CASE STUDY: Changes in nutrient composition of cattle diets fed at 2 Southwestern cattle facilities experiencing bird depredation

Two experiments were conducted to evaluate changes in nutrient composition of cattle diets at 2 cattle feeding facilities experiencing bird depredation of diets. In Exp. 1, samples from 8 diets (concentrate level from 52 to 78% as fed) were collected from feed troughs at 0, 6, and 24 h after feeding. Ash, DM, and CP increased (P < 0.01) at 6 and 24 h after feeding and starch decreased (P < 0.01), but NDF and ADF remained unchanged (P > 0.10). Separately, in a location not accessible to the cattle, differently processed corn, soybean meal, and a high-concentrate diet were placed in a feed trough; corn feedstuffs were preferred (P < 0.01) over soybean meal, and all nutrients decreased (P < 0.01) over time. Maximum starch loss was observed at 83% of initial starch content over a 24-h period. In Exp. 2, pelleted diet samples (59% corn as fed) were collected from feed buckets at 0, 8, and 24 h after feeding at a calf facility. Most components (DM, CP, NDF, ADF, ash) increased (P < 0.01), whereas starch decreased (P < 0.01) between 0 and 8 h after feeding, but all components remained unchanged (P > 0.10) between 8 and 24 h. Birds feeding in the troughs and feed buckets included pigeon (Columbia livia), mourning dove (Zenaidura macroura), and greattailed grackle (Quiscalus mexicanus). The economic loss of bird depredation at Southwestern cattle feeding operations can be attributed to cost of grain, starch depredated, and nutrient losses to cattle.