Browsing by Author "Henry, Darren D."
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Item Characterization of bacterial DNA identified in abscessed and non-abscessed bovine hepatic tissue at the time of harvest(2021) Stotz, Miranda K. (TTU); Henry, Darren D.; Crossland, Whitney L. (TTU)Bacteriological characterization of bovine liver abscesses has been accomplished by cultural methods but DNA methods are still needed, as many bacteria are not conducive to laboratory culture. In addition to this gap in research, there have been no studies which identify the bacterial presence within healthy, non-abscessed liver tissue. The objective of this study was to compare the bacteriome of both abscessed and non-abscessed bovine livers in an observational case–control study design. Fifty-six livers, obtained from Holstein steers, were scored according to a modified Elanco liver abscess score description where A− was partitioned into active abscesses or scarred where only scars were present. Parenchyma tissue was collected from non-abscessed livers (n = 22) and scarred livers (n = 7), and purulent material was collected from abscessed livers (n = 24), and DNA was extracted for 16s rRNA gene sequence-based bacterial analysis. Across liver samples, 21 total phyla were identified with a mean of 14. Predominant phyla, accounting for >98% of reads, were Fusobacteria (51.7%), Bacteroidetes (26.9%), Proteobacteria (8.03%), Firmicutes (5.39%), Cyanobacteria (3.85%), and Actinobacteria (2.21%). Proteobacteria, Cyanobacteria, and Firmicutes were greater in non-abscessed and scarred livers, whereas Fusobacteria and Bacteroidetes prevailed in abscessed livers. Non-abscessed livers shared 3,059 operational taxonomic units (OTU) with abscessed livers (total OTU of all livers = 4,167), but non-abscessed livers had greater richness and evenness, whereas abscessed livers had greater dominance (P ≤ 0.0014). Liver score affected the relative abundance of OTU (R = 0.463; P = 0.001) but abscessed livers shared ≥ 40% similarity and were not different from each other (P ≥ 0.370). Of the predominant OTU (top 10 as a % of reads), three OTU (Fusobacteria necrophorum, Bacteroides spp., and Trueperella pyogenes) were shared across both abscessed and non-abscessed livers. Fusobacterium necrophorum was the dominant OTU regardless of liver score, and the single most abundant OTU, even among non-abscessed livers. We describe bacterial DNA detected in non-abscessed bovine liver tissue for the first time, which indicates possible presence of viable bacteria with pathogenic potential in apparently healthy liver tissue.Item Effects of bismuth subsalicylate and encapsulated calcium-ammonium nitrate on feedlot beef cattle production(2019-12) Mejia Turcios, Sebastian Edoardo; Henry, Darren D.; DiLorenzo, Nicolas; Sarturi, Jhones; Crossland, WhitneySulfur is an important element for the ruminant animal, this mineral occurs in essential amino acids such as cysteine, cystine, and methionine, and it is also important for the metabolism of a number of ruminal microorganisms. The effects of S on cattle health and performance have become a concern after the cattle industry started utilizing co-products from the ethanol sector to feed cattle. These coproducts carry levels of sulfur that can surpass the requirements of beef cattle, which can negatively affect performance and health in the feedlot. When cattle consume diets with high levels of dietary S, H2S occurs in the rumen that can enter the bloodstream after being inhaled, and can caused cellular necrosis in the brain, resulting in the expression of PEM. Additionally, dry matter intake can be reduced due to the discomfort created by high concentrations of H2S within rumen, and S can act as a trace mineral antagonist, which can create deficiencies. Many strategies have been investigated to combat the negative effects of S in beef cattle production. Nitrate has been primarily investigated as a CH4 mitigator in ruminants. When nitrate enters the rumen, it acts as a H2 sink, and reduces the substrate availability for methanogenesis. Bismuth subsalicylate has been observed to be an effective H2S mitigator when it has been provided to humans and rat. The results observed during the current study in in vitro ruminal fermentation indicate that bismuth subsalicylate and nitrate can be added in the diet of ruminants without affecting ruminal fermentation. During the in vivo portion of this study, nitrate showed a reduction of dry matter intake and average daily gain; however, feed efficiency was not affected. Final body