Final Report for GS08-069
Project Information
Fall-born steers (n=60) were used to examine age at harvest and differing forage types on average daily gains, carcass characteristics, and instrumental color characteristics. Steers were placed on annual ryegrass in late fall and allowed to graze. At the onset of grazing, the first group (n=10) of steers were harvested to serve as a baseline for the remaining 5 groups. Every 56 days, a group of steers were harvested until all 6 groups had been harvested. In late spring, remaining steers were moved to a warm-season pasture. Data indicate that increased days on forage allowed for greater marbling, hot carcass weight and greater amounts of backfat.
Introduction
Forage-fed beef has gained momentum in the past years due to a variety of reasons. One reason is the rise of input costs of shipping cattle to the Midwest and High Plains for finishing in feedlots. This has been the mainstream of the industry since the 1950’s when the feedlots were established. Recent spikes in fuel and feed has forced producers to examine alternative finishing strategies for their cattle. Not only have the spikes hurt the cattle feeding industry, but constant rises in fuel and feedstuffs have impacted the producers’ bottom line. Another reason is that producers want to keep their investments local, which is virtually impossible if the cattle are shipped 1000 miles away for feeding. The obvious solution would be to build feedlots in the southeast for the cattle for finishing, however, environmental and climate factors do not allow for this type of operation. Due to the abundant rainfall and high humidity, feedlots are not feasible alternatives for finishing. Lack of economical feedstuffs also do not allow for the construction and operation of these feedlots.
Local, organic and natural products have also risen in popularity among consumers. The need to know where their food comes from is at an all time high and some producers have taken advantage of this. While organic and natural products create an excellent marketing ploy, most beef producers do not have the capabilities to do so. Moreover, the lack of regulation in the organic market also creates problems for producers. However, locally produced commodities such as forage-fed beef provide an excellent opportunity for producers to market their products. Whether it is a freezer beef operation or a small scale fresh meat market, the opportunity for income is great if a market is established.
While the southeast is not suitable for large scale feedlot finishing, the same things that make it unsuitable for such uses, make it extremely suitable for forage production. The ample amounts of rainfall and the amount of land available for forage production provide an excellent opportunity for large scale forage finishing of beef. This capability allows producers to keep their investment local by allowing for the production and sale of their product within their respective regions. The climates and soils in the southeastern region of the United States are well-suited to forage production and near year-round grazing, and offering opportunities to develop high forage stocker and finishing systems (Allen et al., 1996). Feeding forages can offer economic benefits greater than those of feed grains due to the fact that they are generally less expensive than feed grains per unit of energy or protein (Dixon and Stockdale, 1999). Brown et al. (2005) contributed part of the economic benefit of forages to the fact that there is no cheaper method of harvesting swards than is afforded directly from grazing. Early research in the area of forage finished beef showed promise for producers. However, with the industry shifting towards feedlot finishing in the 1950’s and 60’s, research slowed and moved more towards that of feedlot finished beef. However, in recent years, research has shown a renewed interest in forage finishing.
Kerth et al. (2007) found in a trial using both beef from a traditional feedlot feeding regimen and beef that was fed ryegrass that about 20% of consumers were willing to pay a premium for the forage-fed beef. They went on to conclude that in a niche market, the opportunity for a viable market could be present and could be a good alternative for producers. Consistency and quality have long been issues for forage-finished beef. Crouse et al. (1984) found that cattle on a forage diet had lower amounts of marbling, KPH, hot carcass weights and live weights compared to cattle on a grain diet. However, shear force values and sensory evaluation values were similar among the two divergent groups. This indicates that although notable physiological differences can exist between feeding regimens, similar quality parameters can be met. It is possible that the very things that make forage-fed beef different from grain fed beef such as fat cover and carcass size can benefit the producers of forage-fed beef by offering a smaller carcass with less total fat.
Literature Cited
Allen, V. G., J. P. Fontenot, R. F. Kelly, and D. R. Notter. 1996. Forage systems for beef production from conception to slaughter: III. Finishing Systems. J. Anim. Sci. 74: 625-638.
