LIBRARY, A 8c M COLLEGE. CAVPUS. 6000-L180 TEXAS AfiRlCULTURAL EXPERIMENT STATIUN A. B. CONLNER, DIRECTOR COLLEGE STATION, BRAZOS QIIOIINTY, TEXAS BULLETIN NO. 471 " ' l I ' DECEMBER, 1932 DIVISION OF RANGE ANIMAL HUSBANDRY THE RELATION OF BODY SHAPE OF FEEDER ISTEERS TO RATE OF GAIN, TO DRESSING PER CENT, AND TO VALUE OF DRESSED CARCASS AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS T. O. WALTON, President STATION STAFF? Administration : Veterinary Science: A. B. Conner, M. S., Director *M. Francis, D. V. M., Chief R. E. Karper, M. S., Vice-Director H. Schmidt, D. V. M., Veterinarian Clarice Mixson, B. A., Secretary **F. P. Mathews, D.V.M., M.S., Veterinarian M. P. Holleman. Chief Clerk R. A. Goodman, D. V. M., Veterinarian t J. K. Francklow, Asst. Chief Clerk Plant Pathology and Physiology: Chester Higgs, Executive Assistant J. J. Taubenhaus, Ph. D., Chief Howard Berry, B- S“ Teehhieal ASSt- W. N. Ezekiel, Ph. D., Plant Pathologist Chemistryi Farm and Ranch Economics: G. S. Fraps, Ph. D., Chief; State Chemist L, P, Gabbard, M, S., Chief S- E- Asbllry, M- s» Chemiet W. E. Paulson, Ph. D., Marketing J- F- Fudge, Ph- 13-. Chemist TTC. A. Bonnen, M. S., Farm Management E- C- Carlyle, M- 5-, Asst- Chemist 1**W. R. Nisbet, B. S., Ranch Management T- L- ogiel‘, B- S» Asst- Chemist A. C. Magee, M. S., Farm Managemen A. J. Sterges, M. S., Asst. Chemist Rural Home Research: : Ray Treichler. M- 8-. Asst- Chemist Jessie Whitacre, Ph. D., Chief W~ H- Walliel‘. Asst- Chemist Mary Anna Grimes, M. S., Textiles Velma Graham. Asst. Chemist Elizabeth D. Terrill, M. A., Nutrition Jeanne F. DeMottier, Asst. Chemist sail Survey; _ R. L. Schwartz, B. S., Asst. Chemist **W_ T, Carter, B, 8,, Chief C- M- Pmifldefs, B- S» ASSt- Chemist E. H. Templin, B. S., Soil Surveyor Hiiftiellltlife! A. H. Bean, B. S., Soil Surveyor S- H- Yarnell. 36- D» Chief R. M. Marshall, B. S., Soil Surveyor Range Animal Husbandry: Botany; J- M- Jones. A- M" Chief V. L. Cory, M. S., Acting Chief B. L. Warwick, Ph. D., Breeding Investiga. Swine Husbandry; S. P. Davis, i/Vool Grader Fred Hale, M. S., Chief 1**Je H. Jones, B. S., Agent in Animal HUSb. Dairy Hugbandyy; .5 EIIKOIHOlOQYI O. C. Copeland, M. S., Dairy Husbandman ~ F. L. Thomas, Ph. D., Chief; State Poultry Husbandry: Entomologist R. M. Sherwood, M. S., Chief H- J- Reinhard. B. S., Ent0m0l0gi$t J. R. Couch, B.S., Asst. Poultry Husbandman R. K. Fletcher, Ph. D., Entomologist Agrigultura] Engineering; W. L. Owen, Jr., M. S., Entomologist H_ P, Smith, M, 3,, Chief J. N. Roney, M. S., Entomologist Main Station Farm; J. C. Gaines, Jr., M. S., Entomologist G_ T, McNess, Superintendent 3- E- J011635. M. S., Erlwmologist Apiculture (San Antonio): F. F. Bibby, B. S., Entomologist H. B. Parks, B. S., Chief "E. W. Dunnam, Ph. D., Entomologist A. H. Alex, B. S., Queen Breeder “R. W. Moreland, B. S., Asst. Entomologist Feed Control Service: C. E. Heard, B. S., Chief Inspector F. D. Fuller, M. S., Chief C. Siddall, B. S., FOUIbTOOG Inspector James Sullivan, Asst, Chief S. E. McGregor, B. S., Foulbrood Inspector S, _ Pearce, Secretary 11810110111)" i J. H. Rogers, Feed Inspector E. B. Reynolds. Ph. D., Chief K. L. Kirkland, B. s., Feed Inspector R- E- Karper, M- 3-, AEPOYIOIniSt S. D. Reynolds, Jr., Feed Inspector P. C. Mangelsdorf, Sc. D., Agronomist P. A. Moore, Feed Inspector D. T. Killough, M. S., Agronomist E. J. Wilson, B. S., Feed Inspector Publications: H. G. Wickes, D. V. M., Feed Inspector A. D. Jackson, Chief SUBSTATIONS No 1. Beeville, Bee County: No. 9, Balmorhea, Reeves County: R. A. Hall, B. S., Superintendent J. J. Bayles B. S., Superintendent No. 2, Lindale, Smith County: No. 10, College Station, Brazos County: P. R. Johnson, M. S., Superintendent R. M. Sherwood, M. S., ln Charge "B. H. Hendrickson, B. S., Sci. in Soil Erosion L. J. McCall, Farm Superintendent "R. W. Baird, B. s., Assoc. Agr. Engineer No. 11. Nacogdoches. Nacogdoches County: No. 3, Angleton, Brazoria County: H. F. Morris, M. S., Superintendent R. H. Stansel, M. S., Superintendent **No. 12, Chillicothe, Hardeman County: H. M. Reed, M. S., Horticulturist **J. R. Quinby, B. S., Superintendent No. 4, Beaumont, Jefferson County: **J. C. Stephens, M. A., Asst. Agronomist R. H. Wyche, B. S., Superintendent No. 14, Sonora, Sutton-Edwards Counties: "H. M. Beachell, B. S., Junior Agronomist W. H. Dameron, B. S., Superintendent No. 5, Temple, Bell County: I. B. Boughton, D. V. M., Veterinarian Henry Dunlavy,'M. S., Superintendent W. T. Hardy, D. V. M., Veterinarian C. H. Rogers, Ph. D., Plant Pathologist O. L. Carpenter, Shepherd H. E. Rea, B. S., Agronomist “C. G. Babcock, B. S., Asst. Entomologist S. E. Wolff, M. S., Botanist No. 15, Weslaco, Hidalgo County: "H. V. Geib, M. S., Sci. in Soil Erosion W. H. Friend, B. S., Superintendent ‘*H. O. Hill, B. S., Junior Civil Engineer S. W. Clark, B. S., Entomologist No. 6, Denton, Denton County: W. J. Bach, M. S., Plant Pathologist P. B. Dunkle, B. S., Superintendent J. F. Wood, B. S., Horticulturist "I. M. Atkins, B. S., Junior Agronomist N0. 