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CONTENTS PAGE PLAN OF THE EXPERIMENTS 107 DISCUSSION OF RESULTS 110 Gains and Feed Consumption 110 Carcasses 112 SUMMARY AND CONCLUSIONS... . 119 Urbana, Illinois May, 1942 Publications in the Bulletin series report the results of investigations made or sponsored by the Experiment Station Effect of Exercise on Quality of Beef By SLEETER BULL and H. P. RUSK* WITHIN the last five or six years there has been an increased use of pasture for fattening beef cattle because of the pro- gram of the Agricultural Adjustment Administration. More pasture means more exercise for the cattle and the question naturally arises: how will the additional exercise affect gains and quality of beef? Many people believe that exercise lowers the quality of lean meat by making it tougher, drier, and darker in color. Others contend that exercise improves the flavor. Since no reliable information is available to answer the question, the authors present the results of two experiments conducted in 1929 and 1930 in cooperation with the U. S. Department of Agriculture thru the Bureaus of Animal Industry, Home Economics, and the part of Agricultural Economics which is now the Agricultural Marketing Service. Altho the experiments were not planned and carried out with the pasture problem in mind, the results obtained with the steers exer- cised under controlled conditions can be applied to the case of cattle walking on pasture. The experiments herein reported are part of a larger study which this Station is making of factors generally believed to affect the quality of beef. 2 A discussion of the chemical aspects of these experiments has already been published. 3 PLAN OF THE EXPERIMENTS In the first experiment, which was run from February 13 thru June 15, 1929, a period of 123 days, 8 Hereford steer calves were graded as feeders and divided into two lots of 4 each. Both lots were 'SLEETER BULL, Chief in Meats; and H. P. RUSK, formerly Chief in Cattle Husbandry. "Results of certain phases of this study have already been published: BULL, SLEETER, OLSON, FRED C., and LONGWELL, JOHN H. Effects of sex, length of feeding period, and a ration of ear-corn silage on the quality of baby beef. 111. Agr. Exp. Sta. Bui. 355. 1930. BULL, SLEETER, SNAPP, R. R., and RUSK, H. P. The effect of pasture upon the grade of beef. 111. Agr. Exp. Sta. Bui. 475. 1941. 'MITCHELL, H. H., and HAMILTON, T. S. Effect of long-continued muscular exercise upon the chemical composition of the muscles and other tissues of beef cattle. Jour. Agr. Res., 46, No. 10, pp. 917-941. 1933. 107 108 BULLETIN No. 488 [A/ay, closely confined in pens. One lot was exercised lightly up to the day of slaughter by working the steers individually for about an hour a day in a treadmill. After correcting the figures to make allowance for the angle at which the treadmill was set, it was computed that, if the exercised steers had walked on the level they would have gone 451 miles during the test, or an average of 3.7 miles a day at the rate of 4.1 miles an hour. 1 The exercised steers were full-fed a ration of shelled corn, cotton- seed meal, corn silage, and alfalfa hay, but an attempt was made to limit the feed for the unexercised steers so that they would gain at the same rate and be in the same condition as the exercised steers. The second experiment was begun January 7 and was continued thru May 18, 1930, a total of 132 days. Eight Hereford steers were used and the plan of this experiment was essentially the same as that of the first except