PSXIII-21 Effects of Bacterial Direct-Fed Microbial Mixtures on Beef Cattle Feeding Behavior

Abstract

Abstract The effects of bacterial direct-fed microbial (DFM) mixtures on beef cattle feeding behavior were evaluated. Six ruminally cannulated crossbred Angus steers (BW = 520 ± 30 kg) were used in a replicated 3 × 3 Latin Square design. Steers were offered a steam-flaked corn-based finishing diet to ad libitum during three, 28 d periods (21-d adaptation and 7-d collection). Treatments assigned were: 1) Control (no DFM, lactose carrier only); 2) Treat-A [L. animalis, P. freudenreichii; B. subtilis; and B. licheniformis, at 1:1:1:3 ratio, respectively; totaling 6 × 109 CFU (50mg)/animal-daily minimum (Chr.Hansen]; and 3) Treat-B, the same DFM combination, but with doses at 1:1:3:1 ratio. Bacterial counts were approximately 30% greater than the minimum expected. The DFM diluted mixtures and carrier (Control) were pre-weighed and stored at -20°C until incorporated into the diet (2 g· animal-1· /day-1) 10 min prior to feeding. For mixing, approximately 1 kg (as is) of the diet being offered was removed from the individual recipient, DFM was mixed by hand, and the mixture was incorporated into the feed allocated for the day. The feeding behavior assessment consisted of a 24 h continuous visual observation (every 5 min) performed by trained personnel. Animals were assessed on d 26 of each period (no other management other than cleaning of the stall), while time spent eating, ruminating, resting, active, and drinking were taken. Time spent chewing was accounted for by adding time spent eating and ruminating. In addition, records allowed the count of the number of meals taken, as well as the time spent on each meal. Data were analyzed using the GLIMMIX procedure of SAS, with animal considered as the experimental unit, the fixed effects of treatment, and random effect of square, period, and animal (square). F-test protected pre-planned orthogonal contrasts was used to compare Control vs. Treat-A and Control vs. Treat-B. Meal number (16/d) and length (8 min/meal) were not affected by treatments (P ≥ 0.54). Main feeding behavior variables consisting of rumination (198 min/d), eating (117 min/d), chewing (315 min/d), drinking (22 min/d), resting (929 min/d), and active (174 min/d) were not affected (P ≥ 0.24) by treatments. A tendency was observed (P = 0.08) where animals offered the Treat-B spent numerically less time ruminating per unit of digestible DM and OM intake compared with Control (13.5 vs. 15.5, and 13.7 vs 15.6 min/kg, respectively). Other behaviors measured in min/kg of DM, NDF, and ADF intake were not affected (P ≥ 0.17) by treatments [rumination (11.5, 60.2, and 181), eating (6.5, 34.4, and 104), chewing (18, 94.6, and 285), and drinking (1.2, 6.6, and 19.8) min/kg, respectively]. The bacterial DFM mixtures offered appear not to directly affect the feeding behavior of beef cattle consuming a steam-flaked corn-based finishing diet.