TEXAS AGRICULTURAL EXPERIMENT STATION A. B. CONNER, DIRECTOR College Station, Texas BULLETIN NO. 661 OCTOBER 1944 EFFECTS OF FATNESS ON TENDERNESS OF LAMB SYLVIA COVER, A. K. MACKEY, C. E. MURPHEY, J. C. MILLER, H. T. BASS, C. L. BELL, AND CARL HAMALAINEN Division of Rural Home Research AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS Gibb Gilchrist, President . , E18-1044-4M-L180 [Blank Page in Original Bulletin] Tenderness is one of‘ the important components of palata- bility in meat. A reliable, easily applied guide t0 tenderness would be of great value to all who buy meat. A theory widely held for some time is that the fatter the animal the tenderer its meat will be. Conclusive evidence supporting this theory is lacking. In some of the experiments set up to test this theory, the fatter or full-fed lamb was somewhat more tender than the limited-fed one, but in other experiments the limited-fed one was more tender. In view of the wide variations and even contradictory results found in these tests, it seems doubtful that fatness influences ten- derness in lamb to any marked extent. Neither fatness nor thinness can be used as a guide to tender- ness in buying lamb. No attempt was made to study the effect of fatness on factors of palatability other than tenderness. . CONTENTS Introduction Plan of Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Experimental Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . L? Weights of Lambs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. Tests for Fatness Length of Storage Period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Methods of Cooking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Methods of Testing Tenderness . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. _p Collagen Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. g Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .e_ ,1, First Experiment. Lambs Fed in One Lot, Not Paired . . . . . . . . Second Experiment. Unpaired Lambs Fed in Two Lots. Carcasses Paired . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. _ Third Experiment. Lambs Paired, Fed in Two Lots . . . . . . . . . . .; .l Fourth, Fifth, and Sixth Experiments. Paired Lambs Fed ' Individually . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ._= Re-examination of Results from Third Experiment . . . . . . . . . Results from Combined Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. a v‘; Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ,5 Summary and Conclusions . . . . . . . . . . . . . . . . . . . .’ . . . . . . . . . . . . . . . . . . . . Literature Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 7. , EFFECT OF FATNESS ON TENDERNESS OF LAMB Sylvia Coverl, A. K. Mackeyg, C. E. Murphey3, J. C. Miller4, H. T. Basss, C. L. Bell“, and Carl HamalainenY. effenderness is one of the important components of palatability in meat. reliable, easily applied guide to tenderness would be of great value to all w buy meat. theory widely held for some time is that the fatter the animal the iderer its meat will be. Conclusive proof of this theory is lacking. QThe early references in animal husbandry literature were not based . experimental evidence and so must be regarded as personal opinion. sby (1) in 1908 stated, “Experience has shown that the tenderness palatability of the lean meat are notably greater when it is accom- ied by considerable fat.” Hall (13) in 1910 explained the association lmarbling and tenderness by postulating that the increased tenderness 3-: from a decrease in the elasticity of the connective tissue due to deposition of fat therein. Bull (5) in 1916 considered that the main for fattening an animal is to increase flavor, quality and tender- of the lean meat, by the deposition of fat between the muscle fibers. i by (2) in 1917 and Henry and Morrison (17) in 1916 explained that animal has fat deposited between the bundles of muscle fibers thus . ating them, and that the lean from such an animal is more tender f,“ the lean from an animal which has not been fattened. Helser (16) 1929 expressed the opinion that well marbled meat is more tender and than meat deficient in fatness. Hammond (14) in 1932, after show- f; that the correlation between marbling and tenderness for different cles-from the same carcass is not significant, stated, “No doubt such lrrelation does exist with animals of different degrees of fatness.” vu p t some evidence has been collected from research studies which may = -bred lambs from near Sonora were used. The lambs were selected f“? paired on thebasis of similarity as to sex, breeding, conformation, “ light, and fleece covering. EXPERIMENTAL PROCEDURE Weights of Lambs _or the first experiments, initial and final weights were based on an "1 ge of two successive day weights. For the last two experiments, successive day weights were used. For the third, fourth, fifth and p] experiments, the difference in initial weights between‘ members of was not more than two pounds except in a few cases. Tests for Fatness cass grades were secured because they help to give a picture of glamb carcasses. Carcass grades are not an accurate indication of fat- :, because fatness. is only one of three factors used in determining ‘ther the grade will be Choice, Good, Medium or Common. No thin i? would be graded Choice, but a fat