Steam-flaked Corn-based Finishing Diet Research Articles

22 Effects of trace mineral source and chromium propionate supplementation on rumen fermentation, growth performance, and carcass characteristics in finishing beef steers

Abstract Crossbred beef steers [n = 400; body weight (BW) = 370 ± 8 kg] were used to evaluate the effects of trace mineral (TM) source and chromium propionate (Cr) on rumen fermentation characteristics, plasma glucose and mineral concentrations, performance, and carcass characteristics in feedlot steers fed a steam-flaked corn-based finishing diet. Steers were blocked by initial BW and randomly assigned within block to 1 of 4 treatments (10 steers/pen) with 10 pens per treatment. The experimental design was a randomized complete block design with a 2 x 2 factorial arrangement of treatments. Factors included: 1) TM source [sulfate or hydroxychloride (IntelliBond] Cu, Mn, and Zn TM supplemented at 18, 40, and 90 mg/kg DM, respectively) and 2) with or without supplemental Cr (KemTRACE) at 0.0 or 0.25 mg/kg DM. Steers were individually weighed on d -1 and 0 and every 28 d throughout the experiment. Jugular blood samples and rumen contents were collected from 10 steers per treatment on d 28 and 84 of the experiment for plasma glucose and TM concentration and volatile fatty acid analysis, respectively. On d 154 of the experiment, steers were harvested at a commercial abattoir and carcass data was collected. Data were analyzed on a pen mean basis for a randomized complete block design using PROC MIXED of SAS. There was no TM source by Cr supplementation interactions for any of the response variables measured, therefore only main effects are reported. Overall ADG (P = 0.03) and gain:feed (P = 0.02) were greater in steers receiving supplemental Cr when compared with steers not supplemented with Cr. Hot carcass weight (P = 0.04), dressing percentage (P = 0.01), longissimus muscle area (P = 0.03), and USDA yield grades (P = 0.04) were greater in steers receiving hydroxychloride TM compared with steers receiving sulfate TM. Steers supplemented with Cr had a greater dressing percentage (P = 0.01) and longissimus muscle area (P = 0.04) compared with steers not supplemented with Cr. On d 28 of the experiment, ruminal acetate concentrations were lesser (P = 0.01) and ruminal propionate concentrations tended to be greater (P = 0.12) in steers receiving hydroxychloride TM compared with steers receiving sulfate TM. Steers supplemented with Cr had greater ruminal acetate concentrations (P = 0.04) and plasma glucose concentrations (P = 0.05) on d 28 of the experiment when compared with non-supplemented controls. These data indicate the Cr supplementation and TM source can influence feedlot steer performance, carcass characteristics, and rumen fermentation characteristics.

107 Bacterial direct-fed microbial mixtures effects on beef cattle ruminal degradability kinetics

Abstract The effects of bacterial direct-fed microbial (DFM) mixtures on beef cattle ruminal degradability were evaluated. Six ruminally cannulated beef steers (BW = 520 ± 30 kg) were used in a replicated 3 × 3 Latin square design and offered a steam-flaked corn-based finishing diet to ad libitum intake during three, 28-d periods. Treatments were: 1) Control (no DFM, lactose carrier only); 2) Treat-A (L. animalis, P. freudenreichii; B. subtilis; and B. 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 approximately 30% greater than the minimum expected. Pre-dehydrated (55ºC for 72 h) diets and forage substrates were ground (2 mm) and placed into 10 × 20 cm (28 µm) nylon bags (8 and 5 g, as-is respectively). The diet-substrate included a mixture of (DM basis) steam-flaked corn (70%), alfalfa hay (10%), and wet corn gluten feed (20%). The forage-substrate was represented by ‘WW-B Dahl’ Old World bluestem (Bothriochloa bladhii). Substrate in-situ bags were placed within a nylon mesh (with weights) at the ruminal ventral sac, and reversely removed at 0, 2, 4, 8, 12, 20, 32, 48, 64, 72, and 96 h after feeding. Samples were removed, rinsed, and dehydrated for 72 h at 55oC. Residues were composited within period, steer, incubation-time, corrected for residual moisture and were used to fit a first-order kinetics model using the NLIN procedure of SAS (animal = experimental unit). Steers offered Treat-A tended to show an increase on the rate of degradation of NDF (P = 0.15) and ADF (P = 0.10) fractions; increased (P < 0.01) hemicellulose potentially degradable fraction (B); and increased (P = 0.02) the effective degradable fraction of NDF (tendency for ADF, P = 0.08) at pre-established rate of passages of 4, 5, and 6% of the diet-substrate compared with Control, while tending to have a reduced rate of degradation for the overall DM (P = 0.06) and OM (P = 0.08) fractions. When the in-situ bags containing the forage-substrate were incubated, steers offered Treat-A showed an increased (P < 0.01) lag time (T0) for hemicellulose compared with Control, while those offered Treat-B had a decreased (P = 0.02) hemicellulose potentially degradable fraction (B) compared with Control. The effective degradable fraction for hemicellulose at pre-established rate of passages of 4, 5, and 6% tended (P = 0.09) to numerically increase for steers offered Treat-A compared with Control. The combination of bacteria in Treat-A enhanced the ruminal degradation of high-quality fiber components, as indicated by the improvements observed within the more degradable fractions from ingredients used in the diet and the forage substrates. Further assessment is warranted to investigate post-ruminal nutrient disappearance.

