Pasture and animal production in silvopastoral and open pasture systems managed with crossbred dairy heifers

Abstract

The objective of this study was to evaluate the pasture traits and performance of crossbreed dairy heifers in a silvopastoral system (SPS) and open pasture (OP) of Urochloa decumbens, after 14-years of management. In the SPS, an average reduction of 46% in the photosynthetically active radiation (PAR) was calculated in relation to the OP. Experimental design was a randomized complete block, with three replications and two treatments (SPS and OP), evaluated in two seasons (summer and autumn), during three years. The paddocks were managed under continuous stocking with Holstein × Gyr heifers. The herbage mass was greater in OP, but a greater leaf and lower dead material percentages were observed in the SPS. The OP had higher tiller population than SPS only in the first year. The herbage accumulation was higher in the OP during autumn; however during summer only a trend was observed. The crude protein content was greatest in SPS, while the fiber constituents and forage digestibility did not vary with system. The stocking rate was greater in OP in the second year and similar between systems in the other years. Average daily gains were similar between systems, regardless of season and experimental year, while the OP showed a greater gain per area in the third experimental year. Despite of the difference in some variables, after 14–16 years of establishment, it was observed only a small decrease in the animal productive per area in SPS in the last year, in relation to OP, which indicates a high resilience of SPS, even under intense shading.