Browsing by Subject "Grazing -- Mexico -- Chihuahua (State)"
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Item Evaluation of short duration grazing on an oak-bunchgrass range type in the central region of Chihuahua, Mexico(Texas Tech University, 1987-05) Soltero-Gardea, SergioIn 1982, tv7o case studies of grazing management were established on an oak-bunchgrass range type in Northern Mexico to compare short duration grazing (SDG) with continuous year-long grazing (CG) in terms of vegetation and animal response; to determine the nutritive content of cattle diets; and tc assess voluntary forage intake and evaluate cow weights under SDG. Total plant cover was reduced from 1982 pre-treatment levels of 26.7 percent to 21.9 percent by 1986. Basal cover of grasses was reduced (P < 0.05) from 13.6 percent in 1S82 pre-treatment levels to 6.9 percent by 1986 under SDG; whereas in CG, grass basal cover was reduced from 1982 levels of 10.4 percent to 6.5 percent by 19 66. The greater reduction of grass cover under SDG may have been because of higher stocking rate than CG. Generally, foliar cover of forbs increased under both SDG and CG; however, the increase in forbs was of greater magnitude under CG. Basically, shrub foliar cover did not change from pre-treatment levels under SDG or CG after four years of study. Within the SDG case study, differences (P < 0.05) were found in biomass of grasses among five strata at different distances from the central watering facility. Standing crop biomass of grasses was 40 to 123 percent less within 300 m of the cell, cover compared to biomass in the other four strata. Organic matter intake was greater in the SDG case study (88.5 g/hg BW*^75) than CG (69.4 g/kg BW^75) during the growing season over 20 years of evaluation. However, during the dry season, intake was similar in both SDG and CG (45.6 and 38 g/kg BW respectively). In SDG, intake increased with incremental changes in forage availability and grazing pressure. Dietary crude protein and digestible organic natter were similar under SDG and CG. Dietary CP values found under SDG and CG indicated that protein requirements for nursing cows are not met during February through June. Weights of nursing cows were slightly greater in CG than under SDG. Calf weaning weights adjusted to 205 days were similar in both SDG and CG.