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The question of optimum size of beef cattle has been discussed and debated for at least 150 years. We have gone all the way from the “Durham Ox” that weighed nearly 2 tons at 10 years of age to “Comprest” cattle that matured at less than one-fourth that weight. It would seem that if there were a size that is most efficient, we would have arrived at it by trial and error by this time. But, we still do not know how big beef cattle should be. Maybe there has been too much trial and error and not enough of the scientific method applied to the problem.The main problem is that we have continued to search for the “ideal” beef animal, to fit all cattle into one mold, to have perfection in all traits, economic and aesthetic, in each and every breed. And then, we have continually changed our concept of the ideal animal.

Forty Hereford cattle were allotted to four groups of 10 head each. These lots consisted of steers, implanted steers, bulls and implanted bulls. The subcutaneous implantation in the ear of 84 mg. of diethylstilbestrol was made at the beginning of the feeding period and again 84 days later.Treatment of steers lowered the carcass grade; treatment of bulls produced carcasses of higher grade. From the implanted cattle slightly heavier pituitary glands and significantly heavier adrenal glands were obtained. Thyroid glands of the implanted bulls were significantly lighter in weight than the same gland of the untreated bulls but treatment of steers had little effect on the weight of this gland. Measurement of the lumbo-sacral angle gave evidence that treatment made this angle much more acute.Implanting of bulls increased the percentage of fat while the reverse appeared to be true in the case of the steers. In comparison, the 76.7% edible portion found in bull carcasses was lowered to 75.0% in the carcasses from treated bulls. Implantation raised the edible portion from 69.9% in the untreated steers to 72.0% in the treated steers. Measurement of the cross section area of the longissimus dorsi muscle correlated directly with the edible portion data. An organoleptic test at 13 days post-mortem indicated only slight differences in tenderness.

A ration of ground ear corn, soybean oil meal and poor quality timothy hay was significantly improved by the addition of trace minerals or molasses when fed to fattening steer calves. Molasses was of no apparent benefit when added to a ration which included trace minerals or good quality mixed hay.There were highly significant differences in rates of gain of steers fed various amounts of protein. The amount of protein in the ration was of much greater importance when fed with poor quality timothy hay than with good quality mixed hay. Results obtained indicate the presence of some beneficial factor in good quality hay other than protein or trace minerals.Cane molasses seemed to have some sparing effect on protein requirement when a ration sub-opitmal in protein was fed but not with a ration markedly deficient in protein. This effect was a result of increased feed consumption and not improved feed utilization.

In dry lot fattening trials bulls gained more economically and significantly faster than steers. The subcutaneous implantation of stilbestrol significantly increased the rate of gain, this increase being greater in steers than in bulls. Stilbestrol treatment significantly increased the grade of bull carcasses but reduced slightly the grade of steer carcasses. There appeared to be no advantage in feeding bulls for a period, castrating, and finishing as steers.

Samples of high-moisture shelled and ground ear corn stored in conventional silos were found to contain significant amounts of acetic and lactic acids. A feeding experiment with triplicate lots of seven steers each showed that 1 lb. of lactic acid, fed as 44% technical grade lactic acid, replaced 2.8 lb. of other feeds in a fattening ration for cattle.Laboratory experiments with whole-plant and ground ear corn ensiled in glass jars showed that the acetic and lactic acid contents of the resultant silages were directly related to the moisture content of the material ensiled. Acid production during ensiling was increased approximately 100% by the addition of 1% calcium carbonate.Addition of 1% dolomitic limestone to whole-plant corn ensiled in conventional silos increased acid production by 40%. Steers fed the treated silage tended to require slightly less silage dry matter per unit of gain than those fed the untreated.Ear corn was picked when the whole ears contained 46% moisture. One-third was ground through a burr mill and ensiled, one-third was ground and ensiled with 1% dolomitic limestone and one-third was artificially dried. Steers fed the treated or untreated ear corn silage gained slightly faster and required, on the dry corn basis, 15% less corn per 100 lb. gain than those fed the dry corn.Digestion experiments with wether lambs showed that addition of limestone did not decrease the digestibility of organic matter, cellulose, crude fiber, protein or ether extract of the whole-plant or ground ear corn silages.

