Maintenance of mixed grass-legume pastures for stand longevity and improved animal utilization is a challenge in warm-season climates. The goal of this study was to assess grazing management on stand persistence, forage intake, and N balance of beef heifers grazing mixed pastures of Brachiaria brizantha and Arachis pintoi. A two-year experiment was carried out in Brazil, where four grazing management were assessed: rest period interrupted at 90%, 95%, and 100% of light interception (LI) and a fixed rest period of 42 days (90LI, 95LI, 100LI, and 42D, respectively). The LI were taken at 50 points at ground level and at five points above the canopy for each paddock using a canopy analyzer. For all treatments, the post-grazing stubble height was 15 cm. Botanical composition and canopy structure characteristics such as canopy height, forage mass, and vertical distribution of the morphological composition were evaluated pre-and post-grazing. Forage chemical composition, intake, and microbial synthesis were also determined. A randomized complete block design was used, considering the season of the year as a repeated measure over time. Grazing management and season were considered fixed, while block and year were considered random effects. In the summer, legume mass accounted for 19% of the canopy at 100LI, which was less than other treatments (a mean of 30%). The 100LI treatment had a greater grass stem mass compared with other treatments. In terms of vertical distribution for 100LI, 38.6% of the stem mass was above the stubble height, greater than the 5.7% for other treatments. The canopy structure limited neutral detergent fiber intake (P = 0.007) at 100LI (1.02% of BW/d), whereas 42D, 90LI, and 95LI treatments had NDF intake close to 1.2% of BW/d. The intake of digestible organic matter (OM; P = 0.007) and the ratio of crude protein/digestible OM (P < 0.001) were less at 100LI in relation to the other treatments. The production of microbial N (P < 0.001) and efficiency of microbial synthesis (P = 0.023) were greater at 95LI and 90LI, followed by 42D and less at 100LI. Overall, the range from 90 to 95% of LI is the recommendation to interrupt the rest period, since this strategy enhanced community stability, forage intake, and nutritional value of the diet. Under on-farm conditions, brachiaria grass and forage peanut pastures should be managed at a range height of 24 to 30 cm.

Tropical forage legumes were first used on a wide scale, starting well before the 1950s in the northeasterly Australian state of Queensland (Shaw, 1961). The famous "Townsville Stylo" (Stylosanthes humilis Kunth) was introduced into thousands of ha of pastures in Queensland and made an important contribution to extensive beef production in northern Australia (Gardener, McCaskill, & McIvor, 1993; Humphreys, 1967). Many Brazilian students working on pastures and agronomy studied in Australia in the 1960s and 1970s and brought back the idea of using Stylosanthes spp. in Brazilian pastures. The Centro Internacional de Agricultura Tropical (CIAT), Cali, Colombia, starting in the 1970s, accumulated a large collection of forage legumes, listed today as 21,083 tropical legume accessions, including over 4,000 of the genus Stylosanthes alone (CIAT, 2019). A considerable effort was made to work with this germplasm in Brazil, mainly by Embrapa and CEPLAC. The first Stylosanthes materials tested were highly sensitive to the fungal disease anthracnose and resistant accessions had to be selected. In Brazil, two cultivars of Stylosanthes were released in 1983, Pioneiro and Bandeirantes, and while in trials their performance was satisfactory (Sousa, Andrade, & Thomas, 1983a, 1983b) there was

Nitrogen (N) inputs to pasture systems coupled with grazing management strategies based on monitoring and control of canopy structure may provide conditions for greater productivity and enhanced forage nutritive value. This 2‐year study assessed canopy structure and nutritive value responses of three pasture treatments, namely, (1) mixed Marandu palisadegrass (Brachiaria brizantha [Hochst. ex A. Rich.] R.D. Webster [syn. Urochloa brizantha Stapf]) cv. Marandu and forage peanut (Arachis pintoi Krapov. & W.C. Greg.) cv. BRS Mandobi pastures without N fertilizer (GRASS + LEGUME); (2) monoculture Marandu palisadegrass pastures fertilized with 150 kg N/ha (GRASS + N); and (3) monoculture Marandu palisadegrass without N fertilizer (GRASS). Grazing management was similar across pasture treatments, using continuous stocking and a target canopy height of 20–25 cm. Herbage mass was greater in GRASS + N and GRASS + LEGUME pastures than in GRASS in summer and spring (p = .014). The leaf:stem ratio in the grass mass (p = .731) was similar between treatments. Grass crude protein (CP) and in vitro digestible dry matter (IVDDM) were greatest in the GRASS + N pasture (p < .001). Grass neutral detergent fibre (NDF) concentration was greater at GRASS and GRASS + LEGUME pastures than in GRASS + N (p < .001). Forage peanut had a greater IVDDM and CP concentration and a lower NDF concentration than Marandu palisadegrass. Nitrogen application or the presence of the legume increased green herbage mass and improved forage nutritive value in canopies with similar height.

Mixed grass/legume pastures are an alternative to grass monocultures for increased beef cattle production in tropical climates. The objective of this study was to evaluate the productivity of beef cattle grazing either a mixed pasture of Brachiaria brizantha cv. Marandu grass and Arachis pintoi (forage peanut) cv. Belomonte or a Marandu monoculture, under rotational stocking. Five trials were conducted over a period of nine years in north-eastern Brazil where the sward structure (forage, grass and legume mass) and animal performance were compared for a mixed Marandu grass/ forage peanut pasture, and a Marandu grass monoculture with 120 kg N ha −1 y −1 .Stocking rate was adjusted to maintain forage allowance at 4% body weight/day. A block design was used with four replicates, and warm and cool seasons within each trial were considered, using repeated measurements over time. In the warm season, the forage mass in the mixed pastures was 17% greater than in the monoculture (p = .049), and the stocking rate, average daily gain and liveweight gain per ha were 16.4%, 20.0% and 28.7% greater (p = .004, p < .001 and p < .001 respectively). The average daily gain showed a positive linear relationship with the legume proportion in the sward (p < .001). The mixed forage peanut/Marandu pasture sustained significantly greater beef cattle production (789 kg ha −1 y −1 ) compared to the N-fertilized grass monoculture (655 kg ha −1 y −1 ). Appropriately managed, mixed pastures of forage peanut/Brachiaria pastures are sustainable and have high potential for use in the humid tropics. K E Y W O R D SArachis pintoi, beef cattle, Brachiaria, fertilized pasture, mixed pasture, warm-season legume

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