Effects of Walnut (Juglans regia L.) Green Husk Supplemented to Total Mixture Ration on In Vitro Rumen Fermentation Parameters and Microbial Protein Synthesis

The aim of this experiment was to determine the effects of walnut (Juglans regia L.) green husk (WGH) supplemented to ration on rumen fermentation by in vitro gas production technique. WGH was supplemented at different ratios (0%, 2%, 4%, 6%, 8%, and 10%) to the total mixture ration formed from 80%/20% roughage/concentrate feed. Experimental rations were incubated with 1/2 rumen fluid/artificial saliva mixture in in vitro gas production syringes in a water bath at 39°C ± 1°C for 24 h. WGH supplemented to the ration at different ratios increased in vitro organic matter digestibility (IVOMD), gas production (GP), ruminal ammonia nitrogen (NH₃-N), and pH values linearly and quadratically. Methane ratio in total gas, metabolizable energy (ME) value, true digestibility (TD), and microbial protein (MP) synthesis also increased quadratically. With the supplementation of WGH to the ration, acetic acid (AA) concentration decreased linearly, while acetic acid/propionic acid ratio (AA/PA) decreased both linearly and quadratically. Overall, it was observed that WGH had positive effects on many rumen fermentation parameters. It is thought that the use of WGH in ruminant ration should be supported by new experiments with different supplementation ratios or ration mixtures.