The effects of stilbestrol implantation and level of corn silage in the ration upon the protein requirement of fattening steer calves were studied. Protein requirement, as measured by rate of gain and carcass grade, was not significantly influenced by stilbestrol. When fed with approximately one-third, one-half or two-thirds of a full feed of ground ear corn, well-eared corn silage was found to have a high estimated net energy value. The level of corn silage included in the ration had no apparent effect upon the amount of protein required.

The results of a three-year, top-cross breeding experiment with three lines of Hereford cattle have been reported. Montana Line I and Nebraska Line I bulls were selected on type and feed lot performances and subsequently bred to randomly selected, outbred cows. The performance of the progeny of these inbred line bulls were compared with those of outbred bulls which had been selected on beef type. A total of 67 steers and 74 heifers were studied.Analysis revealed surprisingly few line differences. Nevertheless, evidence is strong enough to suggest real advantages in favor of the two inbred lines in respect to gain 90–182 days, average daily gain on test and weight per day of age. These data tend to show that the Montana Line I and Nebraska Line I sired calves tended to be more efficient in their conversion of TDN. to meat. However, no useful line effects were observed in the carcass data.

Factors influencing the efficiency and accuracy of heritability estimates based on paternal half-sib correlations have been examined. It is concluded that, in any one experiment, the number of offspring per sire, k, plays an important role in determining the sizes of the errors of estimate. Optimum values of k, k′, for different heritability levels are presented together with a method for calculating the best k value, k′o, to use when heritability is estimated for several characteristics. Minimum numbers of offspring necessary for estimating heritability to a given accuracy are also discussed.

Ten linear body measurements were taken in duplicate on eight Hereford steers by two investigators. The components of variance due to steers, investigators, steer and investigator interaction and measurement error were estimated and compared. Results of this study indicated that heart girth, circumference at navel, length of body, width of chest, depth of chest and height at hooks and withers had the highest steer components and the lowest investigator, interaction and error components. After this study, additional cattle were measured.Significant differences in circumference at navel, height at hooks, height at withers and body length were found between calves sired by bulls from different lines of breeding when compared on a constant weight basis.Ratios of weight to height and weight to length were calculated and correlated with dressing percentage, area of rib eye and edible portion. In both steer and heifer data, the two ratios were positively correlated with area of rib eye and negatively correlated with edible portion. These ratios were positively correlated with dressing percentage in steers but not in heifers.Percent edible portion is highly influenced by the amount of fat trim in the carcass. Therefore, a ratio of edible portion to bone was calculated and correlated with the weight to height and weight to length ratios. The edible portion to bone ratio is also influenced by the degree of fatness of the carcass. A formula for correcting the edible portion to bone ratio to a constant fat trim percentage is presented.

Sixty-two mature, non-pregnant, non-lactating Hereford and Charolais cows were used to study the effect of cow size and condition and protein content of the ration upon energy requirements for maintenance. Complete pelleted rations which contained 6.9, 9.1 or 12.0% total crude protein were individually fed once daily to cows in dry lot which were bedded with sawdust. Each ration was fed to supply digestible energy at theoretical maintenance levels for periods of 12 to 16 wk. or at 0.75 times maintenance for 6 wk. and at 1.25 times maintenance for 6 wk. Changes in bodyweight of each cow were estimated from regression lines fitted to weekly weights. Height at the hooks was recorded in centimeters and condition was estimated by ultrasonic measurement or a visual score.The level of energy as fed appeared adequate for maintenance. When fed at 1.0 times maintenance there was little average gain or loss of bodyweight and the average weight change obtained from feeding at 0.75 and 1.25 times maintenance also approached zero. Least-squares analysis of the data showed no significant differences in bodyweight gain or loss between rations or breeds. In one experiment there was greater variation in weight change within two observations on the same cow than that obtained between cows. However, there was a tendency for cows with a high weight-height ratio to gain more than cows with a low weight-height ratio, as indicated by partial regression coefficients of 0.127 and 0.094 obtained in two separate experiments. Cows that had a high degree of finish tended to gain weight while those that were in a thin condition lost weight when the amount of energy fed was based on their metabolic body size. There was a highly significant correlation between condition and weight-height ratio. An equation which would adjust maintenance requirements to the condition of the cow was estimated to be—kcal DEm=130W0.75kg−(W/H−4.0) 1,716