Brown, Jr., A. H., P. K. Camfield, Z. B. Johnson, L. Y. Rakes, F. W. Pohlman, C. J. Brown, B. A. Sandelin, and R. T. Baublits. 2005. Interaction of beef growth type x production system for carcass traits of steers. Asian-Aust. J Anim. Sci. Vol. 18, No. 2:259-266.
Crouse, J. D., Cross, H. R., Seideman, S. C. 1984. Effects of a grass or grain diet on the quality of three beef muscles. J. Anim. Sci. 58: 619-325.
Dixon, R. M. and C. R. Stockdale. 1999. Associative effects between forages and grains: consequences for feed utilization. Aust. J. Agric. Res. 50:757-73.
Kerth, C. R., Braden, K. W., Cox, R., Kerth, L. K., Rankins, Jr., D. L. 2007. Carcass, sensory, fat color, and consumer acceptance characteristics of Angus-cross steers finished on ryegrass (Lolium multiflorum) forage or a high-concentrate diet. Meat Sci. 75: 324-331.
The objectives of this project were: 1) examine differences between cool- and warm- season forages, 2) examine effects of age at harvest on quality and carcass characteristics, 3) examine forage effects on quality and shelf life characteristics of the differing age and forages on the cattle, 4) provide information to producers and researchers on the differences between cool- and warm-season forages effects on beef cattle.
Research
Fall born steers (n=60) were used to examine the effects of forage type and age on average dialy gains, carcass, instrumental color, and quality characteristics of forage-finished beef. Steers were held on dormant pasture until late fall and were then placed (December 9, 2008) on annual ryegrass and allowed to graze. Steers were stratified using starting weight into predetermined harvest groups and at the onset of grazing, Group 1(n=10) was harvested to serve as a baseline for the remaining groups. Groups were numbered in the order of harvest date where Group 1 was the first group and Group 6 was the last group. Every 56 days thereafter groups were harvested. Steers were weighed every 28 days to access average daily gains and forage value. After harvest group 4, steers were moved to a bermudagrass and fescue pasture for 28 d. Steers were then moved to a crabgrass pasture for the duration of the grazing period. Steers were allowed to graze in the same pasture to eliminate variation among forages in differing pastures. Twenty-four hours postmortem, carcass characteristics were recorded. Characteristics included ribeye area, hot carcass weight, kidney, pelvic and heart fat, backfat at the twelfth and thirteenth rib, marbling amount, lean and fat color, and pH. Left strip loins were then removed; vacuum packaged and aged in dark until muscles were 14 days postmortem.
Upon completion of aging, steaks were cut and designated to one to three treatments. Treatments were 14 days aging, 21 days again, and simulated retail display for seven days. The 14 days aging steaks were vacuum packaged and frozen until time of analyses. The 21 days aging steaks were vacuum packaged, and stored in dark for 7 days and then frozen until time of analyses. The simulated retail display steaks were placed on a foam tray with an absorbent pad and overwrapped with PVC film and placed in a retail coffin case. Instrumental color was recorded for the steaks in display using a Hunter Labs Miniscan using the 10o standard observer with illuminant D 65. CIE L*, a*, b* and reflectance values were taken. Hue angle or trueness of red was calculated as Tan-1(b*/a*), saturation index or vividness was calculated by taking the square root of (a*2 + b*2), and the 630/580 nm ratio was calculated by dividing the reflectance values at 630 nm by the reflectance values at 580 nm for the oxymyoglobin to metmyoglobin proportion. Warner-Bratzler shear force values for steaks were determined by using the method of Kerth et al. (2003).
Data were analyzed using mixed model procedures in SAS. Fixed effect for carcass characteristics and average daily gain was harvest group. Fixed effects for shear force were harvest group and aging treatment. Instrumental color fixed effects were harvest group and day and analyzed as a repeated measure. Days 0 and 6 (starting day and ending day of display) were used for the analysis of instrumental color. When there was a significant F-Value for the model, means were separated with the Fisher’s protected LSD using the PDIFF option of SAS. Least squares means were generated by using the LSMEANS option of SAS.
Literature Cited
Kerth, C. R., Blair-Kerth, L. K., Jones, W. R. 2003. Warner-Bratzler shear force repeatability in beef longissimus steaks cooked with a convection oven, broiler, or clam-shell grill. J. Food Sci. 68: 668- 670.
