Use of extensive winter feeding systems for backgrounding beef calves and the effect on finishing

The introduction of low heat unit corn varieties in western Canada has led to questions on how this crop might fit into an extensive backgrounding program. Therefore, a 3-yr study was conducted to evaluate the effects of grazing standing whole-plant corn (Zea mays L. 'Pioneer P7443R') or swathed whole-plant barley (Hordeum vulgare 'Ranger') compared with barley hay fed in drylot pens on beef steer performance during backgrounding and feedlot phases. The effect of backgrounding system was also assessed during finishing when steers were fed diets based on barley grain or corn grain. Each yr, 120 Angus steers (BW = 250.5 ± 1.8 kg) were allocated to 1 of 3 replicated (n = 2) backgrounding systems: (1) field grazing swathed whole-plant barley (BSG; 11.2% CP, 60.6% TDN); (2) field grazing standing whole-plant corn (CG; 8.7% CP, 64.6% TDN); or (3) drylot (DL) bunk feeding of processed barley hay (10.9% CP, 57.2% TDN) for an average 78 d (42 to 95 d) trial. All calves received 2.5 kg/d of a range pellet supplement (16% CP, 78% TDN). Treatment groups were similar (P > 0.05) in final BW (295.8 ± 5.0 kg), ADG (0.59 ± 0.03 kg/d), and G:F ratio (0.187 ± 0.03 kg/kg). The cost of gain of DL, BSG, and CG steers was CAN$6.32, CAN$3.14, and CAN$2.96/kg, respectively. Following backgrounding, each replicate group of steers was subdivided and placed in a feedlot for finishing on either a barley- (12.2% CP, 75.4% TDN) or corn grain-based (11.3% CP, 74.7% TDN) diet for an average of 120 d. There were no backgrounding system, finishing, or backgrounding system × finishing interaction effects (P > 0.05) for feedlot DMI, ADG, G:F, or carcass characteristics. Study results suggest that grazing either swathed barley or whole-plant corn for 65 d during backgrounding can reduce (P = 0.05) costs by CAN$60 and CAN$70/steer, respectively, compared with feeding steers barley hay in a drylot.