Trace mineral source and chromium propionate supplementation affect performance and carcass characteristics in feedlot steers.

Angus-crossbred steers (n = 400; 369.7 ± 7.6kg) were used to determine the influence of trace mineral (TM) source and chromium propionate (Cr Prop) supplementation on performance, carcass characteristics, and ruminal and plasma variables in finishing steers. Steers were blocked by body weight (BW) and randomly assigned within block to treatments in a 2 × 2 factorial arrangement, with factors being: 1) TM source (STM or HTM) and 2) Cr supplementation (0 or 0.25mg Cr/kg DM, -Cr or + Cr, respectively). Treatments consisted of the addition of: 1) sulfate TM (STM; 90, 40, and 18mg/kg DM of Zn, Mn, and Cu, respectively), 2) STM and 0.25mg Cr/kg DM from Cr Prop, 3) hydroxychloride TM (HTM; 90, 40, and 18mg/kg DM of Zn, Mn, and Cu, respectively), and 4) HTM and 0.25mg Cr/kg DM from Cr Prop. Each treatment consisted of 10 replicate pens with 10 steers per pen. Body weights were obtained on consecutive days at the initiation and termination of the 154-d study. Steers were fed a steam-flaked corn-based finishing diet. Ractopamine hydrochloride was fed for the last 31 d of the study. Ruminal fluid and blood samples were obtained from one steer per pen on days 28 and 84 for ruminal volatile fatty acids (VFA) and plasma TM and glucose analysis. Steers were slaughtered at the end of the study and individual carcass data were collected. No Cr × TM source interactions (P = 0.48)were detected. Steers supplemented with HTM had greater (P = 0.04) hot carcass weight (HCW), dressing percentage (DP), longissimus muscle (LM) area, and USDA yield grade (YG), and tended (P = 0.12) to have greater average daily gain (ADG) than those receiving STM. Average daily gain, gain:feed, dressing percentage, and longissimus muscle area were greater (P = 0.04) for + Cr steers compared to-Cr steers. Hot carcass weight tended (P = 0.06) to be greater for + Cr steers. Ruminal acetate concentrations at 28 d were lesser (P = 0.01) for HTM vs. STM steers, and greater (P = 0.04) for + Cr steers compared to-Cr steers. Plasma concentrations of Zn, Cu, and Mn were not affected by TM source or Cr supplementation. Steers supplemented with Cr had greater (P = 0.05) plasma glucose concentrations than-Cr steers at 28 but not at 84 d. Results of this study indicate replacing STM with HTM improved carcass characteristics in finishing steers, and Cr Prop supplementation improved steer performance and carcass characteristics.

PSXI-29 Influence of a Direct Fed Microbial on Growth Performance, Carcass Data, and Immune Function in Feedlot Finishing Steers