carcass might be graded Medium ‘F ommon if low enough in conformation and quality. ysical separations into fat, lean and bone were made, for the leg and i rcass, and the percentage separable fat calculated. The leg was sat the stifie joint and half-way between the rise of the pelvic’ arch the point of the aitch bone. The cod and flank fat were removed be- Qthe separations were made. Values for separable fat seemed to be as i, an indication of the fatness of the animal as the determination of l extract, and were much more easily determined. The right side of garcasses was used for these tests on raw meat. ‘ er extractions were made for the leg only and in the first experiment f The fat and lean were mixed and ground before sampling for mois- ifand ether extract determinations. Special procedures were necessary '_btain a homogeneous sample for analysis because of the excessive pints of fat in some of the lambs. These determinations were so 'ous that ether extractions were discontinued after the first experiment. ings of the posterior surface of the rack were made during the f and second experiments. The tracings gave clear indications of the thickness of the fat covering on the backs of the paired lambs pere not suitable for use as a quantitative measure of fatness. . q: _, Length of Storage Period l the first experiment two storage periods were used. After each hter 4 carcasses were stored for 7 days and the others for 14 days. ~- remaining experiments, one storage period of 7 days was used. \ 10 BULLETIN NO. 661, TEXAS AGRICULTURAL EXPERIMENT STATION Methods of Cooking Oven temperature (9, 11) and the internal temperature to which:- meat is cooked (24) have been shown to affect the tenderness. Thesef tors were controlled by using a standardized cooking procedure. The were roasted on a rack in an uncovered pan without water, salt or i; in an oven regulated at 150° C. until the internal temperature reached 7 :59. The cuts from the left side of the carcass were used for cooking. ' Methods of Testing Tenderness Subjective tests were made on the semimembranosus muscle, w: while still hot was dissected out and sliced into sections 2 inch thick; slices were cut into small samples approximately %x%x% inch. It is’) known that the thicker a roast is sliced, the greater the apparent It ness. This was the reason for having the samples for subjective tes It nearly uniform in size as possible. Scores obtained from tests by weighted adjectives were used as? only measure of tenderness in the first experiment. The adjectivesf weightingsiwere: Very tough, 1.0-1.5; Tough, 1.5-2.5; Neutral, 2.5, Tender, 3.5-4.5; Very tender, 4.5-5.0. Each judge received on his L three samples from each of the four roasts, making a total of 12 judged at one period. The samples for any particular judge were k from the same position in the muscle and the same position in the ‘ 31 The 12 samples were placed on the plate of each judge according chart. The placing was the same for all judges, but was deliberately v; from time to time to prevent any judge from knowing which three of“ samples came from the same roast. In later experiments where the by weighted adjectives were obtained only as supplemental data, placing of the samples was determined by the method used for the p i_ eating method. Tenderness by the paired eating method (10) was used _as the of test for tenderness in all the experiments except the first. In this me a sample from the limited-fed lamb was compared with an identical “l1 from the full-fed lamb. Theo judges recorded on a judging sheet wl_ sample of the pair was more tender. The total number of paired sa tested and the number in favor of the full-fed lamb were used for calcula the tenderness-percentage. In the results for the full-fed lamb, the "r3" a tenderness-percentage above 50 indicates that the majority of the j ments were in favor of the full-fed lamb, but a tenderness-percentage l! 50 indicates that the majority of the judgments were in favor of the lim’ ., fed lamb. The tenderness-percentages were calculated for each pairg A vidually and for the group as a whole. The mechanical shearing device was used in the last 3 experimen one-inch core was cut from a definite place in a particular muscle : the pounds of stress required to shear across the core of meat were a tained. Tough meat gives higher shear values than does tender meat. EFFECTS OF FATNESS, ON TENDERNESS OF LAMB. 11 Collagen Tests Analyses for collagen were made by two methods, a modification of the soluble nitrogen method of Bogue (4) and a modification of the gelatin- tannate method of Spencer, Morgulus and Wilder (25). Meat _for the de- terminations was obtained from the circles of cooked meat left from the shearing tests and from similar positions in the raw muscle. The pieces were shaved as thin as possible with a sharp knife and macerated in a mortar. Enough acetone was added to cover the meat completely, and the meat _was ground until thoroughly saturated with acetone. The mixture was allowed to stand overnight at room temperature. The acetone evaporated, leaving a slightly moist powder which was spread on a shallow, enameled pan and placed in a gentle current of air from a fan. When it was crisp and dry, it was transferred to a mortar and ground. The product was a fine lightweight powder having