Effects of feeding different probiotic types on metabolic, performance, and carcass responses of Bos indicus feedlot cattle offered a high-concentrate diet.

Two experiments were designed to evaluate the effects of different probiotic combinations on rumen fermentation characteristics, performance, and carcass characteristics of feedlot Bos indicus beef bulls offered a high-concentrate diet. In experiment 1, 30 rumen-fistulated Nellore steers were blocked by initial body weight (BW = 350 ± 35.0 kg) and within blocks (n = 10), animals were randomly assigned to receive: 1) high-concentrate diet without probiotic supplementation (n = 10; CONT), 2) CONT plus 1 g per head of a probiotic mixture containing three strains of Enterococcus faecium and one strain of Saccharomyces cerevisiae (3.5 × 109 CFU/g; n = 10; EFSC), and 3) CONT plus 2 g per head of a probiotic mixture containing Bacillus licheniformis and Bacillus subtilis (3.2 × 109 CFU/g; n = 10; BLBS). The experimental period lasted 35 d, being 28 d of adaptation and 7 d of sampling. From day 34 to day 35 of the experimental period, ruminal fluid and fecal samples were collected every 3 h, starting immediately before feeding (0 h) for rumen fermentation characteristics and apparent nutrient digestibility analysis, respectively. In experiment 2, 240 Nellore bulls were ranked by initial shrunk BW (375 ± 35.1 kg), assigned to pens (n = 4 bulls per pen), and pens randomly assigned to receive the same treatments as in experiment 1 (n = 20 pens per treatment). Regardless of treatment, all bulls received the same step-up and finishing diets throughout the experimental period, which lasted 115 d. In both experiments, data were analyzed as orthogonal contrasts to partition-specific treatment effects: 1) probiotic effect: CONT vs. PROB and 2) probiotic type: EFSC vs. BLBS (SAS Software Inc.). In experiment 1, no contrast effects were observed on nutrient intake, overall nutrient digestibility, and rumen fermentation analyses (P ≥ 0.13). Nonetheless, supplementation of probiotics, regardless of type (P = 0.59), reduced mean acetate:propionate ratio and rumen ammonia-N concentration vs. CONT (P ≤ 0.05). In experiment 2, no significant effects were observed for final BW and dry matter intake (P ≥ 0.12), but average daily gain and feed efficiency tended to improve (P ≤ 0.10) when probiotics were offered to the animals. Probiotic supplementation or type of probiotic did not affect carcass traits (P ≥ 0.22). In summary, supplementation of probiotics containing a mixture of E. faecium and S. cerevisiae or a mixture of B. licheniformis and B. subtilis reduced rumen acetate:propionate ratio and rumen ammonia-N levels and tended to improve the performance of feedlot cattle offered a high-concentrate diet.

Two experiments were designed to evaluate the effects of different probiotic combinations on rumen fermentation characteristics, performance, and carcass characteristics of feedlot Bos indicus beef bulls offered a high-concentrate diet. The two probiotics consisted of a mixture containing three strains of Enterococcus faecium and one strain of Saccharomyces cerevisiae or a mixture of Bacillus licheniformis and Bacillus subtilis. Supplementation of probiotics, regardless of type, reduced acetate:propionate ratio, and mean rumen ammonia-N concentration and tended to improve the performance of feedlot cattle offered a high-concentrate diet, demonstrating the potential of this technology to be used as a feed additive for beef cattle.

Effects of Megasphaera elsdenii administration on performance and carcass traits of finishing Bos indicus feedlot cattle.

