Effects of bacterial direct-fed microbial combinations on beef cattle growth performance, feeding behavior, nutrient digestibility, ruminal morphology, and carcass characteristics.

The effects of the dietary inclusion of a mixture of bacterial direct-fed microbial (DFM) on feedlot beef cattle growth performance, carcass characteristics, nutrient digestibility, feeding behavior, and ruminal papillae morphology were evaluated. Crossbred-Angus steers (n = 192; initial body weight (BW) = 409 kg ±â€…8 kg) were blocked by BW and randomly assigned into 48 pens (4 steers/pen and 16 pens/treatment) following a randomized complete block design. A steam-flaked corn-based fishing diet was offered to ad libitum intake once daily for 153 d containing the following treatments: (1) Control (no DFM, lactose carrier only); (2) treat-A (Lactobacillus animalis, Propionibacterium freudenreichii, Bacillus subtilis, and Bacillus licheniformis), at 1:1:1:3 ratio, respectively; totaling 6 × 109 CFU (50 mg)/animal-daily minimum; and (3) treat-B, the same DFM combination, but with doses at 1:1:3:1 ratio. Bacterial counts were ~30% greater than the minimum expected. Data were analyzed using the GLIMMIX procedure of SAS, with pen as the experimental unit, the fixed effect of treatment, and the random effect of BW-block, while preplanned contrasts comparing Control × treat-A or treat-B were used. Steers offered treat-A had increased carcass-adjusted average daily gain (P = 0.03) by 6.7%, gain efficiency (P < 0.01) by 6%, tended (P = 0.07) to have increased carcass-adjusted final BW by 15 kg, and hot carcass weight (P = 0.07) by 10 kg, while treat-B did not differ (P ≥ 0.17) from control. Overall dry matter (DM) intake (P = 0.36) and other carcass traits (P ≥ 0.13) were not affected by treatments. Steers offered treat-A tended to have increased digestibility of DM (P = 0.07) by 3%, neutral detergent fiber (P = 0.10), and hemicellulose (P = 0.08) by 9% compared with control, while treat-B did not differ (P ≥ 0.10) from control. No treatment × period interactions (P ≥ 0.21) or main effects of treatment (P ≥ 0.12) were observed during 24-h feeding behavior. Steers ruminated, ate, chewed, and were more active (P ≤ 0.01) during the second behavioral assessment (day 113), while drinking behavior was not affected (P ≥ 0.88). Ruminal papillae morphology and ruminal ammonia concentration (ruminal fluid collected at slaughter facility) were not affected by treatment (P ≥ 0.39). Steers offered the DFM treat-A had improved growth performance and it positively affected carcass weight and nutrient digestion. The DFM combinations did not seem to affect feedlot cattle feeding behavior or ruminal papillae morphology.

Direct-fed microbials (DFM) are naturally occurring microorganisms that alter cattle ruminal fermentation and intestinal function and have been shown to improve growth performance and nutrient digestibility of cattle. The use of DFM in animal feed has continuously increased in feedlots as an alternative to traditional antibiotic additives, which have gained negative public perception and additional regulatory scrutiny. High-energy diets can induce physiological challenges to cattle, especially when based on high starch availability ingredients, which may negatively affect animal growth performance. Such physiological digestive challenges may be overcome by a target combination of DFM bacterial strains (Lactobacillus animalis, Propionibacterium freudenreichii, Bacillus subtilis, and Bacillus licheniformis). These microorganisms individually have shown to have positive effects on finishing cattle offered high-energy diets, which highlights the need for research to optimize DFM types and doses to enhance the use of bacterial strains that can positively affect cattle growth performance, carcass traits, nutrient digestibility, and other variables relevant to the physiology of digestion. In the current experiment, feedlot steers offered a specific bacterial DFM combination/dose had improved average daily gain and feed efficiency, which were reflected as a positive influence on hot carcass weight and digestibility of nutrients, while not effectcting feeding behavior and ruminal morphology.

The effects of a nutritional packet (live yeast, vitamins C and B1, and electrolytes) offered to steers in a calf-fed system on growth performance, nutrient digestion, feeding behavior, carcass characteristics, and ruminal variables.

