Effect of monensin and monensin and tylosin combination on feed intake variation of feedlot steers

• Published in: Journal of animal science Vol. 73; no. 1; pp. 39 - 44
• Main Authors: Stock, R. A, Laudert, S. B, Stroup, W. W, Larson, E. M, Parrott, J. C, Britton, R. A
• Format: Journal Article
• Language: English
• Published: Savoy, IL Am Soc Animal Sci 01-01-1995; American Society of Animal Science; Oxford University Press
• Subjects: Animal productions; Animals; Biological and medical sciences; Cattle; Cattle - physiology; Diet; Dietary Fats - standards; Digestive system; Drug Combinations; Eating - drug effects; Eating - physiology; Edible Grain - standards; Fatalities; Feeds; Fundamental and applied biological sciences. Psychology; Male; Medicago sativa - standards; Monensin - pharmacology; Random Allocation; Silage - standards; Terrestrial animal productions; Tylosin - pharmacology; Vertebrates; Vertebrata; Mammalia; Farming animal; Food intake; Ox; Supplemented diet; Artiodactyla; Tylosin; Ungulata; Comparative study
• ISSN: 0021-8812; 1525-3163; 0021-8812
• DOI: 10.2527/1995.73139x

A trial involving four commercial feedlots and an individual feeding trial evaluated the effect of monensin and monensin/tylosin on intake variation and deaths from digestive disorders. Four commercial feedlots in Texas and Colorado fed 2,904 yearling crossbred steers (340 kg) high-grain diets containing approximately 82% grain, 8% silage and alfalfa hay, 4% fat, and 6% supplement (DM basis). Steers were allotted randomly to one of three monensin/tylosin levels: 1) no monensin or tylosin (control); 2) 22 mg/kg of monensin and 11 mg/kg of tylosin; or 3) 33 mg/kg of monensin and 11 mg/kg of tylosin. Monensin/tylosin reduced DMI (P < .05) and improved ADG (P < .05) and feed efficiency (P < .01). Intake variation associated with dry matter offered per pen was not different among treatments. In the individual feeding trial, feeding 27 mg/kg of monensin reduced (P < .10) DMI variation during grain adaptation and during d 57 to 70 and d 97 to 110 compared with the control (no monensin) diet. The magnitude of intake variance was 5 to 10 times greater with individually fed steers than with steers fed in the commercial feedlot pens. When the DMI of the individually fed steers were averaged and treated as a pen of steers, DMI variance was reduced drastically and was not different between treatments. We interpret these data to indicate that monensin and monensin/tylosin reduce feed intake variation among individual steers within a pen of steers. Pen means mask individual animal variation to the point that it is difficult to detect treatment differences.