Abstract

GUERRERO-CARDENAS, Israel et al. Seasonal variation of the nutritional content in the diet of the desert bighorn sheep (Ovis canadensis weemsi), in Baja California Sur, Mexico. Acta Zool. Mex [online]. 2018, vol.34, e3412113.  Epub Oct 25, 2018. ISSN 2448-8445.  https://doi.org/10.21829/azm.2018.3412113.

Bighorn sheep (Ovis canadensis) is one of the largest native wild ungulates in North America. It is a selective herbivore, feeding on forage with high nutrient values. The aim of this study was to evaluate the seasonal variation in the nutritional quality of the species consumed by bighorn sheep in the Sierra El Mechudo, BCS Mexico. Samples were collected in the four seasons of 2010 and 2011, and for the analyses we consider percentages of ash, crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), ether extract (EE), and in vitro digestibility of dry matter (IVDMD). Seasonal changes were found in the nutrient content of plant species that were studied. The largest number of forages with high percentages of nutrients found in spring were for Viscainoa geniculata (71.9% IVDMD), Buddleja corrugata (11.7% ash), Lysiloma candida (22.03% crude protein), Condalia globosa (56.9% FDA), Aristida adscensionis (80.2% NDF) and Bursera epinnata (5.3% EE). In winter, the highest percentages of nutrients were for Opuntia cholla (71.7% IVDMD), Fouquieria diguetii (16.04% PC) Bouteloua aristidoides (78.4% NDF) and Croton caboencis (5.7% EE). While for the summer and fall only two species with high values were ​​found: L. candida (9.1% ash) and Krameria parvifolia (50.2% FDA). Based on two selection indicators (Bonferroni and Ivlev) three species per year were found to be primarily selected during different seasons. Caesalpinia placida was the only species selected in the two years, particularly during autumn and winter. We found that the principal nutrients (ash or minerals, crude protein, ether extract) of forage consumed were associated mainly with the second stage of gestation (late summer and all autumn) and with the first and second stages of parturition and lactation (winter and spring). In the Sierra El Mechudo, females select plant species of good and medium quality, getting the best combination of nutrients.

Keywords : Crude protein; energy; ethereal extract; fibers; IVDMD; physiological condition; proximal chemical analyses.

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