The addition of approximately 0.5% each of high calcium, ground limestone and urea to whole-plant chopped corn at the time of ensiling increased the lactic acid content of the resultant silage by 78% on a dry basis. Treated and untreated silages were fed with soybean oil meal, alfalfa hay, minerals and dry, ground ear-corn to triplicate lots of growing-fattening heifers for 224 days. Heifers fed the treated silage gained significantly faster and required significantly less feed per cwt. gain than those fed the untreated silage.Ear-corn, 40.6% moisture, was artificially dried, ensiled without treatment or ensiled with 1% high calcium, ground limestone and approximately 6% additional water. When fed, the treated silage contained 125% more lactic acid than the control silage. The two silages and dry corn were fed to triplicate lots of growing, fattening steers for 224 days. Steers fed the treated silage gained at a faster rate, required less feed per cwt. gain, had a higher dressing percentage and graded higher than steers fed the untreated silage or dry ear-corn. These differences were all statistically significant. Dry matter losses during storage and feeding were 16.8, 16.5 and 12.6% for the treated silage, untreated silage and dry ear-corn, respectively.

Two experiments are reported in which the feed lot performance and carcass quality of early and late castrated steers and bulls were studied. There were no significant differences in these factors between steers castrated at approximately one month of age and those castrated after weaning at approximately seven months of age. Bulls gained significantly faster than steers and required less feed per unit of gain. The bulls were not as well finished as the steers at time of slaughter which influenced the carcass characters studied. The steers had a significantly higher dressing percentage and lighter hides. Bull carcasses graded significantly lower, had less fat trim and a higher proportion of edible meat. When based on an appraised live market value the bull carcasses yielded edible meat of comparable quality at a cost of ten to twelve cents per pound less than steers.

Two experiments designed to study the protein requirements of pregnant ewes are reported. Six lots of twenty ewes each were included in each experiment. In the first experiment rations which contained approximately 7, 10, and 13 percent total crude protein were compared and in the second rations containing 5, 8, and 11 percent protein.No statistically significant differences were found between the various rations in fleece weight, birth weight of lambs, or weight of lambs at thirty days of age. Some trends were noted, however, in that the ewes fed the lowest levels of nitrogen tended to shear lighter fleeces and their twin lambs weighed slightly less at thirty days.The death loss of ewes was somewhat higher on the low-protein rations. The low nitrogen intake may have been a predisposing factor in a number of these deaths.Nitrogen balance experiments showed no significant differences in nitrogen retention between the three levels of nitrogen intake during early and mid gestation. In late pregnancy the ewes fed the higher levels of nitrogen retained significantly larger amounts.A highly significant correlation (r=0.69) was found to exist between nitrogen retention and digestible dry matter intake. Covariance analysis showed that, at the levels fed in these investigations, the amount of nitrogen stored was influenced more by the amount of dry matter digested than by the amount of nitrogen fed.The results obtained indicate that present recommendations with respect to amounts of crude protein for pregnant ewes may be decreased when the rations fed are adequate in other nutrients.

A reversal of wool pigmentation from white to black and vice versa has occurred in Hampshire sheep fed rations low in vitamins A and D.Vitamin A treatments to depleted sheep of Hampshire origin brought no response in pigmentation pattern.A reversion to original wool pigmentation was noted when vitamin D was administered to lambs previously treated with vitamin A.Sheep of Delaine-Merino × Rambouillet ancestry or Columbia-type sheep that were heterozygous for black showed no pigmentation reversal pattern.There was a difference between Hampshire lambs in their response to rations deficient in vitamins A and D.

Stilbestrol, implanted as a pellet subcutaneously, did not consistently stimulate gains of growing-fattening pigs as with beef cattle and lambs.The non-treated controls required from 5.2 to 13.7% more feed per hundred pounds gain than did the treated pigs.Treatment of gilts with the levels used is not to be recommended because of prolapse of the uterus as a result of the stilbestrol.Stilbestrol treatment caused teat development in both sexes, a mild nymphomaniac response and extreme swelling of external genitalia of gilts, and in barrows, a restored ability for erection and renewed sex desire.Subcutaneous implantation in the ear is not to be recommended because of greater chance for encapsulation or cyst formation around the pellet in that area.