weight was reduced by nitrate and as a result, hot carcass weight was also reduced. Digestibility of nutrient was only affected for dry matter and organic matter where bismuth tended to increased digestibility of these two variables. The data observed in this experiment also indicate that bismuth reduces the absorption of Cu; therefore, it is recommended to supplement cattle with Cu when bismuth is being administered. Some of the results observed in this study are in disagreement with previous data, therefore, more research should be performed to evaluate the effects of nitrate and bismuth subsalicylate within the rumen in order to elucidate some of the results observed in the feedlot.Item Effects of calcium-ammonium nitrate on performance and greenhouse gas production of beef steers grazing a mixed winter forage(2020-08) Osorio, Andrea Osrio; Henry, Darren D.; Sarturi, Jhones O.; Crossland, Whitney; West, ChuckTwo experiments were performed to evaluate the effects of calcium-ammonium nitrate (CAN) on in vitro fermentation, in vivo CH4 production, and performance of beef steers. For experiment 1, in vitro batch cultures were conducted as a randomized complete block design using 1 of the following basal substrates: wheat (Triticum aestivum; 100% substrate DM; W); and wheat + finely ground corn (wheat:corn = 88:12, DM basis; WC; Table 3.1). Treatments included: W; WC; WC + 2% CAN in the substrate DM (WCN); and WC + 0.67% urea in the substrate DM (WCU). Treatments WCN and WCU were isonitrogenous. Two ruminally-cannulated steers were used as ruminal fluid donors. Serum bottles (125-mL) containing 50 mL of a 4:1 buffer:ruminal fluid inoculum and 0.7 g of substrate were incubated for 48 h at 39 °C under constant agitation (60 rpm). In vitro organic matter digestibility (IVOMD) was determined simultaneously in separate 100mL centrifuge tubes, the procedure consisted of 48 h of ruminal fermentation at 39 °C under constant agitation (60 rpm) followed by 48 h of post-ruminal digestion with 6 mL of 20% HCl and 2 mL of a 5% pepsin solution were added. Data were analyzed using the MIXED procedure of SAS using a randomized complete block design with 4 replicated days (block). For experiment 2, thirty-six Angus crossbred steers (332 ± 25 kg) were used in a generalized randomized block design grazing a mixed winter forage using wheat (Triticum aestivum), triticale (Triticosecale Wittmack), and rye (Secale cereale) for 48 d. The effects of CAN were evaluated on in vivo methane production, performance, supplement intake, and blood urea nitrogen (BUN) of beef steers. Cattle were blocked by BW (n = 3; 12 head/block) and randomly assigned to 1 of 3 treatments (4 steers/treatment in each block): 1) winter pasture + corn (0.3% of BW; PC), 2) WC + 328 mg/kg of BW encapsulated CAN (eCAN; PCN) and 3) PC + 124 mg/kg of BW urea (PCU). Treatments PCN and PCU were isonitrogenous. For experiment 2, data were analyzed as a generalized randomized block design, using the MIXED procedure of SAS. Steers was considered the experimental unit. The model included the fixed effects of treatment and the random effect of block. Blood urea nitrogen data were analyzed using the MIXED procedure of SAS with repeated measures. The model included the fixed effects of treatment, day, and treatment × day interaction and the random effect of block. The covariance structure used was compound symmetry. For both experiments significance was declared at P ≤ 0.05 and tendencies were discussed at 0.05 < P < 0.10. For experiment 1, a treatment effect was observed for IVOMD (P = 0.010), where IVOMD was greater (P ≤ 0.049) for WC and WCU versus W. An increase (P ≤ 0.005) in NH3-N was observed for WCN, and WCU treatments when compared to WC. Methane production in mM, mmol/g of substrate incubated, and mmol/g of substrate fermented were significantly reduced (P < 0.001) by WCN when compared to the other treatments. A treatment effect was observed for butyrate (P = 0.007) and valerate (P = 0.022), where butyrate was greater for WCU versus W (P = 0.043). While no differences were observed for acetate:propionate among treatments. For experiment 2, cattle consuming PC had a greater (P = 0.001) supplement intake versus NPN treatments. Concentrations of BUN were affected by day, d-24 (18.598 mg/dL) being greater compared to d-0 (8.215 mg/dL), d-35 (10.549 mg/dL) and d-49 (14.574 mg/dL). Methane production (g of CH4/d, g of CH4/kg of BW, and g of CH4/kg of MBW) was not different among treatments. Also, ADG was not affected by treatment (P = 0.984). The amount of eCAN consumed by