Performance of F1 Holstein × Gyr heifers and Productivity of Marandu grass Pasture Overseeded with Winter Forage During the Dry-Wet Transition Period

This study assessed the productive and structural traits of the forage canopy and the performance of heifers grazing Marandu grass pastures overseeded with winter forages during the dry–wet transition in a tropical region. A completely randomized split-plot design with three replicates was used to compare three systems: Marandu grass overseeded with Oats and Ryegrass; Marandu grass overseeded with Oats and Clovers; and Marandu grass in monoculture. Holstein × Gyr heifers, averaging nine months of age with an initial body weight of 225.42 ± 50.27 kg, were managed under irrigated rotational grazing, with two days of occupation and 28 days of rest. Measurements were taken over three grazing cycles. Total forage mass and Marandu grass mass increased in the final cycle, with no differences among systems. The proportion and mass of winter forages did not differ between treatments, although overseeded pastures maintained about one-third of their composition as winter species. Animal performance was similar across systems, with greater body weight observed at the end of the experimental period. In conclusion, overseeding winter forages in irrigated Marandu grass pastures does not increase forage production or animal performance but does promote botanical diversification, with Oats showing better adaptation under these conditions.