinary Medical Center, Kansas State University

By: F.M. Byers and G.T. Schelling, Beef Cattle Nutrition & Growth; H.R. Cross, Meats and Muscle Biology;
Department of Animal Science’, Texas A&M University, College Station, Texas 77843

June, 1987

Note: Reference to a company, breed or trade name does not imply approval or endorsement by Texas A&M University or Texas Agricultural Experiment Station.

Here are the results of the Nutrient Density of Beef From Longhorn Cattle project:

Introduction

Of the many challenges that the cattle industry must address in the coming years, none is more fundamental than maintaining consumer demand for beef. Results of the National Consumer Retail Beef Study (Savell et al., 1987) indicate that the industry could increase total demand by reducing trimmable fat on retail cuts of beef. While this can be accomplished by trimming fat from the carcass, the resulting product will reflect the cost of producing and trimming that fat and the product may still have more seam fat that is more saturated than desired.

Efficient production of highly palatable lean beef must be a primary objective of the beef cattle industry in order to compete in the long term. Current yearly production of the 6 billion pounds of waste and trim fat, equivalent to two Iowa corn crops in feed energy, must be reduced as rapidly as possible. While extensive trimming of beef fat occurs from slaughter though the consumer and results in a reasonable lean beef product being consumed, only preventing this excessive fat deposition where it occurs will correct the image of beef as a fat, high-calorie product.

The beef industry has been burdened by the delusion that consumers would buy the beef that the industry chose to produce. Meanwhile, other industries developed products that the consumers wanted and now fill a substantial share of the protein market. Consumers will no longer automatically buy what the beef industry produces. Producers must assess the kinds of products consumers desire and develop profitable programs to produce them irrespective of traditions.

Perception of the need to reduce caloric intake reflects consumer recognition of excess energy consumption and associated overweight conditions as a national health problem. Consumers have evolved to a “lean conscious society” where a high priority is placed on ways to get and stay trimmer. People are more concerned about exercise and diet as they contribute to this change in life-style. In no area is this more evident than in their selection of and desire for leaner beef products with less fat than provided by traditional beef. While leaner beef products will assist in reducing caloric intake, it is also consistent with overall cattle industry objectives to reduce the wasteful production of excessive carcass fat.

In concert with desires of consumers to be, think and eat “leaner” as a reflection of fitness-diet-health concerns, they are also interested in reducing fat consumption, especially saturated fat, and are concerned about cholesterol levels - both dietary and circulating. The “fat beef’ image is causing increasing numbers of consumers to consider diet changes, in large measure because of their perception of the “high” caloric content of beef. Consumers are also concerned about other nutritional factors as well, especially as they perceive a relationship to health.

Our beef cattle industry has evolved from production of extremely lean beef based largely on “Longhorn Type” cattle in extensive grazing systems in the nineteenth century to production of very fat beef from small size “British Breeds” in the mid-twentieth century. This evolution has continued during the second half of the twentieth century with selection of large framed, late maturing, large mature size “Exotic” types of cattle. Recent consumer pressure for leaner beef has accelerated this change and encouraged consideration of many new cattle breeds not formerly a part of the U.S. beef cattle industry. The Texas Longhorn has again surfaced as a breed with a potential contribution to make to the beef cattle industry. Longhorn cattle, especially as crosses, have received attention in recent years as a potential component of some beef production systems. While some information exists relative to growth and efficiency in feedlot situations, no information is available on the nature of the fat deposited or the cholesterol content of lean tissue in beef from Longhorn cattle. Therefore, the current study was conducted with the following objectives:

  1. To determine the cholesterol content of muscle and intramuscular fat (edible portion) from Longhorn cattle vs typical beef cattle.
  2. To measure the profile of fatty acids in intramuscular carcass fat from Longhorn cattle and typical beef cattle.
  3. To determine relative fat content of Longhorn beef vs typical beef cattle at similar carcass grade endpoints.
  4. To evaluate palatability traits of Longhorn vs typical beef carcasses at USDA Good and Choice quality grade endpoints.
  5. To assess change in fat and lean content of Longhorn beef (cholesterol, fatty acids) with change in degree of finishing.