The results of three double reversal, nitrogen balance experiments conducted with mature ewes are presented. These experiments were designed to determine the effect of methionine supplementation upon the utilization of various amounts and sources of protein.When the results of the three experiments, in which five different rations were studied, are considered the addition of DL-methionine significantly increased nitrogen retention. The supplemental methionine had considerably greater effect when added to certain rations than when added to others. Possible reasons for these differences are discussed.L-methionine intake and excretion values were determined microbiologically in two of the experiments. The results of these analyses indicated that the supplemental methionine was either completely utilized or destroyed.When fed at approximately the same level of protein intake dehydrated alfalfa had a significantly higher biological value than field peas. The data presented suggest that some factors other than the level of protein intake or amino acid make-up influenced the utilization of protein in these experiments.

The results of four experiments are presented. There were no consistent differences in lamb production from ewes fed rations approximately equal in total digestible nutrients but which varied from 6.8 to 11.0 percent total protein. There were no apparent differences in production between ewes fed linseed meal or dried skimmilk as a protein supplement to a grass hay, shelled corn ration.Pregnant Shropshire ewes averaging 135 pounds in body weight remained in positive nitrogen balance, made satisfactory gains and gave birth to thrifty lambs when fed an average of 0.10 pound digestible protein per ewe daily. No improvement in utilization of protein or production was noted from the addition of 0.10 percent DL methionine.Further work is needed relative to the protein requirements of pregnant ewes.

A total of 992 blood samples of pregnant ewes fed various kinds and amounts of protein were analyzed for oxyhemoglobin, total serum proteins, serum albumins and serum globulins. Considerable variation was found in these constituents between individual sheep and between bi-weekly samples from the same ewe.Ewes fed rations low in protein had lower serum albumins than those fed a liberal or adequate amount of protein. Low protein rations also caused a reduction in oxyhemoglobin. Serum globulins were not affected by the rations fed.When fed at an equal level of protein there were no differences in blood proteins between ewes fed linseed meal and those fed dried skim milk as the protein supplement.Ewes with high oxyhemoglobin levels tended to have high serum albumins and low serum globulins. In these experiments serum globulins predominated over serum albumins. The oxyhemoglobin, total serum protein and serum globulin levels of individual ewes were highly correlated between years.

Two 23factorial experiments with two rations and three periods were conducted with growing-fattening steer calves. The rations consisted of a full feed of ground ear corn with limited corn silage or a full feed of corn silage and no additional grain. The periods were time constant in the first experiment and for a constant amount of gain in the second. A third experiment with the same rations and two time-constant periods was conducted with growing-fattening heifer calves.Results obtained were consistent in that cattle fed the ear corn ration gained significantly faster than those fed the silage ration, and these increased gains were similar whether the ground ear corn was fed in the first, middle or last part of the feeding period. Dressing percent was increased significantly when the ear corn ration was fed during the later periods. Some differences in carcass traits were noted; however, these were not significant and were not consistent in all experiments. Marbling scores were as high when ground ear corn was full fed early in the growing-fattening period as when fed prior to slaughter.

Silages were made from well-eared, well-matured corn which had received a normal rate of fertilization and from corn which had received an additional 200 lb. of nitrogen per acre. Neither silage contained significant amounts of nitrates. However, the high nitrogen-fertilized silage contained less beta carotene.Hereford steer calves grazing green pasture had high initial blood plasma carotenoids but low levels of vitamin A. After being fed a carotene-deficient ration consisting of white corn, molasses dried beet pulp and soybean meal for 61 days, plasma carotenoid levels declined markedly but vitamin A values increased to normal. The carotene-deficient ration at different levels of intake resulted in varying rates of gain but did not influence the rate of vitamin A depletion.Fifty-six steers which had been fed the depletion ration for 137 days were fed silage rations for 126 days. Blood plasma carotenoid and vitamin A levels quickly returned to normal after the silage rations were fed, and supplemental vitamin A had no measureable effect.Forty-two non-depleted steers were fed silage rations for 182 days, followed by a full feed of ground ear corn for 56 days. Feeding 20,000 I.U. of vitamin A per head daily brought about no improvement in performance or carcass value. However, plasma vitamin A values of nonsupplemented steers declined when the ear-corn ration which contained suboptimum amounts of carotene was fed.Growing-fattening steers were able to meet their daily vitamin A requirements from the carotene supplied by the corn silages. There were no apparent differences in feeding value of silages from corn which had received normal or excessive amounts of nitrogen fertilization.