that the exercised calves were worked for longer periods and all calves were paired as to initial weight and feeder grade. The pairing follows: Steers 23 and 84, 21 and 9, 43 and 62, and 36 and 34. The second calf of each pair was exercised heavily and the feed of its unexercised pair mate was restricted. However, the weights of the exercised and unexercised steers were not kept so nearly alike as in the first experiment because it was not considered feasible to restrict the feed consumption of the unexercised steer as rigidly as would have been necessary to accomplish this. The exercised calves were worked two at a time in a large treadmill for about three hours a day. When the figures were corrected to take into account the angle at which the treadmill was set, it was computed that the steers would have walked on the level an equivalent of 1,181 miles during the test, or an average of 8.9 miles a day at the rate of 3.1 miles an hour. As in the first experiment the exercise was continued up to the day of slaughter. In both experiments all steers were weighed for three consecutive days at the beginning of the experiment and before slaughter ; the average of the weights was used in computing gains. The slaughter weights were obtained by weighing the steers on the morning of slaughter after they had been taken off feed the night before. After slaughter the contents of the digestive tract were weighed and the 'The amount of walking done by the steers in these experiments is com- parable to that done by cattle under actual pasture conditions. The Texas Station found that "in pastures averaging slightly less than one section in area, the daily travel of cattle averaged 3.3 miles" during the year. The monthly averages ranged from 1.4 miles a day in December to 4.7 miles a day in May. These observations were made monthly for three years. (Tex. Agr. Exp. Sta. Bui. 367. 1927.) The North Dakota Station reported that cattle on a 30-acre pasture with fair grazing walked 1^ miles a day; on a 100-acre pasture with good grazing they walked 3Me miles a day ; and on a 640-acre pasture with scant grazing, 5Vi miles a day. These observations were made on one day only. (N. Dak. Agr. Exp. Sta. Bui. 154. 1921.) cfl ^ E - S W o J3 te - E g E O 3 '7. " .= S 8 E O CM g c t/i a g a rgl C (jo I E Q 110 BULLETIN No. 488 [May, amount was deducted from the slaughter weight to obtain the "net body weight." The animals were graded as slaughter cattle before slaughter and the carcasses were graded afterwards. One side of each carcass was then divided into wholesale cuts which were subdivided into lean, fat, and bone, and the physical composition of the cuts and carcasses was thus calculated. Following the recommendation of the Committee on Cooperative Meat Investigations of the State Agricultural Experiment Stations and the U. S. Department of Agriculture, the 9th, 10th, and llth ribs were used for the cooking and palatability studies. 1 The wholesale rib cut from one side of each carcass was sent to the Bureau of Animal Indus- try at Beltsville, Maryland. The ribs were cooked according to the method used in other cooperative investigations with state agricul- tural experiment stations and tests were made for resistance to shear- ing as a mechanical measure of toughness 2 and for palatability including tenderness. 