This study evaluated the effects of Megasphaera elsdenii administration at the beginning of the feedlot period on performance of Bos taurus indicus bulls. On d 0, 383 Nellore bulls (initial shrunk body weight 384 ± 29.2 kg; initial age = 24 ± 2 mo) were assigned to treatments in a randomized complete block design. Treatments consisted of 1) 14 d adaptation diet and transition to a finishing diet (CONT), 2) CONT plus oral administration of 20 mL of Lactipro-NXT (M. elsdenii) on d 0 of the study (MEG-14), 3) CONT diet, consisting of 6 d of adaptation diet plus oral administration of 20 mL of Lactipro-NXT on d 0 of the study (MEG-6), and 4) No adaptation diet and oral administration of 20 mL of Lactipro-NXT on d 0 of the study (MEG-0). Experimental period lasted 119 d. No treatment effects were observed for any of the performance parameters evaluated herein (P ≥ 0.15). Nonetheless, a treatment × wk interaction was observed for DM, NEm, and NEg intakes (P < 0.0001). For all these parameters, MEG-0 and MEG-6 had a reduced intake vs. MEG-14 and CONT in the first wk of the study (P ≤ 0.05). For the carcass traits, no effects were observed for HCW (P ≥ 0.24), whereas MEG-6 had a greater REA when compared with MEG-0 and MEG-14 (quadratic effect; P = 0.04) and MEG-administered bulls tended to have a greater BFT vs. CONT (P = 0.08). In summary, M. elsdenii administration at the beginning of the feedlot period did not improve performance, whereas reducing the length of the adaptation period for 6 d improved REA of finishing Bos taurus indicus bulls.

Feeding the combination of essential oils and exogenous α-amylase increases performance and carcass production of finishing beef cattle.

Two experiments were conducted to evaluate the performance responses of finishing feedlot cattle to dietary addition of essential oils and exogenous enzymes. The treatments in each experiment consisted of (DM basis): MON-sodium monensin (26 mg/kg); BEO-a blend of essential oils (90 mg/kg); BEO+MON-a blend of essential oils plus monensin (90 mg/kg + 26 mg/kg, respectively); BEO+AM-a blend of essential oils plus exogenous α-amylase (90 mg/kg + 560 mg/kg, respectively); and BEO+AM+PRO-a blend of essential oils plus exogenous α-amylase and exogenous protease (90 mg/kg + 560 mg/kg + 840 mg/kg, respectively). Exp. 1 consisted of a 93-d finishing period using 300 Nellore bulls in a randomized complete block design. Animals fed BEO had higher DMI (P < 0.001) but similar feed efficiency to animals fed MON (P ≥ 0.98). Compared with MON, the combination of BEO+AM resulted in 810 g greater DMI (P = 0.001), 190 g greater average daily gain (P = 0.04), 18 kg heavier final body weight (P = 0.04), and 12 kg heavier hot carcass weight (P = 0.02), although feed efficiency was not significantly different between BEO+AM and MON (P = 0.89). Combining BEO+MON tended to decrease hot carcass weight compared with BEO alone (P = 0.08) but not compared with MON (P = 0.98). Treatments did not impact observed dietary net energy values (P ≥ 0.74) or the observed:expected net energy ratio (P ≥ 0.11). In Exp. 2, five ruminally cannulated Nellore steers were used to evaluate intake, apparent total tract digestibility of nutrients, and ruminal parameters in a 5 × 5 Latin square design. Feeding BEO increased the total tract digestibility of CP compared to MON (P = 0.03). Compared to MON, feeding the combination of BEO+MON increased the intake of CP (P = 0.04) and NDF (P = 0.05), with no effects on total tract digestibility of nutrients (P ≥ 0.56), except for a tendency (P = 0.09) to increase CP digestibility. Intakes of all nutrients measured, except for ether extract (P = 0.16) were greater in animals fed BEO+AM when compared with MON (P ≤ 0.03), with no differences on total tract nutrient digestibilities (P ≥ 0.11) between these two treatments. In summary, diets containing the BEO used herein enhanced DMI of growing-finishing feedlot cattle compared with a basal diet containing MON without impair feed efficiency. A synergism between BEO and AM was detected, further increasing cattle performance and carcass production compared to MON.