Feed resources and feeding techniques of small ruminants under extensive management conditions

Abstract

Studies are discussed of the nutritional ecology of small ruminants under extensive conditions in northeastern Mexico. Spanish range goats selected greater amounts of foliage from shrubs (browse) than forbs and grasses throughout the year. Apparently high levels of the shrub Acacia rigidula (blackbrush) in the diets might have negatively influenced nutrient intake of goats. However, levels of crude protein and minerals in the annual diet were sufficient to meet adult goat requirements. Botanical composition of monthly diets of Pelibuey×Rambouillet range sheep grazing in a buffelgrass ( Cenchrus ciliaris) pasture affected nutrient intake. In those months when level of browse increased in diets, the nutrient intakes increased. Native shrubs growing mixed with buffelgrass in pastures were important diet components for grazing sheep, especially during Fall and Winter. Browse during spring and summer provided adequate levels for sheep production of macro and trace elements, except for Cu which was deficient in most months. Browse also contributed a major percentage to the annual diets of white-tailed deer ( Odocoileus virginianus, texanus) in northeastern Mexico. Even though browse provided food and cover for deer, high levels of shrubs negatively influenced the digestibility of their monthly simulated diets. In addition, P concentrations were very low, and high levels of digestion of forb plants in the digestive tract of deer may underestimate the composition of forbs in feces.