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The effects of dietary inclusion of live bacteria mixtures on feedlot beef cattle feeding behavior were evaluated. Crossbred-Angus yearling steers (n = 192; initial BW = 409 kg ± 8 kg) were blocked by body weight (BW) and randomly assigned into 48 pens (4 steers/pen; 16 pens/treatment) following a randomized complete block design. A steam-flaked corn-based fishing diet was offered ad libitum once daily containing the following treatments: 1) Control, in which no direct fed microbial (DFM) was offered (lactose as carrier only); 2 and 3) Probiotic mixtures at distinct concentrations [Mixture A and B, at 2g/animal-daily (lactose used as carrier)]. Orts DM were quantified daily and subtracted from total dietary DM offered to calculate DM intake. Feeding behavior activities (continuous 24 h) were visually assessed (d 106 and 113) by trained personnel, where time spent on each activity was recorded every 5 min. Data were analyzed using the GLIMMIX procedures of SAS and pen was considered the experimental unit. No treatment × period interactions (P ≥ 0.21) were observed. Main feeding behavior variables consisting of time spent ruminating, chewing, eating, and drinking in minutes per day were not affected (P ≥ 0.17) by treatments, while steers in general ruminated, ate, chewed, and were more active (P ≤ 0.01) during the second behavioral assessment, regardless of treatments. Rates of intake in minutes per kg of DM, OM, fiber and digestible DM, OM, and fiber were not affected (P ≥ 0.12) by treatments; however more time spent (P < 0.01) ruminating, eating, and chewing in minutes per kg were observed on d113 compared to d106 regardless of treatments. Drinking time (min/d) and drinking rates (min/kg) were not affected (P ≥ 0.81) by period. The DFM mixtures did not negatively affect feeding behavior of yearling steers consuming steam-flaked corn-based finishing diets. [ABSTRACT FROM AUTHOR]

The effects of dietary inclusion of live bacteria on feedlot beef cattle apparent total tract nutrient digestibility were evaluated. Crossbred-Angus yearling steers (n = 192; initial BW = 409 kg ± 8 kg) were blocked by body weight (BW) and randomly assigned into 48 pens (4 steers/pen; 16 pens/treatment) following a randomized complete block design. A steam-flaked corn-based fishing diet was offered ad libitum once daily containing the following treatments: 1) Control, in which no direct fed microbial (DFM) was offered (lactose as carrier only); 2 and 3) Probiotic mixtures at distinct concentrations [Mixture A and B, at 2g/animal-daily (lactose used as carrier)]. Orts DM were quantified (if any) daily and subtracted from total dietary DM offered to calculate DM intake. Fecal samples were collected twice daily (0700 and 1700 h) for 5 consecutive days (d 68 to 72) from at least 3 steers per pen, while feed samples were collected daily. Samples were composited within period, dehydrated (55°C), and ground (1mm) for further analyses. Total fecal output was estimated with a dietary internal marker (288-h indigestible NDF) and used to calculate nutrient digestibility. Data were analyzed using the GLIMMIX procedure of SAS and pen was considered the experimental unit. Intakes of DM, OM, NDF, and ADF during the digestibility assessment were not affected (P = 0.13) by treatments. Steers offered DFM mixture-A tended to increase digestibility of DM (P = 0.07; 79.3 vs. 77.1%), NDF (P = 0.10; 56.9 vs. 51.6%), and hemicellulose (P = 0.08; 59.4 vs. 53.9%) compared with control, while digestibility of ADF was not affected (P = 0.24) by treatment. The DFM mixture-A seemed to positively affect apparent digestibility of nutrients in steers consuming a steam-flaked corn-based finishing diet, in which improvements in the fiber fraction digestion seemed to be a meaningful contributor. [ABSTRACT FROM AUTHOR]

The effects of the dietary inclusion of live bacteria mixtures on feedlot beef cattle ruminal papillae morphology were evaluated. Crossbred-Angus yearling steers (n = 192; initial BW = 409 kg ± 8 kg) were blocked by body weight (BW) and randomly assigned into 48 pens (4 steers/pen; 16 pens/treatment) following a randomized complete block design. A steam-flaked corn-based fishing diet was offered ad libitum once daily during 153 d containing the following treatments: 1) Control, in which no direct-fed microbial (DFM) was offered (lactose as carrier only); 2 and 3) Probiotic mixtures at distinct concentrations [Mixture A and B, at 2g/animal-daily (lactose used as carrier)]. Upon harvest at a federally inspected slaughter facility, epithelium samples were collected from the cranial sac of the rumen, immersed in a 70% alcohol, and preserved under refrigeration (5°C). Ruminal tissue fragments were trimmed (1cm2), in which papillae were completely counted within the fragment, followed by the removal of 12 random individual papillae for further area measurement using electronic scanning (ImageJ). Data were analyzed using the GLIMMIX procedure of SAS and pen was considered the experimental unit with the fixed effect of treatment and the random effect of block. Regardless of treatments, average papillae area in cm2 (P = 0.39; control: 0.38, DFM mixture-A: 0.40, DFM mixture-B: 0.37), papillae number within fragment (P = 0.70; control: 47, DFM mixture-A: 52, DFM mixture-B: 49), absorptive surface area in cm2/fragment cm2 (P = 0.87; control: 37, DFM mixture-A: 39, DFM mixture-B: 38), and ruminal absorptive surface area (P = 0.74; control: 97%, DFM mixture-A: 97%, DFM mixture-B: 97%) were not affected compared with control. The addition of DFM mixtures did not seem to affect ruminal papillae physical aspect, although the long-term effects of dietary inclusion of live bacteria on ruminal morphology needs to be further evaluated. [ABSTRACT FROM AUTHOR]