16, Iowa Park. Wichita County: No. I, Spur, Dickens County: C. H. McDowell, B. S., Superintendent R. E. Dickson, B. S., Superintendent L. E. Brooks, B. S., Horticulturist B. C. Langley, M. S., Agronomist No. 19, Winterhaven, Dimmit County: No. 8, Lubbock, Lubbock County: E. Mortensen, B. S., Superintendent D. L. Jones, Superintendent **L. R. Hawthorn, M. S., Horticulturist Frank Gaines, Irrig. and Forest Nurs. , Teachers in the School of Agriculture Carrying Cooperative Projects on the Station: G. W. Adriance, Ph. D., Horticulture J. S. Mogford, M. S., Agronomy S. W. Bilsing, Ph. D., Entomology F. R. Brison, B. S., Horticulture V. P. Lee, Ph. D., Marketing and Finance W. R. Horlacher, Ph. D., Genetics D. Scoates, A. E., Agricultural Engineering J. H. Knox, M. S., Animal Husbandry A. K. Mackey, M. S., Animal Husbandry A. L. Darnell, M. A., Dairy Husbandry *Dean, School of Veterinary Medicine. TAs of February 1, 1933. "In cooperation with U. S. Department of Agriculture. TTOn leave. tIn cooperation with Texas Extension Service. Individual gains, dressing percentages; and commercial value of the carcasses 0f steers at the end of the fattening period can be predicted with only slight success at the beginning of the feeding period. Even with careful measuring and weighing of the animals as was done in this experiment, “the shape and size of the feeder steer indicated only to a slight extent its desirability at the end of the feeding period. There is a slight tendency for long-bodied, tall steers with big middles but small flanks and thin loins to make faster gains. Steers that are already fleshier than the others when feeding begins and that are heavy in proportion to their bony measure- ments are somewhat apt to dress the highest at the end of the feeding period. The most desirable cuts 0f meat tend to come from steers which are large in their fleshy measurements but small in most bony measurements at the beginning of the feed- ing period. Conformation is often the only basis available for judgment and of course should be given some consideration at all times. However, the data indicate that no score card or standard based on conformation could ever be so accurate that the future per- formance of individual steers could be predicted from it with but few mistakes. CONTENTS Introduction 5 Previous work 5 Material used in this study 6 Method of _ calculation 7 Homogeneity of correlations 7i Measurements used ‘ 8 Results 11 Biometric relations between initial weight, gain, final weight, carcass weight, and dressing per cent 11 Relation of measurements and initial weight to gain .......................... --13 Miscellaneous measurements and gain 17 Body measurements and dressing per cent 17 Miscellaneous measurements and dressing per cent . 19 Conflict of ideal conformation for large gains and for high u dressing percentages 20 Initial conformation as related to the commercial desirability of the meat produced 20 The measures of commercial desirability ....................................... -_20 Score cards for high appraisal prices 23 Score cards for maximum meat values per live pound _____________ -_24 Miscellaneous measurements and meat value ............................... --25 General considerations 26 Summary 29 Literature cited 29 'mal"llp;fi‘< {- ~_ ..~ BULLETIN NO. 471 DECEMBER, 1932 THE RELATION OF BODY SHAPE OF FEEDER STEERS TO RATE OF GAIN, TO DRESSING PER CENT, AND TO VALUE OF DRESSED CARCASS J AY L. Lusn* The idea that there is an intimate relation between the outward appear- ance or conformation of an animal and its inward physiology or function- ing is old and widespread. If such relations exist and are close it should be possible, by paying proper attention to external conformation, to achieve considerable success in selecting animals which would function as desired. As applied to domestic animals these relations in one way or another are the basis of much of what is taught in stock judging. Many of the objec- tives of stock