Nutritive value for ruminants of green tea grounds as a replacement of brewers' grains in totally mixed ration silage

Four wethers were used in a 4×4 Latin square to study the fermentation quality, digestibility and nitrogen balance of totally mixed ration (TMR) silages which included wet green tea grounds (WGTG). Experimental treatments were control (no WGTG added, CTG), 50 g/kg (low level, LTG), 100 g/kg (medium level, MTG), and 150 g/kg (high level, HTG) of TMR dry matter (DM) as WGTG. The WGTG were substituted for wet brewers grains (WBG) in experimental TMR. All TMR silages were ensiled for 45 days and irrespective of the WGTG addition, they were well preserved with low pH and ammonia-N contents, and high lactic acid content. The voluntary feed intake of TMR silage was not affected by WGTG inclusion (P=0.486). Digestibilities for LTG and MTG treatments were not different from CTG. However, the digestibility of DM, organic matter, crude protein and energy were slightly lower for the HTG treatment, compared to CTG (P<0.05). With progressive increases in WGTG concentrations, the nitrogen intake and fecal nitrogen increased (P<0.05), but the urinary nitrogen and retention nitrogen not different among treatments. No differences among treatments were observed in pH level and total volatile fatty acids concentrations. However, the rumen ammonia-N contents tended to decrease with increasing level of WGTG (P=0.063). The study suggests that a WGTG level of 150 g/kg of the diet DM can be recommended for silage based TMR.