Evaluation of a long-established silvopastoral Brachiaria decumbens system: plant characteristics and feeding value for cattle

Abstract

One of the main challenges of using a silvopastoral system (SPS) is maintaining pasture and animal productivity over time. Our objective was to compare the productive characteristics and nutritive value of signal grass (Brachiaria decumbens cv. Basilisk) and the liveweight gain of dairy heifers in a SPS and open pasture (OP, signal grass under full sunlight) during the rainy seasons of four experiments between 2003 and 2016, which characterised systems from their 6th to 19th years after establishment in south-eastern Brazil when analysed together. The experimental design was a randomised complete block in a 2 × 4 factorial scheme (two production systems (SPS and OP) and four experiments (2003–2004, 2004–2007, 2011–2014 and 2014–2016)). From the 7th year onwards, the progressive reduction of photosynthetically active radiation negatively impacted the productive characteristics of the SPS pasture. Total forage mass was reduced by 19% in SPS compared with the OP in 2004–2007, 38% in 2011–2014 and 31% in 2014–2016. Crude protein content was 23% and 30% higher in the SPS than in the OP in 2011–2014 and 2014–2016, respectively. However, during the study period (until the 19th year), the liveweight gain of heifers was similar between systems since the higher crude protein content available in SPS contributed to improved forage nutritional value. From the 17th to the 19th year, weight gain per area was lower in the SPS compared with the OP (169 vs 199 kg ha–1), although the difference between systems was small. Signal grass presents a high degree of phenotypic plasticity in response to changes in shade levels, which gives this species a high potential for use in SPS.

Seasonal changes in carbon and nitrogen metabolism of Brachiaria decumbens in a long‐term silvopastoral system

“…Several studies have shown that at moderate levels of shading (20%-29%), it is possible to sustain Brachiaria spp. pasture productivity (do Nascimento et al, 2019;Lima, Paciullo, Silva, et al, 2019).…”

“…grandis trees had an average height of 29 m and DBH of 45 cm, with 50 trees per hectare. The A. mangium trees were 14.2 m tall and 32 cm DBH, with 16 trees per hectare after 19 years of growth (Lima, Paciullo, Silva, et al, 2019).…”

“…Webster) is a tropical C 4 grass, with the potential for rapid growth associated with its greater efficiency in CO 2 assimilation. It is widely used in pasture-based livestock production systems as an herbage species that is moderately tolerant to shading and thus adapts to various edaphoclimatic conditions (Baruch & Guenni, 2007;Lima, Paciullo, Silva, et al, 2019). Overall, forages adapted to shade can adjust their morphophysiology by modifying the allocation of biomass and photoassimilates to maximize light capture (Paciullo et al, 2017).…”

Tree volume estimation for small silvopastoral systems: do we really need the height variable to obtain sufficiently accurate results?

“…Among the practices proposed by the Brazilian Low Carbon Agriculture Plan (Brazil 2021), integrated crop-livestock-forest (ICLF) systems (also known as agrosilvopastoral systems) stand out as a sustainable alternative to overcome grassland degradation, while keeping livestock profitable (Carnevalli et al 2019;Lima et al, 2019;Resende et al 2020;Lemes et al 2021;Pezzopane et al 2021;Vieira Júnior et al 2022).…”

APSIM - Tropical Pasture parameterization for biomass production, light and water competition in a silvopastoral system with >i<B. brizantha>/i< cv. Piatã and >i<E. urograndis>/i<

“…Tropical pastures such as Brachiarias and Panicums can adapt to a certain level of light restriction, although growth limitations may occur when shade levels are greater than 35 to 40% Lima et al, 2019). PAR transmission around 60% represented reductions in the forage accumulation (Pontes et al, 2016;Pezzopane et al 2020a).…”