a meaty odor. It was transferred to a weighing dish and placed in a desiccator. After 3 or 4 days it had reached constant weight and was stored at room temperature until the analyses could be made conveniently. About 0.5 gram of the dry meat powder, weighed accurately, was transferred to a 50 ml. centrifuge tube. About 15 ml. distilled water were added and the mixture autoclaved at 15 pounds pressure for 2 hours, to convert the insoluble collagen into soluble gelatin. While still hot, the mixture was centrifuged and the clear liquid de- canted. To the solid material, hot distilled water was added, the mixture stirred vigorously for about one minute, centrifuged, and the liquid de- canted. This procedure was repeated twice more. The combined decantates were used in the two methods. Soluble nitrogen was determined in the decantate by the Kjeldahl procedure and expressed as grams soluble nitrogen per 100 grams total nitrogen in the dry meat powder. The procedure for the gelatin-tannate method is as follows: The four decantates were collected directly into a 250 ml. centrifuge bottle, acidified with 1 ml. 10% H2804 and 10 ml. 10% tannic acid reagent. The bottle was left in the refrigerator (6-10°C) overnight to complete the pre- cipitation. The next day the fiuffy, sticky precipitate was centrifuged, the clear liquid decanted, and the bottle inverted to drain for several minutes. To the gelatin-tannate precipitate in the bottom of the bottle was added 1 ml. 10% NaOH and 10-15 ml. hot distilled water. The precipitate dis- solved completely, giving a brown solution in which the nitrogen was determined by the Kjeldahl procedure. The results were calculated as grams of gelatin tannate-nitrogen per 100 grams total nitrogen. RESULTS First Experiment. Lambs Fed in One Lot, Not Paired No increase in tenderness scores was noted with increase in length of _feeding period (Table 1). Only the tenderness scores of the three judges present at each judging period were used. When these scores were analyzed by variance, it was found that there was no significant difference in ten- derness between killings nor between storage periods, but significant differ- 12 BULLETIN NO. 661, TEXAS AGRICULTURAL EXPERIMENT STATION 625a mimwi s23 gnome?“ muwwi 3E2 v5 Mo 9309A it 3 await/wt“ fivlva melwa “awlfii gilxY: .25. 18w wEfEN. S.m:|8.w@ eoawlmmsm Ma melwa welwa Fwwlmf Bwfilwms En. Immm mefiwlvvm. 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EFFECTS OF FATNESS ON TENDERNESS OF LAMB l 13 ences were obtained between carcasses regardless of method of handling. However, a correlation based on the tenderness scores and the percentage ether extract of all of the individual carcasses was not significant, either when the scores of the three judges present at each judging period were used, or when the mean scores of all of the judges were used. That the lambs in the beginning differed greatly in tenderness is in- dicated by the fact that the range for the first period of slaughter includes the lowest and highest tenderness scores for the legs in the entire ex- periment (Table 1, B, Stored 1 Week). A highly significant difference between the scores of different judges seemed to indicate that different standards of tenderness were used by the different judges. The method of testing tenderness, therefore, was changed in subsequent experiments. There were difficulties in the production side of the project also. The range (Table 1, B) in percentage ether extract of the legs in the first period of slaughter shows that one of these lambs was fatter before it was placed on feed than some of those slaughtered in the next four periods after they had been on feed for some time. The means for the groups (Table 1, A) show the average separable fat and ether extract apparently remained almost stationary from the 42nd day through the 84th day of the feeding. This indicates that the average fatness of the lambs was not increasing during this period. The average daily gains made by these animals in the last two weeks before slaughter were very erratic. (Table 1, A and 1, B). It seemed wise to examine the method of selection critically. The lambs for the first killing had been selected by weight as follows: After the weight of the lambs had been arranged in order from the lightest to heaviest, the fourth from the lightest lamb was selected, and counting from it every sixth lamb was chosen. While this method of selection was ex- pected to give a representative sample of the fatness of the entire lot of lambs at the beginning of the experiment, perhaps other variables, present in a group of 48 lambs even from the same flock, were large enough to defeat the original purpose. Lambs for the later killings were selected on the basis of gains. At killing time, the average daily gains in pounds for all of the live lambs for the preceding two week period were arranged in order from the smallest to the largest. The third from the smallest gainer was selected, and counting from it every fifth lamb was selected for the second killing, and every fourth for the third killing. .Then the second from the smallest gainer was selected, and counting from it every third lamb was selected for the fourth killing, every second for the fifth killing, and all that were left were used for the sixth killing. (Because one died during the test there were only 7 in the sixth killing). Thus the lowest and the highest gainers in each two-week period were left alive until the last killings. No distinction was possible between gains caused by fatness and those caused by growth. Gains made previous to the last period were disregarded. This method gave a representative sample of 14 BULLETIN NO. 661, TEXAS AGRICULTURAL EXPERIMENT STATION 0.0 . . . . . . . . .. 