Diets of domestic and wild herbivores grazing in common in a rangeland of Mendoza Province, Argentina

GUEVARA, J. C.; ALLEGRETTI, L.I.; ESTEVEZ, O.R.; MONGE, A.S; PAEZ, J.A.; CONY, M.A.

Horizons in Earth Science Research Vol. 1

Nova Science Publishers Inc.

Lugar: Hauppauge, New York, USA; Año: 2009;

Diets of domestic (goats, horses, and cattle) and wild (European hare) herbivores were compared in good and poor range conditions and in summer and winter in an area of 10 000 ha located in the south of Mendoza. Twenty five fresh fecal samples were collected from each herbivore from the ground. Diet botanical composition was determined by analysis of fecal material using the microhistological technique. Food availability was estimated considering forage cover as an approximate measure of availability. The Taylor selection index was calculated. The overlap in diet composition between animals was estimated using the Kulcyznski similarity index.  Differences in plant aerial cover, proportions of plant categories in forage availability and diets were determined between areas and seasons by H statistics of Kruskal-Wallis ANOVA. For the pool of seasons, the good condition area showed significantly higher total vegetation cover, forage cover and grass proportion than those from the poor condition area. Grasses were the main component of cattle diet in summer. The same was verified in horses in both seasons in good conditions and in summer in poor conditions. All the herbivores consumed a higher proportion of grasses in summer than in winter in both condition areas. Shrubs were the principal item of the diet in both seasons and range condition in goats and E. hare and in cattle in winter. Considered as preferred species as those that had this selectivity category at 50% o more of the cases, in the pool of cases (herbivores, range conditions and seasons), the following shrubs were preferred: Acantholippia seriphiodes, Atriplex lampa, Fabiana, Hyalis argentea, Junellia ligustrina and Schinus o’donellii. These species, except Junellia were preferred in good condition. Prosopidastrum   globosum was added to the previous ones in poor condition. In summer, only Acantholippia, Hyalis and Junellia were preferred. Atriplex, Fabiana, Prosopidastrum, and Schinus are added to the latter species in winter. In the pool of cases and in the two range conditions, Panicum urvilleanum, Schismus barbatus, and Stipa spp. were the preferred grasses. In summer all the grasses were preferred and in winter only Panicum and Stipa. The greatest competition was observed between E. hare and goats (diet overlap = 0.60) and horses-cattle (0.61), both in winter. In conclusion, we found differences in the proportion of grasses and shrubs in diet composition, preference of species and diet overlap according to range conditions and seasons. This suggests that land managers would obtain advantages of multi-species over single-species herbivores grazing.