Carlos G. Pedreira, Valdson J. Silva, Mariana F. Abdal, Felipe N. Lima, Liliane S. Silva, Mateus C. Pereira, Carla M. Marassatto, Debora C. Basto and Aliedson S. Ferreira, Dept. Zootecnia, ESALQ - Univ. de Sao Paulo, Piracicaba, SP, Brazil
In Brazil, forage production is key because it is the main feed resource used to feed the largest commercial cattle herd in the world. Thus, management factors that influence forage production, and that can be used in decision-making within the production system must be well understood. For newly released Cynodon grasses, technical and scientific information are still scarce in tropical regions, especially for Jiggs and Vaquero bermudagrasses. The objective of this study was to evaluate the annual and seasonal (cool versus warm season) yield of Tifton 85, Jiggs and Vaquero bermudagrasses in response to clipping frequencies (every 14, 28 and 42 days) under irrigation in southeastern of Brazil. The trial was set in a completely randomized design with treatments corresponding to the combination of genotypes and clipping frequencies in a factorial arrangement, with four replications. Total accumulated forage increased with the reduction in clipping frequency. Under the 42-d schedule Jiggs was more productive than the other grasses (26.1 Mg MS ha-1), but in the six warmest months of the year yield was similar to that of Tifton 85 at the frequencies of 28 and 42 days (average of 11.7 and 16.6 Mg MS ha-1 respectively), indicating that the difference in total yield between Jiggs and Tifton 85 is due to cool-season yield. Vaquero was less productive at the frequencies of 28-d and 42-d (7.8 and 9.7 Mg MS ha-1, respectively) in warm-season and total yield (13.4 and 17.0 Mg MS ha-1, respectively). During the cool-season regardless of clipping frequency, Tifton 85 was less productive (2.4, 2.7 and 4.6 Mg MS ha-1 for 14-d, 28-d and 42-d, respectively) than Jiggs and Vaquero (average of 3.2, 5.6 and 8.0 Mg MS ha-1 for 14-d, 28-d and 42-d, respectively). Vaquero under the 42-d schedule had a less pronounced seasonal growth, mainly because poor forage production in warm-season. Due to greater production, Jiggs and Tifton 85 are the best choicer to producers and the harvest schedule of 28-d or 42-d could be adopted for high yields, although leaf/stem ratio of the harvested forage should be considered in the decision.