Influence of Spring Burning on Cattle Diets and Performance on the Edwards Plateau

Immediately following spring burning of Edwards Plateau rangeland, steer diets had a higher percentage of grass and lower percentage of forbs than diets from unburned range. Intake of pricklypear cactus was greater on burned range than on unburned during the fiist summer and fall following the fire. Ash content of steer diets in the bum was generally higher, due primarily to increased use of pricklypear cactus on burned sites. Steer diets from burned range contained significantly higher in vitro digestible organic matter (IVDOM) during June. Increased use of pricklypear cactus contributed to a signiftcantly higher IVDOM during September and October and lower percent crude protein from September to November in the burn. Heifers gained significantly more on burned range during June and August and also when averaged across the entire S-month grazing period. Burning has potential as a useful tool to increase cattle production from Edwards Plateau rangeland. Fire is recognized as a major ecological factor in many rangeland ecosystems (Daubenmire 1968) and is gaining acceptance as a range improvement tool (Scifres 1980). Livestock prefer burned to unburned areas (Humphrey 1949) and generally have greater weight gains on burned areas (Anderson 1960, Anderson et al. 1970, Woolfold et al. 1973). Anderson (1964) reported increased gains following late spring burning in the Kansas Flint Hills and attributed this to increased protein content and digestibility of little bluestem (Schizuchyrium scoparium). Greene (1935) reported a 14.5 kg/yr/head. increase in steer gains following annual winter burning in the longleaf pine (Pinuspalustris) belt and noted that two-thirds of this advantage in gain was made before June of each year. Hilmon and Hughes (1965) found that cattle gain increased 17 and 39 kg/ha after burning timbered range in Georgia and Florida, respectively. This increase in gain was attributed to greater palatability, quality, and production of wiregrass following burning. In Mississippi Greene (1929) reported annual burning of bluestem pastures increased cattle gain by 20 kg/ ha. Greene attributed this increased gain to greater availability of green forage on burned pastures, and noted that the best gain occurred 60 to 90 days following the fire, with no difference in gain between burned and unburned pastures after that time. In Florida, Kirk and Hodges (1970) reported annual winter burning of half of the range each year increased weaned calf crop from 53 to 69%, gain/calf from 10.1 to 13.1 kg/ha, and gain/cow from 81.6 to 106.1 kg. No published data relating livestock performance to prescribed burning are available for Texas rangelands. Little data are available from any area which relates animal gains following burning to changes in livestock diet quality or composition. The purpose of this investigation was to determine the influence of burning on botanical and nutrient contents of diets and cattle gains on Edwards Plateau rangeland. Authors are, respectively. Extension range specialist, Texas Agricultural Extensiqn Service, Fort Stockton; professor, Department of Range Science, Texas ABM Umversity, College Station;and professor.Texas A&M University Agrwltural Research Station, Sonora. At the time of this research, McGinty was a research assistant, De rtment of Range Science, Texas A&M University. r hs report is published with approval of the Director, Texas Agricultural Experiment Station as TAManuscript received May 20, 1981. JOURNAL OF RANGE MANAGEMENT Z%(2), March 1983 Study Area The study was conducted on the George Brockman Ranch near Sonora, Texas, in the Edwards Plateau. The Edwards Plateau is a partially dissected remnant of an uplifted plain capped chiefly by resistant limestones (Long 1962). Soils on the study area are Lithic Haplustolls of the Tarrant and Kavett series (Wiedenfeld and McAndrew 1968). Climate of the area is semiarid, mesothermal with an average annual evapotranspiration and rainfall of approximately 90 and 57 cm, respectively. May and September are the wettest months and average about 8 cm of precipitation each. Droughts are common and 53% of the years have below-average precipitation. Edwards Plateau summers are warm and dry with an average July temperature of 30” C. Average Januarytemperature is 90 C (Long 1962). The study area lies within the live oak-Vasey shin oak (Quercus virginiana-Quercus pungens var vaseyanal) vegetation type (Harris 1958). Dominant herbaceous plants on the study site included common curlymesquite (Hilaria belangeri), threeawn (Aristida spp.), sideoats grama (Bouteloua curtipendula) hairy tridens (Erioneuron pilosum), Texas wintergrass (Stipa leucotricha), red grama (Bouteloua trifida) and sedges (Curex spp.). Woody plants of importance were live oak, Vasey shin oak, Texas persimmon (Diospyros texana), honey mesquite (Prosopis glandulosa var gkwadulosa), ashe juniper (Juniperus ashei), redberry juniper (Juniperus pinchoti), and lotebush (Condalia obtusifolia). Vegetation of the area has changed significantly due to past overgrazing by livestock and elimination of fires(Bray 1906). Until approximately 1945 the Brockman Ranch was stocked with cattle, sheep, and goats at a yearlong rate of 3.0 to 4.0 ha/ AU. From 1945 to the present the yearlong stocking rate was 8.5 ha/AU, with cattle, sheep, and goats. A 162-ha fenced pasture which was representative of the soils, topography, and grazing history on the ranch, was selected for study. Range condition on the low stony hill range site was rated as mid-good using Soil Conservation Service evaluation procedures. Within the past 5 years selected woody plants, particularly juniper and honey mesquite, had been mechanically cleared.