Average daily gains were highest (P < 0.05) for Group 2, but were not different (P > 0.05) from Group 4. Groups 5 and 6 had similar (P > 0.05) values and were lower than the other groups. Average daily gains were different as expected due to differences in the amount of days that each group was on forage. It would then be expected that as the cattle grew larger, gains would decline. In agreement, Pyatt et al. (2005) found that in feedlot cattle as that number of days on feed increased, average daily gains decreased. Moreover, Groups 5 and 6 grazed warm-season forages in the latter parts of their time on forages. It is generally accepted that cool season small grains are more palatable than that of warm-season perennial forages.
Group 6 had greater (P < 0.05) amounts of backfat, marbling, bone maturity, yield grade, hot carcass weights and live weights compared to all other groups. The higher hot carcass weights, live weights, yield grade and bone maturity is expected due to the increased days on forage and older physiological age compared to the other groups. Increased backfat and marbling of group 6 suggest that chemical maturity had been reached and more energy was being partitioned to fat accretion rather than growth resulting in greater amounts of both types of fat. May et al. (1992) using steers fed a feedlot diet found that maturity, marbling scores, backfat thickness and carcass weight all increased with increased days on feed. Group 1 had the highest (P < 0.05) pH among groups while all other groups were not different (P > 0.05) from each other. Group 1 having a higher pH is most likely a function of energy stores due to the low energy diet that the steers were consuming prior to the onset of grazing. The stress of transport and a new location could have exhausted glycogen stores and reduced lactic acid production resulting in higher ultimate pH. Group 1 also had the smallest (P < 0.05) ribeye area, however, groups 4, 5, and 6 had the largest ribeye areas with similar (P > 0.05) values. Values for kidney, pelvic and heart fat showed Group 6 having the highest (P < 0.05) amount but not different (P > 0.05) from Group 4. Fat b* values which are a measure of yellowness revealed Group 6 having more (P < 0.05) yellow fat than Groups 2 and 4 but was not different (P > 0.05) from Groups 3 and 5.
Main effects of harvest groups and aging treatment for shear force were significant; however the interaction of the two was not. Group 2 steaks required the greatest (P < 0.05) amount of force to shear through compared to all other groups. Group 3 had a lower (P < 0.05) value than Group 2, but had a greater (P < 0.05) value than the other 4 groups which were not different (P > 0.05) from each other. Aging treatment showed 14d and 21d aging were not different (P > 0.05), however, the simulated retail display steaks required less (P < 0.05) force than the other two treatments. The reasoning for the differences between harvest groups is not known. Cold-shortening could be a potential reason for the differences between the groups, however, that cannot be confirmed because sarcomere lengths were not measured. The differences in the aging treatments are most likely a function of increased degradation within the muscle. However, the lack of significant differences between the 14 d aging and 21d aging treatment suggest that by d 14 of aging, proteolysis was near complete or that more aging was needed to show differences. The simulated retail display steaks having a lower value than the other two treatments suggest that the increased holding temperature (2o C for 21d aging vs. 5o C for simulated retail display) increased proteolysis as compared to the 21 d aging group.