Experimental Procedures

Sixty-one Hereford (n=12), Longhorn x Hereford (n=24) or Longhorn (n=25) steers were used in this project. The Hereford (British) and Longhorn x Hereford (British cross) calves were obtained from one ranch in Nebraska while the Longhorn cattle were collected from many locations in Texas. The Longhorn cattle were a random sample and were contrasted to the Herefords from one ranch to reflect typical British beef cattle, and not to represent any specific breed. They were fed at the Texas Agricultural Experiment Station, McGregor, TX to provide carcasses of all cattle types, ranging in fatness and in quality grade from Good to Choice. Cattle were fed in three groups by cattle type and half of the steers in each group were initially allotted to each slaughter group. Cattle were weighed and backfat was measured at 28 day intervals via real-time ultrasound.

Steers were fed in small fenced lots with feed and water available at all times. The experiment was begun February 10, 1986 and the last group was slaughtered on September 8, 1986. Feeding periods ranged from 93 to 210 days for respective cattle groups. All cattle were started on high roughage starter ration, switched to an intermediate ration and then placed on a high grain finishing ration from mid-March to slaughter.

Respective groups were transported 90 miles to the TAMU Meat Science and Technology Center, College Station, TX, as targeted fatness endpoint of the group was reached. Following slaughter, all carcasses were weighed and were USDA (1976) graded following a 48 hour chill in a 1-2C cooler. Fat content was measured on each carcass via carcass density (specific gravity, Garrett Hinman, 1969). A 9-10-11 rib section was removed from the right side of each carcass to provide steaks for sensory, shear, lean, fat, fatty acid and cholesterol analysis. Separable rib tissue was measured by physical dissection of the 9-10-11 rib section.

Steaks (2.54cm thick) taken from the loin of each side were double wrapped in freezer paper, frozen and stored (-1OC) until all cattle had been slaughtered. Steaks were thawed (2C) for 14 to 16 hours prior to cooking to an internal temperature of 70C (monitored with a Honeywell Electronic 112) on an open-hearth Farberware broiler. Cooking losses were recorded. Steaks for Warner-Bratzler shear determinations were cooled to ambient temperature (22C) and a minimum of four cores (1.27 cm diameter) were removed as outlined by AMSA (1978). Each core was sheared once.

Loin steaks for sensory panel evaluation were cooked as previously described for shear force steaks. After cooking, steaks were trimmed of exterior fat, cut into 1.27 cm cubes and served warm to an eight member, trained, sensory panel (AMSA, 1978). Twelve steaks were served at each session, and one session was held (mid-morning) each day. Panelists evaluated each sample for differences in juiciness (1=extremely dry, 8=extremely juicy), muscle fiber and overall tenderness (1=extremely tough, 8=extremely tender). Connective tissue amount (l=abundant amount, 8=none) and overall palatability (1=extremely undesirable, 8=extremely desirable).

Total fat content of the longissimus muscle was determined by extraction with chloroform-methanol (2:1). An aliquot of the extract was evaporated under a stream of nitrogen, saponified with alcoholic potassium hydroxide, separated with pyrogallol, acidified and prepared for spectrophotometric cholesterol analyses. A second aliquot of the chloroform-methanol extract was esterified for fatty acid analyses and chromatographed on a gas chromatograph with a capillary column.

All data were analyzed using the SAS general linear models procedure (SAS Institute Inc., 1982), with main effects of cattle type, endpoint and the interaction evaluated. Treatment means for significant main effects were separated via Fishers Protected LSD.

Results and Discussion

The British, British cross and Longhorn cattle used in this project averaged 326, 279 and 212 kg at initiation of the feeding period. Cattle were fed toward targeted fatness endpoints, and as a result, feeding periods varied and ranged from 93 to 210 days.