00.00 00. 00 0000.00 000.0 000.0 00 00 00.00 00 0000 . . . . . . . . .. 0.0 00.00 00.00 0.000 000.0 000.0 00.00 00.00 00 0000. 0.0 . . . . . . . . . . 00.00 00.00 0.000 000.0 000.0 00.00 00.00 00 0000 . . . . . . . . .. 0.0 00.00 00. 00 5:00.002 000.0 000.0 00.00 00.00 00 0000 0.0 . . . . . . . . .. 00.00 00.00 0.000 000.0 000.0 00.00 00.00 00 0000 0.0 . . . . . . . . .. 00.00 00.00 0000000 .0005! 000.0 00.00 00.00 00 0000 . . . . . . . . . . 0.0 00.00 00.0 0000000 0.00001 000.0 00.00 00.00 00 0000 . . . . . . . . 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I 0000 000.0 000.0 00.00 @000 m0 5S . . . . . . . . .. _.< 5M: :00 0000 000.0 0&0 00.00 00.0w 00 3S 0.0 . . . . . . . . .. <04: F: I c000 :50 000.0 00 0: 0m 5 3 .55 0.0 . . . . . . . . I 050m ENE 000000 000.0 000.0 $800 05m.» 2w NRO . . . . . . . . .. 0.0 072 00.: 0000 #000 000.0 00.0: m»? 3 fiww . . . . . . . . .. we .341 _N.0~ 0000 000.0 000.0 0m 00 00.00 3w 08w NJ» . . . . . . . . . . 00.2 mm.“ 0000 000.0 $0.0 00.00 00.? $0 Nfiw 5v 05mm Si: 03000 0.00.0 000.0 00AN~ 00.0w v0 wth 0.0 00.»; 3.0 E0252 $0.0 $0.0 3.9 05w... v0 05m né 0N4; N70 E3002 000.0 v0.0.0 @500 3.0m H” wmwm 1e BULLETIN NO. 661, TEXAS AGRICULTURAL EXPERIMENT STATION gains at the time of killing, but such factors as Weather might influence gains in a two-week period in a way not related necessarily to the fat- ness of the animal. Illustrations may be observed in Table 2. In the group killed after 42 days on feed, No. 2852 had the highest average daily gain but the lowest percentage ether extract. In the group killed after 70 days on feed, No. 2813 10st weight in the last two week's, yet had the highest percentage ether extract. Thus from the results of the first experiment _it appeared that biological variations between animals, differences in standards of tenderness used by the judges, and the method of selecting fat and thin lambs were problems which had not been solved satisfactorily. l Second Experiment. Unpaired Lambs Fed in Two Lots. Carcasses Paired When all the data were taken as one sample, a difference in tenderness between the full-fed and limited-fed lambs was obtained. Sixty-nine per cent of the paired judgments were in favor of the full-fed lamb (Table 3). The Chi-square was 14.9, which is highly significant since it was above 6.635. However, when the data from the individual pairs were observed, it was noted that the lowest percentage of judgments in favor of the full- fed lamb were found not only in the two pairs having the least but also in the pair which had the greatest difference in fatness. Erratic data of this sort tend to discount the results of statistical analyses, because such analyses are valid only for homogeneous data, and these results appear to indicate that the data are not homogeneous. Third Experiment. Lambs Paired, Fedin Two Lots When all the data by the paired eating method in Experiment Three were taken as one sample, there was again a difference in tenderness between the full-fed and limited-fed lambs with 61% of the judgments in favor of the full-fed lambs (Table 4). This difference is highly significant (Chi- square 17). However, when the individual data are examined, it is noted that in about one-fourth of the pairs the limited-fed lamb was the more tender. Moreover the difference in fatness between full-fed and limited-fed lambs is not significantly correlated with their tenderness-percentages. This may be observed without calculation from Table 4, in which the pairs of lambs are arranged in order of difference in fatness. The expected order for the corresponding tenderness-percentages is not apparent. Furthermore, after grouping the pairs having a difference in fatness of above 10%, those having a difference of 5-10%, and those having less than 5%, the per- centage of judgments in favor of the full-fed lamb does not show the ex- pected descending order. Thus there was no increase in unanimity of judg- ments in favor of the full-fed lamb as the difference in fatness increased. It seems reasonable to expect that it would.have occurred if degree of fatness is an important factor in tenderness. I] 17 60155.35 owEE oc 22S E9: o@fifi=3¢0..i. 530E... * .8305.» v.68 ma? QQHE 05F.» mm mmfiioocom. @2593 E Eum 28w wma$>< 2.5.3 E 5E9: M35 .—uQ.:GAfl mvmmauudU -QuO1fl QkvF im wok men-ad Ufiumfiinu: JHQET-Qfiflmm wiouom .M U-JNE. B M A L F O $ i _ .2 wfinw+nmmoqi*w€0~ 020500 82D H 02 | 03 52D H 05 I 00a 00.2 000 =0h 02 00H ==m |||| 00200 102524 20h 00255 =50 00553 00255 00:15 00 00 0005:: 0022 5 0m05@00@n~ R000. 050500000 500500.60 UQJQOE M5300 00.500 zn 0005000000. 0000000 5 .23 2n052$m m2 5 05 0320000. 2.2m 0000000 0005:: 0000.80 050 .5 .02:& 2:55 ....2=_.2=0 .5: .0. @390 I] EFFECTS OF FATNESS ON TENDERNESS OF LAMB 19 Table 5. Third Experiment. Weights and Gains of Paired Lambs Fed in Two Lots. Live weight in pounds Average Carcass number daily gain entire period Initial Final pounds Daiysd — on ee Limited Limited Limited Limited Full fed fed Full fed fed Full fed fed Full fed | fed 3036 l 3035 75.0 73.0 109.0 74.0 354 .010 96 3026 3027 76-. 