judging, particularly in the fat classes, rest on an associa- tion between outward conformation and present yields or proportions of cuts rather than on a close relation between present conformation and future anatomy or future functioning. . Such agreement of opinion as has been reached in regard to what con- stitutes an ideal type of individual has come about largely through the unorganized exchange of personal experience of breeders and judges. Judging standards have changed from time to time and one cannot often be sure in any one case whether the change was an improvement or the reverse. As particularly vivid illustrations of this may be cited the escutcheon or “milk mirror” which came into much prominence in the judging of dairy cattle from sixty to thirty years ago but has now gone back to comparative obscurity, and the changes in the type of swine preferred by judges at the leading shows from 1910 to 1925. There has been little systematic collection and analysis of observations on large groups of animals to determine objectively what type of animal would most nearly fulfill the desired purpose. This Bulletin presents the results of some studies made at the Texas Station on the relation between present conformation and future perform- ance in beef steers, and is an extension of studies reported in Bulletin 385. The specific problem was to find what conformation in feeder steers, as indicated by measurements made at the beginning of the feeding experi- ment, was associated with the ability to njake large gains, with a high proportion of dressed meat to the live weight at the end of the feeding experiment and with a dressed carcass which would be highly esteemed by the meat trade. PREVIOUS WORK No extensive study of the relation between body "measurements of steers and their subsequent performance in the feed lots or at slaughtering time has come to our attention. Several short studies of the changes in average measurements during fattening have been published, usually incidental to *Formorly Animal Husbandman, Texas Agricultural Experiment Station. Now Professor of Animal Husbandry in charge of breeding investigations, Iowa. State College. 6 BULLETIN NO. 471, TEXAS AGRICULTURAL EXPERIMENT STATION some major objective of a feeding trial. Two Wyoming bulletins (3, 4) dealt primarily with the relation of actual measurements to the thing which the live stock judge has in mind when he speaks of “type,” so far as type can be expressed in a series of grades from very low-set to very rangy. ' Severson and Gerlaugh published in 1917 “A statistical study of body weights, gains, and measurements of steers during the fattening period” (13). They calculated the simple correlation coefficients between a large number of body measurements and the gains which the steers subsequently made. Those correlation coefficients were calculated without any correc- tion for heterogeneity of data and probably would have been somewhat higher if such corrections had been made. Nearly all the correlations were small. No attempt was made to combine the simple correlations into a multiple correlation so as to determine Whether each measurement had a relation to gain largely independent of that involved in other measure- ments or whether the different measurements were various expressions of nearly the same attribute of the steers so far as each showed any relation to gain. MATERIAL USED IN THIS STUDY The data studied here consist of various measurements and perform- ances of 241 steers divided among 25 different lots which were fed out in the feedlots at Substation No. '7 near Spur, Texas, during the period of 1922-1929. The first 19 lots are described in some detail on pages 7 to 12 of Bulletin 385 of the Texas Station. The remaining six lots were of similar breeding and included the steers born in 1927 and in 1928. There was no culling or selection among the steers except that nine which entered the feedlot were discarded because each made a gain which was less than the average gain of the lot in which that particular steer was fed by at least as much as three times the standard deviation of the gains of his lot mates. It is probable that in every such case there was something genuinely wrong with the health of the abnormal steer although that something was not visible when the feeding experiment was begun and in some cases was not definitely identified even by the end of the experiment. “l” Only four lots of steers were not bred at Substation No. 14. In most lots all of the steers in