A summary of data collected at slaughter is presented in Table 1. Target fatness (backfat) endpoints were the basis for slaughter and, based on earlier research (Adams et. al., 1982; Holbert et al., 1982), lower outside fat endpoints were planned for Longhorns with greater fat for crosses and greatest fat for British cattle at each carcass target. As is evident from Table 1, this objective was met with lower backfat for Longhorns than for crosses, and for British cattle at each slaughter endpoint(l or 2).

Table 1. Carcass Endpoint Criteria For Cattle Types Fed.

Cattle averaged low to average Good marbling at time one, and average Good to low Choice marbling at the second slaughter endpoint. It is of interest that while quality grade of Longhorns was similar to British cattle at time one, actual backfat was approximately one half that of British cattle (.11 vs .20 cm). Internal fat (kidney, pelvic and heart fat; KPH) was greatest for Longhorns and least for British cattle, reflecting a difference in distribution of fat. British crosses at the second slaughter point had similar or greater marbling scores than British cattle while actual backfat was only two-thirds that of the British cattle.

Yield grade was similar for all breed groups at the first endpoint and was less desirable (greater fat) for British cattle (4.5) than for crosses (3.6) or Longhorns (3.0) at the second slaughter endpoint.

Overall, while all breed groups averaged average Good in quality grade and average Slight in marbling (348, 360, and 357 for British, British crosses and Longhorn), Longhorns and British crosses had less backfat (.11, .16 vs .26 cm) and better yield grades (3.0, 3.4, vs 3.8) than British cattle. In general, these data indicate that Longhorn and British crosses reached average Good quality grade with less outside trim fat and more desirable yield grades than British cattle. This reflects the lower priority for outside fat deposition in Longhorn and their crosses.

These results are consistent with responses noted in two earlier studies. At similar carcass weights, (Adams et al., 1982) Longhorn cattle had only one-third as much backfat (5.1 vs 16.5 and 18.5 mm) as Hereford and Angus (British) cattle. Yield grade, reflecting carcass leanness, was a full grade better for Longhorn than Hereford or Angus cattle (2.4 vs 3.4 and 3.8). In another study (Holbert et al., 1981), Longhorn-cross cattle, while somewhat lighter in carcass weight, (321 vs 341 Ib), had more desirable marbling but had less external fat (.23 vs .36 cm) and more desirable yield grade (3.2 vs 4.1) than Hereford cattle.

Collectively, these studies indicate the tendency for Longhorn cattle to produce leaner carcasses at similar endpoints to typical British cattle. It is interesting to note that in all studies, although Longhorn cattle had less backfat than typical beef breeds, they actually had similar or more marbling in all three studies.

Reflecting differences observed for backfat, both subcutaneous and intermuscular fat via physical separation (Table 2) were lower for Longhorns than for crosses and British cattle. Separable fat averaged 20.6% for Longhorns and was similar at either slaughter endpoint. In both British crosses and British cattle, percentage separable fat increased from the first to the second slaughter period and was greater than for Longhorns at all periods.

Table 2. Separable Components of the 9-10-11 Rib
From Cattle of Three Types.

Fat content of the longissimus muscle (Table 3) paralleled other responses with Longhorns having less fat (3.7%) than British crosses or British cattle which were similar (5.7, 5.4%). Fat content was similar within cattle type for both slaughter endpoints, and averaged 4.8 and 5.1% for time one and two, indicating that longissimus muscle fat did not change with additional time on feed in this study.

Table 3. Fat and Cholesterol Content of Longissimus Muscle
From Cattle of Three Breed Types.

