Table 4.
Effects of level and source of fat in the diet of pregnant beef cows during the second and third trimesters of gestation on prepartum performance of the dam and birth weight of the progeny
| Treatments1 | Contrasts2 | |||||
|---|---|---|---|---|---|---|
| LF | CAN | FLX | SEM | LF vs. HF | CAN vs. FLX | |
| Item3 | (n = 10) | (n = 10) | (n = 10) | |||
| Start of trial | ||||||
| Days until calving, d | 183 | 183 | 184 | 2.02 | 0.87 | 0.52 |
| BW, kg | 664 | 662 | 664 | 19.1 | 0.79 | 0.67 |
| CC-BW, kg | 659 | 657 | 658 | 19.0 | 0.72 | 0.69 |
| BCS | 2.65 | 2.59 | 2.63 | 0.04 | 0.37 | 0.46 |
| Thin, % of cows | 0.0 | 0.0 | 0.0 | — | — | — |
| Optimal, % of cows | 98.2 | 97.8 | 93.3 | 2.87 | 0.44 | 0.10 |
| Overconditioned, % of cows | 1.8 | 2.2 | 6.7 | 2.73 | 0.50 | 0.28 |
| SCFT | ||||||
| Rib, mm | 4.8 | 4.1 | 4.4 | 0.20 | 0.03 | 0.34 |
| Rump, mm | 4.7 | 4.9 | 4.5 | 0.30 | 0.99 | 0.32 |
| Mid of trial | ||||||
| Days until calving, d | 99 | 99 | 100 | 2.02 | 0.87 | 0.52 |
| BW, kg | 711 | 707 | 706 | 5.90 | 0.37 | 0.84 |
| ADG, kg/d | 0.57 | 0.55 | 0.51 | 0.17 | 0.27 | 0.45 |
| CC-BW, kg | 693 | 688 | 687 | 5.45 | 0.25 | 0.78 |
| CC-ADG, kg/d | 0.41 | 0.38 | 0.34 | 0.18 | 0.15 | 0.41 |
| End of trial | ||||||
| Days until calving, d | 23 | 23 | 24 | 1.49 | 0.87 | 0.51 |
| BW, kg | 758 | 751 | 752 | 4.44 | 0.19 | 0.87 |
| Cumulative ADG, kg/d | 0.59 | 0.55 | 0.55 | 0.11 | 0.09 | 0.88 |
| CC-BW, kg | 708 | 697 | 697 | 4.07 | 0.04 | 0.98 |
| Cumulative CC-ADG, kg/d | 0.31 | 0.25 | 0.24 | 0.12 | <0.01 | 0.76 |
| BCS | 2.80 | 2.64 | 2.68 | 0.12 | 0.01 | 0.52 |
| Change | 0.13 | 0.05 | 0.04 | 0.12 | 0.12 | 0.96 |
| Thin, % of cows | 0.0 | 0.0 | 0.0 | — | — | — |
| Optimal, % of cows | 86.8 | 96.4 | 97.1 | 7.55 | 0.03 | 0.84 |
| Overconditioned, % of cows | 13.2 | 3.6 | 2.9 | 7.55 | 0.03 | 0.84 |
| SCFT | ||||||
| Rib, mm | 5.5 | 4.2 | 4.8 | 0.36 | <0.01 | 0.14 |
| Change, mm | 0.7 | 0.1 | 0.4 | 0.39 | 0.15 | 0.48 |
| Rump, mm | 5.7 | 5.0 | 5.5 | 0.32 | 0.25 | 0.26 |
| Change, mm | 1.0 | 0.0 | 1.0 | 0.35 | 0.25 | 0.06 |
| Birth weight of calves | ||||||
| All calves, kg | 40.2 | 42.4 | 43.3 | 1.08 | <0.01 | 0.24 |
| Bull calves, kg | 41.4 | 44.6 | 45.2 | 1.08 | <0.01 | 0.68 |
| Heifer calves, kg | 39.0 | 40.5 | 41.0 | 1.65 | 0.20 | 0.73 |
1LF = low-fat diet; CAN = high-fat diet including canola seed-based pelleted feed; FLX = high-fat diet including flaxseed-based pelleted feed.
2HF = average of CAN and FLX.
3CC-BW = BW corrected for conceptus (NRC, 2000); CC-ADG = ADG based on conceptus corrected BW; cumulative ADG = ADG from the start of trial; thin = BCS < 2.5; optimal = 2.5 ≤ BCS ≤ 3.0; overconditioned = BCS > 3.0; SCFT = subcutaneous fat thickness.