a single lot were sired by the same bull, that is, were half brothers through their sire and in some cases were slightly related through their dams. None of the steers were inbred. Because the steers within most lots were half brothers to each other, each lot was more uniform genetically than is usually the case with experimental cattle. Nevertheless the standard deviations were large enough that any very important or universal relation between conformation and per- formance should have been visible in the data, even though it might not have been quite as large here as it would have been among a group of steers all belonging to the same herd but not otherwise related. ‘>b - _..<.-._ swgam THE RELATION OF BODY SHAPE OF FEEDER STEERS TO RATE OF 7 l GAIN, TO DRESSING PER CENT, AND TO VALUE OF DRESSED CARCASS METHOD OF CALCULATION Each lot was treated as a unit in the calculations. The correlation coefficients were calculated by the ordinary product moment method, using for convenience the form outlined by Wallace and Snedecor (14). Standard deviations wherever mentioned are based on the n-1 formula, which in- volves the idea of “degrees of freedom.” I After the primary correlation coefficients were thus calculated they were averaged together by Fisher’s Z-method (2). A detailed example of this method of averaging is shown on pages 856 and 857 of Volume 42 of the Journal of Agricultural Research (6). Homogeneity of Correlations Various tests were applied to see whether the calculated correlations were appreciably different for steers of the three different kinds of breed- ing, for steers born in different years, for steers fed in different seasons, or for steers of different ages and hence of different initial weights. The average correlations for two-year-old steers were based on but 16 degrees of freedom, those for yearlings were based on 64 degrees of freedom, and those for calves were based on 86 degrees of freedom. In comparing these averages there are 1424 comparisons between two average values of Z. Only 28 (2%) of these comparisons showed differences in Z larger than twice their standard errors. Only 5 of the comparisons (1 /3 of 1%) showed differences in Z larger than three times their stand- ard error. Such differences are well within the limits of sampling errors. On account of these findings it is not thought that combining the correla- tions calculated on steers of the three different ages introduced any material error. If there was any general difference at all the correla- tions were highest for the yearlings and lowest for the two-year-olds. Similar tests seemed to show no real difference between the correlations obtained in the five different feeding seasons. However, when the correla- tions were compared according to the breeding of the steers it was found that the correlations generally existing among the back-crosses were lower than in the other groups. This may be interpreted in two ways: (a) as evidence of the “disharmonic” crossing about which biologists are in dispute (1, 12) or, (b) as caused by the back-crosses having been more uniform in age and size within each lot than the other steers were. Table 7 shows that the back-crosses were distinctly less variable in weight and in nearly all measurements than the other groups. For this reason corre- lations calculated upon them are less affected by differences in general size than are the correlations calculated in the other groups and hence are smaller. In the subsequent calculation of multiple correlations com- pensation for this is made by including variables such as initial weight, heart girth, body length, chest depth, etc., which also express differences in general size. The conclusions thus obtained approximate those which would have been obtained by the use of ratios, from which the effects of differences in general size have been largely cancelled. Therefore it is 8 BULLETIN NO. 471, TEXAS AGRICULTURAL EXPERIMENT STATION believed that the conclusions subsequently drawn are not biased by includ- ing, in a single average, correlations calculated on the small back-cross group even though these appear to have been really a little smaller than similar correlations calculated on the other steers. MEASUREMENTS USED Twenty three different measurements were studied. They are described in detail in Bulletins 385 and 409 of the Texas Station. Figures 1 and 2 show the location of 17 of these measurements. The other six are de- scribed on page 22 of Texas Station Bulletin 409. Fig. 1——Side