Cholesterol content of the longissimus muscle was similar across cattle types and slaughter endpoints with no relationship to measures of fatness. Cholesterol levels (60 mg/l00 g) are about 10 units lower than often quoted beef muscle levels (i.e. 7Omg/100 g), and are similar to recently reported values for muscle samples from beef cows (55, Eichorn et. al., 1986), and for bison, Hereford and Brahman (64, 66, 64, Koch et al., 1987). Since cholesterol is a vital component of cells for metabolic function, it is found in all meat products. Fat typically has about twice the cholesterol content of muscle (Eichorn et. al., 1986). However, it is not necessarily related to fat and beef of varying fat content may or may not differ in cholesterol content. Based on this and other recent research, it is unlikely that muscle cholesterol levels will differ across cattle types. The cholesterol level in people reflects both diet and synthesis by the body to maintain vital functions. Diet makes a much smaller contribution (i.e. 10%) to total circulating cholesterol levels than does synthesis which provides upwards of 90% of all circulating cholesterol. A variety of dietary factors may he involved either directly or indirectly in circulating blood cholesterol levels. Of concern to the beef industry is the level of fat and the ratio of saturated, monounsaturated and polyunsaturated fats.

Fat in beef, is by nature, usually somewhat more saturated than fat from poultry, pork (Figure 1) and fish. Both total as well as saturated fat have been implicated in increasing serum cholesterol levels. While it is possible to change the degree of saturation of beef fat slightly with diet, beef fat is normally about half (45%) saturated. The degree of saturation of fat from Longhorn cattle has not previously been reported.

Figure 1. Fatty Acid Composition of Raw Lean Muscle Food Products.

Fat is comprised of many different fatty acids, and each has unique properties. Recently, two kinds of fatty acids have received attention with implications for cardiovascular function. The “fish” fatty acids, termed “omega 3’s” and found in cold-water fishes reflecting their food supply, have been associated with a reduction in body cholesterol synthesis. They are normally not found in appreciable levels in mammals, and were not found in lipid extracts of muscle fat from cattle in this study.

Another category of “favorable” fatty acids are “monounsaturated” fatty acids, have one double bond and are thus unsaturated. The most favorable appears to be 18:1, oleic acid, which is relatively high in olive oil and thus is associated with “Mediterranean” diets. Over one-third of longissimus muscle fat in all cattle (Table 4) was comprised of oleic acid. Recent research indicates that stearic acid (C 18:0) is rapidly converted to C 18:1 in man and thus may also have beneficial cardiovascular implications.

Percent Fatty Acid Composition of Longissimus Muscle
From Cattle of Three Types.

Percent of Fatty Acids by Class in Longissimus Muscle
From Three Cattle Types.

Considering fatty acid profiles by major classes as saturated, monounsaturated and polyunsaturated (Table 5) allows a perspective of overall differences in composition. Beef fat is typically less than half saturated and longissimus muscle fat from cattle in this study was less than 50% saturated. Interestingly, muscle fat from Longhorn cattle was less saturated (4 1.8%) than from British crosses or British cattle which were similarly (47.9, 48.9%). This difference was due primarily to greater levels of polyunsaturated fatty acids with a smaller increase in monounsaturated fatty acids. Fatty acid classes generally reflect cattle type differences in percent longissimus muscle fat. Longhorn cattle had less fat in the longissimus muscle and the fat present was more unsaturated. It is unknown the degree to which this difference in fatty acid composition is due to cattle type or to the level of fat present. What can be concluded is that at a similar marbling endpoint, Longhorn cattle had less longissimus muscle fat and it was less saturated.

Steaks taken for taste panel and shear force analyses were not aged beyond the 48 hour initial chill as opposed to the additional (48 - 96 hour) aging time that usually occurs in the marketing chain. As a result, the taste panel and shear force values observed while in the acceptable range, are lower in acceptability than would be expected in these same steaks evaluated following more typical aging conditions. Responses of a trained taste panel to steaks from cattle types at both endpoints are indicated in Table 6. All sensory ratings were within or above the 4 to 5 range, the minimum for acceptability (McKeith et al., 1984). Sensory ratings were similar across cattle types and did not change between slaughter endpoints. All groups produced acceptable beef based on ratings for sensory traits. Shear force averaged below 4 kg for all groups and below the level which is normally considered the upper limit for acceptability. Taste panel sensory and shear force evaluations in the earlier studies also indicated that beef from Longhorn cattle was similar in all measures of eating quality to beef from typical grain fed cattle. All cattle in these three studies were fed high grain feedlot rations over periods ranging from 93 to 210 days and Longhorn, as well as typical beef breeds, produced carcasses with very desirable eating qualities.

