Effects of winter-feeding system on beef cow performance, ruminal fermentation, and system costs

• Published in: Applied Animal Science 2020-10, Vol.36 (5), p.731-744
• Main Authors: Jose, D., Larson, K., McKinnon, J.J., Penner, G.B., Damiran, D., Lardner, H.A.(Bart)
• Format: Article
• Language: English
• Subjects: corn grazing; drylot feeding; extensive winter system; rumen metabolism; swathed barley grazing
• ISSN: 2590-2865; 2590-2865
• DOI: 10.15232/aas.2020-01983

The objective was to evaluate the effects of a winter-feeding system on (study 1) forage biomass and quality, DMI, beef cow performance, system costs, and (study 2) ruminal fermentation. In study 1, over 3 yr, 60 dry, pregnant Angus cows were stratified by BW (658.2 ± 15 kg) and randomly allocated to 1 of 3 replicated (n = 2) winter-feeding systems. Winter-feeding systems included (i) grazing standing whole-plant corn (STCOR; Zea mays L. ‘DKC 26-25’; 10.0% CP, 67.6% TDN); (ii) grazing swathed whole-plant barley (SWBAR; Hordeum vulgare L. ‘Ranger’; 11.5% CP, 60.5% TDN); and (iii) drylot feeding barley hay (DLHAY; Ranger; 10.3% CP, 54.2% TDN). In study 2 (yr 1 and yr 2), 9 ruminally cannulated beef heifers (529 ± 39 kg) cycled through the 3 winter systems in a replicated 3 × 3 Latin square design, with 21-d periods to evaluate the effects of system and day of forage allocation on ruminal fermentation. Forage utilization was greatest (P = 0.01) for the DLHAY (84.4 ± 5.9%), intermediate for SWBAR (63.9 ± 2.5%), and least for STCOR (51.1 ± 4.4%) system. Winter-feeding system did not differ (P = 0.21) for initial BW (665 ± 17 kg), final BW (679 ± 25 kg), initial (4.2±0.94 mm) and final rib fat thickness (4.9±0.86 mm), and BCS (P = 0.36; final BCS = 2.8 ± 0.10; BCS change = 0.07 ± 0.14; 5-point scale). Mean ruminal pH was greatest (P = 0.02) for DLHAY (6.59) compared with SWBAR and STCOR forages (6.42 and 6.44, respectively). The area (pH × min/d) and duration that pH was