steers grazing a mixed-winter forage did not improve performance or decrease enteric CH4 emissions.Item Effects of dietary microbial inoculants on beef cattle feedlot growth performance and carcass traits, apparent nutrient digestibility and ruminal characteristics(2022-12) Lopez, Alejandra M.; Sarturi, Jhones O.; Johnson, Bradley J.; Henry, Darren D.The effects of the dietary inclusion of a mixture of bacterial direct fed microbials (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 BW = 409 kg ± 8 kg) were blocked by 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 for 153 d containing the following treatments: 1) Control, in which no DFM was offered (lactose as carrier only, 2 g/animal-daily); 2) Treat-A ( L. animalis DSM33570, P. freudenreichii DSM34127; B. subtilis DSM32324; and B. licheniformis DSM17236, at 1.3; 1.3; 1. 3, and 3.9 × 109 CFU/animal-daily, respectively); and 3) Treat-B, consisting of the same microbial combination, but with doses as follows: 1.3; 1.3; 3.9; and 1.3 × 109 CFU/animal-daily. Data were analyzed using the GLIMMIX procedure of SAS, in which pen was considered the experimental unit with the fixed effect of treatment and the random effect of BW-block, while pre-planned contrasts comparing Control × treat-A or treat-B were performed. Steers offered treat-A increased carcass adjusted ADG (P = 0.03) by 6.7%, gain efficiency (P < 0.01) by 6%, tended (P = 0.07) to increase 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 DM intake (P = 0.36) and other carcass traits (P ≥ 0.13) were not affected by treatments. Steers offered treat-A tended to increase digestibility of DM (P = 0.07) by 3%, NDF (P = 0.10) and hemicellulose (P = 0.08) by 9% compared to 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 for feeding behavior. However main effects of phase showed steers ruminated, ate, chewed, and were more active (P ≤ 0.01) during the second behavioral assessment, while more (P < 0.01) time spent ruminating, eating and chewing in minutes per/kg were observed on d 113 vs. 106. Ruminal morphology (P ≥ 0.39) and ruminal ammonia concentration (P = 0.44) were not affected by treatments. Steers offered the DFM treat-A had improved growth performance and it seemed to positively affect carcass quantity, while treat-B did not show similar potential. The DFM combinations did not seem to affect feeding behavior neither ruminal papillae morphology.Item Effects of Synovex® C and H growth implants administered to beef heifers post-weaning on subsequent ovarian activity and fertility during their vrgin breeding season(2019-08) Adams, Austin James; Rathmann, Ryan J.; Jackson, Samuel P.; Henry, Darren D.The objective of this study were to examine the influence of growth promoting implants on replacement heifer fertility when administered post-weaning. Three treatments were applied: 1) Non-implanted control (NIC; n=4), 2) Synovex-C [10 mg of estradiol benzoate and 100 mg of progesterone, Zoetis, Florham Park, NJ] (SYNC; n = 6), and 3) Synovex H [200 mg testosterone propionate and 20 mg estradiol benzoate, Zoetis, Florham Park, NJ] (SYNH; n = 5). Heifers were implanted post-weaning (mean age = 234 d) and managed in the same pen continuously through the entire duration of the study. Heifers were provided ad libitum native grass hay and limit fed a grower ration targeted to achieve 0.85 kg per day of body weight (BW) gain in order to allow heifers an opportunity to reach puberty prior to the start of their virgin breeding season. Individual BW were collected on d 0, 28, 56, 84, 112, 140, and 197. Prior to ovarian scanning, heifers were synchronized via a 5-d CO-synch + CIDR protocol. Ten days following synchronization, heifers were administered an additional injection of GnRH to restart ovarian follicular growth. Subsequently, transrectal ultrasonography was performed daily to quantify ovarian activity dynamics through spontaneous ovulation and then again 7-d later to document the resulting corpus luteum (CL) size. Plus, daily coccygeal blood samples were acquired for progesterone analysis from spontaneous ovulation through the 7-d CL scan. Data was analyzed as a generalized randomized block design with implant treatment as a fixed effect and age at implantation as a covariate. Heifers were assigned blocks based on light and heavy BW groups. Overall, the implanted heifers had an increased rate of BW gain for the entire trial (P ≤ 0.03) and a substantial increase in pelvic area (P < 0.01). There were no differences observed between treatments in hip height (P = 0.19), frame score (P ≥ 0.19), body