view of Hereford steer showing the location of the various measurements studied. A, Length of head. B, Length of body. D, Depth of chest. E, Width at eyes. K, Flank girth. M, Muzzle circumfrence. P, Height over withers. R, Chest girth. T, Height over hips. U, Paunch girth. V, Cannon circumference. Y, Length of Pelvis. The instruments used in taking measurements are shown in Figure 3. The error in taking a single measurement such as these has been studied on dairy cattle (9) and found to be about one or two per cent of the mean measurement in most cases. It was certainly a little larger than that on these steers, since many of these were rather wild. Each measurement was taken three times, several other different measurements being taken between repetitions, so as to give the steer opportunity to change posi- tions. The average of the three measurements was used in subsequent calculations. THE RELATION OF BODY SHAPE OF FEEDER sTEERs TO RATE OF 9 GAIN, TO DRESSING PER CENT, AND TO VALUE OF DRESSED CARCASS Besides the measurements there were for each steer initial and final weights (each of which was the average of weights read to the nearest pound or the nearest two pounds on three consecutive days), warm dressed Fig. 2—T0p view of Hereford steer showing the location of the various measurements studied. A, Length of head. B, Length of body. E, Width at eyes. H, Width at hooks. J, Width at pelvis or thurls. K, Flank girth. L, Width at loin. M, Muzzle circumference. N, Width at pin bones. R, Chest girth. U, Paunch girth. W, Width of chest. Y, Length of pelvis. carcass weight (to the nearest pound), appraisals of the commercial Worth of the dressed meat (made independently by three or more salesmen for Fig. 3—-—-Instruments used for measuring steers. A, Cattle measuring standard with spirit level attached, Lydtins model. B, Caliper used for measuring pelvic region and for loin width. C, Caliper used for measuring length of head and width at eyes. D, Steel tape used for measuring girths and circumferences. 10 BULLETIN NO. 471, TEXAS AGRICULTURAL EXPERIMENT STATION all except the 1922 and 1923 steers, which were appraised by only one man), and weights of the caul and ruffle fat (to the nearest tenth of a pound). Combinations and ratios of these primary observations were used as variables in the following cases: 1. Gain=Final feedlot Weight —— Initial feedlot weight Warm carcass weight Final feedlot weigi? 3. ' Meat value per steer=(Appraised price of meat)><(Warm carcass weight) 2. Dressing per cent: _ Meat value per steer 4. Live meat value per pound=_$?_” .7 “v1.7-1. Final feedlot weight 5. Estimated fatness: 9.073 (Caul fat)-f_.936 (Warm carcass weight) Final feedlot weight —.4496 The equation for estimating fatness was derived from a former study (5). The figure obtained by this equation when multiplied by 100 expresses the estimated percentage of the steer’s finad feedlot live weight which is fat, in the chemical sense of the word. In applying this equation to these data both caul fat and ruffle fat were included by using instead of the individual caul fat the following term: (Individual caul fat-llndividual ruffle fat)><(Total caul fat for that lot) (Total caul fat for that lot)_|_(Total ruffle fat for that lot) This was done so as to utilize both caul and ruffle fat in estimating fat- ness and to minimize errors arising from caul variations not directly related to fatness. No equation was available for including both caul and ruffle directly; so this was done indirectly by substituting for the actual caul fat the above term, which expresses the combined caul and ruffle fat for the individual steer reduced to about the magnitude of the caul fat alone by being multiplied by the ratio of the total caul fat for that lot to the combined total of caul and ruffle fats for that lot. Twelve of the measurements and the warm dressed carcass weights besides the feedlot Weights were taken on all 241 steers. Four more measurements (cannon circumference, pelvis length, pelvis width, and width at hooks) and carcass appraisals and caul and ruffle weight were taken on all steers born after 1921 (218 head). Width at pinbones was not taken on the 1921 steers and was inadvertently omitted for the 1924 and 1925 steers also. Elbow and knee heights and the sternum heights were taken on less than half the steers. Measurements were taken the same week the steers were started on feed except in three lots which had been measured two months earlier and which were not measured again