Produção e composição química do leite, consumo e digestibilidade de forragens tropicais manejadas em sistema de lotação intermitente

Abstract

The objective of the study was to compare chemical composition, in vitro dry matter digestibility (IVDMD), of leaves, stems and hand plucked samples, as well as milk yield and composition, body weight variation, body condition score and dry matter intake of three grasses. The treatments were: tanzania grass (Panicum maximum Jacq.), stargrass (Cynodon nlenfuensis Vanderyst) and marandu grass (Brachiaria brizantha Staf). All grasses were fertilized with 200 kg/ha.year N and K2O and 50 kg/ha.year of P2O5. Pastures were managed in a rotational grazing system with threeday paddock occupation and two grazing intervals: January and February with 24 days and March, April and May with 30 days. There were 24 cows, eight per treatment. A complete randomized block design was used. The stargrass leaves had 18.5% crude protein (CP) and 79.9% neutral detergent fiber (NDF) on the stems, respectively, which were higher than the other grasses. Stargrass also had higher NDF (72.8%) and lignin (7.1%) in hand plucked samples. The marandu in vitro dry matter digestibility (IVDMD) (64%) was higher than that of stargrass (59.4%). The treatments were different for milk yield and the mean (9.8) for tanzania and marandu grasses were higher than the 8.4 kg/cow.day for stargrass. Milk protein of cows managed on tanzania grass (2.9%) was higher than that of (2.8%) of stargrass. There was no treatment difference for milk fat, total solids, body condition, body weight and feed intake. Stargrass had higher NDF and lignin, however lower IVDMD and milk yield in relation to tanzania and marandu grasses. © 2009 Sociedade Brasileira de Zootecnia.