Effects of a nutritional packet strategically offered to calf-fed system steers on growth performance, nutrient digestibility, feeding behavior, ruminal variables, and carcass characteristics were evaluated. Angus crossbred steer-calves (N = 60; body weight [BW] = 234 ±â€…4 kg) were used in a randomized complete block design (block = BW) and stratified into two treatments: 1) control; and 2) 30 g/steer-daily (dry matter [DM] basis) of a nutritional packet containing (steer-daily basis): Live yeast (Saccharomyces cerevisiae; 1.7 × 1010 CFU), vitamin C (Ascorbic acid, 162 mg), vitamin B1 (thiamin hydrochloride, 400 mg), sodium chloride (2.4 g), and potassium chloride (2.4 g). Animals were offered (electronic feed-bunks [SmartFeed, C-Lock Inc., Rapid City, SD]), a steam-flaked corn-based finishing diet to ad libitum (individual intake), once daily for 233 d. Treatments were offered during the first and last 60 days on feed (DOF). The GLIMMIX procedure of SAS was used, with steer as the experimental unit, treatment and phase (for feeding behavior and digestibility) as fixed effects, and BW-block as a random effect. Steers offered the nutritional packet had 14% less (P < 0.01) intake and 18% greater (P = 0.01) feed efficiency during the initial 30 DOF. Intake (days 0 to 233) was 6% greater (P = 0.02) for steers offered the nutritional packet, while BW gain was not different (P ≥ 0.44). Greater (P = 0.02) dressing percent (61.1% vs. 62%) for steers offered the packet was observed, while other carcass variables were not different (P ≥ 0.33). Digestibility of DM, organic matter, and fiber were greater (P < 0.01) for steers offered the packet. Steers offered the packet spent 13% less time eating during the first 60 DOF, while during the last 60 DOF a 14% greater meal frequency and 12.3% smaller mean meal size (treatment × phase interaction, P < 0.02) were observed. Steers offered the packet had a reduced (P ≤ 0.01) mean meal duration during both phases. Regardless of treatment, a decreased rumination (P ≤ 0.03) and chewing (P ≤ 0.01) activities were observed for the last 60 DOF compared to the first 60 DOF. Ruminal papillae area was 30% greater (P = 0.02) and the total volatile fatty acid (VFA) tended (P = 0.09) to be greater for steers offered the nutritional packet. The nutritional packet offered to calf-fed steers improved feed efficiency during the initial 30 d after arrival, while inducing superior overall intake, nutrient digestibility, dressing percentage, ruminal papillae area, and total ruminal VFA.

The effects of a Nutritional Packet (live yeast, vitamins C and B1, and electrolytes) offered during the final phase of feedlot steers on growth performance, nutrient digestion, and feeding behavior.

The effects of a Nutritional Packet offered to beef steers during the final 64 d of the feedlot-finishing phase on growth performance, carcass characteristics, nutrient digestibility, and feeding behavior were evaluated. Angus-crossbred steers (N = 120; initial body weight = 544 ± 52 kg) were assigned to 30 pens (4 steers per pen; 15 pens per treatment) in a randomized complete block design where pen was the experimental unit. A steam-flaked corn-based finishing diet was offered to ad libitum, and the treatments were as follows: 1) control and 2) 30 g per steer-daily (dry matter basis) of the Nutritional Packet. The Nutritional Packet was formulated to provide 1.7 × 1010 CFU per steer-daily of Saccharomyces cerevisiae, 162 mg per steer-daily of vitamin C; 400 mg per steer-daily of vitamin B1; 2.4 g per steer-daily of NaCl, and 2.4 g per steer-daily of KCl. Data were analyzed using the GLIMMIX procedure of SAS with the fixed effect of treatment and the random effect of block. The average daily gain (P = 0.89), dry matter intake (P = 0.57), and gain efficiency (P = 0.82) were not affected by the inclusion of the Nutritional Packet. Digestibility of dry and organic matter, and neutral and acid detergent fiber increased (P ≤ 0.02) for steers offered the Nutritional Packet, while a trend for the same response was observed for hemicellulose (P = 0.08). The 12th rib backfat thickness increased (P = 0.02) for carcasses of steers offered the Nutritional Packet, followed by a greater (P = 0.03) calculated yield grade, whereas other carcass traits were not affected (P ≥ 0.32). While the steers under the control diet decreased behavior activities on day 63, a consistent pattern of feeding behavior measurements (activity min/d and min/kg of dry and organic matter, fiber fractions, and digestible nutrients) were observed for steers consuming the Nutritional Packet during both feeding behavior assessment periods (treatment × period interactions, P ≤ 0.03). Overall time (min/d) spent on rumination, drinking, active, chewing, and resting were not affected (P ≥ 0.28) by treatments. The Nutritional Packet offered to steers during the final 64 d on feed induced an improvement in apparent digestibility of nutrients and carcass fat deposition, without affecting growth performance or other carcass quality indices. Such effects associated with the more consistent feeding behavior of steers receiving the Nutritional Packet may warrant a shorter time on feed during the final portion of the finishing phase.

Excessive intake of rapidly fermentable nutrients by feedlot cattle can result in clinical or subclinical disorders that impair nutrient digestion, while negatively affecting animal development and health. Incidences of subclinical digestive disturbances may increase during the last days on feed in cattle fed in confinement. Manipulation of diets with probiotics (live yeast), vitamins (C and B1), and electrolytes (NaCl and KCl) to aid subclinical digestive disorders faced by cattle offered high-energy diets was addressed in the current experiment. The use of such nutritional technologies is based on previous reports that these technologies can stabilize ruminal pH, improve nutrient digestibility, enhance rumen microbial growth and energy metabolism, reduce oxidative stress, augment immune function, and prevent vitamin deficiencies induced by energy-dense diets. Therefore, it was important to investigate the effects of a packet containing these technologies during the feedlot final days on feed. When offered to steers during the final 64 d prior to harvest, a Nutritional Packet containing live yeast, vitamins C and B1, and electrolytes improved digestibility of nutrients and carcass fat deposition, while reducing variation in feeding behavior. Such effects may warrant an earlier harvest date when animals receive the packet.