Harvest groups by day interactions were significant for all instrumental color measures. The L*, or lightness values interaction occurred due to Group 1 being different (P < 0.05) from all other groups on day 0, but was similar (P > 0.05) to other groups on day 6. As expected, there was a decline in L* values from day 0 to day 6, except for Group 1, which had a lower value on day 0 than on day 6. This is likely due to the fact that Group 1 had a high ultimate pH which allows for a darkening effect known as DFD, or dark, firm and dry. The lightening effect could be a result of losing moisture and allowing increased light scattering which would raise the L* values. The a* interaction occurred because on day 0, Group 6 was higher (P < 0.05) than groups 2 and 4, however, on day 6, Group 6 was similar (P > 0.05) to group 4 and lower (P < 0.05) than Group 2. The a* values, or redness decreased from day 0 to day 6 which is expected for steaks packaged in PVC film. The reasoning for the greater decline of Group 6 than Groups 2 and 4 is not known. Several factors can be involved in maintaining color characteristics such as metmyoglobin reduction potential, antioxidant status and the amount of unsaturated of fatty acids and free fatty acid amount. The amount, type and unsaturation of fatty acids may play a role in the loss of color stability due to the radical species that are developed during the oxidation processes of fatty acids causing damage or oxidation of the myoglobin pigments (For review see Faustman and Cassens, 1990).The b* or yellowness value interaction was caused by Group 1 having a higher (P < 0.05) value than all other groups on day 0, but was similar (P > 0.05) to other groups on day 6. Once again, b* values deteriorated as expected from day 0 to day 6. The hue angle interaction was caused by Group 1 having a higher (P < 0.05) value than the other Groups on day 0, but was similar (P > 0.05) to other groups on day 6. Hue angle values increased from day 0 to day 6 of display showing a decrease in the trueness of red color among the steaks. The saturation index or vividness interaction was due Group 1 having a higher (P < 0.05) index on day 0 compared to having a similar (P > 0.05) value to other groups on day 6. The values for saturation decreased from day 0 to day 6 indicating a loss of vividness among steaks which is expected. The 630/580 nm ratio, which is a measure of oxymyoglobin to metmyoglobin proportion, had a significant interaction caused by Group 1 having a higher (P < 0.05) oxymyoglobin proportion on day 0 compared to day 6 when it’s values were similar (P > 0.05) to other groups. As expected, oxymyoglobin proportions decreased from day 0 to day 6 indicating that oxidation of the heme iron from the ferrous state to the ferric state.
Literature Cited
Faustman, C. and R. G. Cassens. 1990. The biochemical basis for discoloration in fresh meat: A review. J. Muscle Foods. 1: 217-243.
May, S. G., Dolezal, H. G., Gill, D. R., Ray, F. K., Buchanan, D. S. 1992. Effects of days fed, carcass grade traits, and subcutaneous fat removal on postmortem muscle characteristics and beef palatability. J. Anim. Sci. 70: 444-453.
Pyatt, N. A., Berger, L. L., Faulkner, D. B., Walker, P. M., Rodriguez-Zas, S. L. 2005. Factors affecting carcass value and profitability in early-weaned Simmental steers: II. Days on feed endpoints and sorting strategies. J. Anim. Sci. 83: 2926-2937.
Educational & Outreach Activities
Participation Summary:
This research was done as part of a requirement for the dissertation of Clinton W. Rowe with an expected completion date of December, 2010.
Project Outcomes
The data indicate that it is possible to produce forage-fed beef into to the late summer months and still have good carcass characteristics. Moreover, the data indicates that gains of greater than 0.5 kg/day can be achieved over a period of 280 days, indicating that regardless of forage type, production can remain high. Marbling and backfat accretion still remain a problem for forage-finished beef in that the diets do not generally have enough energy to produce highly marbled beef. However, Group 6 achieved an average low choice designation with a small amount of marbling. Color stability of forage-fed beef is still convoluted in that the exact mechanisms involved in color deterioration are not fully understood. However, with the industry standards shifting to modified atmosphere packaging, the PVC overwrap represents the worst case scenario which shows promise.
Economic Analysis
Economic analyses were not part of this proposed project.
Farmer Adoption
Although farmer adoption was not a part of this project, some preliminary data were presented to approximately 120 farmers and ranchers at the Auburn University Locally Produced, Locally Marketed Field Day. The Field day took place at the E. V. Smith Research Center and on the campus of Auburn University. The data used were from cattle harvested prior to the field day. It presented a unique setting where the farmers and ranchers could see the data from previous groups as well as the groups that were destined to be harvested at a later date. The focus of the presentation was not to tell the farmers and ranchers what to do, but rather options on what they could do. Data that were presented were carcass characteristics and average daily gains as well as weather and rainfall data. The field presentation was then followed by a question and answer and discussion session to allow for the exchange of ideas and also to answer questions not discussed in the presentation. More time is needed to examine the amount of farmer adoption.
Areas needing additional study
Areas that are in need of additional research are forages and meat quality. Due to the variability among forages in regards to energy and meat quality impacts, more research is needed to elucidate forages that can provide good growth characteristics without impacting meat quality. Variability among carcasses also needs to be addressed. The lack of a standard of identity in the forage-finished beef market will eventually need to be addressed by means of cattle biological size or by the amount of finish. Moreover, common forage types among differing areas of the southeast could potentially help with producing and maintaining a standard of identity.