PSI-6 Effect of Calcium Magnesium Carbonate And/or Tylosin Phosphate Supplementation on Behavior and Rumination Activity in Yearling Beef Steers Fed a Finishing Diet

Abstract

Abstract The objective of this study was to evaluate the effects of CaMg(CO3)2 (MIN-AD, Papillon Agricultural Company, Easton, MD; MA) and or tylosin phosphate (Tylan, Elanco, Indianapolis, IN; TY) supplementation on 24-hour behavior and rumination activity of yearling beef steers fed a finishing diet. A 2 × 2 factorial arrangement of treatments was used resulting in 4 dietary treatments: no MA and no TY (-MA/-TY), MA and no TY (MA/-TY), no MA and TY (-MA/TY), or MA and TY (MA/TY). Beef steers (n = 158; 469 ± 18.0 kg) were randomly assigned to dietary treatments with pen (n = 20 pens total, 10 pens/main effect mean, and 5 pens/simple effect mean) serving as the experimental unit. The MA was included at 1.5% of the diet (DM basis) in replacement of dry-rolled corn and TY was provided at 90 mg·animal-1·d-1. Observation began at 0800 h and ended at 0750 h the following day, resulting in a 24-hour observation period. Observations were recorded on a pen basis, with number of animals/type of activity recorded every 10 minutes on d 42 on feed (22 d on finisher). Activity categories included number of animals drinking (DR), eating (EA), active (standing; AC), ruminating (RU), and resting (RE) per pen. Chewing (CHE) was determined as the sum of eating and ruminating activity. Data were analyzed as a randomized complete block design with the fixed effects of MA, TY, and their interaction; block (pen location) was considered a random effect. An interaction was noted between MA and TY for time spent drinking (P = 0.03) and ruminating (P = 0.01). Steers from -MA/TY spent more time drinking compared with the -MA/-TY and MA/TY steers; steers from MA/-TY were intermediate (P < 0.10). Steers from -MA/-TY ruminated 28% longer compared with MA/-TY steers (P = 0.05) and 20% longer than -MA/TY (P = 0.05), steers from MA/TY ruminated 16% longer than steers from MA/-TY (P = 0.05), while steers from -MA/TY were intermediate (P > 0.10). The main effect of MA tended to increase time spent eating by 19.3% (P = 0.06); however, no differences (P ≥ 0.28) were noted for the main effects of MA or TY for minutes/day spent chewing, resting, or active. These results indicate that supplementation of MA may alter feeding behavior, resulting in increased minutes/day spent eating. In addition, supplementation of TY and MA may result in increased water intake, and alter time spent ruminating per day.