Table 7.
Effect of supplementing ruminally protected lysine (LYS), arginine (ARG), or their combination on carcass characteristics of feedlot steers
| Treatment1,2 | P-value | |||||||
|---|---|---|---|---|---|---|---|---|
| Item | CON | ARG | LYS | LYS + ARG | SEM4 | ARG | LYS | LYS × ARG |
| Hot carcass weight, kg | 388.0 | 390.0 | 389.3 | 387.9 | 3.40 | 0.92 | 0.91 | 0.62 |
| Dressing, % | 62.1 | 62.1 | 62.3 | 62.4 | 0.22 | 0.88 | 0.25 | 0.92 |
| Fat thickness, cm | 1.41 | 1.38 | 1.21 | 1.26 | 0.050 | 0.84 | 0.01 | 0.48 |
| Longissimus muscle area, cm2 | 90.0 | 90.3 | 93.8 | 92.7 | 0.92 | 0.68 | 0.01 | 0.48 |
| Kidney, pelvic, heart fat, % | 2.0 | 1.9 | 1.9 | 1.9 | 0.17 | 0.64 | 0.17 | 0.29 |
| Yield grade | 3.1 | 3.0 | 2.7 | 2.8 | 0.07 | 0.63 | <0.01 | 0.43 |
| Marbling score3 | 414 | 419 | 419 | 414 | 23.1 | 0.99 | 0.99 | 0.84 |
| Quality grade distribution | ||||||||
| Select, % | 0.0 | 0.0 | 0.0 | 3.3 | 0.02 | 0.34 | 0.34 | 0.34 |
| Choice−, % | 52.1 | 45.1 | 64.7 | 38.6 | 0.12 | 0.17 | 0.80 | 0.42 |
| Choice average, % | 34.4 | 41.0 | 14.6 | 44.2 | 0.10 | 0.09 | 0.42 | 0.27 |
| Choice+, % | 3.4 | 6.8 | 7.4 | 10.2 | 0.04 | 0.47 | 0.40 | 0.94 |
| Prime, % | 10.2 | 7.1 | 13.4 | 3.7 | 0.06 | 0.30 | 0.99 | 0.59 |
1Treatments were 1) a diet with no arginine or lysine supplementation (CON), 2) rumen-protected arginine (16% metabolizable arginine, Ajinomoto Heartland, Chicago, IL) top-dressed at 63 g/steer daily (ARG), 3) rumen-protected lysine (25% metabolizable lysine, AjiPro-L, Ajinomoto Heartland) top-dressed at 40 g/steer daily (LYS), and 4) a diet with both arginine and lysine top-dressed at 63 and 40 g/steer daily, respectively (ARG + LYS).
2Five pens/treatment; 5 to 6 steers/pen.
3Practically devoid = 100 to 199; slight = 200 to 299; small = 300 to 399; modest = 400 to 499; moderate = 500 to 599; slightly abundant = 600 to 699.
4Standard error of the mean.