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

Studies are discussed of the nutritional ecology of small ruminants under e xtensive conditions in northeastern Mexico. Spanish range goats selected gr eater amounts of foliage from shrubs (browse) than forbs and grasses throug hout the year. Apparently high levels of the shrub Acacia rigidula (blackbr ush) in the diets might have negatively influenced nutrient intake of goats . However, levels of crude protein and minerals in the annual diet were suf ficient to meet adult goat requirements. Botanical composition of monthly d iets of Pelibuey x Rambouillet range sheep grazing in a buffelgrass (Cenchr us ciliaris) pasture affected nutrient intake. In those months when level o f browse increased in diets, the nutrient intakes increased. Native shrubs growing mixed with buffelgrass in pastures were important diet component fo r grazing sheep, especially during Fall and Winter. Browse during spring an d summer provided adequate levels for sheep production of macro and trace e lements, except for Cu which was deficient in most months. Browse also cont ributed a major percentage to the annual diets of white-tailed deer (Odocoi leus virginianus, texanus) in northeastern Mexico. Even though browse provi ded food and cover for deer, high levels of shrubs negatively influenced th e digestibility of their monthly simulated diets. In addition, P concentrat ions were very low, and high levels of digestion of forb plants in the dige stive tract of deer may underestimate the composition of forbs in feces. (C ) 1999 Published by Elsevier Science B.V. All rights reserved.