by: Guillermo Scaglia
Louisiana State University, Agricultural Center, Iberia Research Station
In the United States, much of the beef produced and sold before World War II was from grass- or limited grain-fed cattle. However, development of the modern large-scale cattle feeding industry in the 1950s and 1960s increased supplies of grain-fed beef and, by the early 1970s, many American consumers were able to find only beef from heavy, grain-fed cattle in supermarkets.
In recent years, consumer demand has grown for products produced through less industrialized animal production systems and, in this group, forage-finished beef programs are included.
Rationale for Finishing Beef Cattle on Forage
Use of pasture and forage is the world's most common beef production system. Through photosynthetic processes, green plants combine nutrients obtained from the soil and sunlight to produce plant material and compounds that can be harvested and processed by the ruminant animal into edible tissues. Until recently, the focus of most beef weaning program research was to evaluate the impact of age and diet on calf performance, with particular interest on pre-conditioned health programs, maximizing weight gain and acclimation of calves for concentrated feeding systems in feedlots for the slaughter market.
Development of a forage-based system necessitates research to evaluate its potential for weaning and continuation in forage-based replacement heifer and harvest (market) systems. Successful livestock production depends on forage programs which supply large quantities of adequate quality, homegrown feed. Major percentages of the feed units for beef (83 percent) and dairy (61 percent) cattle come from forages.
Forages provide benefits to the local environment. Perennial forage species are deep-rooted and consequently greatly reduce erosion and protect watersheds from flooding. Soil erosion losses from pasture have been estimated to be about 0.12 tons per acre compared to more than 1.7 tons per acre under conventionally cultivated cropland. Extensive root systems of forages add significant amounts of soil organic matter. A three-year-old perennial forage crop has been reported to return more than twice the soil organic matter as annual cereal grain crops.
Energy conservation is another benefit. Nutrient recycling from grazing animals lowers fertilizer inputs as compared to row-crop production, and pesticide usage tends to be lower on grasslands than other crop areas.
Though there are advantages, grazing programs using small-grain forages have faced several challenges, including too much or too little precipitation causing delayed planting, poor growth and muddy conditions. Establishment of annual grasses into living, partially killed or completely killed perennial sods is becoming increasingly possible with a combination of ecological strategy, conservation tillage and herbicide-resistant plant varieties.
A major limitation to producing beef from forage for the harvest market is the uneven seasonal distribution of forage production and associated nutritive value. Forages can supply up to 75 percent of the metabolizable energy and dietary crude protein requirements of grazing livestock. Forage composition influences intake, digestion rate, rate of passage through the animals and nutrient-use efficiency. Forage plants differ in available energy derived from total non-structural carbohydrates, fiber digestibility and protein degradation in the rumen. Botanically diverse pastures can extend the grazing season, improve system stability and help meet season-long nutritive demands of cattle.
Intensive rotational pasture stocking and interseeding or overseeding can improve forage nutritive value and herbage distribution over the grazing season. Additionally, grazing animals distribute manure across the field contributing to soil fertility and can result in reduced purchased fertilizer inputs. However, the nitrogen (N) to energy ratio in grazed herbage is often not balanced for efficient capture of forage nitrogen by livestock.
Forage combinations can be created to improve the N to energy ratio. Legumes added to forage-based diets improve overall weight gain of ruminants. Cattle stockered and finished on alfalfa-orchardgrass pastures had greater gains and more desirable carcass traits than those finished on tall fescue-based pastures with and without legumes.
Legumes are an important component of a grazing system because they extract atmospheric N and convert it to plant-available forms within their roots. The amount of N fixed by legumes varies among species due to soil conditions, amount of available water and other seasonal factors and it can range from 9 to more than 121 pounds per acre of N annually. A Texas study found that adding a cool-season clover to a warm-season perennial grass extended the grazing season, raised the nutritive value higher than the grass alone, and provided excellent summer weed control.
A holistic and integrated approach is intended in my research at the Iberia Research Station in order to integrate production, product evaluation (safety, nutrition and consumer acceptance), and marketing of the product with educational program aimed at assisting producers in starting integrated forage-fed beef businesses and improving the production and economic viability of existing forage-fed beef enterprises.
Annually, 54 steers are assigned to one of three forage systems (treatments under evaluation) immediately after I receive them and remain in that forage system until the time of harvest at an age of 17 to 19 months. At this time, carcass information is collected, rib sections obtained, samples are transported to the laboratory and a myriad of analyses are conducted, including consumer evaluation of the beef produced.
All systems have the same stocking rate (2.5 acres/head): Systems 1 and 2 have 3 paddocks (Paddocks A,B and C which are 45, 35 and 20 percent of the area, respectively); System 3 has 5 paddocks (Paddocks A,B,C,D and E which are 20, 20, 45, 7.5 and 7.5 percent of the area, respectively). The three-system treatments represent different forage sequences with different degrees of management complexity and expertise required for appropriate utilization of resources.
Are these the only options? Of course not, but these systems will provide information that will help define appropriate systems and forage resources to use. An explanation of what forage is available in each paddock follows above right.
Data are being collected and will be analyzed at the end of the project. It will be made available to all producers at field days, producer meetings, newsletters, magazines and other possible venues.
All this work can only be done when you are able to interact and cooperate with faculty members from other disciplines and beef cattle producers. I am lucky to be able to do so with very accomplished individuals from the School of Animal Sciences, Food Science, Agricultural Economics and Agribusiness, and School of Plant, Environmental and Soil Sciences, from the Louisiana State University Agricultural Center and the Department of Food Science and Nutrition at Southern University.
Similarly, forage-fed beef producers from the region have devoted time to interact with me providing feedback that strengthen the project and aid in determining future areas of research. This research has been possible through competitive grants provided by Southern SARE and USDA/AFRI.
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