Andrea K. Watson
Karla H. Jenkins
Date of this Version
Gardine, S. E. 2018. Corn residue grazing as a component of semi-confined cow-calf production and the effects of post-weaning management on feedlot performance. MS Thesis. Univ. of Nebraska, Lincoln.
Grazing corn residue can be a valuable alternative to harvested winter feed in a cow-calf production enterprise. The objectives of the first study were to: 1) determine the sample size needed to accurately estimate yield of corn grain and residue and 2) evaluate changes in residue quality throughout the fall/winter and spring-grazing seasons. Results suggest that 6-10 plants serve as a representative sample for grain yield while 7- 10 plants are needed for a representative sample of residue yield. In vitro OM digestibility was greatest at the beginning of the fall and spring grazing seasons and declined over time (P < 0.01). In vitro OM digestibility of available residue declined 21% over the fall-grazing season and 51% throughout the spring-grazing season. A second study evaluated the effects of 2 winter cow-calf production systems on cow-calf performance at 2 locations. Cows wintered on cornstalks at ENREC lost BW and had a 0.46 unit decrease in BCS, while cows in the dry-lot gained BW and had a 0.24 unit increase in BCS (P < 0.01). At PREC, BCS increased by 0.03 units for cows wintered in the dry-lot and decreased by 0.26 units for cows wintered on cornstalks (P = 0.04). At ! both locations, calves wintered in the dry-lot had greater ADG and BW per d of age compared to calves wintered on cornstalks (P ≤ 0.03). A partial budget suggests that lower winter production inputs may be significant enough to compensate for reduced performance of calves when cow-calf pairs are wintered on cornstalks. A third experiment evaluated the effects of winter cow-calf production system and post-weaning management on finishing performance and carcass characteristics of calves sourced from experiment two. Calves that had previously been winter grazed on cornstalks had lighter initial BW entering the finishing phase than calves wintered in the dry-lot (P < 0.01). Calves directly adapted to a finishing diet following weaning had greater finishing ADG (P < 0.01) and improved G:F (P < 0.01). Calves that were fed a growing diet prior to the finishing phase produced 35 kg greater final BW (P < 0.01) and 23 kg greater carcass weight (P < 0.01). Directly finishing calves resulted in greater net profit compared to growing calves prior to the finishing phase (P < 0.01) as the extra carcass weight did not offset the cost of the additional 49 days in the feedlot.
Advisor: Andrea K. Watson