2 p. / The beef industry has done a good job of improving the sustainability of the beef industry over the past 22 years. This fact sheet summarized the changes that have been made.

Four groups of weanling Hereford heifers were placed on four different winter planes of nutrition for a period of two years according to the following pattern: Group I - Low plane of nutrition Group II - Medium-low plane of nutrition Group III - Medium-high plane of nutrition Group IV - High plane of nutrition During the summer seasons the heifers were kept on pasture providing the same feeding level for all animals. The one year old heifers were bred during the months of June and July. All animals were weighed weekly and feed consumption was recorded weekly. To illustrate the growth rate of the heifers, K-values were calculated for all animals by the method of least squares and their growth curves were constructed. At the end of the second winter period all parturition data were carefully recorded and the rate of growth of the calves studied. From the results obtained in this experiment the following conclusions can be drawn: (1) The first post-weaning winter period is very important in regard to the feeding level of young growing heifers. The medium-low plane of nutrition (Group II) showed the best results from the economic point of view. (2) Young heifers can be bred as yearlings if the previous winter-feeding level allows them to grow continuously and to reach at least 700 pounds body weight before the breeding period starts. (3) The gestation period did not result in a decreased growth rate of the bred heifers. (4) The physical difficulties of parturition in two year old heifers do not appear to be insurmountable if the winter plane of nutrition is adequate. (5) The lactation period means a heavy drain on the young female hence a high level of nutrition must be provided in terms of sufficient amount of pasture dry matter during the grazing season. (6) Average birth weight of calves was 62.9 pounds, being higher for bull calves than heifer calves. (7) Pasture dry matter requirements for beef cattle may be calculated from the following equation: DM = 0.17 w•⁷ (w is animal weight given in pounds) / Land and Food Systems, Faculty of / Graduate

In recent years research has expanded the knowledge one has of the actual costs Involved in the growth process of meat producing animals. These studies have shown that at the higher weights a larger proportion of the gains are made up of high cost fat tissues. Initially it was thought that this fat deposition served a useful purpose in making meat tender, but it is now known that this original premise was incorrect. Fat is no longer desired by the consumer above a certain minimum level. The feedlot operator therefore has the option of taking advantage of this phenomenon and shipping animals at a lighter weight, at a lower cost, and with the possibility of doing this at a higher profit margin than is the case at present. A study has been made of the total costs involved in the production of a pound of live animal weight under feed-lot conditions and of the changes in these costs that occur as the animal achieves a higher total body weight. It was found that on the average, each additional pound of gain requires between .006 and .028 more pounds of feed than did the previous pound. As a result of these studies, an Economic Shipping Weight was proposed as a means of signifying the beginning of an increase in the average cost of production and hence, a decrease in. the rate of return to investment. The Economic Shipping Weight was defined as that weight at which the feed cost of an additional pound of gain is equal to the current value of a pound of live animal weight. In the application of this theoretically derived shipping weight to a practical feedlot operation having a total fixed investment of $162,938.00, it was found that the total return to investment was increased from $8,822 to $22,503. This increase resulted in a change in the rate of return to investment from 5.44% to 13.81%. The major part of this increase in the total margin was due to a reduction in the average feed cost of each pound of gain from 20.2¢ to 17.4¢. The total margin between sales revenues and animal purchase and feed costs was increased by $5,485.00. This reduction in feed costs was caused by a lowering of the average amount of feed required per pound of gain as the animals were theoretically shipped 41 lb. lighter than in the actual operation. Originally they were sold at an average weight of 998 lb. Seventy-six percent of them received a Choice grade. The analysis was carried out under the assumption that they would only receive a Good grade price at the Economic Shipping Weight. Other savings arose from a reduction in the total interest charges on feed purchases because of the lower total feed consumption, and from a reduction in the total feed freight bill. These two savings amounted to $4,716.00. The remaining saving resulted from a smaller in process feed cost. A study was also made of the relative advantages for the beef industry of stressing the production of Good grade beef as opposed to Choice grade beef. It appears that an economic advantage could be gained by the packing house operators, feedlot operators, and retailers, if this were to become the main grade produced. As consumers are now making most of their meat purchases on the basis of a lack of fat, Good grade meat is also more acceptable to them. The feasibility of using Dairy breed animals as a meat source was examined as a means of producing leaner meat at a lower cost than beef breed meat. These animals were shown to have a definite economic advantage at any body weight because they used feed more efficiently. Dairy breed bulls were also shown to produce meat more economically than any other dairy or beef breed animal and resulted in meat which is more desirable to the consumer. Because of their greater efficiency they had an Economic Shipping Weight of 1050 lb. as opposed to 900-950 lb. for beef breed animals. There was, however, a certain risk involved in their production because of the wide variation in the grades they may receive. / Business, Sauder School of / Finance, Division of / Graduate