Abstract One hundred and eighty crossbred beef steers (405.9 ± 2.3 kg) were used to determine the impact of a direct fed microbial (DFM) on growth performance, carcass characteristics, and immune response in finishing beef cattle. Steers were blocked by body weight and randomly assigned, within block, to 1 of 2 treatments (3 replicates/treatment: 30 steers/replicate). Groups within a replicate were randomly assigned to treatments. Treatments included: 1) no DFM (control) and 2) DFM supplementation at 50 mg/animal/d [BOVAMINE DEFEND Plus containing Lactobacillus animalis, Propionibacterium freudenreichii, Bacillus licheniformis, and Bacillus subtilis]. All steers were fed a high concentrate, steam-flaked corn-based finishing diet. Individual feed intake was recorded daily via the GrowSafe system. Body weights were collected every 28 d. Jugular blood samples were collected from all steers on day 0 and 112. On d 55 of the experiment, 10 steers per pen (30 steers per treatment) were randomly selected and injected, subcutaneously with 4.0 mg of ovalbumin (OVA). Jugular blood samples were collected from each steer on d 0, 7, 14, and 21 post injection. On d 112 of the experiment, the same steers were injected with the same dose of OVA and intramuscularly with 5 mL of a 25 % pig red blood cell (PRBC) solution. Jugular blood samples were collected from each steer on day 0, 7, 14, and 21 post injection. After receiving the finishing diet for 185 d, cattle were transported to a commercial abattoir and slaughtered. Hot carcass weights were collected at the time of slaughter. Carcasses were allowed to chill for 24 h before carcass data were collected. Data were analyzed as a completely randomized block design and individual animal within pen was considered the experimental unit. Initial body weight, final body weight, and overall feed efficiency were similar across treatments. Steers receiving DFM had greater (P < 0.01) body weights and average daily gains on d 28 and 55 and greater (P < 0.04) dry matter intakes over the entire experiment compared with controls. Hot carcass weight, longissimus muscle area, quality grade, and marbling score were similar across treatments. However, dressing percentage (P < 0.02) was greater in steers receiving DFM compared with controls. Antibody titers to OVA and PRBC and d 112 interferon gamma concentrations were similar across treatments. However, red blood cell superoxide dismutase activity was greater (P < 0.05) in DFM-supplemented cattle compared with controls on d 112 of the experiment. These data suggest that BOVAMINE DEFEND Plus supplementation improves growth performance during certain periods of the finishing phase, increases overall dry matter intake and carcass yield, and may impact antioxidant status in beef cattle.

PSXIII-21 Effects of Bacterial Direct-Fed Microbial Mixtures on Beef Cattle Feeding Behavior

Abstract The effects of bacterial direct-fed microbial (DFM) mixtures on beef cattle feeding behavior were evaluated. Six ruminally cannulated crossbred Angus steers (BW = 520 ± 30 kg) were used in a replicated 3 × 3 Latin Square design. Steers were offered a steam-flaked corn-based finishing diet to ad libitum during three, 28 d periods (21-d adaptation and 7-d collection). Treatments assigned were: 1) Control (no DFM, lactose carrier only); 2) Treat-A [L. animalis, P. freudenreichii; B. subtilis; and B. licheniformis, at 1:1:1:3 ratio, respectively; totaling 6 × 109 CFU (50mg)/animal-daily minimum (Chr.Hansen]; and 3) Treat-B, the same DFM combination, but with doses at 1:1:3:1 ratio. Bacterial counts were approximately 30% greater than the minimum expected. The DFM diluted mixtures and carrier (Control) were pre-weighed and stored at -20°C until incorporated into the diet (2 g· animal-1· /day-1) 10 min prior to feeding. For mixing, approximately 1 kg (as is) of the diet being offered was removed from the individual recipient, DFM was mixed by hand, and the mixture was incorporated into the feed allocated for the day. The feeding behavior assessment consisted of a 24 h continuous visual observation (every 5 min) performed by trained personnel. Animals were assessed on d 26 of each period (no other management other than cleaning of the stall), while time spent eating, ruminating, resting, active, and drinking were taken. Time spent chewing was accounted for by adding time spent eating and ruminating. In addition, records allowed the count of the number of meals taken, as well as the time spent on each meal. Data were analyzed using the GLIMMIX procedure of SAS, with animal considered as the experimental unit, the fixed effects of treatment, and random effect of square, period, and animal (square). F-test protected pre-planned orthogonal contrasts was used to compare Control vs. Treat-A and Control vs. Treat-B. Meal number (16/d) and length (8 min/meal) were not affected by treatments (P ≥ 0.54). Main feeding behavior variables consisting of rumination (198 min/d), eating (117 min/d), chewing (315 min/d), drinking (22 min/d), resting (929 min/d), and active (174 min/d) were not affected (P ≥ 0.24) by treatments. A tendency was observed (P = 0.08) where animals offered the Treat-B spent numerically less time ruminating per unit of digestible DM and OM intake compared with Control (13.5 vs. 15.5, and 13.7 vs 15.6 min/kg, respectively). Other behaviors measured in min/kg of DM, NDF, and ADF intake were not affected (P ≥ 0.17) by treatments [rumination (11.5, 60.2, and 181), eating (6.5, 34.4, and 104), chewing (18, 94.6, and 285), and drinking (1.2, 6.6, and 19.8) min/kg, respectively]. The bacterial DFM mixtures offered appear not to directly affect the feeding behavior of beef cattle consuming a steam-flaked corn-based finishing diet.

