Preference Indices for Forage Species Grazed by Spanish Goats on a Semiarid Shrubland in México

Abstract

Ramirez, R. G., Sauceda, J. G., Narro, J. A. and Aranda, J. 1993. Preference indices for forage species grazed by Spanish goats on a semiarid shrubland in Mexico. J. Appl. Anim. Res., 3: 55–66.

Botanical composition of diets of Spanish goats was studied on the Facultad de Agronomia, V. A N. L. Experimental Station with the objectives to determine monthly differences in preference indices of forage species grazed by Spanish goats on a blackbrush (Acacia rigidula) dominated shrubland. From June, 1988 to May, 1989, four esophageally fistulated mature goats were used to collect fistula extrusa samples. Botanical composition of the grazed area (25 ha) determined on 25 permanent line transects (10 m long), was 77, 15 and 8% shrubs, forbs and grasses, respectively. Contribution of shrubs, forbs and grasses to the annual diets averaged 83.4, 10.3 and 6.4%, respectively. Major shrubs in the annual diets were blackbrush (54. cenizo (Leucophyllum texanum) (16.7%), palo verde (Cercidium macrum) (3.8%), hackberry (Celtis pallida) (2.6%) and soapbrush (Porlieria angustifolia) (2.2%). Blackbrush was preferred in all sampling periods. Palo verde was preferred during summer and autumn seasons and avoided in other seasons, whereas soapbrush, castela (Castela texana) and cenizo were mostly preferred during winter and spring seasons. Hackberry was preferredby goats only in August, November and December. Cat claw (Acacia greggii) was often preferred without a seasonal pattern. Polianthes maculosa was the most important forb, comprising 2.9% in the annual diets. Preference indices for forbs were inconsistent. Buffelgrass (Cenehrus ciliaris) was the main grass in the diet of goats, comprising 4.9% in the annual diets. It was preferred by goats in all months, except in September. This study showed that botanical composition of the diets was related to the presence of plant species in the herbage.

Key words:

• Spanish goats
• botanical composition
• preference indices
• ranges
• México