when the feeding experiment began. THE RELATION OF BODY SHAPE OF FEEDER STEERS TO RATE OF 11 GAIN, TO DRESSING PER CENT, AND TO VALUE OF DRESSED CARCASS RESULTS Biometric Relations Between Initial Weight, Gain, Final Weight, Carcass Weight, and Dressing Per Cent The relations between these variables are shown in Figure 4 drawn according to Wright’s method of path coefficients (15). The numbers shown in Figure 4 are standard regression coefficients except that the +32 between initial weight and gain is a primary correlation coefficient. Three of the variables pictured, initial, final, and carcass weights, are observed directly from the data. Gain and dressing per cent are rigidly determined by the observed three. “Other” represents all factors other than initial weight and gain which affect the weight of the dressed carcass. INITIAL *"° FINA Ly DRE ss mo ,0 PER CENT a?’ GAIN‘ OTHER Fig. 4—Path coefficient diagram showing biometric relations between weight and dressing per cent. Since the relations between initial weight, gain, and final weight are purely additive, the multiple correlation between initial weight and gain as independent variables and final as the dependent should be unity. Actually this is 1.02 when calculated from these average coefficients where slight discrepancies have crept in from the Z-method of averaging and correcting for the bias of small numbers. The standard regression coefficients from initial weight to dressing per cent and from gain. to dressing per cent are +51 and ——.17 when cal- culated directly and are+.51 and —-.24 when calculated indirectly from the diagram in Figure 4. The discrepancy is largely due to the pro- nounced multiplicative relations existing between final weight, carcass weight, and dressing per cent, along with the very high correlation between final weight and carcass weight. Ninety-six and four-tenths per cent of the observed variance in carcass weight would disappear if all the steers weighed the same amount at the start and gained the same amount. The value of the standard regression coefficient from “other” to carcass weight is deduced from the difference. Only 23 per cent of the observed variance in dressing per cent would disappear if initial weight and gain were alike for all steers. 12 BULLETIN NO. 4T1, TEXAS AGRICULTURAL EXPERIMENT STATION The following conclusions seem justified by these quantitative relations: 1. Initial weight is more important than gain in predicting variations in final weight, carcass weight, and dressing per cent. This does not have a fundamental physiological significance since the relative importance of the two is influenced by the range of initial weights among the steers within each lot. Initial weight would appear less important if the initial weights had been less variable and the range in gain had remained the same. The range in initial weights within each lot was not extreme in these experiments (see Table 7). It corresponds to a coefficient of varia- tion of about 11 per cent to 14 per cent. Hence the effect of range in enhancingthe apparent importance of initial weight is no larger in these data than it is in the usual feeding experiment. 2. Gain counts for more with final weight than with carcass weight or dressing per cent. This seems to mean that a considerable part of the variations in observed gain are “fill? or at least an increase in other parts of the body than the dressed carcass. An increase in observed gain will result if the steer has more feed and water in him when weighed on the final day or less when weighed on the initial day. Such an increase in observed gain is not paralleled by a corresponding increase in carcass weight and therefore is actually paralleled by a decrease in dressing per i ' cent. The barely negative primary correlation between gain and dressing per cent is therefore a combined result of two entirely different processes. The first is the relation just pictured whereby gain automatically shows more extreme effects of “fill” than either initial or final weights, a rela- tion which by itself would lead to a strong negative correlation between gain and dressing per cent. Second, in so far as observed gain does represent a genuine gain in fat and other material which remains on the carcass, just so far is gain positively associated with dressing per cent. Presumably the effects of “fill” on observed gain and in modifying the, relation between gain and dressing per cent would be less important in long feeding periods than in these