Table 6. Sensory and Shear Force Evaluation of Steaks
From Cattle of Three Types.

Table 7. Carcass Composition at Two Endpoints
For Cattle of Three Types.

Overall carcass composition (Table 7) indicated that all cattle had reached a similar percentage carcass fatness endpoint. Thus, differences in fatness discussed earlier reflect differences in priorities for fat distribution to different locations.

Longhorn cattle preferentially deposited fat in internal nonmuscle areas while Herefords placed a greater priority on subcutaneous and intramuscular fat while crosses tended to be intermediate. Also, fat accretion was greater between endpoints I and 2 for Hereford (73% of weight gain) than for crosses (44%) than for Longhorn (16%). A greater fraction of carcass tissue accretion in Longhorn and crosses was lean tissue than for Herefords, reflecting both the slower rate of growth of Longhorns and their later maturity.

Ramifications

The current beef cattle population includes cattle of nearly all conceivable types and sizes. They are fed or receive a wide variety of feedstuffs, both grazed and harvested, which range from poor quality mature range grasses to high energy feedlot rations with most combinations in-between. They are managed in systems including wintering, backgrounding, summer grazing, growing, forage finishing and high grain feedlot programs. While the traditional end product of these diverse cattle/resource combinations was yield grade 3 choice grade beef with 30-35% carcass fat, consumer preference for a leaner beef product indicates the need to devise cattle-feedstuff systems to economically produce this kind of beef. This will require “targeted programs for targeted products” using all the technology available.

While a diversity of beef products are needed, all must be separated from the current image of fat cattle and fat beef. Producers must focus on producing and effectively marketing “BEEF LEAN”, and develop an association of beef with active life-styles, healthful living and the trim frame of reference. Producers must be engineered to coincide with consumers needs, and to address consumer fears, both perceived and real.

Misinformation on beef products has been frequently provided in recent years, and many groups have promoted reducing red meat consumption for a wide variety of reasons. The most common are because it is high in calories, saturated fat, and cholesterol. However, these assertions are untrue for typical beef and beef is actually nearly as unsaturated as other food (Figure 1) and lower in cholesterol than some foods that would be substituted in weight control diets (Figure 2). Based on carcass beef disappearance, the average person in the U.S. eats about 102 lbs of beef per year. However, when trim losses along the retail chain to the beef that is actually consumed are considered, actual beef consumption is only about 2.5 oz. per person per day.

Figure 2. Cholesterol Content of Cooked Foods.

An average 3 oz. of cooked lean beef provides only 73 mg. of cholesterol, less than 25% of the American Heart Association recommendation of 300 mg. per day. An average 3 oz. portion of cooked lean beef provides only 192 kcal of energy, less than 10% of a 2000 kcal diet. Less than half of this energy (85 kcal) comes from the 9.35 g of fat, and the saturated fat component contributes only 40 kcal. As a consequence, total and saturated fat from lean beef contribute about 4 and 2% of a total daily allowance of 2000 kcal. These levels of calories from fat are far below the AHA’s recommendations of no more than 30 and 10% of total calories from fat and saturated fat respectively. As is evident, lean beef fits well within dietary guidelines; the challenge is to produce beef that is lean in the carcass and does not need extensive trimming along the retail chain to make it lean.

Unique challenges face the beef industry to design and develop new technologies that will allow production of beef lean, rather than require extensive trimming to make it lean. This will require development of greater lean tissue deposition through the life cycle and extensive redirection of feed energy from fat to protein growth through all phases of growth. This can only be accomplished in an orderly fashion where all segments of the industry target on the same goal and integrate available technology with feed resources and animal growth.

Feeding and management systems can be advised to allow production of more desirable beef products from all cattle types, and based on the current research, Longhorn cattle are no exception. Acceptable lean beef with less fat and a desirable fatty acid profile can be produced from Longhorn cattle.

