Nutritive Content of Sheep, Goat, and White-Tailed Deer Diets on Excellent Condition Rangeland in Texas

Abstract

A one-year study was initiated in August, 1975, to examine the nutritive content in diets of four kinds of sympatric ruminants on excellent condition rangeland of the Edwards Plateau in Texas. Sheep, Angora goat, and Spanish goat diets were collected from animals fitted with permanent esophageal cannulae. Nutritive content of white-tailed deer diets was estimated by hand-plucking representative forages as the deer were observed grazing them. Mean, annual levels of crude protein (CP) were similar among the four kinds of animals. All diets were lowest in CP dunrng January and February, with livestock diets showing higher levels than deer. However, deer diets were higher in CP than sheep and goat diets during spring and summer. During January and February, the livestock diets warranted only minimum protein supplementation while deer diets were significantly below recommended levels. Digestible energy (DE) levels were higher for sheep diets than for diets of either goats or deer. Similarly, the goat diets were higher in DE than deer diets. The DE levels were generally adequate for sheep but critically low for Angora goats during late gestation. Deer diets were very low in DE during winter and again in early summer, coinciding with the period of peak lactation. Energy would appear to be more limiting for animal production than protein under the conditions of this research. Several kinds of herbivores are sympatric on the Edwards Plateau of Texas. The smaller herbivores using the rangeland are sheep, Angora goats, Spanish goats, and whitetailed deer (Odocoileus virginianus L.). Sheep and Angora goats were introduced at the turn of the century, while Spanish goats are a more recent introduction. White-tailed deer have long been part of the endemic fauna. Sheep differ from goats in their foraging preference (McMahan 1964). There are indications that Spanish and Angora goats express different forage preferences under certain conditions (C.A. Taylor, pers. comm.); however, these differences apparently were minor on excellent condition rangeland (Bryant et al. 1979). Differences in observed forage preferences and in nutrient requirements of the different kinds of animals suggest that each may require different management to obtain optimum production. Good range management practices have generally been thought to benefit animal production. Thus, as more producers strive to improve their ranges, it is important to determine, seasonally, nutrients that may limit animal production on ranges in higher condition classes. Information Authors are assistant professor, Range and Wildlife Management, Texas Tech University, Lubbock 79409; professor, Department of Range Science, Texas AM and professor in charge, Texas A&M University Research Station at Sonora 76950. Portions of this research were submitted in partial fulfillment of requirements for the Ph.D. degree in Range Science at Texas A&M University by Bryant. The authors gratefully acknowledge the assistance of Charles A. Taylor and Ed Huston of the Texas Agricultural Experiment Station. This report is TA 14973 from the Texas Agricultural Experiment Station. Manuscript received March 26, 1979. on nutrient levels in diets from excellent condition rangeland was not available for the Edwards Plateau. The objective of this study was to determine the nutritive content of diets selected by sheep, Angora goats, Spanish goats, and white-tailed deer on an excellent condition