Twelve 5-year-old beef steers, with an average weight of 2000 lbs., fitted with rumen canulae were used in a 4 × 4 incomplete Latin square design to examine the impact of the direct fed microbial Propionibacterium acidipropionici CP 88 (PA) on rumen fermentation characteristics, in vitro CH4, CO2, and N2 production, and in vivo CH4 and CO2 production. All steers were housed in the same pen equipped with eight GrowSafe feeding stations to monitor individual animal feed intake and one GreenFeed System to estimate individual animal CH4 and CO2 production. Steers were fed a corn-silage-based diet throughout the experiment. Treatments consisted of PA administered at: (1) control (0.0); (2) 1.0 × 108; (3) 1.0 × 109; and (4) 1.0 × 1010 cfu∙animal−1∙day (d)−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 in vitro DM digestibility determination. Following a 14 d washout period, animal treatments were switched and the experiment repeated until the 4 × 4 Latin square was complete. In vivo propionic acid molar proportions and total VFA concentrations were greater (p < 0.05) in steers receiving PA when compared with controls. All other in vivo rumen fermentation characteristics were similar across treatments. In vitro DM disappearance (p < 0.05) and total VFA (p < 0.05) were greater and CH4 lesser (p < 0.04) in fermentation vessels incubated with rumen fluid from animals receiving PA when compared with controls. Dry matter disappearance (p < 0.03) and propionic acid molar proportions increased (p < 0.04) linearly as the dose of PA increased. In vitro total VFA tended (p < 0.08) to increase linearly and CH4 production per unit of DM digested tended (p < 0.09) to decrease quadratically in response to PA dose. All other in vitro rumen fermentation characteristics were similar across treatments. These data indicate that PA impacts in vivo and in vitro rumen fermentation characteristics.

Fifty-four multiparous beef cows with calves were used to evaluate the effects of Mo source (feed or water) on reproduction, mineral status, and performance over two cow-calf production cycles (553 days). Cows were stratified by age, body weight, liver Cu, and Mo status and were then randomly assigned to one of six treatment groups. Treatments were (1) negative control (NC; basal diet with no supplemental Mo or Cu), (2) positive control (NC + Cu; 3 mg of supplemental Cu/kg DM), (3) NC + 500 µg Mo/L from Na2MoO4·2H2O supplied in drinking water, (4) NC + 1000 µg Mo/L of Na2MoO4·2H2O supplied in drinking water, (5) NC + Mo 1000-water + 3 mg of supplemental Cu/kg DM, and (6) NC + 3.0 mg of supplemental Mo/kg diet DM from Na2MoO4·2H2O. Animals were allowed ad libitum access to both harvested grass hay (DM basis: 6.6% crude protein; 0.15% S, 6.7 mg Cu/kg, 2.4 mg Mo/kg) and water throughout the experiment. Calves were weaned at approximately 6 months of age each year. Dietary Cu concentration below 10.0 mg Cu/kg DM total diet reduced liver and plasma Cu concentrations to values indicative of a marginal Cu deficiency in beef cows. However, no production parameters measured in this experiment were affected by treatment. Results suggest that Mo supplemented in water or feed at the concentrations used in this experiment had minimal impact on Cu status and overall performance.

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.

Renergy™ is a proprietary blend of organic acids with a proposed mode of action of increasing ruminal propionate production. Little is known about the efficacy of Renergy™ supplementation in modifying ruminal fermentation in beef cattle consuming high-grain diets. Therefore, eight Angus steers (BW 531.7 ± 20.4 kg) fitted with ruminal cannulae were used to determine the effects of Renergy™ on ruminal fermentation characteristics. Steers were fed a high concentrate diet (DM basis: 13.6% CP, 1.38 Mcal/kg NEg, and 2.02 Mcal/kg NEm) with no monensin sodium or tylosin phosphate added to the diet for 30 d prior to the initiation of the experiment. Treatments consisted of control (CON; no supplemental Renergy™) and Renergy (REN) fed at 27.6 g.animal-1.d-1 (n = 4 steers/treatment; experimental unit = animal). Following the 30 d diet adaptation period, dietary treatments were initiated for 28-d. On day 28, rumen fluid was collected at 3 h post feeding and analyzed for VFA, pH, and NH3. Ruminal pH (P = 0.62) and NH3 (P = 0.56) were unaffected by treatment. However, total VFA (P = 0.05) and propionate (P = 0.03) production were increased by Renergy, 13.3% and 25.7% respectively. There was a tendency (P = 0.14) for acetate production to be increased 10.9% in steers supplemented with Renergy™. Butyrate was unaffected (P = 0.51) by treatment. However, isobutyrate production was lower (P &lt; 0.01) in steers receiving Renergy™. Feeding Renergy™ also resulted in 25% less (P = 0.07) L-lactate production. Under conditions of this experiment, results indicate that supplementing Renergy™ for 28d to beef cattle consuming high concentrate diets impacts ruminal fermentation 3 h post feeding.

Rumen fluid from three beef steers (480 ± 10 kg), fitted with rumen canulae, were used to investigate the impact of Ca dose and olive meal on in vitro rumen fermentation characteristics. Steers were fed a high concentrate finishing diet for 21d, and rumen fluid was collected from each steer 2h post-feeding. A 2 x 4 factorial arrangement of treatments was used for this experiment. Factors included: 1) 0 or 5% olive meal and 2) Ca dose: 0, 0.02, 0.04, and 0.08% Ca from CaCl2. A McDougall’s buffer-rumen fluid mixture (1:1; 30 mL) was added to conical tubes containing 0.5g of the ground basal diet and incubated at 39°C for 0, 4, 8, and 12h (5 replicates per treatment per time point). After incubation, supernatant was removed for VFA analysis and the remaining digesta was dried to determine DM disappearance (DMD). At 4 and 8h post incubation digestion tubes containing 0.04% Ca had greater (P &lt; 0.001) DMD when compared to all other Ca doses. At 12h post incubation, DMD was greater (P &lt; 0.001) in digestion tubes containing 0.02% and 0.08% Ca compared to all other Ca doses. At 8h post incubation, molar proportions of acetic acid were greater (P &lt; 0.03) in digestion tubes containing olive meal compared to no olive meal and were greater (P &lt; 0.001) in digestion tubes containing 0.08% Ca compared to all other Ca doses. At 12h post incubation, isobutyric acid (P &lt; 0.01) and butyric acid (P &lt; 0.02) were greater in digestion tubes containing 0.02% and 0.04% Ca compared to all other Ca doses. Butyric acid was lesser (P &lt; 0.02) with olive meal inclusion at 12h. Total VFA concentrations were similar across treatments. These data suggest that Ca and olive meal can impact in vitro fermentation characteristics.