Table 4.
Item | Roughage level | Supplemental fat | SEM1 | P-value | ||||
---|---|---|---|---|---|---|---|---|
30% | 60% | −FAT | +FAT | Roughage | Fat | Roughage × Fat | ||
Pens (steers) | 12 (36) | 12 (36) | 12 (36) | 12 (36) | - | - | - | - |
Days on feed | 58 | 58 | 58 | 58 | - | - | - | - |
Growth performance | ||||||||
Initial body weight, kg | 200 | 199 | 200 | 200 | 6.00 | - | - | - |
Final body weight, kg | 285 | 269 | 270 | 284 | 11.2 | 0.08 | 0.13 | 0.94 |
Dry matter intake, kg/d | 6.00 | 5.92 | 5.87 | 6.04 | 0.297 | 0.85 | 0.64 | 0.94 |
Average daily gain, kg | 1.47 | 1.20 | 1.21 | 1.46 | 0.144 | 0.07 | 0.09 | 0.91 |
Gain efficiency2 | 0.249 | 0.204 | 0.207 | 0.246 | 0.016 | 0.01 | 0.03 | 0.80 |
Observed NE, Mcal/kg3 | ||||||||
Maintenance | 2.09 | 1.84 | 1.86 | 2.07 | 0.08 | 0.01 | 0.02 | 0.88 |
Gain | 1.42 | 1.21 | 1.23 | 1.40 | 0.07 | 0.01 | 0.02 | 0.87 |
Observed:expected NE ratio4 | ||||||||
Maintenance | 1.02 | 1.09 | 1.02 | 1.08 | 0.05 | 0.22 | 0.18 | 0.80 |
Gain | 1.03 | 1.11 | 1.03 | 1.11 | 0.06 | 0.22 | 0.16 | 0.76 |
Health | ||||||||
Cattle treated for respiratory disease5, % | ||||||||
First Treatment | 50.0 | 47.2 | 44.4 | 52.8 | 9.61 | 0.82 | 0.49 | 0.82 |
Second Treatment | 19.4 | 11.1 | 8.33 | 22.2 | 6.50 | 0.32 | 0.10 | 0.32 |
Third treatment | 11.1 | 2.78 | 5.56 | 8.33 | 6.10 | 0.14 | 0.62 | 0.62 |
Number of antimicrobial treatments required | 1.75 | 1.34 | 1.51 | 1.58 | 0.272 | 0.11 | 0.78 | 0.30 |
Mortality, %, (n) | 8.33 (3) | 2.78 (1) | 5.56 (2) | 5.56 (2) | 3.87 | 0.31 | 1.00 | 0.31 |
1 Standard error of the mean.
2 Gain-to-feed ratio (G:F; kg/kg).
3 Calculated according to Zinn and Shen (1998).
4 Expected values were calculated using the NASEM (2016)—Beef Cattle Nutrient Requirements Model, empirical solution model, based on the diet composition presented in Table 1.
5 Calves were observed daily for bovine respiratory disease (BRD) signs according to the 4-point scale method based on depression, anorexia, respiratory, and temperature (“DART” system) as described by Step et al. (2008) and Wilson et al. (2015).