The intercropping of grasses and legumes increases nutrient availability for grazing beef cattle: evaluation of three pasture-finishing systems

Abstract

Sustainable beef cattle production requires understanding of forage composition and nutrient availability to ensure animal performance and to promote responsible use of natural resources. This study aimed to evaluate how pasture intercropping and fertilization affect nutrient availability for finishing grazing cattle. The experiment was conducted from August 2021 to August 2022 at Embrapa Southeast Livestock (São Carlos, SP, Brazil). Three treatments were evaluated with three replications each: 1) degraded pasture of Urochloa decumbens cv. Basilisk (DEG); 2) dryland pasture with a mixture of U. decumbens cv. Basilisk and U. brizantha cv. Marandu, recovered with 200 kg.N-urea.ha^-1.year^-1 (REC); 3) dryland pasture with a mixture of U. decumbens cv. Basilisk and U. brizantha cv. Marandu intercropped with Cajanus cajan cv. BRS Mandarim (MIX). Leaf mass accumulation was determined through forage mas sampling every 28 days, followed by weighing, drying in oven (65ºC - 72 h), morphological separation of components and chemical analysis (MIX: sum of grass and legume mass). A total of 27 animals were allocated to pastures, with stocking rate adjustments based on the "put-and-take" technique. Nutrient accumulation data were subjected to ANOVA and means compared by the Fisher test (5%) via PROC MIXED in SAS^®. The highest dry matter leaf mass was observed in the MIX treatment (2,113.7ᵃ kg/ha.year⁻¹), followed by REC (715.3ᵇ kg/ha.year⁻¹) and DEG (343.7ᶜ kg/ha.year⁻¹). Crude protein availability was 179.2ᵃ, 79.0ᵇ, and 26.0ᶜ kg/ha.year⁻¹ in MIX, REC, and DEG, respectively. Gross energy values were 510.3ᵃ, 223.9ᵇ, and 95.6ᶜ kJ/ha.year⁻¹ for MIX, REC, and DEG. These results demonstrate that pasture management significantly influences nutrient availability for grazing cattle. MIX notably improved both forage quality and quantity, while DEG resulted in the lowest nutritional outputs, underscoring the negative effects of pasture degradation. Intercropping with legumes and targeted fertilization are effective strategies to enhance nutrient supply for finishing grazing cattle.