Effect of Dried Citrus Pulp and Cage Layer Manure in Combination with Monensin on Performance and Tissue Mineral Composition in Finishing Steers2

Abstract
An 83-day feeding trial was conducted with 32 steers to evaluate the effect of including 0 or 33 g monensin per metric ton in diets containing either dried citrus pulp or corn as a main energy source and either cage layer manure or soybean meal as a source of supplemental nitrogen. Steers averaged 259 kg initially. A 2 × 2 × 2 factorial arrangement of dietary treatments was used. No influence of monensin or dietary energy sources on body weight gain of animals was observed. However, steers fed soybean meal gained faster (P<.01) than those fed cage layer manure. Monensin reduced daily feed intake from 9.21 to 8.20 kg/head and decreased feed to gain ratio from 8.42 to 7.22. Carcass evaluation revealed no effect of treatment on quality grade, but dressing percentage and yield grade for steers fed soybean meal were higher (P<.05) than those for steers fed cage layer manure. Feeding cage layer manure at the 20% level increased (P<.01) Ca in kidney and Cu in liver and decreased (P<.01) Mn in liver. Including citrus pulp in the diets increased Zn (P<.01) in muscle and Fe (P<.05) in kidney and decreased (P<.01) liver Mn. A second, 64-day experiment was conducted with 32 steers to determine the effect of including monensin (33 g/metric ton) in diets containing either dried citrus pulp or corn as the main energy source. Steers averaged 400 kg initially. A 2 × 2 factorial arrangement of dietary treatments was used. Daily weight gain was not affected by treatments. Monensin decreased (P<.01) daily feed intake from 11.50 to 9.91 kg/head and decreased (P<.05) feed to gain ratio from 11.07 to 10.16. Monensin increased (P = .03) ruminal propionic acid concentration and decreased (P<.01) acetic acid to the same extent whether the primary energy source was corn or dried citrus pulp. There was no influence of treatments on dressing percentage, quality grade or yield of carcasses. Copyright © 1980. American Society of Animal Science . Copyright 1980 by American Society of Animal Science