REFERENCES

AMSA. 1978. Guidelines for cookery and sensory panel evaluation of meat. American Meat Science Association and National Live Stock and Meat Board.

AOAC. 1980. Official Methods of Analysis (13th Ed.). Association of Official Analytical Chemists. Washington, DC. Adams, N.J. and F. Fox. 1974, Performance of various types of cattle. Proceeding, West. Sect. Amer. Soc. Anim. Sci. 25:52.

Adams, N.J., G.C. Smith and Z.L. Carpenter. 1982. Performance, carcass and palatability characteristics of Longhorn and other types of cattle. Meat Sci. 7:67.

Breidenstein, B.C. 1983. Contribution of red meat to the U.S. diet. National Live Stock and Meat Board. Breidenstein, B.C. 1985. Red meat: Nutrient composition and actual consumption. National Live Stock and Meat Board.

Byers, EM. 1980. Systems of beef cattle feeding and management to regulate composition of growth to produce beef carcasses of desired composition. OARDC. Res. Circ. 258:1.

Byers F.M. 1982. Nutritional factors affecting growth of muscle and adipose tissue in ruminants. Fed. Proc. 41:2562.

Eichhorn, J.M., L.J. Coleman, E.J. Wakayama, G.J. Blomquist, C.M. Bailey and T.G. Jenkins. 1986. Effects of breed type and restricted versus ad libitum feeding on fatty acid composition and cholesterol content of muscle and adipose tissue from mature bovine females. J. Anim. Sci. 63:781.

Garrett, W.N. and N. Hinman. 1969. Reevaluation of the relationship between carcass density and body composition of beef steers, J. Anim. Sci. 28:1.

Holbert T., L.M. Schake, J.W. Savell, J. Brenni, J. Caldwell and W.E. McCoy. 1982. Feedlot performance and carcass characteristics of Hereford and Texas Longhorn x Hereford steers. Texas Agri. Exp. Sta. Tech. Rep. 81-1.

Holbert T., L.M. Schake, J.W. Savell, J. Brenni, J. Caidwell and W.F. Mccoy. 1982. Feedlot performance and carcass characteristics of Hereford and Texas Longhorn x Hereford steers. Beef Cattle Res. in Texas. p. 67.

Koch, R.M., iD. Crouse and S.C. Seideman. 1987. Bison, Brahman and Hereford carcass characteristics. J. Anim. Sci. (Suppl. 1):l24.

McKeith, F.K., J.W. Savell, G.C. Smith, T.R. Dutson and Z.L. Carpenter. 1984. Tenderness of major muscles from three breed types of cattle at dilferent times-on-feed. in: Beef Cattle Res. in Texas. pp 39-44. College Station.

Rhee, K.S.,T.R. Dutson. G.C. Smith, R.L. Hostetler and R. Rciser. 1982. Cholesterol content of raw and cooked beef longissimus muscles with different degrees of marbling. J. Food Sci. 47(3):7 16-7 19.

SAS Institute Inc. 1982. SAS Users Guide: Statistics, 1982 Ed. Cary. NC.

Savell, J.W., R.E. Branson, H.R. Cross, D.M. Stiffler, J.W. Wise, D.B. Griffin, and G.C. Smith. 1987. National Consumer Retail Beef Study: Palatability evaluations of beef loin steaks that differed in marbling. J. Food Sci.: (In Press).

Smith, G.C., N.J. Adams, and Z.L. Carpenter. 1981. One hundred years of progress: Longhorn vs Hereford vs three-breed cross-bred cattle. In: Bc Cattle Science Handbook. Volume 18. p. 230.

USDA. 1976. Official United States standards for grades of carcass beef. Title 7, Ch. 28, Pt. 2853. Sections 102-107. Code of Federal Regulations, USD Washington, DC.

Here are the results of the Nutrient Density of Beef From Longhorn Cattle project:

"Texas Longhorn Breeders Association of America"

2315 N. Main Ste. 402, Fort Worth, TX 76106
PHONE (817) 625-6241 FAX (817) 625-1388
E-mail: tlbaa@tlbaa.org