Herbage accumulation, nutritive value, and organic reserves of continuously stocked Ipyporã and Mulato II brachiariagrasses

Abstract

While Brachiaria sp. grasses are important components of sustainable foragelivestock systems in the Amazon Biome, cultivar diversification is needed to reduce risk from pests and diseases. Brachiaria hybrid ‘BRS RB331 Ipyporã’ (B. ruziziensis × B. brizantha) was released in 2017 as an alternative for intensively managed forage-livestock systems. Our objective was to compare herbage accumulation (HA), nutritive value, and organic reserves of Ipyporã and standard hybrid ‘Mulato II’ (B. ruziziensis × B. brizantha × B. decumbens) under continuous stocking during 2 yr in the Amazon Biome. Treatments were the two cultivars replicated four times in a randomized complete block design, and each experimental unit was 1.5 ha. Pastures of Mulato II presented ~15% greater HA than Ipyporã (17360 vs. 14930 kg DM ha-1 yr-1) across the 2 yr, and Mulato II leaf mass was greater than Ipyporã (1440 vs. 1900 kg DM ha-1) in the dry season. Both cultivars had greater herbage mass, HA, and herbage bulk density during the rainy season of 2016/2017 compared with 2017/2018 due to a shorter period of water deficit (30 d) and greater rainfall (2147 vs. 1762 mm) in the first than second year. Mulato II herbage crude protein was 10 g kg-1 greater than Ipyporã. In this severe risk region for spittlebug, Mulato II required spittlebug monitoring and control due to occurrence of foliar damage. Although Ipyporã had lower HA, no spittlebug damage was evident. Thus, Ipyporã is an attractive alternative for diversification of forage-based livestock systems in the Amazon Biome.