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 ± 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.

Granulated Cane Sugar as a Partial Replacement for Steam-Flaked Corn in Diets for Feedlot Cattle: Ruminal Fermentation and Microbial Protein Synthesis

The aim of this study was to evaluate the influence of supplemental granulated cane sugar (GCS) levels (0, 13.3, 26.6, and 39.9% on a dry matter basis) in a steam-flaked corn-based finishing diet on measures of ruminal fermentation and the site and extent of nutrient digestion. Four Holstein steers (251 ± 3.6 kg live weight) with “T” type cannulas in the rumen and proximal duodenum were used in a 4 × 4 Latin square experiment to evaluate the treatments. The experiment lasted 84 d. Replacing steam-flaked corn (SFC) with GCS linearly decreased the flow of ammonia-N (NH3-N) to the small intestine, increasing the flow of microbial nitrogen (MN; quadratic effect, p = 0.02), ruminal N efficiency (linear effect, p = 0.03) and MN efficiency (quadratic effect, p = 0.04). The ruminal digestion of starch and neutral detergent fiber (NDF) decreased (linear effect, p ≤ 0.02) as the level of GCS increased. The postruminal digestion of organic matter (OM), neutral detergent fiber (NDF), and starch were not affected by the GCS inclusion. However, postruminal N digestion decreased (linear effect, p = 0.02) as the level of GCS increased. There were no treatment effects on total tract OM digestion. However, total tract NDF and N digestion decreased (linear effect, p ≤ 0.02) as the level of GCS increased. The ruminal pH decreased (linear effect, p &lt; 0.01) as the GCS increased in the diet. The ruminal acetate molar proportion decreased (linear effect, p = 0.02) and the ruminal valerate molar proportion tended to increase (linear effect, p = 0.08) as the level of GCS increased. It is concluded that replacing as much as 13% of SFC with GCS in a finishing diet will enhance the efficiency of N utilization (g non-ammonia-N entering the small intestine/g N intake) without detrimental effects on total tract OM digestion. The inclusion of GCS decreased the ruminal proportion of acetate linearly without an effect on the acetate-to-propionate ratio or estimated methane production. Some of the effects on N utilization at a high level of GCS inclusion (27 and 40%) can be magnified by the differences in the CP content between diets. A higher level of GCS supplementation in the diet decreased the ruminal pH below 5.5, increasing the risk of ruminal acidosis.

340 Growth Performance and Carcass Characteristics of Beef Steers Consuming Finishing Diets with an Added Nutritional Packet in a Calf-fed System

Abstract The effects of a nutritional packet containing a direct-fed microbial combined with vitamins/electrolytes offered to beef steers in a calf-fed system on growth performance and carcass characteristics were evaluated. Angus crossbred steer-calves (n = 60; BW = 234 ± 4 kg) were assigned to a randomized complete block design (block = body weight; steer = experimental unit) and stratified into two treatments: a) control (no packet, finely-ground corn carrier only); and b) 30 g of DM/animal-daily of a nutritional packet [live-yeast (Saccharomyces cerevisiae; 8.7 Log CFU/g), Vitamin C (5.4 g/kg of Ascorbic acid), Vitamin B1 (13.33 g/kg of Thiamine hydrochloride), and electrolytes of sodium chloride (80 g/kg) and potassium chloride (80 g/kg)]. Animals were individually offered [electronic feed-bunks (Smart-Feed/C-Lock Inc.)] a steam-flaked corn-based finishing diet ad libitum, once daily for 233 d. Treatments were offered during the first (phase-1) and last (phase-2) 60 d on feed. Body weight measurements were taken every 30 d before feeding. Data were analyzed using the GLIMMIX procedure of SAS. Steers offered the nutritional packet had 14% less (P &amp;lt; 0.01) intake and 18% greater gain efficiency during the initial 30-d on feed, while such advantage did not (P ≥ 0.26) persist when accounting for the initial 60 d for either variable. Overall intake (d0 to d233) was 6% greater (P = 0.02), while carcass-adjusted ADG (1.61 vs. 1.56), and carcass-adjusted gain efficiency (0.198 vs. 0.204) were unaffected (P ≥ 0.44) compared with control, respectively. Dressing percent of steers offered the packet was 1 percentage-unit greater (P = 0.02), while other carcass variables were unaffected (P ≥ 0.33). Calf-fed steers seem to benefit from such nutritional packet during the initial 30 d after feedlot arrival, while both superior intake and dressing percentage appears to last until cattle harvest.

