Efecto de la rotación de corral sobre la composición botánica y selectividad de la dieta de las cabras en un matorral micrófilo desértico

Abstract

The effect of two grazing systems on botanical composition and dietary selection of goats grazing on a desert grassland in northern Mexico was researched. One grazing system consisted of a continuous grazing around a permanent pen (traditional system). The other system consisted of two pens, 800 m apart, in which goats were rotated throughout the year. Feces of 7 goats per herd were collected during 4 consecutive days, during the four seasons of the year. These samples underwent micro histological analyses. During drought period, the shrubs percentage was 35 points higher (P<0.01) in the goat’s diet under pen rotation, as compared to goats under continuous grazing. Acacia farnesiana was the most abundant species in the goats diet in both groups (45 and 27 % for the drought period). During summer (rainy season), shrubs represented 46 and 22 % of the diet for goats under pen rotation and continuous grazing, respectively. In summer, grazing system significantly (P<0.05) altered the grass proportion in the goats diet. Grasses contributed 14 % to the diet in animals under continuous grazing, whereas these group of plants contrib uted only 1.1% to diet for those goats under pen rotation. During the rainy season forbs represented 64 and 53 % of the diet for goats under continuous grazing and pen rotation, respectively. In all seasons forbs were more (P<0.05) abundant in goats diet under con tinuous grazing. Goats exhibited strong selectivity for Acacia berlanderi, Acacia farnesiana, Atriplex canescens, Solanum eleagnifolium y Sphaeralcea angustifolia. It was concluded that pen rotation resulted in higher proportion of legume and lower proportion of forbs in the goats diet.