In the first study 30 Hereford steers were fed a ration of either steam rolled barley or a 50:50 mixture of barley and alfalfa leaf meal pellets. In addition to these basal rations groups of animals on each, were fed a protein supplement with Diethylstilbestrol (D.E.S.) at levels such that each animal received either 0, 10, or 18 mgm. of D.E.S./head/day. The hormone treatment of animals fed the barley ration did not affect the growth rate or feed efficiency but a significant increase in hemoglobin levels from 8.96 to 10.40 gm. % Hb. and in the red cell counts from 8.25 million/mm³ to 9.50 million/mm³ resulted. A similar increase in red cell count from 8.7 million/mm³ to 9.6 million/mm³ resulted from hormone treatment of the animals fed the 50:50 barley-alfalfa ration. There was also an apparent, but insignificant, increase in haematocrits on both rations due to hormone treatment. This treatment resulted in a significant increase in the ratio of blood acetic to propionic acids on the barley ration from 82.3:1 to 195.3:1 but, did not cause a change in total blood volatile fatty acids (V.F.A.). There was an increase in the blood acetic-propionic ratio on the barley-alfalfa ration due to D.E.S. addition. This was from 97:1 to 159:1 at 10 mgm. D.E.S./head/day, to 233:1 at 18 mgm. of D.E.S./head/day but, was insignificant due to high within-group variability. There was an apparent difference between the three blood parameters (Haematocrit, Hemoglobin, Red Cell Counts) on the two control rations due to the higher iron content of the barley-alfalfa ration. This, and an apparent decrease in thyroid weights were shown to be insignificant. In the second study, using an all barley ration and a protein supplement containing a high iron concentration, there was a stimulation in growth rate and feed efficiency due to D.E.S. The animals were started on D.E.S. at 718 lb. (cf. 465 lb. for Study I). The increase in the three blood parameters was again observed on the low iron rations but, on the high iron ration there was an apparent but insignificant decrease in these parameters due to D.E.S. The animals fed the control high iron ration produced an haematocrit and red cell count that was significantly higher than that of the control low iron ration, indicating a possible deficiency in the original supplements. On the low iron ration there was a significant increase in total blood V.F.A. from 0.88 meq./l. to 1.19 meq./l. in response to D.E.S. supplementation but, on the high iron ration the increase was insignificant. The difference between the two control rations (0 D.E.S., high and low iron) total blood V.F.A. was shown to be significant, 0.88 vs. 1.08 meq./l. at P< .05. A method of preparation of feed and liver samples for analysis of their mineral content by atomic absorption spectrophotometry was developed. There was shown to be a significant increase in liver copper storage on the low iron ration with increased levels of D.E.S. The feeding of a high iron ration caused a significant decrease (P< .05) in the level of copper in the liver from 84 ppm. to 37 ppm. A slight but insignificant increase in liver iron levels on the high iron ration and through the treatment with D.E.S. was observed. / Land and Food Systems, Faculty of / Graduate