PSIX-5 Ruminal Papillae Morphology and Volatile Fatty Acid Profile of Beef Steers Consuming Finishing Diets with an Added Nutritional Packet in a Calf-fed System

Abstract The effects of a nutritional packet containing a direct-fed microbial combined with vitamins/electrolytes offered to beef steers in a calf-fed system on ruminal papillae morphology and volatile fatty acid (VFA) profile were evaluated. Angus crossbred steer-calves (n = 60; BW = 234 ± 4 kg) were assigned to a randomized complete block design (block = body weight; steer = experimental unit) and stratified into two treatments: a) control (no packet, finely-ground corn carrier only); and b) 30 g of DM/animal-daily of a nutritional packet [live-yeast (Saccharomyces cerevisiae; 8.7 Log CFU/g), Vitamin C (5.4 g/kg of Ascorbic acid), Vitamin B1 (13.33 g/kg of Thiamine hydrochloride), and electrolytes of NaCl (80 g/kg) and KCl (80 g/kg)]. Animals were individually offered [electronic feed-bunks (Smart-Feed/C-Lock Inc.)] a steam-flaked corn-based finishing diet ad libitum once daily for 233 d, while treatments were offered during the first and last 60 days on feed only. Upon harvest (federally inspected facility), individual samples of ruminal cranial sac epithelium and rumen content (quickly frozen) were collected. Preserved (70% alcohol at 5oC) ruminal tissue fragments were trimmed (1 cm2), in which papillae were counted, followed by a random removal of 12 individual papillae for further area measurement using electronic scanning (ImageJ). Data were analyzed using the GLIMMIX procedure of SAS. Steers offered to nutritional packet had a 30% increased (P = 0.02) average papillae area, which induced a tendency (P = 0.14) to improve ruminal absorptive surface area (89 vs. 93%), while not affecting ruminal papillae number (P = 0.39). Molar proportions of acetate, butyrate, and propionate were not affected (P ≥ 0.51) by treatments, while total VFA (mM) tended (P = 0.09) to increase by 8% for animals consuming the nutritional packet. The nutritional packet seemed to improve ruminal fermentation products while positively affecting ruminal papillae morphology.

PSVII-18 Feeding Behavior of Beef Steers Consuming Finishing Diets with an Added Nutritional Packet in a Calf-fed System

Abstract The effects of a nutritional packet containing a direct-fed microbial combined with vitamins/electrolytes offered at the beginning and end of the finishing phase to beef steers in a calf-fed system on feeding behavior were evaluated. Angus crossbred steer-calves (n = 18; BW = 234 ± 4 kg) were assigned to a randomized complete block design (block = body weight; steer = experimental unit) and stratified into two treatments: a) control (no packet, finely-ground corn carrier only); and b) 30 g of DM/animal-daily of a nutritional packet [live-yeast (Saccharomyces cerevisiae; 8.7 Log CFU/g), vitamin C (5.4 g/kg of ascorbic acid), vitamin B1 (13.33 g/kg of thiamine hydrochloride), and electrolytes of NaCl (80 g/kg) and KCl (80 g/kg)]. Animals were individually offered [electronic feed-bunks (Smart-Feed/C-Lock Inc.)] a steam-flaked corn-based finishing diet ad libitum once daily for 233 d, while treatments were offered during the first (phase-1) and last 60 d (phase-2) on feed only. Feeding behavior activities were assessed in min/d by using CowManagerTM ear tag sensors. Data were analyzed using the GLIMMIX procedure of SAS. There was no treatment × phase interactions (P ≥ 0.15), except that steers receiving the nutritional packet tended (P = 0.10) to spend more time (6 vs. 9 min/kg) eating digestible DM during phase-2 only. Regardless of phase, steers consuming the nutritional packet spent more time (P = 0.04) eating per kg of hemicellulose. Regardless of treatment, a decreased rumination (P ≤ 0.03) and chewing (P ≤ 0.01) activity-variables were observed for the phase-2 compared to phase-1. Steers receiving the nutritional packet exhibited superior time spent on eating activities, especially during the final 60 d before slaughter, and fiber seems to be the major driver inducing such effect. Towards the end of the finishing phase, cattle reduced rumination and chewing compared to the arrival phase.

