Table 1.
Body weight (BW) and change in BW of young steers weaned at different ages 1 and supplemented a control (CON) or rumen by-pass (RBL) treatment.
| Age at BW Collection | Weaning Group | Treatment | p-Value | |||
|---|---|---|---|---|---|---|
| Early 1 | Traditional 1 | CON | RBL | Weaning | Treatment | |
| n 2 | 24/12 | 24/12 | 24/12 | 24/12 | - | - |
| BW, Kg | ||||||
| Birth Weight | 35.2 ± 1.2 | 33.9 ± 1.1 | 33.8 ± 1.1 | 35.3 ± 1.2 | 0.66 | 0.84 |
| 150 d of age | 195.9 ± 4.8 | 195.6 ± 4.6 | 195.0 ± 4.7 | 196.5 ± 4.6 | 0.97 | 0.81 |
| d-14 3 | 195.9 ± 4.8 | 240.5 ± 5.3 | 218.6 ± 5.5 | 217.72 ± 5.3 | <0.0001 | 0.90 |
| d-7 | 196.4 ± 4.5 | 240.1 ± 4.2 | 218.6 ± 4.4 | 217.9 ± 4.2 | <0.0001 | 0.90 |
| d 0 4 | 207.4 ± 4.9 | 246.4 ± 4.7 | 228.2 ± 4.8 | 225.6 ± 4.7 | <0.0001 | 0.69 |
| d 22 | 231.1 ± 4.6 | 269.1 ± 4.4 | 252.3 ± 4.5 | 247.9 ± 4.4 | <0.0001 | 0.49 |
| d 45 | 252.7 ± 4.8 | 288.8 ± 4.5 | 272.6 ± 4.7 | 268.9 ± 4.5 | <0.0001 | 0.58 |
| d 66 | 262.9 ± 4.7 | 313.9 ± 4.6 | 293.4 ± 4.7 | 283.4 ± 4.6 | <0.0001 | 0.16 |
| d 90 | 284.2 ± 5.4 | 322.5 ± 5.2 | 306.6 ± 5.3 | 300.1 ± 5.3 | <0.0001 | 0.40 |
| Change in BW, Kg | ||||||
| Adaptation 3 | 11.6 ± 3.3 | 5.9 ± 3.1 | 9.6 ± 3.2 | 7.8 ± 3.1 | 0.21 | 0.69 |
| First 45 d 5 | 45.3 ± 1.4 | 42.4 ± 1.4 | 44.3 ± 1.4 | 43.4 ± 1.4 | 0.15 | 0.63 |
| Last 45 d 6 | 31.2 ± 2.9 | 37.5 ± 2.8 | 33.7 ± 2.8 | 35.0 ± 2.8 | 0.14 | 0.75 |
Data presented as LSM ± SEM; 1 Age at weaning: early = 150 ± 11 d (n = 24); traditional = 210 ± 11 d (n = 24); 2 n is 24 per treatment from d 14 to d 45 and after harvest of 12 animals is reduced to an n of 12; 3 d 14 through d 1 of treatment (n = 48); adaption period for the feeding trial; 4 Start of treatment; first day of the feeding trial for 45 D and 90 D steers; 5 d 0 through d 45 of treatment (n = 48); length of treatment for 45 D steers; first half of the feeding trial for 90 D steers; 6 d 46 through d 90 of treatment (n = 24); second half of the feeding trial for 90D steers. There was no significant 2 or 3 way interactions (p > 0.37), so main effects are presented.