0 78. 0 111.0 S7 .0 232 .060 151 3015 3016 60.0 58.0 96.0 55.0 290 —.024* 124 3058 3056 58. 0 60. 0 92 .0 69. 0 309 .082 110 3068 3067 70 0 72.0 108.0 85.0 292 .100 130 3066 3059 73 0 72.0 109.0 71.0 277 ——.008* 130 3069 3070 75 0 73.0 99.0 75.0 250 .021 96 3024 3025 72 0 76.0 101.0 102.0 162 .145 179 3023 3022 85 0 81.0 128.0 95.0 250 .081 172 3040 3041 46 0 48.0 87.0 73.0 285 .174 144 3033 3032 71 0 71.0 96.0 65.0 214 -——.051* 117 3085 3086 59 0 62.0 80.0 64.0 191 018 110 3076 3077 67 0 70.0 100.0 59.0 241 ——.080* 137 3045 3044 48 0 48.5 94.0 77.5 305 .192 151 3082 3079 66 0 66.0 100.0 85.0 236 .132 144 3073 3072 69 0 70.0 90.0 85.0 122 .087 172 3007 3006 77 0 77.0 108.0 81.0 301 .039 103 3012 3013 66 0 65.0 104.0 72.0 277 .051 137 3009 3008 65 0 67.0 86.0 74.0 169 .056 124 3097 3096 67 0 66.0 l 79.0 64.0 116 ——.019* 103 3083 3080 57 0 57.0 l 95.0 81.0 1 325 .205 117 Meanp‘ . . . . . . . . .. 66.8 67.2 1 98 7 75.9 | l l *Loss instead of gain. Initial and final weights and average daily gains of these paired lambs are given in Table 5. Not all of the full-fed lambs gained as well as could be desired. It may be noted that some of the limited-fed lambs lost weight during the test. Fourth, Fifth, and Sixth Experiments. Paired Lambs Fed Individually In these tests the paired judgments in favor of the full-fed lamb were 57%, 38%, and 58% respectively (Table 6). When the three experiments were taken as one sample, 49% of the paired judgments were in favor of the full-fed lamb and 51% in favor of the limited-fed lamb. This ratio of 49:51 does not differ significantly from a 50:50 ratio and indicates no differ- ence in tenderness between full-fed and limited-fed lambs. This finding is based on 14 pairs of lambs and on 164 paired judgments. When the individual data are examined the percentages of paired judg- ments in favor of the full-fed lamb are very erratic, ranging from 9% to 97% in Experiment Four, from 8% to 81% in Experiment Five, and from 33% to 83% in Experiment Six. The scores from weighted adjectives were obtained by using the fol- lowing weightings: 5 =1 very tender, 4 = tender, I neutral, 2 = tough, and 1 I very tough. The scores of full-fed and limited-fed lambs respective- ly averaged 3.9, 3.7 in Experiment Four; 3.6, 3.8 in Experiment Five; 3.7, 20 BULLETIN NO. 661, TEXAS AGRICULTURAL EXPERIMENT STATION 9m l 9w Java»: 25> 31w l 9m cwwcwk Sm l n.m._¢.5:oZ 5N I f £58. f I 6:3 E5 Ea... v.53 wvm-w3@Em_ 2E3 330a 3 wooU wwuwhm 9:3 2:9: c2450 3n @035 mo: mEQQQEaO-i £453 0.5a was» n52 055*: 9m AME; i?» MmEuawBB wfifiomvwr . . . . . . . . . . . . . . _ . . . . . . . . . . . . . . . . . 4 . . . . . . . . . . . . . .. 9m 9m imw 93+ H ma-lmmm 9w+ Hwgmlmdm .262 38:3 9i mzwfiz>wwfi mo iaEq5m 9cm 9M: L . . . . . . . . . . . . . . . . . . . . . . . . I wm 9m mm _ . . . . . . . . .._o.:+ Howfllwwml 9m loam . . . . . . .. :32 93 o E . . . . . . . . . . . . . . . . . . . . . . . . H . . . i 5 m 9m :2 9m + H 92 l 9E f. l 93 i; f; i. m 93 i: . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. m m 9m mm 92+ H 92 l Em 93 l 93 i; t; =.=_ .6: .353 si-ch mazoifonnfl 6 03am. 71 21 EFFECTS OF FATNESS ON TENDERNESS OF LAMB 625a m2. vw ca "E22. 3E1 vac: “on moi-om wwho oucoum .39» oEww v.3 E ocvifiwaoQ zhocmnwsi twang.» o5 >2 fiiflcwczkonxo woo fiEoooE 25 oo 3E2 o>c Jmfioh dwoo co ooofin can? E5 i5 E52 zfiBohw m3 “:03 55F JQZMDOQENMM X vZOwwH-m ma? MMNE Aimw 312v hi: >=~=m==D* 2: 2% 2% ooo. 5N. o . mo o . ow o. mo o . E 4h h om imiw -59“ Io. ohm. o . mo o. mm o. wo o. $ o~ .+ ohm. + o8. SN. o. MK 9.2. f2 m . No wmmm mmmm wnEmJ oobam|ocunzuoaxfl 22E \ ||. 1| | |:||| |t1_ al| 1i: 1|| i’ i II llli[f Q2 r84 $m.+ o3. oom. o.om ho: m? hon >>momm 32mm hmfi _8.+ omh.+ w: oZh hmw hA: m9. 9Q moon Hmwo o3 23+ §wa+ 2:. oom o.mo o.hm m1? m? flown woman m2 93+ m:.+ $1. wan. odm ca: hon 3K m8» m8» N2 omo h | ohm . + 92. mmm. o . Q o . i: o. s. h . oo >>mmo 39:. whEmJ cE/Plocoiiomxw sfisoh , | ca o8 ::h o3 i .5 :2: } o8 F: :2; ca T v2 :21; i m2 i w: =§ Hazefi v0.2.5 vpéei 835i wusifi E3 so I|||< ll| ‘Ill Ill’! lv| PQQ 93o? 9,3 omwq v2.5a 33:3 Gib 12:5 255:: |l|||s 2225a l: 5mm hzwo vmw~o>< woczoa E 3:93.» 0Z4 mwmohmo QC nEmJ >:a:E>=.:~ warn maEaA watch .3 mEnU on: 3:303 Jam 1:: 62k daeh mEoEIoaxH d. 03a? 22 BULLETIN NO. 661, TEXAS AGRICULTURAL EXPERIMENT STATION Table 8. Chemical Tests for Collagen in Raw and Cooked Semimembranosus Muscle. Raw (right) Cooked (left) Carcass Grams soluble Grams gelatin- Grams soluble 1 Grams gelatin- number nitrogen tannate nitrogen nitrogen tannate nitrogen‘ per 100 grams per 100 grams per 100 grams | per 100 grams total nitrogen total nitrogen total nitrogen ; total nitrogen Full Limited Full Limited Full Limited Full Limited Full Limited fed fed fed fed fed fed fed fed § fed 1e 2999 2998 11.4 11.4 8 8.7 13.2 12.5 7.9 9.3 3614 3615 12.0 10.9 4 7.5 11.7 11.5 8.0 8.4 l 5 5A 11.4 11.0 8.5 8.1 12.7 12.2 8.6 9.4 324s 3200 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9.1 9.8 i 7.3 7.4 3613 3612 11.5 12.3‘ 8.8 8.3 11.7 11.4 8.4 8.2 2978 2979 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9.6 10.1 6.8 7.1 Mean... . . . . . . .. 