The objective of this study was to evaluate effects of supplementation of ${eta}$-mannanase (CTCZYME$^{(R)}$, CTCBIO, Inc.) on feed intake, growth performance and fecal health of calves fed two levels (3% vs. 8%) of palm kernel meal (PKM). A total of nine Holstein calves were divided into three groups, and fed a conventional starter containing 3% PKM (CON), CON+0.1% CTCZYME$^{(R)}$ (TRT1), or a starter containing 8% PKM+0.1% CTCZYME$^{(R)}$ (TRT2). No clinical symptom of calves was observed through the trial. We did not find significant differences among the treatments on mean feed intake, growth performance, or fecal health during the four-week experimental period. Feed efficiency tended to be improved by adding CTCZYME$^{(R)}$ (0.46, 0.87 and 0.52 for CON, TRT1 and TRT2, respectively). Compared with CON (921 g/d and 786 g/d), TRT2 had lower feed intake (727 g/d) and average daily gain (ADG, 631 g/d) before weaning. However, feed intake (2300 g/d) and ADG (1012 g/d) were similar or even higher in TRT2 than CON (2269 g/d and 560 g/d) after weaning. This was probably due to the effect of a large amount of mannan-oligosaccharide released from PKM by ${eta}$-mannanase. Salmonella was not detected any fecal samples. No significant difference was observed in the number of fecal E. coli or fecal properties including color, smell, and watery indexes among the treatments. We conclude that a calf starter containing 8% PKM with 0.1% CTCZYME$^{(R)}$ is comparable with a conventional starter in feed intake and growth performance of calf, which is beneficial in terms of reduction in feed cost.