Table 4. Effect of RPL-T on feed intake, duodenal starch degradability, and net profit in Holstein steers

	Item	Treatment¹⁾
	Item	RPL-T 0.0 mg/kg BW	RPL-T 19.1 mg/kg BW	RPL-T 95.6 mg/kg BW	RPL-T 191.1 mg/kg BW
Total	Feed intake (g/d) (DM)	6,940 ± 199.1^b	7,460 ± 128.5^a	7,810 ± 89.8^a	7,660 ± 141.6^a
Total	Fecal flow (g/d) (Wet)	7,075 ± 462.1^a	6,800 ± 462.9^ab	6,960 ± 202.5^ab	5,600 ± 556.5^b
Starch	Intake (g/d)	4,164 ± 119.5^b	4,476 ± 77.1^a	4,686 ± 53.9^a	4,596 ± 85.0^a
	Fecal flow (g/d)	303 ± 34.9^a	264 ± 19.5^ab	264 ± 13.3^ab	212 ± 20.9^b
	Disappearance (g/d)	3,861 ± 93.5^b	4,212 ± 68.5^a	4,422 ± 66.1^a	4,384 ± 89.4^a
	Disappearance (%)	92.7 ± 0.68^b	94.1 ± 0.38^ab	94.4 ± 0.34^a	95.4 ± 0.47^a

Each value is presented as mean ± SE (n = 4).
Values with different superscripts in the same row differ significantly at p < 0.05 (ANOVA; Duncan’s).
RPL-T, rumen-protected L-tryptophan; BW, body weight; DM, dry matter.