The latest generation of functional feed additives, known as postbiotics, provides stable and bioactive metabolites that improve cattle gut health and nutrient absorption. This study investigated the effects of the postbiotic-based feed supplement extra pure metabolites (XPM), which is generated from the fermentation of Saccharomyces cerevisiae, on digestibility and growth performance in native Sahiwal heifers grown in tropical environments. Twelve heifers of the same age and weight were split into two groups; one group was given a conventional basal diet (control), which consisted of green fodder (sorghum + wheat straw), while the other group received XPM supplements for ninety days. Feed intake, body condition score, average daily gain (ADG), and nutritional digestibility (DM, CP, and NDF) were among the parameters assessed. The results showed that XPM supplementation increased the digestibility of dry matter and crude protein and considerably (P < 0.05) improved ADG and feed conversion efficiency. In comparison to controls, treated heifers also showed improved rumen stability and greater physical health. Yeast-derived postbiotics optimize rumen microbial activity, reduce gut pathogens, and promote positive fermentation pathways, all of which contribute to improved nutrition utilization and metabolic efficiency. The study shows that XPM supplementation can enhance animal health and production efficiency without the need for antibiotics, providing a sustainable and safe method of feeding dairy cattle. The use of postbiotics like XPM promotes increased productivity in tropical dairy production and is consistent with the global movement toward livestock systems free of antibiotics.