Influence of BOVAMINE DEFEND Plus on growth performance, carcass characteristics, estimated dry matter digestibility, rumen fermentation characteristics, and immune function in finishing beef steers

One hundred and eighty crossbred beef steers (406.0 ± 2.2 kg) were used to determine the impact of a novel direct-fed microbial (DFM) on growth performance, carcass characteristics, rumen fermentation characteristics, and immune response in finishing beef cattle. Steers were blocked by body weight (BW) and randomly assigned, within block, to 1 of 2 treatments (3 replicates/treatment: 30 steers/replicate). Treatments included: (1) no DFM (control) and (2) DFM supplementation at 50 mg ∙ animal-1 ∙ d-1 (BOVAMINE DEFEND Plus). All steers were fed a high-concentrate finishing diet and individual feed intake was recorded daily via the GrowSafe system. BWs were collected every 28 d. On day 55, 10 steers per pen were injected with ovalbumin (OVA). Jugular blood samples were collected from each steer on days 0, 7, 14, and 21 post injection. On day 112, the same steers were injected again with OVA and intramuscularly with a pig red blood cell solution. Jugular blood samples were collected from each steer on days 0, 7, 14, and 21 post injection. On day 124, rumen fluid was collected from 3 steers per treatment and used to estimate in vitro rumen fermentation characteristics. Equal numbers of steers per treatment were transported to a commercial abattoir on days 145, 167, and 185 of the experiment, harvested, and carcass data were collected. Initial BW was similar across treatments. On days 28 and 55, steers receiving DFM had heavier BW (P < 0.01) compared to controls. The average daily gain was greater in DFM-supplemented steers from days 0 to 28 (P < 0.01) and days 0 to 55 (P < 0.01) of the experiment compared to controls. Overall dry matter intake (DMI) was greater (P < 0.04) and overall feed efficiency was similar in DFM-supplemented steers compared to controls. Dressing percentage (P < 0.02) was greater in steers receiving DFM compared to controls. Antibody titers to injected antigens were similar across treatments. However, red blood cell superoxide dismutase activity was greater (P < 0.05) in DFM-supplemented steers compared to controls. In vitro molar proportions of isobutyric and butyric acid were greater (P < 0.01) and dry matter (DM) digestibility tended (P < 0.07) to be greater in rumen fluid obtained from steers supplemented with DFM. These data suggest that BOVAMINE DEFEND Plus supplementation improves growth performance during the initial period of the finishing phase, increases overall DMI and dressing percentage, and may impact antioxidant status in beef cattle.

PSIII-16 The Influence of Olive Byproduct Supplementation on American Wagyu Feedlot Performance and Carcass Characteristics

Eighty-three American Wagyu steers (725 ±10.7 kg) were used to evaluate the effects of olive byproduct supplementation on feedlot performance and carcass characteristics. We hypothesized that with supplementation of olive byproduct would improve feedlot performance and longissimus muscle intramuscular fat composition. Steers were blocked by initial body weight (BW) and randomly assigned within block to one of two treatments. Treatments consisted of: 1) Control diet (basal ration with no olive byproduct) + 1 kg of supplemental cracked corn per animal per day, or 2) Control diet + 1 kg of supplemental olive byproduct per animal per day. Steers were housed in feedlot pens (n=4 steers/pen; 11 replicates/treatment) and fed a traditional American Wagyu finishing diet (DM basis: 68.4% DM, 14.3% CP; 74.8% TDN, 1.16 Mcal/kg NEg, 5.3% crude fat). Diets were delivered to pens, once daily, in the morning in amounts to allow ad libitum access to feed over a 24 h period. Olive byproduct and cracked corn were top-dressed to the appropriate treatment pens immediately after delivery of the basal ration. Steers were individually weighed on d -1 and 0, and approximately every 28 d throughout the 177 d experiment. Equal numbers of steers per treatment were slaughtered throughout the experiment and carcass data were collected. Data were analyzed using a mixed effects model of SAS (SAS Inst. Inc.) for a randomized complete block design. Steers receiving olive byproduct had a lower final BW (P &lt; 0.01) when compared to steers receiving the control diet. Longissimus muscle long chain fatty acids C18:1 and C:22:0 were greater (P &lt; 0.05) and C18:0 lesser (P &lt; 0.05) in controls when compared to steers supplemented with olive byproduct. Under the conditions of this experiment, feeding olive byproduct reduced final BW and had minimal impacts on longissimus muscle fatty acid composition.

PSVIII-13 Influence of Propionibacteria Acidipropionici on Short Chain Fatty Acid and Methane Production in Fistulated Beef Steers

Twelve steers, fitted with rumen canulae were used in a 4 x 4 Latin square design to examine the impact of the direct fed microbial Propionibacteria acidipropionici (PA) on rumen fermentation characteristics. All steers were housed together in one pen equipped with GrowSafe feed intake monitoring stations and one Greenfeed system used to estimate in vivo methane production. Steers were fed a corn silage-based diet throughout the experiment. Treatments consisted of PA administered at: 1) 0.0; 2) 1.0 x 108; 3)1.0 x 109; and 4) 1.0 x 1010 CFU∙animal-1∙day-1. Treatments were administered directly into the rumen as a single bolus dose daily. On day 7 and 14 of each period, rumen fluid was collected from each steer 2 h post treatment administration for VFA analysis and for determining in vitro fermentation characteristics. Following a 14d washout period, animal treatments were switched, and the experiment repeated. Data were analyzed as a 4 x 4 Latin square design. In vivo propionic acid molar proportions (25.4 vs 23.6±0.24) and total VFA concentrations (125.2 vs 121.3±1.87) were greater (P &lt; 0.05) in steers receiving PA compared with controls. In vitro DM disappearance (P &lt; 0.05; 63.3% vs 59.2%±1.12) and total VFA (P &lt; 0.05; 147.9 vs 145.2±1.76) were greater and methane (ml/g DMD) lesser (P &lt; 0.04; 13.1 vs 15.6±0.11) in fermentation vessels incubated with rumen fluid from animals receiving PA compared with controls. Dry matter disappearance (P &lt; 0.03) and propionic acid (P &lt; 0.04) increased linearly as dose of PA increased. In vitro Total VFA tended (P &lt; 0.08) to increase linearly and methane production tended (P &lt; 0.09) to decrease quadratically in response PA dose. In vivo methane production was similar across treatments. In conclusion, PA addition improved in vivo and in vitro rumen fermentation characteristics.