11.6 11..4 8.6 8.2 11.3 11.3 7.8 8.3 3.4 in Experiment Six (Table 6). These values indicate little difference be- tween paired samples. Even the small differences in the averages were not consistently in favor of the full-fed lamb. Shear values are the pounds of stress required to shear across a one- inch core of meat. Tender meat gives lower shear values than does less tender meat. The average shear values for full-fed and limited-fed respec- tively were: 21.4, 20.7 pounds in Experiment Four; 21.3, 23.0 pounds in Experiment Five; 18.3, 20.2 pounds in Experiment Six (Table 6). These values indicate little difference in tenderness between paired samples. Even the small differences in the averages were not consistently in favor of the full-fed lamb. Weights and gains of the paired lambs fed individually are given in Table 7. None of these lambs lost weight during the test. The chemical determinations for collagen by both methods are given in Table 8. Since the soluble nitrogen method measures not only the gelatin nitrogen but other soluble nitrogen compounds as well, the col- lagen values by this method are higher than those by the gelatin- tannate method. Little difference between the full-fed and limited-fed lambs was found. The small differences observed are probably within ex- perimental error. Spencer, Morgulus, and Wilder (25) reported values for raw biceps femoris (a muscle in the hind leg) ranging from 7.4 to 14.5% within their control group of 8 rabbits. The values in Table 10 for raw muscle from 8 lambs and cooked muscle from 12 lambs fall within a much narrower range. The values appear to be close enough to indicate that in respect to collagen content, the lambs in the fifth experiment were fairly well paired. EFFECTS OF FATNESS ON TENDERNESS OF LAMB 23 Re-examination of Results from Third Experiment After the data on the individually fed lambs had been obtained, and it was noted that some of the pairs had to be discarded because they did not eat well under the experimental conditions, it occurred to the authors that the lambs which did not gain in Experiment Three might also be discarded. When this was done 16 of the original 21 pairs of lambs were left. The tenderness-percentage then dropped from 61 to 57% and was no longer highly significant. The data from the selected lambs (Table 9) are slightly in favor of the fatter lambs, but still are not consistent. The range in tenderness-percentage is 25-94%, as wide as that found with the individually fed lambs. Results from Combined Data When the selected data from the paired lot-fed lambs were combined with those from the individually-fed lambs, a total of 30 pairs was ob- tained. For all of these pairs only 54% of the total judgments were in favor of the full-fed lamb, while 46% were in favor of the limited-fed lamb. In view of the wide variations and the contradictory results found in each of these four tests, it seems doubtful that fatness influences ten- derness in lamb to any marked extent. Both carcass grades and tenderness scores were obtained for some of the animals in the present study. The totals include 13 Choice carcasses, 17 Good, 8 Medium and 8 Common. In the scores used here 4 I tender and I neutral. The tenderness scores for Choice, Good, Medium and Com- mon respectively averaged 3.8, 3.9, 3.8, and 4.0. These data indicate that the tenderness scores were not influenced by the grade of the carcass. Hunt (19) reported tenderness scores for legs of lamb using a score card in which 6 I tender, 5 I slightly tender, and 4 I slightly tough. In only 2 of his lots did the carcass grades include both Choice and Common. The scores he reported for Choice and Common respectively were: Lot III, 6.00 and 5.75; Lot IV, 4.00 and 5.75. It is apparent that in Lot III the leg from the Choice carcass was only slightly more tender than the one from the Common carcass, while in Lot IV the leg from the Choice carcass was not only less tender than the one from theCommon carcass but was graded slightly tough. His results then appear to be as contradictory as those obtained in the present study. If, as seems likely, his Choice car- casses were fatter than his Common carcasses, these data lend support to the idea advanced here that fatness does not influence tenderness in lamb to any marked extent. The relationship between carcass grade and fatness observed in lambs from the present study is shown in Tables 10 and 11. In Table 10 the fat- ness was determined by the separable fat in the carcass. In this table it may be noted that within each carcass grade there were animals which differed considerably in fatness. The ranges within carcass grades were: Choice 22%-33%, Good 17%-33%, Medium 13%-21%, and Common 9%- 24 BULLETIN NO. 661, TEXAS AGRICULTURAL EXPERIMENT STATION dfinEmm wfifin .3 233 59G w3w_:o~mU**** awoohxwf“ .23 v3-5a of can» hwwcwo v35 ma? n52 UQHTUQZE: vnuac.“ .23 o5 mcisw gamma? wwimw minim“ =<* ****.\lm. ‘iivwm :6 v3. 3w + H mmwilqwaw w?» + H 842i .52.. .. . . .§@2 mm w~ mom. ma», S... +ugwmlfiam ma; luofifilfifi owom mwom mw wH omo. o2 22m [Tflmwomlmflimm momrm +namzm~lfiwwfi woom moon 5 M: 5o. RN 3a +uw9mzlfimam $4“ +uww.m_lwm.w_ 2cm mSm 03mm w. mmo. Sm flow + H wmdmlfifimm 52v + H mwsfililow ooom B3 0.21m 2 t5. mmfi w; +nI.2|$.mw mod +n2i|w12 NR5 m8» nw wfi m2. 8N 3e +uw§cwlmflmm mmm Lwuomwfilmmogm $8M Nwom 3 m: N2 mom ma...