Effects of supplementing spring-calving beef cows grazing barley crop residue with canola meal and wheat-based dry distillers grains with solubles on performance, reproductive efficiency, and system cost

A 2-yr experiment was conducted to determine the effects of supplementing canola meal and wheat-based dry distillers grains with solubles (wDDGS) on the performance of wintering cows grazing barley straw-chaff. Each year, a 24-ha field was seeded with forage barley (Hordeum vulgare 'Ranger'). The mature crop was swathed and combined to collect straw-chaff crop residue (STCH; 5.7% CP, 51% TDN) in 22 ± 5 kg piles. The field was divided into six 4-ha paddocks. Each year, 60 pregnant Black Angus cows (yr 1: BW = 641.4 ± 10.6 kg, BCS = 2.7 ± 0.1, gestation d = 121 ± 2; yr 2: BW = 685.2 ± 9.1 kg, BCS = 2.6 ± 0.1, gestation d = 108 ± 2) were randomly allocated to 1 of 3 replicated (n = 2) supplement treatments: (1) 100% wDDGS (39.2% CP, 78.8% TDN, DM basis); (2) 50% wDDGS plus 50% canola meal (50:50); or (3) 100% canola meal (42.6% CP, 71.5% TDN, DM basis) while winter grazing (49 and 39 d for yr 1 and yr 2, respectively) on STCH piles. The supplementation rate was 0.41% of BW or 2.6 kg/d. Supplementation strategy did not influence (P > 0.05) STCH DMI (11.4 ± 0.55 kg/d), cow BW change (−3.0 ± 1.90 kg), final BCS (2.5 ± 0.02), and subsequent reproductive performance. The results indicate that approximately one quarter (24-28%) of the winter feeding period can be filled by grazing barley STCH residue with supplementation and that canola meal was equal to wDDGS as a supplement for beef cows consuming barley STCH residue.