Effects of Utilizing Spent Coffee Ground as Protein Source for Ruminant Diet by In Vitro Study

The aim of this research was to explore the substitution of palm kernel cake (PKC) with spent coffee grounds (SCGs) in ruminant diets through in vitro experiments. The research employed a completely randomized design. These treatments consisted of SCG substituting PKC at 0%, 25%, 50%, 75%, and 100%. Results indicate that SCG contains higher concentrations of CP and EE compared to PKC, while PKC displays elevated levels of NDF and ADF relative to SCG. The cumulative gas production at 72 h exhibited a significant quadratic difference (p < 0.01). IVDMD demonstrated a linear decline with increasing levels of SCG substitution (p = 0.001). The highest ruminal NH₃-N concentration was observed in the group with 50% SCG substitution, whereas the 75% and 100% substitution groups displayed the lowest values (p < 0.05). At 4 h post incubation, the total VFA concentration and the proportions of C2 and C4 showcased a linear reduction (p < 0.05), whereas the proportion of C3 displayed a significant quadratic difference (p = 0.030), with the 50% substitution level exhibiting the highest. The populations of Ruminococcus albus and Prevotella bryantii after 4 h post incubation experienced a notable linear decrease (p < 0.01). In conclusion, it is recommended to substitute PKC with SCG at levels ranging from 50% to 75%.