Effect of Delonix regia seed meal supplementation in Thai native beef cattle on feed intake, rumen fermentation characteristics and methane production

•Methane (CH4) gas formed by the fermentation of rumen in ruminant animals.•Delonix regia (DR) seed contains high condenses tannins and saponins.•We supplemented DR in the in Thai native beef cattle.•Supplementation of DR seed meal at 270 g/d resulted in improving total feed intake, rumen fermentation and N balance while there was reduced DM digestibility, protozoal population and CH4 production in beef cattle.

The aim of this research was to investigate the effect of supplementing Delonix regia (DR) seed meal on feed intake, digestibility, rumen fermentation, nitrogen balance and CH4 production in Thai native beef cattle fed on rice straw. Four Thai native beef cattle with the initial body weight (BW) of 100 ± 5.0 kg were randomly assigned according to a 4 × 4 Latin square design to receive DR seed meal supplementation at 0, 90, 180 and 270 g/d. The present results revealed that the total intake (g/kg BW0.75) was significantly increased with the inclusion of dry matter (DM) seed meal at 270 g (P < 0.05). DM and OM digestibility were decreased when increasing DR seed meal levels (P < 0.05). Ruminal NH3-N concentration increased in beef cattle receiving DR seed meal. Supplementation of DR seed meal did not alter fungal zoospores' concentration (P > 0.05), whereas the protozoal population was at 0, 4 h post feeding, and the mean values reduced when increasing the levels of DR seed meal supplemented (P < 0.05). The concentration of propionic acid at 4 h post feeding and its average concentration were significantly highest when 270 g DR seed meal was supplemented (P < 0.05). Estimation of CH4 concentrations and CH4 per dry matter intake were found reduced when increasing its DR seed meal concentration. In addition, N absorption, N retention and proportion of N retention to N intake were enhanced when 270 g DR seed meal was supplemented (P < 0.05). Thus, the inclusion of DR seed meal at 270 g/d resulted in improving total feed intake, rumen fermentation and N balance whereas there was reduced DM digestibility, protozoal population and CH4 production in beef cattle fed rice straw base.