463 Effects of Winter Cow-Calf Production System on Cow-Calf Performance.

Limited traditional forage resources have prompted interest for alternative cow-calf production systems. This study evaluated the effects of 2 winter cow-calf production systems on cow-calf performance in a summer-calving, intensively managed cowherd. The study was conducted over 3 years in eastern Nebraska (ENREC) and 2 years in western Nebraska (PREC). Lactating, crossbred beef cows (n=127 at ENREC; n=56 at PREC) with summer-born calves were utilized in the study. In year 1, cow-calf pairs within location were blocked by cow BW (4 blocks at ENREC; 2 blocks at PREC), stratified by calf age, and assigned randomly within strata to 1 of 2 winter cow-calf production treatments with 4 (ENREC) or 2 (PREC) replications per treatment. Treatments were 1) dry-lot feeding (DL) or 2) cornstalk grazing with supplementation (CS). In the subsequent years, cows within location were assigned to the same treatment as assigned in year 1. The trial was initiated at the beginning of cornstalk grazing (mid-November) within each location. Dry-lot pairs within location were limit-fed a crop residue and distillers-based diet formulated to maintain a lactating cow in early gestation. A dried distillers grain-based pellet was supplemented to pairs wintered on cornstalks at a rate of 2.4 kg DM/pair daily. The trial was completed when winter cornstalk grazing ended (mid-April), which coincided with weaning. Cow-calf pairs grazed on average 152 and 137 d at ENREC and PREC, respectively. Dry-lot cow-calf pairs were limit-fed 12.3 kg DM (ENREC) or 11.9 kg (PREC) on average throughout the trial. Cows that were managed in the dry-lot at ENREC had greater ending BW and BCS compared to cows grazing cornstalks (P < 0.01). Cows wintered on cornstalks at ENREC lost BW and had a 0.5 unit decrease in BCS, while cows in the dry-lot gained BW and had a 0.2 unit increase in BCS. At PREC, BCS increased for cows wintered in the dry-lot and decreased 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 CS calves (P ≤ 0.03). A partial budget suggests that incorporating winter cornstalk grazing into an intensive production system results in a cost savings of $97 per pair. Lower winter production inputs may be significant enough to compensate for reduced performance of calves when cow-calf pairs are wintered on cornstalks.