BROMATOLOGICAL AND NUTRITIONAL PROFILE OF Dalea bicolor (Willdenow) AT SEMI-ARID REGIONS OF ZACATECAS, MEXICO

Nutritional characterization of forage shrubs provides a basis for proper assessment of rangelands and grazing areas, appropriate supplementation of livestock and reforestation programs. The aim of this study was to evaluate the bromatological profile and nutritional composition of Dalea bicolor Willdenow (silver prairie clover). The shrub was sampled during the four seasons of the year, but presented foliage only in Autumn and Summer. Twenty samples were used per season within a 20-ha plot located in the municipality of Villa de Cos, Zacatecas, Mexico, characterized by its semi-arid climate. The variables measured were dry matter (DM), organic matter (OM), ash, crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), net maintenance energy (NEm), net gain energy (NEg), dry matter intake calculated as percentage of live weight (DMI, %BW), dry matter digestibility (DMD) and forage relative value (FRV). Bromatological evaluations were performed using standard methods, and the nutritional ones were estimatad using the bromatological results. All variables showed statistical differences (P = 0.05) between seasons of the year. In the bromatological results, CP was 9.69 vs 13.51 %, NDF 56.97 vs 63.59 % and ADF 44.56 vs 42.25 % for Autumn and Summer, respectively. In the nutritional profile, the seasons averaged NEm 1.01 vs 1.04 Mcal kg(-1) and NEg 0.65 vs 0.68 Mcal kg(-1) for Autumn and Summer, respectively. It is concluded that Dalea provides the CP for grazing production, which is estimated between 70 and 100 g per kg of dry matter and provides limited NEg.