342 Effects of Direct fed Microbial Mixtures on Beef Cattle Ruminal Fermentation Characteristics, Intake, and Nutrient Digestibility

Abstract 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

PSVII-19 Feeding Behavior of Feedlot Beef Steers Consuming Finishing Diets with an Added Nutritional Packet

Abstract The effects of a nutritional packet offered to beef yearling-steers during the feedlot-finishing phase on feeding behavior were evaluated. Crossbred-Angus steers (n = 30; initial BW = 542 ± 8 kg) were assigned to pens (15 steers/pen; animal = experimental unit) in a randomized complete block design. Steers were offered a steam-flaked corn-based finishing diet ad libitum, and treatments as follows: 1) control and 2) 30 g/steer-daily (DM-basis) of a nutritional packet (live yeast [Saccharomyces cerevisiae; 8.7 Log CFU/g], vitamin C [5.4 g/kg], vitamin B1 [13.33 g/kg], NaCl [80 g/kg], and KCl [80 g/kg]). Ground corn was used as a carrier and included at 1% of diet DM. Orts were subtracted from the dietary DM offered to calculate DM intake. Feeding behavior (meal frequency, meal size, bunk visit duration, and meal criterion) were continuously recorded using the Smartfeed system (individual animals). Three periods during the last 60 days before cattle harvest were assessed: 1) d7-11; 2) d28 -32; and 3) d49-53. Periods were used to compute meal criteria for each animal using the Meal Criterion Calculation (v. 1.9) software. Data were analyzed using the GLIMMIX procedure of SAS. No treatment × period interactions were observed (P ≥ 0.32) for meal frequency, duration (min/meal), and intake (kg/meal). Steers offered the nutritional packet had greater overall meal duration during periods 1 and 3 (75 and 77 min/d; P &amp;lt; 0.01), but did not differ (68 min/d; P = 0.09) for period 2 (Control AVR = 55 min/d). Steers offered the nutritional packet had greater (P ≤ 0.01) meal frequency (20 vs. 16 meals/d), while individual meal duration (3.85 min/meal) and meal intake (0.46 kg/meal) were not affected by treatments (P &amp;gt; 0.86). Improved meal frequency and overall time spent eating, without affecting intake, may induce a more desirable daily distribution of nutrients.

PSVIII-17 Nutrient Digestibility of Beef Steers Consuming Finishing Diets with an Added Nutritional Packet in a Calf-fed System

Abstract The effects of a nutritional packet containing a direct-fed microbial combined with vitamins/electrolytes offered to beef steers in a calf-fed system on apparent total tract nutrient digestibility were evaluated. Angus crossbred steer-calves (n = 60; BW = 234 ± 4 kg) were assigned to a randomized complete block design (block = body weight; steer = experimental unit) and stratified into 2 treatments: a) control (no packet, finely-ground corn carrier only); and b) 30 g of DM/animal-daily of a nutritional packet [live-yeast (Saccharomyces cerevisiae; 8.7 Log CFU/g), Vitamin C (5.4 g/kg of Ascorbic acid), Vitamin B1 (13.33 g/kg of Thiamine hydrochloride), and electrolytes of NaCl (80 g/kg) and KCl (80 g/kg)]. Animals were individually offered [electronic feed-bunks (Smart-Feed/C-Lock Inc.)] a steam-flaked corn-based finishing diet ad libitum, once daily for 233 d. Treatments were offered during the first (phase-1) and last (phase-2) 60 d on feed. At the conclusion of each phase, feed samples were collected once daily (1400 h), while fecal samples twice daily (0700 and 1700 h) from each steer during 4 consecutive days. Fecal and feed sample composites were dehydrated (55oC), ground (1 mm), and analyzed to assess DM, OM, NDF, ADF, and hemicellulose. The 288-h indigestible NDF was used as dietary internal marker to estimate fecal output and used to calculate nutrient digestibility. Data were analyzed using the GLIMMIX procedure of SAS. Intake of DM, OM, and fiber components during both digestibility trials were not affected (P ≥ 0.56) by treatments. Steers offered the nutritional packet had increased (P &amp;lt; 0.01) apparent total tract digestibility of DM, OM, NDF, ADF, and hemicellulose by at least 2.4, 2.4, 8.3, 10, and 7.5%, respectively, in both digestibility phases. Superior nutrient digestibility without affecting nutrient intake may justify a potential enhanced carcass energy deposition.

PSVIII-18 Nutrient Digestibility of Feedlot Beef Yearling Steers Offered Finishing Diets with Direct fed Microbial Mixtures

Abstract 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.

