Grazing intensity affects forage accumulation and persistence of Marandu palisadegrass in the Brazilian savannah

• Published in: Grass and forage science 2019-09, Vol.74 (3), p.450-462
• Main Authors: Euclides, Valéria P. B., Montagner, Denise B., Macedo, Manuel Cláudio M., Araújo, Alexandre R., Difante, Gelson S., Barbosa, Rodrigo A.
• Format: Article
• Language: English
• Subjects: Accumulation; Body weight; Body weight gain; Canopies; canopy structure; Grazing; Grazing intensity; herbage intake; Herbivores; nutritive value; Pasture; Pasture management; Population density; Savannahs; tiller population
• ISSN: 0142-5242; 1365-2494
• DOI: 10.1111/gfs.12422

This 3‐year study evaluated the effects of grazing intensity on herbage and steer responses in continuously stocked Brachiaria brizantha cv. Marandu pasture in the Brazilian savanna. Treatments consisted of three grazing intensity levels, characterized by canopy heights of 15, 30 and 45 cm, measured twice per week. Responses variables included tiller population density (TPD), herbage accumulation rate (HAR) and body weight gain per area (WGA). A decline in TPD (1,237 vs. 767 tillers/m2) was observed from the first to the third grazing years, which influenced the HAR from the first to the third years (90.1 vs. 52.4 kg ha−1 day−1). A marked decline in body WGA (541 vs. 276 kg ha−1 year−1) was observed along the three years in pastures managed at a height of 15 cm, indicating that this is an unstable condition for Marandu palisadegrass pasture. HAR was similar for pastures managed at 30 or 45 cm and was relatively stable during the experimental period, averaging 91.8 and 99.1 kg ha−1 day−1 respectively. Body WGA was similar and constant throughout the experimental period for pastures managed at 30 (596 kg ha−1 year−1) and 45 cm (566 kg ha−1 year−1). Maintaining continuously stocked Marandu palisadegrass pastures at a 15 cm canopy height should be avoided due to long‐term decreases in plant persistence and animal body WGA, particularly when soil P is below critical levels at pasture establishment and during pasture utilization.