The dark, firm and dry (DFD) or dark-cutting condition causes large losses to both the cattle feedlot and meat industry due to its unattractive, dark red colour and its limited shelf life. Dark-cutting, is a direct consequence of low muscle glycogen at slaughter and results in a lack of normal acidification of meat during rigor development causing high pH (>5.8). Glycogen breakdown in muscle may be rapidly triggered by increased circulating adrenaline or by strenuous muscular activity. Several other factors have also been found to lead to the DFD condition in cattle. The aims of this investigation were to determine the incidence of DFD in cattle slaughtered at a South African abattoir and to identify potential causative factors of this syndrome. It was furthermore also important to evaluate the sensory attributes, microbiological quality and hence, shelf life of DFD meat. The incidence of DFD carcasses, based on pH measurements (threshold ~ 5.8) within I h post mortem on 22 178 cattle in the M. longissimus dorsi, was 11.8%. The estimated overall incidence measured over a 5 -day period, testing only cattle supplied by the four main feedlots, was 7.83% (N= 5 659), measuring pH 24 (~5.8), confirmed by colour grades (values of 7 or 8 were classified as DFD). The incidence of dark-cutting beef, also seemed to be feedlot related with the highest being 12.37% and the lowest 1.75%. It is suspected that the incidence of DFD carcasses is higher in extremely hot or cold weather or large fluctuations, and should decrease during the months with milder temperatures. Transport distances did not affect the DFD incidence. In experiment 2, cattle from Feedlot C, transported over a short distance (45 km) had a higher incidence of DFD (9%) than those of Feedlot A (1.7%), transported over the longer distance of 290 km. Long holding periods in the holding pens at the abattoir (>24 h and even as high as 54 h), appeared not to have a significant influence on the occurrence of DFD. There was no correlation between bruised carcasses and DFD carcasses (the respective means of bruising were 6.7% and 3%, and respective mean incidences of DFD were 1.7% and 9%). Using Scheffe's test to compare the effect of gender on the incidence of DFD, significantly more bulls and steers were affected by dark-cutting than heifers (P< 0.0001). Mounting behaviour among young bulls, and social regrouping of steers during the pre-slaughter period, have been shown to increase the incidence of dark-cutting. Avoidance of mixing unfamiliar bulls and steers during transport and holding periods has been recommended to minimise stress. The low incidence of dark-cutters (P > 0.05) in heifers could possibly indicate a non-¬oestrus situation in the majority of the heifers, since a significant association between the presence of oestrus and DFD was shown previously by other researchers. The effect of gender on the incidence of dark-cutting, related to feedlot, was also significant. Higher incidences of DFD were found with steers of Feedlots B, C and 0 (14.5%, 11.6% and 13.7% respectively) than in Feedlot A (1.9%). The lowest overall incidence of dark-cutters was found in Feedlot A (1.7%). It appeared as if the breed type of the cattle had an effect on the dark-cutting beef. The Bos indicus (Brahman-type) animals had a significant effect (P< 0.001), on the colour of the beef when compared with European breeds. Cattle of two feedlots, fasted for periods of 40 hand 60 h, showed that a shorter fasting period had a significant effect (P < 0.001) on the pH. It appeared as if pre-slaughter stress, induced dark-cutting more readily in fasted than in fed cattle. Fasting also inhibited muscle glycogen re-synthesis during recovery of stress. The effect of pre-slaughter handling on the blood composition and muscle glycogen content of cattle of three different feedlots was studied. After transport (phase 1), the glycogen depletion was significant for all three feedlots (P < 0.05). Further glycogen depletion was found after slaughter (phase 2) (P < 0.01). The hematocrit increased after transport, which indicated that animals of Feedlot B (P < 0.0001) experienced stress. During the second phase, a significant decrease in hematocrit for Feedlot B was observed (P < 0.05). For Feedlot A, a non-significant increase was found in phase 1, with a significant (P < 0.05) increase in phase 2. The hematocrit of cattle of Feedlot C, however, showed a significant decrease during both phases. The blood glucose concentration for all three feedlots increased during phase 1, but was not significant. However, the blood glucose concentrations for all three feedlots increased significantly during phase 2 which probably indicated that the animals experienced stress during this period. The increase in creatine kinase was significant (P < 0.01) during both phases 1 and 2 for Feedlot A. Fluctuations were found in the creatine kinase concentrations of Feedlot C. Feedlot B, however, showed a significant decrease in the creatine kinase concentrations. Free fatty acid concentrations for all feedlots increased linearly over the different stages. The high free fatty acid concentrations in blood samples of phase 2, of Feedlots Band C confirmed that these animals experienced stress, especially from the period being held in the pens to after slaughter (P < 0.01 for both). The free fatty acid concentration, appear to be the best blood parameter to relate to meat quality. The DFD incidence during this experiment, for Feedlots Band C, is 35%. For Feedlot A, with the lowest DFD incidence (16%), the increase of free fatty acid concentration was not significant. Although the effect of growth promoters was not tested, the use of beta-agonists as growth promoters may increase the incidence of dark-cutting meat unless a sufficient withdrawal period before slaughter is observed. Feedlots A and C implanted Revelor in 9 month old cattle, while Feedlot B implanted both Synovex S (at 6 weeks) and Revelor (at 4 months). Consumer sensory evaluations indicated that the general appearance (P < 0.05), colour (P < 0.001) and acceptability (P < 0.01) of raw normal steak were preferred significantly to those of raw DFD steak. Twice as many panellists preferred the raw normal steak than raw DFD because of the more attractive red colour, compared to the almost black colour of raw DFD steak. The hedonic ratings of the sensory attributes of fried normal steak versus fried DFD steak were non-significant for all attributes, although it was expected that consumers would find the DFD steak more tender and less flavoursome than normal steak. DFD meat samples (N= 84) were tested over a 7-week period for total aerobic count, Pseudomonas, coliforms and Eschericia coli. Normal beef samples were expected to be acceptable, both on microbiological grounds and sensory evaluations until at least the seventh week. Microbiological spoilage of vacuum-packaged DFD meat took place during the second week and deterioration was more evident during the fourth week, due to the presence of cheesy odours. During the fifth week, green discolouration of the meat was observed. / Dissertation (MSc Agric (Food Science))--University of Pretoria, 2007. / Food Science / unrestricted