315 Feeding Behavior of Beef Steers Consuming Finishing Diets with Added Nutritional Packet

Abstract The effects of a nutritional packet fed to beef steers during the feedlot finishing phase (final 64 d) on feeding behavior were evaluated. Crossbred-Angus steers (n = 120; initial BW = 544 ± 52 kg) were assigned to 30 pens (4 steers/pen; 15 pens/treatment; pen = experimental unit) in a randomized complete block design. Steers were fed, ad libitum, a steam-flaked corn-based finishing diet and treatments were applied as follows: 1) control and 2) 30 g/steer-daily (DM-basis) of a nutritional packet (containing live yeast [Saccharomyces cerevisiae; 8.7 Log CFU/g], vitamin C [5.4 g/kg], vitamin B1 [13.33 g/kg], NaCl [80 g/kg], and KCl [80 g/kg]). The nutritional packet used ground corn as a carrier and was included at 1% of diet DM. Orts were subtracted from the total dietary DM offered to calculate DM intake. Feeding behavior activities were visually assessed by trained personnel twice (d 27 and d 63) for 24 h, when time spent on each activity was recorded every 5 min. Data were analyzed using the GLIMMIX procedure of SAS. Treatment × period interactions (P ≤ 0.03) were observed for eating time (min/d) and eating rates (min/kg of consumed DM, OM, fiber, and digestible DM, OM, and fiber), in which steers fed the nutritional packet spent less time in such activities on d 27 and more time during the assessment on d 63, compared with control. Regardless of period, steers fed the nutritional packet tended (P = 0.07) to spend less time chewing per kg of digestible ADF. Rumination (P ≥ 0.28), drinking (P ≥ 0.40), active (P ≥ 0.92), and resting (P ≥ 0.53) times were not affected by treatment. The nutritional packet affected eating behavior more intensively during the first 27 d of treatment, and digestible ADF seems to be the main feed-fraction inducing such effect.

310 Growth Performance and Carcass Characteristics of Beef Steers Consuming Finishing Diets with an Added Nutritional Packet

Abstract The effects of a nutritional packet fed to beef steers during the final 64 d of the feedlot finishing phase on growth performance and carcass characteristics were evaluated. Crossbred-Angus steers (n = 120; initial BW = 544 ± 52 kg) were assigned to 30 pens (4 steers/pen; 15 pens/treatment) in a randomized complete block design where pen represented the experimental unit. A steam-flaked corn-based finishing diet was fed ad libitum, and treatments were applied as follows: 1) control and 2) 30 g/steer-daily (DM-basis) of the nutritional packet (containing live yeast [8.7 Log CFU of Saccharomyces cerevisiae], vitamin C [5.4 g/kg of Ascorbic acid], vitamin B1 [13.33 g/kg of Thiamine hydrochloride], sodium chloride [80 g/kg] and potassium chloride [80 g/kg]). The nutritional packet used ground corn as a carrier and was included at 1 % of diet DM. Orts were quantified daily (if any) and subtracted from the total dietary DM offered to calculate DM intake. Unshrunk BW were collected on d 0, 21, 42 and 64 before daily feeding at 0630 h. Data were analyzed using the GLIMMIX procedure of SAS. Average daily gain (P = 0.89), dry matter intake (P = 0.57) and, gain:feed (P = 0.66) were not affected by the inclusion of the nutritional packet. The 12th rib fat deposition was increased (P ≤ 0.02) for cattle fed the nutritional packet compared with control (15.70 vs. 13.36 mm, respectively). Consequently, calculated yield grade was also increased (P ≤ 0.03) for cattle consuming the nutritional packet (3.32 vs. 3.02). An improved carcass fat-deposition without any deleterious effects on growth performance potentially warrant less days on feed when cattle receive such nutritional packet.

309 Nutrient Digestibility of Beef Steers Consuming Finishing Diets with an Added Nutritional Packet

Abstract The effects of a nutritional packet fed to beef steers during the final 64 d of the feedlot finishing phase on apparent total tract nutrient digestibility were evaluated. Angus-crossbred steers (n =120; initial BW = 544 ± 52 kg) were assigned to 30 pens (4 steers/pen; 15 pens/treatment; pen = experimental unit) in a randomized complete block design. A steam-flaked corn-based finishing diet was fed ad libitum and treatments applied as follows: 1) control and 2) 30 g/steer-daily (DM-basis) of the nutritional packet [containing live yeast (Saccharomyces cerevisiae; 8.7 Log CFU/g), vitamin C (5.4 g/kg), vitamin B1 (13.33 g/kg), NaCl (80 g/kg) and KCl (80 g/kg)]. The nutritional packet used ground corn as a carrier and was included at 1% of diet DM. Orts were quantified daily (if any) and subtracted from the total dietary DM offered to calculate DM intake. Fecal samples were collected twice daily (0700 and 1700 h) for 5 consecutive days (d 47 to 51) from at least 3 steers within pen. Feed samples were collected daily at time of feeding (0630 h). Fecal and feed samples were composited to represent the collection period, dried (55oC), ground (1 mm), and analyzed to assess DM, OM, NDF, ADF, and hemicellulose. In situ (288 h) iNDF was used as an internal marker to measure apparent total tract nutrient digestibility. Data were analyzed using the GLIMMIX procedure of SAS. Intake of DM, OM, and fiber components during the digestibility period was not affected (P ≥ 0.44) by treatment. Steers fed the nutritional packet had increased apparent total tract digestibility of OM (P = 0.02), DM (P = 0.01), NDF (P = 0.02), ADF (P = 0.01), and hemicellulose (P = 0.08; tendency). Improved nutrient digestibility without affecting nutrient intake may warrant an enhanced energy deposition in the carcass.