“ +uwwsoiikrmw $5 +nfia~lm§i 3% $8 9o m: wS. 22. 5.» +nfiwilmmam fiiw +nfiilwa NA owom £3 $ M2 EH. $8. 8s + H qwfilwmvww $8 +u 3.218 mm $3 3% mm M: :6 omw 8.3+ H miilwimm 2d + H M52! E mm mmom mwom w“ 2 m3 ma. flméiummsfllomwdm $2.. +n§ormol 37mm mmom wmom vim», M: 3o omfl. 5.2+ H E .3! 3.3 22m + H mo. :|o~ . fin Q8» $8 3 wH 9: 2m 54in Idmlfixfim .5.» +uw~xm_lmw.mm $2., $8 E m: Nwo. mom. Moms? H 2 .NH| 22mm 5.2+ H 321$. ~N wmom wmom 133m M: ooo. Nmm. 8.2+ H mmofilwmawm 2.2+ H hfiilfirmm Rom £3 $5 wfi a8. $3 amfi+nwmilgwm >wJA+HmNKh loflimm mmom wmom ©9725 mwcoiwus.“ . w. .632 E REE E @3154 v2 ==m d5“ v2 @3123! v3 =9» afiu P: @0285! n8 ==m v3 @0253 .2 =5 omfinoouom 13o H . @0505 3:3 wvbmnv. £53 mwmobwo E on“ vfimbwavm wfi E on“ BQQQQQQW msmocwhniofimnmvm we mmfiiowaok fioion 3:58 95cm 5am ~28“. oww$>< mmonumo we $23G HQQESG mmdoEU uGQEmuQQNMH 05w EOPu w_GEmF< TLZZuQ-om .6 OTHGF EFFECTS OF FATNESS ON TENDERNESS OF LAMB 25 Table 10. Percentage of Separable Fat in the Carcass from Carcasses of Different Grades Number of carcasses Percentage separable fat Choice Good Medium Common . . . . . . . . . . . . . . . . . . . . 1 . . . . . . . . . . . . . . . . . . . . 1 . . . . . . . . . . . . . . . . . . . . 1 . . . . . . . . . . . . . . . . . . . . 2 . . . . . . . . . . 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 . . . . . . . . . . . . . . . . . . . . 2 . . . . . . . . . . 2 1 1 . . . . . . . . . . 4 . . . . . . . . . . . . . . 3 1 1 1 3 1 . . - . . . . . 2 Total number of carcasses . . . . . . . . . . . . . . . . . . 22 l6 9 17 Table l1. Percentage of Separable Fat in the Leg* from Carcasses of Diflerent Grades. Number of carcasses Percentage separable fat Choice Good Medium Common L‘ v-ilQlOlai-kfibiuliN QLHUINWLJJKMHM Total number of carcasses . . . . . . . . . . . . . . . . . . . 40 40 21 26 *Leg trimmed of flank and cod fat and shank removed at stifle joint. 26 BULLETIN NO. 661, TEXAS AGRICULTURAIi EXPERIMENT STATION 19% separable fat in the carcass. Moreover carcasses of grades Good, Medium, and Common were found within the range 17 %-19%, while the fattest Choice carcasses were no fatter than the fattest Good carcass. In Table 11 fatness was determined by the separable fat in the trimmed leg. In this table it may be noted that within each carcass grade there were animals which differed considerably in fatness. The ranges were: Choice 9%-29%, Good 7%-28%, Medium 7%-15% and Common 5%-14%. In this case carcasses of all grades (Choice, Good, Medium and Common) were found within the range of 9%-14% separable fat in the leg. This over- lapping fatness for different carcass grades could be possible only in the presence of considerable variation in conformation and quality among the carcasses. DISCUSSION The question may be asked whether or not the fat lambs were really fat. In the report of the Chief of the Bureau of Animal Industry for 1938 a classification of lamb carcasses was reported based on percentage ether extract in the entire edible portion of the carcass and on percentage of separable fat in the untrimmed leg. No data for ether extract of the entire carcass were obtained in the present study, and the percentage separable fat in the leg was made on the leg from which the cod and flank fat as well as the shank had been removed. The data from the two studies, therefore, are not comparable. The authors know of no other suitable data for this comparison, but there can be little reasonable doubt of the fatness of those lambs in which the percentage of separable fat represented from i to é of the weight of the entire carcass (Tables 4, 6, 9, 10). Hankins and Ellis (15) obtained coefficients of correlation between the tenderness of the roasted meat as measured by shearing strength and cer- tain indexes of fatness. In lambs tenderness of the leg was correlated with fatness expressed both as the percentage of caul fat and the per- centage of kidney fat. With one lot of cattle tenderness of the longissimus dorsi muscle was correlated with fatness expressed both as the percentage of ether extract in the longissimus dorsi and the percentage of ether ex- tract in the entire edible portion of the 9-10-11 rib cut. In another lot of cattle which was grain fed in dry lot, fatness was expressed as ether extract in the longissimus dorsi muscle and correlated with tenderness of the same muscle. None of these five coefficients was even moderately high, and there was inconsistency among them as to sign. Hankins and Ellis concluded the evidence is strong that variations in tenderness are caused mainly by factors other than fatness. The relationships between tenderness and fatness in the present study were based on tenderness of the semimembranosus muscle in the leg and on separable fat both in the trimmed leg and in the entire carcass. The present study and that of Hankins and Ellis therefore supplement each other. Neither study showed evidence of a relationship between fatness and tenderness. It seems doubtful that such a relationship exists. F’ v ... . ,a.--,-,.,_.,..,, ..