condition score (P ≥ 0.23), or reproductive tract score (P ≥ 0.25). Average overall antral follicle counts were not different across treatments (P = 0.14), however, the SYNH group had higher AFC on d 2 and 3 than the NIC and SYNC groups (P ≥ 0.10). Dominant follicle size at ovulation was similar between treatments (P = 0.14). Follicular wavelength was shorter for SYNH compared to NIC and SYNC (P = 0.02). Corpus luteum volume 7-d post-estrus was similar across treatments (P = 0.63), and circulating progesterone concentrations 7-d post-estrus was not different (P = 0.94). Results from this study demonstrate that implanting replacement heifers post-weaning does not influence pubertal attainment while increasing pelvic area. Overall it doesn’t appear that implants had a deleterious impact on ovarian activity, and in fact, implants containing testosterone may have beneficial effects. Further investigations into their impact on conception rates and subsequent calving ease is warranted with larger sample sizes. Keywords: heifer, growth implant, fertility, ovarian activityItem Evaluation of feeding immunoglobulin-Y to Holstein feeder cattle for the control of liver abscesses(2020-08) Stotz, Miranda K.; Crossland, Whitney L.; Henry, Darren D.; Rathmann, Ryan J.An immunoglobulin-Y (IGY) feed additive that targets Fusobacterium necrophorum and Trueperella pyogenes was compared to tylosin phosphate (TYL) for effect on liver abscess prevalence, severity, bacterial DNA, and antibiotic-resistant (AMR) Enterococcus fecal load in Holstein steers (n = 64; body weight = 388 ± 3.37 kg). Secondary objectives included abscess detection via liver chemistry blood panel and evaluation of bacterial DNA from healthy and abscessed livers. Steers were used in a completely randomized design and allocated to 1 of the following treatments: TYL (tylosin phosphate; daily intake: 90 mg/hd; n = 32) or IGY (daily intake at 2.5 g/hd; n = 32); with a basal ad libitum high concentrate diet for 188 d and individual intake was recorded to determine feedlot performance. After 150 d fecal samples were randomly obtained from each treatment (n = 40) and cultured on Enterococcosel (ENT) agar and ENT amended agar with erythromycin (8 μg/mL) to define the proportion of AMR Enterococcus excreted. Within 48 h of harvest, venous blood was collected for a liver chemistry panel analysis. At harvest, carcasses and livers were graded. Purulent material from liver abscesses and tissue of healthy livers were collected for bacterial DNA analysis. Continuous data variables were analyzed using the MIXED procedure of SAS and ordinal data variables via the FREQ procedure. Treatment did not affect feedlot performance or carcass characteristics, except for greater dry matter intake (P = 0.015) and fat thickness (P = 0.015) for TYL group. Proportion of macrolide-resistant Enterococcus growth from feces was greater for TYL than IGY (42.6 vs. 21.9%, respectively; P < 0.04). Treatment did not affect liver abscess prevalence (TYL = 63% vs. IGY = 52%; P = 0.40), severity (P = 0.23). Abscessation lowered albumin (P = 0.04) but not other blood analytes. Bacterial DNA data indicated that alpha and beta diversity metrics were different between liver abscess severity scores. No difference in relative abundance of F. necrophorum (P = 0.23) or T. pyogenes (P = 0.76) was observed in abscessed livers. In normal livers, relative abundance of T. pyogenes was lesser for IGY than TYL (0.039 vs. 0.44% respectively; P = 0.03), but F. necrophorum was not affected (P = 0.58). Providing IGY rather than TYL did not affect the liver abscess prevalence, severity, and decreased the proportion of AMR Enterococcus shedding in feces by half indicating IGY could be a viable antibiotic alternative.Item Evaluation of steam-flaked corn bulk density manipulation during grain adaptation of beef steers and the use of X-ray fluorescence spectrometry technique to measure apparent total tract digestibility(2019-08) Hoffmann, Carly Ann; Sarturi, Jhones O.; Ballou, Michael A.; Henry, Darren D.In Exp. 1, 6 ruminally cannulated beef steers were used in a CRBD to evaluate bulk densities of steam- flaked corn (SFC; 335 or 412 g/L; n = 3/ trt) on ruminal fermentation and feeding behavior characteristics. In Exp. 2 and 3 the use of a portable X-Ray fluorescence spectrometry (PXRF) technique to measure apparent total tract digestibility (ATTD) was performed using a CRD on seven ruminally cannulated beef steers and eight sheep. In Exp. 1, steers were fed ad-libitum during 6-7d phases consisting of: Hay; Step-up (1, 2, 3, and 