308 Effects of Roughage Source on Growth Performance, Carcass Characteristics, and Rumination Time of Beef Steers Fed Steam-flaked Corn Finishing Diets

Abstract We hypothesized that roughage source would not impact rumination time and growth performance if the different sources provided a similar concentration of dietary neutral detergent fiber (NDF) and physically effective NDF (peNDF). This experiment’s objective was to evaluate rumination time, and growth performance steers consuming finishing diets with differing roughage sources (corn stalks, cotton burrs, or wheat silage). Beef steers (n = 49; BW = 317 + 5.6 kg) were used in a completely randomized design with 3 dietary treatments. Steers consumed a steam-flaked corn-based diet containing corn stalks (CS), cotton burrs (CB), or wheat silage (WS) included at 7% (DM basis). Dietary NDF was similar (P = 0.36) across treatments. Each steer was fitted with a sensory collar to record daily rumination. Weekly ingredient and dietary samples were estimated for physically effective NDF (epeNDF) using the Penn State Particle Separator. Actual physically effective NDF (apeNDF) was calculated based upon rumination time. Neither initial nor final body weight (BW) differed between treatments (P &amp;gt; 0.52); nor did average daily gain (ADG), dry matter intake or carcass adjusted variables of FBW, ADG, empty BW, or empty body fat (P &amp;gt; 0.31). However, gain to feed (G:F) tended to differ (P = 0.06) between treatments. The CS diet had the greatest G:F with no difference (P = 0.75) between CB and WS. Dietary NDF and epeNDF were similar (P &amp;gt; 0.35) among roughage sources; however, CB had the least apeNDF, consistent with lower rumination time (P &amp;lt; 0.01). When energy values were calculated from animal performance, the CS diet had the greatest observed energy values, followed by WS and CB having the least. These results indicate roughage source impacted rumination time, although steers were fed a steam-flaked corn-based finishing diet with similar dietary roughage and NDF inclusions.

251 Effects of Roughage Source on Rumination Time and Ruminal Ph in Steers Fed a Steam-flaked Corn Finishing Diet

Abstract Research is limited on how physically effective fiber from various roughage sources aids in rumination time and ruminal pH of finishing beef cattle. This experiment’s objective was to evaluate rumination time and ruminal pH of beef steers consuming finishing diets with varying roughage sources (corn stalks, cotton burrs, or wheat silage). We hypothesized that roughage type would not impact rumination time and ruminal pH if different sources provide similar dietary neutral detergent fiber (NDF). Ruminally cannulated steers (n = 6; average BW = 644.56 + 13.15 kg) were used in a 3 × 3 replicated Latin square with 3 dietary treatments and 3, 21-d periods (20-d diet adaptation, 1-d sampling). Steers consumed a steam-flaked corn-based finishing diet containing corn stalks (CS), cotton burrs (CB), or wheat silage (WS) included at 7% (DM basis) of the diet. Dietary NDF was similar across treatments. Steers were fitted with a sensory collar to record daily rumination (Allflex Livestock Intelligence). Ruminal pH was measured using a handheld pH probe on d-21 at 0, 3, 6, 12, 24 hr postprandial. The NDF and dry matter intake (DMI) were greatest for steers consuming the WS diet (P &amp;lt; 0.01) while CS and CB diets did not differ (P = 0.81). While dietary NDF and estimated physically effective NDF (peNDF) were similar among roughage sources, CB had the lowest actual peNDF, consistent with lower rumination time (P &amp;lt; 0.01) and lower ruminal pH (P = 0.29). This experiment’s results indicate that roughage source impacted rumination time despite feeding steers a steam-flaked corn-based finishing diet with similar roughage and NDF levels. Using rumination time (min/d) to determine peNDF was a better indicator of rumen function parameters than particle size measured via the Penn State Particle Separator equation.