Although, the application of tannic acid (TA), gallic acid (GA), natural hydrolysable tannins (HT)‐rich ingredients, and HT‐rich feeds in ruminant feeding have been explored in order to modify or manipulate microbial activities of digestive tract of animals, the interaction between HT and gastrointestinal microbiota and the fate of HT metabolites (GA, ellagic acid, pyrogallol, resorcinol, phloroglucinol, catechol and urolithin) derived from gastrointestinal microbial HT metabolism in the animal as a whole and animal products are missing. Incomplete biotransformation of HT and TA to GA, pyrogallol, resorcinol, phloroglucinol and other phenolic metabolites is a prevalent phenomenon discovered by researchers who examine the fate of HT metabolites in ruminant. While the rest of fellow researchers do not even examine the fate of HT metabolites and assume the complete biotransformation and fermentation of HT metabolites to volatile fatty acids (VFA). Only three studies have successfully identified the complete biotransformation and fermentation of HT metabolites to VFA in ruminant. The HT metabolites, mostly pyrogallol, produced through incomplete biotransformation of HT have adverse effects on gastrointestinal microbiota and host animal. Lack of awareness regarding the metabolism of HT metabolites and its consequences would compromise ruminant gastrointestinal microbiota, animal welfare, our environment and the power of research papers’ findings. In this perspective paper, I will bring to attention a new angle on the biotransformation and fermentation of HT metabolites in gastrointestinal tract, the role of gastrointestinal microbiota and deficiency of current approach in isolating tannin‐degrading bacteria from rumen. Also, suggestions for better monitoring and understanding HT metabolisms in ruminant are presented. Significance and Impact of the Study: Different metabolic pathways by gastrointestinal microbiota have been suggested for gastrointestinal hydrolysable tannin (HT) metabolism. We argue that complete biotransformation and fermentation of HT metabolites especially pyrogallol to volatile fatty acids is a unique and evolutionary microbial process and have to be examined separately. Exploring the fate of HT metabolites derived from gastrointestinal microbial HT metabolism in whole animal needs to be closely examined in studies that focuses on application of HT ingredients and its effects on ruminant animal performance. We highlight that making inference based on studies that focused on feeding HT ingredients in ruminant nutrition without considering the fate of HT metabolites; will path a strand of literature that may be questionable. Therefore, the future research should consider the fate of HT metabolites to have a reliable result inference.