3 Color determinations were made with the spectrophotometer 4 on cross sections of the following muscles selected from the major cuts: the lateral head of the triceps brachii from the face of the shoulder arm cut next to the foreshank; the semitendinosus (eye of round), the semimembranosus and adductor (top round) ; the psoas major (ten- derloin) and the longissimus dorsi (eye of beef) from the face of the short loin next to the loin end; the longissimus dorsi from the face of the chuck next to the ribs; the longissimus dorsi from the light end of the ribs ; and in the second experiment only, the biceps femoris from the face of the round next to the rump. DISCUSSION OF RESULTS Gains and Feed Consumption The steers in the first experiment made excellent gains. The un- exercised steers made an average daily gain of 2.6 pounds and the steers given light exercise gained an average of 2.3 pounds a day (Table 1). As might be expected, the exercised steers required con- siderably more feed per 100 pounds of gain: about 17 percent more concentrates, 10 percent more silage, and 10 percent more hay. It is 'A study of the factors which influence the quality and palatability of meat. Issued for the cooperators by the Anim. Husb. Div., Bur. of Anim. Indus., U. S. Dept. of Agr. Mimeo. Rev. ed. Feb., 1927. 'BLACK, W. H., WARNER, K. R, WILSON, C. V. Beef production and quality as affected by grade of steer and feeding grain supplement on grass. U. S. Dept. Agr. Tech. Bui. 217. 1931. 'Supplement of Feb., 1928, to mimeo. pub. cited in footnote 1 above. 4 See 111. Agr. Exp. Sta. Bui. 355 (cited), pp. 219-225. 7942] EFFECT OF EXERCISE ON QUALITY OF BEEF 111 TABLE 1. RATE AND ECONOMY OF GAINS, DRESSING PERCENTAGES, AND GRADES OF STEERS AS AFFECTED BY EXERCISE Experiment 1 (light exercise for 123 days) Unexercised lot Exercised lot Steer 103 Steer 117 Steer 121 Steer 129 Aver- age Steer 116 Steer 119 Steer 80 Steer 125 Aver- age Initial weight Ib. 470 772 2.5 Ib. 525 890 3.0 Ib. 515 832 2.6 Ib. 538 812 2.2 Ib. 512 826 2.6 11 Ib. 487 790 2.5 <6. 527 838 2.6 /&. 555 798 2.0 Ib. 617 907 2.4 Ib. 546 833 2.3 11.7 1.7 7.9 2.0 500 71 338 86 mi. 451 3.7 Average daily gain . . . Average daily ration 1.6 7.9 Alfalfa hay 2.0 Feed per 100 Ib. gain Shelled corn 428 61 308 78 Total distance traveled Rate per day mi. 455 3.7 mi. 450 3.7 mi. 450 3.7 mi. 452 3.7 Rate per hour Dressing percentage. . perct. 56.6 26.9 83.2 78.5 74.5 perct. 58.0 29.1 88.0 83.3 81.2 Perct. 61.5 23.9 83.5 79.5 77.2 perct. 58.5 24.3 88.7 79.6 74.8 perct. 58.7 26.1 85.8 80.2 76.9 Perct. 57.7 25.9 82.4 76.0 77.2 perct. 59.0 27.4 86.2 77.7 78.2 perct. 61.7 26.7 83.0 75.6 76.9 perct. 58.4 23.1 85.4 81.2 75.4 perct. 59.1 25.8 84.3 77.6 76.9 Slaughter grade* Carcass grade* Experiment 2 (heavy exercise for 132 days) Unexercised lot Exercised lot Steer 23 (Pr. 1) Steer 21 (Pr. 2) Steer 43 (Pr. 3) Steer 36 (Pr. 4) Aver- age Steer 84 (Pr. 1) Steer 9 (Pr. 2) Steer 62 (Pr. 3) Steer 34 (Pr. 4) Aver- age Ib. 528 760 1.8 5.0 1.0 7.6 1.8 286 56 432 105 Ib. 540 753 1.6 5.4 1.0 7.6 1.8 337 61 471 115 Ib. 535 753 1.6 5.4 1.0 7.6 1.8 329 60 460 112 Ib. 500 737 1.8 5.3 1.0 7.5 1.8 294 55 419 103 Ib. 526 751 1.7 5.3 1.0 7.6 1.8 312 56 448 109 Ib. 520 723 1.5 8.9 1.0 6.7 1.8 580 64 435 120 mi. 1174 8.9 3.1 Perct. 57.2 14.8 83.2 68.9 64.5 Ib. 535 737 1.5 8.9 1.0 6.7 1.8 580 64 436 121 mi. 1175 8.9 3.1 perct. 56.3 27.8 86.5 79.5 77.2 Ib. 535 727 1.4 9.0 1.0 6.7 1.8 619 68 464 128 mi. 1187 9.0 3.1 Perct. 55.8 18.5 84.0 70.9 72.8 Ib. 500 730 1.7 8.8 1.0 6.7 1.8 507 56 384 105 mi. 1187 9.0 3.1 Perct. 58.2 20.8 87.8 79.0 75.4 Ib. 518 729 1.6 8.9 1.0 6.7 1.8 571 63 430 119 mi. 1181 8.9 3.1 perct. 