Direct fed microbials (DFM) dietary mixture effects on beef cattle ruminal variables, intake, and apparent total tract digestibility were evaluated. Six ruminally cannulated beef steers (BW = 520 ± 30 kg) were used in a duplicated 3 × 3 Latin square design and offered a steam-flaked corn-based finishing diet ad libitum for three 28-d periods (21-d adaptation and 7-d collection). Treatments assigned were: 1) Control (no DFM mixture; lactose only); 2 and 3) DFM mixtures at distinct concentrations [Mixture A and B, at 2 g/animal-daily (lactose used as carrier)]. Ruminal pH and temperature were measured every 6 min (wireless probes). Ruminal samples were collected at 0, 2, 4, 8, 16, and 23 h post-feeding on d28. Feed and fecal samples (collected once and twice daily, respectively) were composited by period and analyzed. Fecal output was estimated with a dietary internal marker (288-h indigestible-NDF). Data were analyzed using the GLIMMIX procedure of SAS. No treatment × time interactions (P = 0.20) were observed. Steers offered mixture-A experienced 300 min/d less (P = 0.04) time under the ruminal pH 5.6, tended (P = 0.13) for a lesser area under the curve of ruminal pH 5.6, while showing a greater (P = 0.04) ruminal pH average (5.67 vs. 5.50), and tended (P = 0.06) for a lesser ruminal temperature (39.2 vs. 39.4°C) compared to control. The ruminal concentration of NH3-N was greater (P = 0.02) for mixture-A compared with control (10.78 vs. 4.35 mg/dL), while animals offered mixture-B tended (P = 0.07) to be greater (9.11 mg/dL) than control. Steers offered DFM mixture-A increased (P = 0.04) ADF digestibility compared with control (39.8 vs. 54.0%), while not affecting DM intake (P = 0.61). The DFM mixture-A induced a safer ruminal pH environment and encouraging fiber degradation and NH3-N release, while not affecting animal intake. [ABSTRACT FROM AUTHOR]

The effects of dietary inclusion of live bacteria on feedlot beef cattle growth performance and carcass characteristics were evaluated. Crossbred-Angus yearling steers (n = 192; initial BW = 409 kg ± 8 kg) were blocked by body weight (BW) and randomly assigned into 48 pens (4 steers/pen; 16 pens/treatment) following a randomized complete block design. A steam-flaked corn-based fishing diet was offered ad libitum once daily containing the following treatments: 1) Control, in which no direct fed microbial (DFM) was offered (lactose as carrier only); 2 and 3) Probiotic mixtures at distinct concentrations [Mixture A and B, at 2g/animal-daily (lactose used as carrier)]. Orts DM were quantified daily and subtracted from total dietary DM offered to calculate DM intake. Two-day consecutive unshrunk BW were recorded before feeding on d 0, 30, 60, 90, 121, and 153 (prior to shipment to a federally inspected slaughter facility). Data were analyzed using the GLIMMIX procedure of SAS and pen was considered the experimental unit, in which F-test protected pre-planned contrasts comparing control versus DFM mixture-A and control versus DFM mixture-B were used. Steers offered mixture-A increased carcass-adjusted ADG (P = 0.03) by 6.7%, gain efficiency (P < 0.01) by 6%, tended to increase carcass-adjusted final BW (P = 0.07) by 15kg and hot carcass weight (P = 0.07) by 10kg. The overall (d 0 to end) DM intake (P = 0.36) was not affected by treatment; however, a subtle (1.2%) decrease (P < 0.01) during the initial 30 days for steers offered DFM mixture-B was observed. Carcass variables (dressing percentage, 12th rib fat, longissimus muscle area, marbling, yield grade, and liver scores) were not affected (P = 0.13) by treatments. Growth performance was improved with DFM mixture-A which seemed to positively affect carcass weight without inducing deleterious effects on other carcass characteristics. [ABSTRACT FROM AUTHOR]