Ruminal degradability of tropical leguminous plants from eastern Amazonia

Abstract

The aim of this study was to evaluate ruminal degradation of dry matter (DM), crude protein (CP), and neutral detergent fiber (NDF) of Cratylia argentea, Flemingia macrophylla (Willd.) Merrill, and Stylosanthes guianensis ‘Campo Grande’ (EMBRAPA), aged 55 and 75 days, in sheep with rumen cannulas, using the in-situ technique. A factorial design of 3 leguminous plants × 2 ages × 6 incubation times was used, totaling 36 experimental units. The experimental period included 14 days for adaptation to diet and 5 days for data collection. Cratylia at both ages and Flemingia aged 55 days showed the highest “a” fraction values for DM degradability. Cratylia aged 55 days and Stylosanthes at both ages showed the highest “a” fraction values for CP. The highest “b” fraction value for DM was 51.27% for Stylosanthes aged 55 days. This rate was lower for the other leguminous plants, especially for Flemingia at both ages. The “b” fraction values for NDF are considered low for Flemingia, what may be the result of lower ruminal degradation. The highest “c” fraction degradation rate for DM was observed in all leguminous plants studied aged 75 days. The highest “c” fraction value for CP was 14.84% for Stylosanthes aged 75 days. The highest Kd fraction values for DM, NDF, and CP were found in Flemingia. Cratylia, and Stylosanthes aged 75 days presented higher effective degradability (ED) values for DM at 2 and 5%/hour compared to Flemingia at both ages. Cratylia and Stylosanthes had the highest ED values for NDF, regardless of their passage rates. Stylosanthes presented higher ED values for CP at both ages, regardless of its passage rate. The highest DM, NDF, and CP potential degradability (PD) was obtained for Cratylia and Stylosanthes, at both ages. The leguminous plants Cratylia and Stylosanthes can be recommended for use as a protein bank and supplementation for ruminants, whereas, Flemingia macrophylla should not be used as a protein supplement for ruminants, because it contains high levels of fibrous fractions.