56.8 20.5 85.4 74.6 72.5 Final weight Average daily gain . . . Average daily ration Shelled corn Cottonseed meal . . . Alfalfa hay Feed per 100 Ib. gain Shelled corn Cottonseed meal . . . Corn silage . . Alfalfa hay Total distance traveled Rate per day Rate per hour Dressing percentage. . Fat in carcass perct. 54.9 19.6 86.5 71.7 70.1 perct. 52.7 18.0 89.8 74.2 71.6 Perct. 51.7 15.5 85.5 69.7 65.7 Perct. 54.7 20.6 85.0 70.9 70.8 perct. 53.5 18.4 86.7 71.6 69.6 Feeder grade* Slaughter grade* Carcass grade* The numerical grades are based upon 100 as a perfect score. A grade of 90 or above means Prime for the slaughter and carcass grades and Selected for a feeder grade. The other scores are the same for all three grades: 80 to 89 is Choice; 70 to 79 is Good-, and 60 to 69 is Medium. A feeder of high grade must have excellent conformation and quality. Since these characters change but little during fattening, a high-grade feeder which grades lower as a slaughter steer or carcass is generally unfinished. 112 BULLETIN No. 488 [May, evident that even light exercise was expensive from the standpoint of feed costs. The steers in the second experiment made only fair gains. As pre- viously stated the steers of the two lots were paired at the beginning of the experiment upon the basis of weight and grade. The unexercised steer in every case made a slightly greater daily gain than his exercised mate. The average daily gain of the unexercised lot was 1.7 pounds and of the exercised lot, 1.6 pounds. For 100 pounds of gain the exercised steers ate 72 percent more concentrates, 9 percent more hay, but 4 percent less silage than the unexercised steers. Carcasses Dressing percentages. Light exercise apparently had no effect upon the dressing percentage (Table 1). In view of this fact it was somewhat surprising to note that the heavily exercised steers of the second experiment dressed higher than the unexercised lot. The exer- cised lot dressed out an average of 56.8 percent and the unexercised lot only 53.5 percent, with no overlapping of data. Not only was there a difference in the average but each exercised steer dressed higher than its unexercised pair mate. Since there were no significant differences in either condition or conformation between the exercised and the unexercised steers of the second experiment, the higher dressing percentage of the exercised steers probably was caused by a smaller amount of fill; that is, con- tents of stomach and intestines (Table 2). The amount of fill, cal- culated in percentage of slaughter weight, was considerably greater in the unexercised than in the exercised steers of the second experiment if figures for the unexercised Steer 36 are omitted. This animal lost a considerable but undetermined amount of paunch contents when he was hoisted at the time of slaughter. Grades. Light exercise apparently had no effect upon carcass grade. All the carcasses in the first experiment graded at least Good with one exception, that of the unexercised Steer 117, grading Choice (Table 1). In the second experiment the carcass of the unexercised steer graded considerably lower than the carcass of its heavily exercised pair mate in every instance except that of Pair 1 (Steers 23 and 84). The differences, however, were not large enough to be considered significant. The carcasses graded from the middle of Medium to the middle of Good. Slaughter data. The percentage of liver was higher in the exer- cised steers in both experiments, as shown by calculations of the pro- portion of different parts of the body to the "net body weight" (Table 2). The differences between the weight of the livers, while apparently 1942} EFFECT OF EXERCISE ON QUALITY OF BEEF 113 TABLE 2. SLAUGHTER DATA ox EXERCISED AND UNEXERCISED STEERS (Expressed as percentage of "net body weight"*) Experiment 1 (light exercise for 123 days) Unexercised lot Exercised lot Steer Steer Steer Steer Aver- Steer Steer Steer Steer Aver- 103 117 121 129 age 116 119 80 125 age "Net body weight, pounds . . .689 .6 819.2 746.3 721.7 746.7 699.8 733.9 703.9 783.9 730.4 Pf ret. perct. perct. perct. perct. perct. Perct. perct. perct. perct. Blood ... 