Effect of deterred and undeterred bird depredation on nutrient composition of a cattle diet and growth performance in cattle at a Southwestern feedlot facility

Abstract Text: A summer study was performed to determine the effect of bird depredation on nutrient composition of a diet fed to and performance parameters of feedlot cattle with open or limited exposure to depredating birds at the University of Arizona West Agriculture Campus (Tucson). This study also investigated feeding preference of individual feedstuffs used at the feedlot. Feeder cattle (n  = 50 ; 170 ± 15 kg) were sorted by gender then randomly assigned to 1 of 8 pens assigned to 1 of 2 treatments: open feed trough exposure to the existing bird population (OP) or limited feed trough exposure to the bird population utilizing self-closing wire gates (LM). Cattle were fed until backfat ultrasound measurement reached 1cm (476.5 ± 2.8 kg). Diets were sampled at 0, 7, and 24 h post-feeding and analyzed for DM, NDF, ADF, CP, ash, and starch. Cattle performance parameters included G:F ratio, ADG, cost per kg of gain, and final BW. On separate days, DM disappearance was recorded for either individual feedstuffs included in cattle diet or grains varying in processing level placed in troughs not exposed to cattle. Cattle and feed data were analyzed as a complete randomized design with pen as the experimental unit. Both CP and ADF were greater (P < 0.02) in OP versus LM troughs at 7 and 24 h, although starch was greater (P < 0.02) in LM versus OP troughs after 24 h. Although LM and OP cattle had equivalent ADG, LM cattle had greater G:F ratio (P < 0.02), lower cost per kg gain (P < 0.05), and tended (P < 0.10) to have lower final BW when compared to OP cattle. Dry matter disappearance for diet feedstuffs was greatest (P < 0.01) for steam-flaked corn, followed by SBM, mineral mix, alfalfa, and urea, respectively. DM disappearance for grain type was greatest (P < 0.01) for whole milo, followed by rolled corn, steam-flaked corn, ground milo, ground barley, ground corn, and whole corn and whole barley, respectively. Birds feeding in the trough included pigeon (Columbia livia), mourning dove (Zenaidura macroura), and Eurasian dove (Streptopelia decaocto). Results indicate that bird populations present at Southwestern cattle feeding operations are capable of altering production parameters in cattle as well as altering nutrient composition in feed through feedstuff preference.

Keywords: bird depredation, cattle, nutrient loss