Animal Performance and Diet Quality While Grazing Corn Residue

A grazing trial compared the effect of stocking rate on corn residue removal and nutrient quality over a 55 d period. Treatments included no removal (control), light grazing (2.5 animal unit months/ha), heavy grazing (4.9 animal unit months/ha), and baling (bale), that were applied to eight 6.6 ha paddocks (2 replications) on a 53 ha center pivot irrigated field of corn residue from mid-December to mid-February. Residue samples were collected prior to and after grazing at 10 locations within each paddock using a 1/2 m 2 quadrat. After collection, samples were sorted by plant part (leaf, stem, husk, cob, and grain), and analyzed for DM, OM, CP, NDF, and in-vitro organic matter disappearance (IVOMD). No three or two-way interactions were observed for amount of residue OM (kg/ha; P ≥ 0.61), but amount of residue differed by plant part and time collected (P ≤ 0.02). Of residue remaining before grazing, stems make up the greatest proportion (42.1%) followed by leaves (33.8%), cobs (14.1%), and husks (9.9%). Little removal of stems (2% of original amount) was observed. Cobs and leaves were moderately removed from the light stocking rate (41.1% and 35.0%, respectively) and heavy stocking rate (26.8% and 20.0%, respectively) compared to control (17.9% and 0%, respectively). Proportionally, most husks were removed from the heavy stocking rate treatment (87.9%), moderately for light stocking rate treatment (54.3%), and least for control treatment (32.3%).Leaf residue (5.6 to 6.1%%) had greater CP compared to husks (3.5 to