Phosphorus loads in waterways are a focus of environmental concern. Animal agriculture\'s contribution to this problem has been documented and efforts are focused on mitigating the issue. The effect of increasing amounts of mineral P supplementation on fecal P characteristics was studied in forage fed beef steers. Eight Hereford steers were fitted with total fecal collection bags and fed four diets with a low P grass hay and supplemented with increasing amounts of a mineral source of P, dicalcium phosphate. Dietary DM P concentrations were 0.10 (no P supplementation), 0.23, 0.34, and 0.45% P. Manure was sampled and dried, followed by analysis for total P and inorganic P (Pi). Blood was collected via jugular venipuncture following each collection period and plasma Pi was quantified. Total fecal P increased linearly with increasing dietary P concentration: 6.44, 10.6, 16.1, and 18.8 g/d (P < 0.0001). Fecal Pi increased linearly with increasing dietary P concentration: 1.58, 2.43, 2.74, and 3.84 g/d (P = 0.0119) Manure P solubility, however, did not increase with increasing dietary P concentration: 23.6, 22.3, 17.3, and 20.2% (P = 0.3646). Plasma Pi increased linearly with increasing dietary P (P = 0.0047). ADG and G:F were not affected by increasing dietary P content. Reducing or eliminating mineral P supplementation to forage fed beef animals is possible, if forage base proves to be adequate in P. Reducing dietary P reduces fecal P excretion and the pollution potential in ecologically sensitive areas like the Chesapeake Bay watershed. / Master of Science

Native Warm Season Grasses (NWSG) provide excellent wildlife habitat and are well adapted to the Southeastern United States. Steaks that were obtained from cattle fed NWSG in the stocker phase and finished on grain and tall fescue were subjected to simulated retail display for 0, 3, 6, and 9 days (graininished) and 0, 3, and 6 (forageinished) days respectively. Grain finished carcasses graded as choice and select while forage finished carcasses were both select and standard. Fat percentage was higher and moisture was lower in steaks from grain finished carcasses when compared to forage finished cattle. Lipid oxidation was lower in forage finished steaks on day 6 (0.35mg malonaldehyde/kg) than grain finished steaks (0.5mg malonaldehyde/kg). The overall acceptability scores given by consumers for both treatment groups were between like slightly and like moderately.

The objectives of this study were to evaluate the effects of: (1) metaphylactic antibiotic administration (none or Excede on arrival); and (2) receiving diet crude protein levels (17.1 % or 11.9 % CP) on respiratory disease incidence, mortality, and growth performance of beef calves received into a stocker system as well as the influence of stocker treatment on feedlot and carcass performance. For the stocker phase, steers (n = 244) were stratified by BW and randomly assigned to 20 pens. Treatments were randomly assigned in a 2 x 2 factorial study design. At the conclusion of the stocker phase, 76 steers were sent to Tri County Steer Carcass Futurity in Lewis, IA. Metaphylactic treatment reduced the incidence of BRD and increasing CP in the receiving ration to 17.1 % resulted in greater ADG. Health, nutrition, and management during the stocker phase can impact feedlot and carcass performance.

No description available.

Two hundred and nine beef carcasses (361 ± 53 kg) from crossbred, grain-finished cattle harvested in a commercial packing plant and evaluated for marbling score, core temperature (n=1), pH, shrinkage, color, and aerobic plate count (n=50) for 24, 48, 72, and 96 h under spray chilling. There were minimal changes in shrinkage among time points (-0.4 to 1.2%; P ≤ 0.002), pH (5.56 to 5.69; P ≤ 0.001), and APC (0.1 to 0.7 log; P ˂ 0.001). Marbling score values were converted to numeric values of 200 (Practically Devoid00) to 1100 (Abundant00). Carcasses with SM or greater marbling score at 24 h had a 34 to 60 points deduction after 96 h of spray chilling (P ≤ 0.042), the SL carcasses had an increase marbling score, from 442 to 469 points. Moreover, SL carcasses had a greater percentage of PUFA (P < 0.001).