periods where the steers were fed about 120 days or a little less. In spite of that consideration, it does seem odd that gain as actually figured from the observed weights doesn’t really mean increase in the weight of carcass more than it seems to. The influence of “fill” is surprisingly large in view of the findings of an earlier study of the importance of day-to-day fluctuations in the live weights of cattle (8). Perhaps a clue to this apparent discrepancy is furnished by Maymone and Sircana (10), who reported evidence of considerable cyclical variation in the weights of cattle of such a nature that the weights would increase over a period of several days and then would decrease over a period of several days. Such variations with a cycle more than two or three days in length, would not have been found in our study of the accuracy of cattle weights. If these cyclical variations are of considerable impor- tance, then the findings of the present study that differences in “fill” are so important in explaining the differences between gains made by dif- ferent individual steers is less surprising. If differences in “fill” really are THE RELATION OF BODY SHAPE OF FEEDER sTEERs TO RATE OF 13 GAIN, T0 DRESSING PER CENT, AND TO VALUE OF DRESSED CARCASS as important as the present data indicate, then the variability in gains of actual flesh is less than the variation in observed gains. If this is gen- erally true and important, then individual animals should exhibit less variation in their ability to utilize feed as measured by respiration calorim- eter trials than they do in individual feed-lot gains. Relation of Measurements and Initial Weight to Gain Table 1 shows the average correlation coefficients for all variables which were observed on all steers. The sampling errors are equivalent to those from a single lot of 169 steers. For the smaller correlations the probable error of each is in the neighborhood of .04 ~to .06. For this reason the correlation coefficients are presented only to the second figure. In all cal- culations they Were carried out to three decimal places. The correlations between one measurement and another prevailingly range from a little above .60 to a little above .80. Those involving chest width are a little smaller than those involving the other measurements. Likewise the correlations between a measurement and the three directly observed weights are prevailingly high. Most of those are above .70 and some are nearly as high as .90. These generally high correlations largely reflect differences between these steers in general size. On the other hand the correlations between the measurements or the weights and gain or dressing per cent are prevailingly low, most of them ranging from about .15 toa little above .40. Only one correlation out of the 136 is negative and that one is not statistically significant. The regularity and size of the correlations between various measure- ments and gain or dressing’ per cent, suggest that there is a significant but small correlation between gain or dressing per cent and general size but that there may be no specific correlation between gain or dressing per cent and a particular shape or ratio of a measurement to general size. (The data studied were measurements instead of ratios or proportions, but the inclusion of several measurements in a multiple correlation analysis gives practically the same information about them as if the various possible ratios between them had been studied directly). If this were so, the inclu- sion of each measurement along with initial weight as independent vari- ' ables in a multiple correlation with gain or dressing per cent as the de- pendent variable would raise the correlation but little over what it was i when the measurement was left out but initial weight was used as a measure of general size. When this was done, only three of the 12 meas- urements made contributions as large as .01 to the squared multiple corre- To lation coefficient where gain was the dependent variable. Similarly only 5 of the 12 measurements added as much as .01 to the i; squared multiple correlation coefficient where dressing per cent was the ‘jijdependent variable. Only 4 of the 12 measurements added as much as .01 7' to the squared multiple correlation coefficient when each measurement in fgturn was studied along with initial weight and gain as the independent f variables and dressing per cent as the dependent variable. BULLETIN NO. A471, TEXAS AGRICULTURAL EXPERIMENT STATION 14 H950 wl4w= mnmowm. :5 ammwmmw o» mwmmmogv 455v; u _ m m u m r 2 w m _ a _ w _ o H n h... . _ m8.