- vwtyywm." EFFECTS OF FATNESS ON TENDERNESS OF LAMB 27 f; Fat deposited in and around the muscle is thought to improve the flavor Eand juiciness of the lean meat, but no attempt was made here to study " the effect of fatness on factors of palatability other than tenderness. E SUMMARY AND CONCLUSIONS », When the study of the effect of degree of fatness on tenderness of lamb was begun, three problems became apparent: selecting comparable linimals, producing differences in fatness and testing tenderness of the jneat. Six experiments are given in detail with critical appraisal of methods nd results. It was found advisable to use paired lambs similar in sex, reeding, conformation, and fleece covering and differing by not more an two pounds in initial weight. One lamb of each pair was full-fed so at it would gain as rapidly as possible and the other limited-fed so that would gain slightly and only enough to keep it in a healthy condition. doth lot feeding and individual feeding were used successfully, but it was ecessary t0 discard some of the lot-fed pairs because the limited-fed lambs ~- lost weight by the end of the test. The paired-eating method was _sed for testing tenderness in paired lambs, but observations were re- rded also from weighted adjectives, mechanical shear, and chemical l‘ alyses for collagen content. The full-fed animal was somewhat more tender than the limited-fed one ‘some pairs, but in other pairs the limited-fed one was more tender. In 'ew of the contradictory results from different pairs within each test, l seems doubtful that fatness influences tenderness in lamb to any marked i Using fatness or thinness as an indication of tenderness may be re- ‘r ded as of doubtful practical value in buying lamb. LITERATURE CITED Armsby, Henry Prentess. 1908. Feeding for meat production. U.S.D.A., Bureau of V_ Animal Industry Bulletin 108, p. 11. . Armsby, Henry Prentess. 1917. The nutrition of farm animals. New York: The Mac- millan Company, p. 358. Black, W. H., Warner, K. F. and Wilson, C. V. 1931. Beef production and quality as affected by grade of steer and feeding grain supplement on grass. U.S.D.A. Tech- nical Bulletin 217. , Bogue, Robert H. 1923. Conditions affecting the hydrolysis of collagen to gelatin. _ Ind. Eng. Chem. 15: 1154-1159; Bull, _Sleeter. 1916. The principles of feeding farmranimals. New York: The Mac- millan Company, p. 31. Bull, Sleeter, Olson, Fred C. and Longwell, John H. 1930. Effects of sex, length of feedrng_ period and a. ration of ear-corn silage on the quality of baby beef." Illinois Experiment Station Bulletin 355. ._7 V in birth weight in sheep. J. Heredity 23: 473-478. A _Chief of Bureau of Animal Industry. Report for 1938. Cover, Sylvia. 1937. The_ effect of temperature and time of cooking on the tenderness of roasts. Texas Agricultural Experiment Station Bulletin 542. Chapman, A. B. and Lush, J. L. 1932. Twinning, sex ratios and genetic variability 28 10. 11. 12. 13. 14. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. BULLETIN NO. 661, TEXAS AGRICULTURAL EXPERIMENT STATION Cover, Sylvia. 1940. Some modifications of the paired eating method in meat cookery research. Food Research 5: 379-394. ' Cover, Sylvia. 1943. of beef. Food Research 8: 388-394. Foster, M. T. and Miller. J. C. 1929. The effects of management and sex on carcasses A of yearling cattle. Missouri Agricultural Experiment Station Research Bulletin 186; Hall, Louis D. 1910. Market classes and grades of meat. Bulletin 147. Hammond, John. 1932. Growth and development of mutton qualities in sheep. Edin- burgh and London: Oliver and Boyd, pp. 534-539. Hankins, O. G. and Ellis, N. R. 1939. Proceedings of the American Society of Animal Production. Annual Report 32: 314-319. Helser, Maurice D. 1929. New York: 123, 168. Henry, W. A. and Morrison, F. B. 1916. Feeds and feeding. Madison: The Henry- Morrison Company, p. 3. Hostetler, Earl H., Foster, John E. and Hankins, O. G. 1936. Production and quality of meat from native and grade yearling cattle. North Carolina Agricultural Experi- ment Station Bulletin 307. Hunt, Wells E. 1935. Fattening thin native lambs. Station Bulletin 379. Jordan, Edna M. 1941. Livestock, meat and wool statistics and related data. U.S.D.A. Agricultural Marketing Administration. - 1932. Illinois Experiment Station ‘Farm meats. The Macmillan Company, p. Maryland Agricultural Experiment Lowe, Belle. Experimental cookery. New York: John Wiley and Sons, Inc., 181. p. Nelson, P. Mabel, Lowe, Belle and Helser, M. D. upon the quality and palatability of beef. Bulletin 272. , Satorius, Mary and Child, Alice M. 1938. Effect of cut, grade and class upon palatabil- ity and composition of beef roasts. Minnesota Agricultural ‘Experiment Station Technical Bulletin 131. Satorius, Mary and Child, Alice M. 1938. Effect of coagulation on press fluid, shear force, muscle-cell diameter and composition of beef muscle. Food Research 3: 619-626. Spencer, H. C., Morgulus, S. and Wilder, V. M. 1937. A micro-method for the deter- mination of gelatin and a study of the collagen content of muscles from normal and dystrophic rabbits. J. Biol. Chem. 120: 257-266. Trowbridge, E. A. and Moffet, H. C. 1932. Yearling heifers and steers for beef pro- duction. Missouri Experiment Station Bulletin 314. Weber, A. D., Loeifel, Wm. J. and Peters, Matilda. 1931. Length of feeding period %n¢ill plane of nutrition as factors in lamb feeding. Nebraska Experiment Station u etin 262. 1930. Influence of the animaPs age Iowa Agricultural Experiment Station 'aoa11oo n 2 v: ‘$818111 Effect of extremely low rates of heat penetration on tendering‘