Effects of Continuous or Rotational Grazing on Goat Diets in a Desert Rangeland

Abstract

Mellado, M., Olvera, A., Dueñez, J. and Rodríguez, A. 2004. Effects of continuous or rotational grazing on goat diets in a desert rangeland. J. Appl. Anim. Res., 26: 93–100.

A one-year experiment with continuous (traditional grazing around a permanent pen, n= 160 goats) anal rotational (grazing around 2 pens, 1.2 km apart, n= 150 goats) grazing was performed in a desert grassland to evaluate the effect of grazing on diet composition and selection in relation to ground cover. Diet composition was determined using microhistological analysis of fresh fecal samples. Continuous grazing resulted in a lower proportion (41.8 vs 65.4% on average throughout the year, P<0.01) of shrubs in the goats diet. Except for the summer, goats in the continuous treatment pasture relied more (P<0.05) on forbs than goats m the rotational treatment (53.1 Us 33.0%, on average throughout the year). The proportion of grasses in the goats' diet did not vary between grazing treatment during the dry season, but during the rainy season goats on the continuously grazed pasture selected more (P<0.01) grasses (7.3 Us 0.7%, average for summer and autumn) than goats in the rotational treatment. Larrea tridentata, the dominating species in the community, was the only plant selected at levels below its ground cover. Results indicate that, under these conditions, goat production would be favoured by alternating the stay of goat flocks between two pens in different sites on the range as goats would depend more on evergreen browse species throughout the year, whereas goats on the traditional grazing system are forced to rely heavily on forbs that made goats more vulnerable to under nutrition during dry periods.

Key words:

• Grazing management
• diet composition
• rangeland
• forage selectivity