3 .4 3.1 3.8 3.1 3.4 3.7 3.7 3.4 3.2 3.5 Head ... 3 .4 3.1 3.2 3.2 3.2 3.3 3.2 3.2 3.2 3.3 Tongue .4 .4 .3 .4 .4 .3 .3 .4 .4 .4 Shanks 1 .8 1.6 1.9 1.9 1.8 1.9 1.9 2.0 2.0 1.9 Liver ... 1 .2 1.3 1.2 1.2 1.2 1.4 1.3 1.5 1.3 1.4 Heart .4 .4 .5 .4 .4 .5 .4 .5 .4 .5 Lungs . . . 1 .5 1.2 1.5 1.7 1.5 1.5 1.2 1.4 1.4 1.4 Spleen .2 .1 .2 .2 .2 .2 .3 .2 .2 .2 Tail 2 .2 .3 .3 .2 .3 .2 .2 .3 .2 Stomach . 3 ,0 3.1 2.9 2.8 2.9 3.1 3.0 3.0 2.7 2.9 Small intestines. . . ... 1 .3 1.6 1.2 1.6 1.5 1.6 1.5 1.5 1.5 1.5 Large intestines. .. . . . 1 .0 .7 .7 .7 .8 .9 .8 .9 .8 .9 Caul fat ... 2 .4 2.7 2.0 1.9 2.2 1.7 2.5 2.1 1.7 2.0 Gut fat ... 2 2 1.7 1.2 1.1 1.5 1.1 1.8 1.7 1.7 1.6 Total killing fat . . . .. . 4 .5 4.4 3.3 3.0 3.8 2.8 4.3 3.9 3.4 3.6 Hide . .. 10 9.8 8.9 10.3 9.7 10.1 9.8 8.8 9.9 9.7 Fill" , 8 .5 7.4 8.4 8.1 8.1 9.1 8.3 8.6 9.9 9.0 Experiment 2 (heavy exercise for 132 days) Unexercised lot Exercised lot Steer Steer Steer Steer 23 21 43 36 (Pr. 1) (Pr. 2) (Pr. 3) (Pr. 4) .. Steer Steer Steer Steer 84 9 62 34 age (Pr. 1) (Pr. 2) (Pr. 3) (Pr. 4) Aver- age "Net body weight," pounds 639.9 638.1 657.1 665.2 650.0 628.1 652.0 644.3 622.4 636.7 pe ret. Perct. perct. perct. perct. perct. perct. perct. perct. perct. Blood.. .. 3 .3 3.8 3.6 3.8 3.6 3.5 3.0 4.3 3.3 3.5 Head .. 3 .8 3.8 3.6 3.5 3.7 3.8 3.5 3.6 3.5 3.6 Tongue .5 .5 .4 .4 .4 .5 .4 .4 .4 .4 Shanks . 2 .1 2.2 2.2 2.0 2.1 2.3 1.9 2.3 2.1 2.2 Liver .. 1 .2 1.1 1.3 1.3 1.2 1.4 1.3 1.4 1.5 1.4 Heart .5 .4 .6 .5 .5 .6 .5 .6 .6 .6 Lungs .. 1 .6 1.6 1.2 1.3 1.4 1.6 1.3 1.4 1.5 1.4 Spleen .2 .2 .2 .2 .2 .2 .1 .2 .2 .2 Tail .2 .3 .3 .3 .3 .3 .2 .3 .3 .3 Stomach . 4 (> 4.0 4.3 3.5 3.9 3.9 3.4 3.7 3.8 3.7 Small intestines. . . . . . 1 .3 1.6 1.3 1.4 1.4 1.5 1.4 1.4 1.7 1.5 Large intestines. . . . .. 1 .(> 1.2 .9 1.0 1.0 .9 .8 .8 1.0 .9 Caul fat .. 1 1.2 1.0 1.3 1.1 1.4 1.8 1.1 1.6 1.5 Gut fat . . 1 .3 1.2 1.2 1.1 1.2 .9 1.7 1.2 1.2 1.3 Total killing fat.... .. 2 .4 2.4 2.2 2.4 2.3 2.3 3.5 2.4 2.8 2.8 Hide .. 9 * 11.5 10.9 9.6 10.5 9.1 8.3 9.4 9.5 9.1 Fill" 13 .5 12.6 13.5 7.6 11.8 10.3 10.7 11.7 11.1 10.9 The "net body weight" is the slaughter weight minus the weight of the contents of the diges- tive tract. b Fill is the contents of the digestive tract expressed as percentage of the slaughter weight "A considerable but unknown amount of fill was lost when the steer was hoisted. significant, may not have been caused by exercise. It seems probable that the feed consumed rather than the amount of exercise was the cause of the larger livers. The exercised steers did consume more pro- tein and it is known that the size of both the liver and the kidney is easily affected by protein. 114 BULLETIN No. 488 [May, Physical composition and condition. An examination of both the physical composition of the separate wholesale cuts (Table 3) and of the dressed carcasses (Table 4) showed that there were no significant differences in physical composition and condition due to exercise. Cutting test. There was no indication that either light or heavy exercise had any effect upon cutting percentages (Table 5). Color of lean. Likewise no differences due to exercise were shown in the color of lean as obtained with the spectrophotometer TABLE 3. PHYSICAL COMPOSITION OF WHOLESALE CUTS AS AFFECTED BY EXERCISE (Expressed as percentage of weight of cut) Experiment 1 (light exercise for 123 days) Unexercised lot Exercised lot Steer Steer Steer Steer Aver- Steer Steer Steer Steer Aver- 103 117 121 129 age 116 119 80 125 age Round Lean . 