Table 2 Effects of age at group housing [G; late grouping (LG) vs. early grouping (EG)] and age at incremental hay supplementation [late hay increment (LH) vs. early hay increment (EH)] on starter dry matter intake (DMI), nutrient intakes, feed efficiency, ADG (weeks 1–13, n = 16 per treatment), and development of heifers through first breeding (n = 7 calves per treatment).
Item | Treatments | SEM | P value | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
LG-LH | LG-EH | EG-LH | EG-EH | Group housing (G) | Hay increment (H) | G × H | Period (P) | G*P | H*P | ||
Starter DMI, g/d | 924 | 887 | 978 | 1066 | 40.1 | 0.01 | 0.53 | 0.14 | < 0.01 | < 0.01 | 0.34 |
Neutral detergent fiber intake, g/d | 199 | 206 | 212 | 247 | 8.89 | 0.01 | 0.03 | 0.13 | < 0.01 | < 0.01 | < 0.01 |
Starch intake, g/d | 296 | 268 | 311 | 322 | 12.6 | 0.01 | 0.50 | 0.14 | < 0.01 | < 0.01 | 0.15 |
Crude protein intake, g/d | 177 | 164 | 186 | 196 | 7.52 | 0.01 | 0.83 | 0.14 | < 0.01 | < 0.01 | 0.78 |
Metabolizable energy intake, Mcal/kg | 5.66 | 5.51 | 5.81 | 6.03 | 0.11 | 0.01 | 0.74 | 0.14 | < 0.01 | < 0.01 | 0.97 |
Total DMI (milk + starter), g/d | 1469 | 1431 | 1522 | 1611 | 40.1 | 0.01 | 0.53 | 0.14 | < 0.01 | < 0.01 | 0.92 |
Average daily gain, g/d | 740 | 686 | 752 | 785 | 26.8 | 0.02 | 0.83 | 0.16 | < 0.01 | 0.06 | 0.68 |
Feed efficiency, ADG/DMI | 0.56 | 0.54 | 0.56 | 0.57 | 0.01 | 0.47 | 0.78 | 0.49 | < 0.01 | 0.48 | 0.49 |
Development of heifers through first breeding | |||||||||||
Age at first artificial insemination, d | 443 | 460 | 442 | 437 | 16.5 | 0.47 | 0.69 | 0.52 | – | – | – |
Average age at first calving, d | 717 | 729 | 693 | 711 | 19.3 | 0.28 | 0.46 | 0.85 | – | – | – |
Average wither height at first calving, cm | 145 | 143 | 146 | 144 | 1.94 | 0.63 | 0.34 | 0.85 | – | – | – |
Average weight at first calving, kg | 584 | 554 | 567 | 558 | 16.8 | 0.70 | 0.24 | 0.54 | – | – | – |
