Propriedades nutricionais e digestibilidade in vitro de gramíneas forrageiras

Abstract

This study aims to discuss the scientific progress obtained about properties and in vitro digestibility of forage grasses of the genera Urochloa and Megathyrsus and their efficiency of use by ruminant animals, through the investigation of works already published on the subject and available in scientific databases nationals and internationals. Forage grasses promise a more practical and economical way of feeding cattle and as such play a fundamentally important role in meat and/or milk production systems. Although, there are variations in the nutritional value of the plant, not only between genera, species or cultivars, but also depending on the maturity of the plant, which influences digestibility and limitations by the animal. In Brazil, the majority of Brazilian pastures are made up of Brachiaria spp. (Urochloa spp.) and Panicum maximus (Megathyrsus maximus). Urochloa performs well in low fertility acidic soils. Megathyrsus is considered one of the most cultivated grasses due to its great potential for generating dry matter. Furthermore, they adapt easily to planted areas and their forage is of excellent quality. The estimation of the constituents of the nutritional value of forage grasses is of great practical importance, whether to allow adequate supplementation of the forage-based diet or to provide subsidies for the qualitative improvement of forages, through genetic selection or more appropriate management techniques. The advantages of using the in vitro technique to evaluate the nutritional value of foods for ruminants are its speed and physical-chemical uniformity. In this work, it is concluded that grasses of the genus Megathyrsus maximus both in the dry period and in the wet period, numerically, present high average values of crude protein and leaf:stalk ratio, with their annual production being higher than the genus Urochloa Brizantha. Although forage grasses present differences in nutritional value, it is worth highlighting that both desirable characteristics and their nutritional value will vary according to the stage of development, cutting or grazing management and fertilization. Furthermore, greater productivity will depend on the region’s greater adaptability.