70 .3 68.7 71.7 71.2 70.5 67.6 67.5 69.7 71.9 69.2 Fat 12 <> 14.9 11.5 12.0 12.8 15.4 13.6 13.3 11.4 13.4 Bone 15. ,3 15.5 16.0 15.4 15.6 16.7 16.4 15.5 15.7 16.1 Tendon ,1 .1 .0 .1 .1 .1 .1 .1 .1 .1 Rump Lean .. 54. ,7 56.1 59.0 55.0 56.2 56.5 57.2 58.4 58.1 57.5 Fat 24. n 5.60 5.35 Flavor of lean 5.60 5.40 5.40 5.00 5.35 5.40 5.20 5 .40 5.80 5.45 A perfect score for each item of palatability is 7. SUMMARY AND CONCLUSIONS Light exercise, equivalent to walking 3.7 miles a day on the level, increased feed requirements per unit of gain. To produce 100 pounds of gain, exercised steers required an average of 17 percent more con- centrates, 10 percent more silage, and 10 percent more alfalfa hay than unexercised steers. Since cattle that are being fattened on pasture often walk as much or more than these exercised steers when grazing is scant or when they have to go considerable distances for water, it is evident that poor pasture is expensive from the standpoint of feed costs. Heavier exercise, equivalent to walking 8.9 miles a day on the 120 BULLETIN No. 488 level, increased feed requirements even more. The heavily exercised steers ate 72 percent more concentrates, 9 percent more hay, but 4 percent less silage than the unexercised steers for 100 pounds of gain. Light exercise had no effect upon dressing percentage, but heavy exercise increased the dressing percentage by reducing the amount of fill. Exercise had no effect upon the development of any organs. Altho the weight of the liver increased with the amount of exercise, this increase was probably caused by the higher protein consumption. As indicated by carcass grade, physical composition of cuts, cutting percentages, and color of lean, exercise had no effect upon the quality of beef. The fact that the color of the lean is not affected by exercise is verified by the conclusions of Mitchell and Hamilton that there were no significant differences in the hemoglobin and iron content of the blood or tissues of the exercised and unexercised steers. While light exercise showed no appreciable effect upon the tender- ness of the beef as measured by the resistance of the cooked rib eye to shearing, there was an indication that heavy exercise decreased the resistance to shearing; that is, that it made the meat more tender. This fact is borne out by the scores on the tenderness of the cooked ribs as recorded by the palatability committee. These scores showed that the rib eyes of the heavily exercised steers were more tender than those of their unexercised pair mates. Results obtained by Mitchell and Hamilton on the collagen content of the muscles also confirm the observation that tenderness increased with heavy exercise. No sig- nificant differences in flavor or other factors of palatability were observed as the result of exercise. The findings of these two experiments thus indicate that, while exercise is expensive from the standpoint of feed cost, the amount of walking required of cattle even on scant pasture does not have a detrimental effect on the quality of beef. On the contrary, it appears that heavy exercise makes beef more tender. 8,050 4-42 23520 1