Nutritional quality of pajonal sprouts (Amelichloa brachychaeta) subjected to high instantaneous grazing pressures

Abstract

The woodlands and grasslands areas of the central semiarid region of Argentina are important for livestock production. The degradation of these systems has led to an increase in puna grass (Amelichloa brachychaeta) patches, whose dispersal strategy makes their management difficult. Grazing could be part of the strategy that allows it to recover its nutritional quality by increasing the rate of tissue renewal to take advantage of its regrowth. The objective was to evaluate the nutritional quality of the regrowth of A. brachyvhaeta and perennial forage species from different stocking treatments with grazing each time the regrowth reached 15 cm (four grazings during the year). On 4 hectares previously subjected to intensive homogenization grazing (38 animals.4 days-1), 8 plots of 5 thousand m2 each were established, with treatments of: 4; 6; 10 and 14 animals. ha-1 with a completely randomized design with two repetitions. Before each grazing, plant phytomass from sprouts was collected for nutritional quality analyzes (NDF, ADF, CP and Digestibility). Regardless of the treatments and grazing dates, differences were observed in the quality of the regrowth of A. brachychaeta and the forage species. Forage species had the highest PB values while the % FDN and FDA were higher in A. brachychaeta. Rotational grazing with high instantaneous loads in A. brachychaeta grasslands is a viable option to use and manage this species, while improving the forage quality of the grassland. It is of utmost importance to take advantage of the sprouts after a previous cut and to maintain the changes caused in the structure of the community.