“ $5M»? ......... .3»: h hm hm hm h» mm hm .3 .8 .mo h» h» hh .mm hm We“; _m=w$r...... .... A5 _ h n am _ mo hm aw h» h» h» .m» .»m hm hm aw um u» 01mm» agar. ......... :AUV _ _ h» _ hm hm h» hm hm _ aw _ .$ .m» hh hm .m» .mm _ .3 m3 s32. .............. Lav _ _ _ .$ .8 .8 _ .3 5 _ =3 _ aw a.» .3 _ .3 .2 b» _ E. 5:52. 5H5 ...... QWC _ .2 .2. _ mm mm _ h» _ .mm .»m h» _ ho hm aw _ .mm h-Eb r055“ ............. :7: _ .3 _ .3 _ .m» _ hm .m» .3 aw _ aw hm mm _ .2 155W NW2? ...... LHC _ hm _ .3 _ .wm .5 .mm _ hm _ hm .m» mm _ .»» was . ...................... L5 _ .3 _ .3 .3 E _ .3 _ aw .3 .5 _ .5 3i“? .................. .25 _ _ _ .2 _ .3 =5 _ .3 .3 am .8 .3 5mm: .................... A5 _ hm h» .m» .3 aw .mh .»h H656? .................. A9 _ .3 hm hm .m» mm .3 Gram... 33% .......... LHV aw .3. .2 .mo .3 MKS; fimmmr». ......... :33 .3 .8 .2 2w Omwommm .................. L9 .3 .$ mm T125 ...................... QC .m» .»m Q3: ........................ k9 _ _ |.3 THE RELATION OF BODY SHAPE OF FEEDER STEERS T0 RATE OF 15 GAIN, TO DRESSING PER CENT, AND TO VALUE OF DRESSED CARCASS These findings tend to confirm the idea that much of the primary correlation of each measurement with gain or dressing per cent is the effect of general size rather than a relation with that specific meas- urement. Table 2 shows (translated into the familiar form of a score card) the standard regression coefficients for several different combinations of measurements with gain as the dependent variable. The first column in Table 2 shows the result when all 12 measurements are included with initial weight. Even a superficial examination of column one indicates that the two head measurements and the width of chest are of little importance. When they are omitted the figures in the second column are obtained. When the three smallest of these (except for initial weight) are omitted the figures in the third column are obtained. These indicate that heart girth and initial weight could both be omitted without much loss in the multiple correlation coefficient. The fourth column shows the result. The remaining five variables between them express, almost as well as when initial Weight and heart girth were included, things in those two variables that were associated with gain. The figures for the last column in Table 2 show the evidence bearing on the fairly common belief that a steer with a short, wide head will be a good “doer.” Height at withers is included with the two head measure- ments in order to eliminate as much as possible of the effects of general size. The multiple correlation obtained by including all three is only a little larger than that obtained with wither height alone (+327). When wither height is left out the multiple correlation between the two head measurements and gain is only a little more than half as much as the simple correlation between gain and initial weight and the sign of the head length regression is reversed. In short the two head measurements either as dimensions or as ratios indicate practically nothing about gain. For most of the variables shown in the first,- four columns of Table 2 the limits of statistical significance lie somewhere around the magnitude of a score of 6 to 9. Scores much smaller than this might be expected to vary or perhaps even to have reversed signs in other data. When we try to visualize the kind of steer which is demanded for maximum gain we see essentially a long-bodied tall steer with a big paunch but narrow loin and small flank girth. The author interprets that to be related to the steer’s anatomy and physiology in the following way: A long-bodied tall steer would be one with a large frame. A large paunch girth would also indicate large frame and perhaps in addition much room for digestive organs. A narrow loin would indicate a steer in thin flesh and therefore ready to make rapid gains. A small flank girth at the beginning of the experiment would indicate a steer carrying little if any “fill.” Such a steer would be in excellent condition to make large gains, especially since non-carcass increases in live weight play a consid- erable part in observed gains. It is of secondary importance that the steer to make maximum gain should be one with a small muzzle, a shallow 16 BULLETIN NO. 4'71, TEXAS AGRICULTURAL EXPERIMENT STATION 831m mlwmmonm OmHm 1.01. m1 35?... _ 215m 503 m? E03 19E mmfiwmm Bmwwcumamuem _ 15001503 15001813 §11 1..<11 ZE:§wm_ o». 53+ .mm .mm .mm 3mm"