4); and a finisher (Fin) diet. Respective SFC bulk densities were constant throughout phases, except Fin when steers were switched to 412. Ruminal pH average was continuously measured (wireless pH probes), and ruminal fluid was collected. A continuous observation (24 h) was used for feeding behavior. The SFC-BD did not affect (P ≥ 0.19) measured variables, except for greater NDF (P < 0.01) and ADF (P = 0.09, tendency) digestibility observed for 412 g/L steers during Step-up 3. Greater (P ≤ 0.01) digestible DMI during Step-up 4 and Fin were observed compared to other phases. Digestible NDF/ADF intakes were greatest (P ≤ 0.05) during HAY-phase. ATTD was lowest (P ≤ 0.05) during HAY-phase. Steers ruminated and chewed the most (P ≤ 0.05) during HAY-phase. Ruminal C2:C3 decreased (P < 0.01) as steers advanced through phases. The SFC bulk density range studied seems to not dramatically affect ruminal fermentation characteristics and feeding behavior. For experiment 2, steers (BW = 520 ± 30 kg) were individually fed a SFC-based finishing diet ad libitum for 21 d (14 d adaptation, 7 d collection). Degradable gel capsules (7.5 g of TiO2 and Cr2O3) were placed inside the rumen. Fecal samples were collected twice daily and immediately frozen (-20oC). For study 2, sheep (BW = 68 ± 3 kg) were individually fed twice daily a SFC-based diet ad libitum for 21 d (14 d adaptation). After adaptation, sheep were moved to metabolism crates for 7 d (5 d of collection). Cr2O3 and TiO2 (2 g, each) were mixed with 5 g WCGF and top dressed onto feed. Total fecal samples (collection harnesses) twice daily were subsampled (50%) and analyzed for marker concentration using atomic absorption (Cr) or spectrophotometry (TiO2) and compared with the values obtained from the PXRF device. Fecal specimens included: fresh (average 22.5 % DM), dried (60oC, 72 h), or dried/ground (1 mm). For experiment 3, total fecal collection (CON) was used to measure marker fecal recovery. Data were analyzed using the GLIMMIX procedures of SAS. The difference between ATTD estimated by wet chemistry and PXRF was not different from zero when using bovine fresh fecal specimens analyzed for Cr (P = 0.40) or Ti (P = 0.14); whereas PXRF used for dried and dried/ground specimens it differed (P ≤ 0.04), in which ATTD was underestimated by 3.6 and 1.1 % for Cr and Ti, respectively. The ATTD of sheep was underestimated (P < 0.01) by 2.4 % compared with CON when Cr was measured by PXRF in dried-only samples. Fresh and dry/ground fecal samples assessed for Cr, and all samples accessed for Ti were not (P ≥ 0.49) affected by marker detection method. For Ti, dried-only sheep fecal specimens did not differ (P = 0.63) from zero. The use of PXRF seems to accurately detect Cr and Ti in fresh beef steers fecal samples, while dried-only and dry/ground fecal samples showed better accuracy for ovine specimens.Item Strategic feeding of a direct-fed microbial and vitamin/mineral complex to feedlot cattle – calf-fed system(2022-12) Rush, Camron; Sarturi, Jhones O.; Crossland, Whitney L.; Henry, Darren D.The effects of a nutritional packet strategically offered to a calf-fed system on growth performance, carcass characteristics, nutrient digestibility, feeding behavior, and ruminal characteristics were evaluated. Angus crossbred steer-calves (n = 60; body weight = 234 ± 4 kg) were assigned to a randomized complete block design (block = body weight) and stratified into 2 treatments: a) control (no packet, finely-ground corn used as carrier only); and b) 30 g (DM basis)-/steer-daily of a nutritional packet [live-yeast (Saccharomyces cerevisiae; 8.7 Log CFU/g), Vitamin C (159 mg/steer-daily of Ascorbic acid), Vitamin B1 (394 mg/steer-daily of Thiamine hydrochloride), NaCl (2.4 g/steer-daily), and KCl (2.4 g/steer-daily)]. Animals were offered [electronic feed-bunks (SmartFeed/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. Digestibility assessments took place within both phases. The GLIMMIX procedure of SAS was used, in which the model used steer as the experimental unit, treatment as fixed effect, and body-weight block as random effect. Steers offered the nutritional packet had 14% less (P < 0.01) intake and 18% greater (P = 0.01) gain efficiency during the initial 30-d on feed. Overall intake (d0 to 233) was 6% greater (P = 0.02) for steers consuming the nutritional packet, while ADG (1.56 vs. 1.61), and gain efficiency (0.204 vs. 0.198) for control and packet, respectively, were unaffected (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 unaffected (P ≥ 0.33). Digestibility of DM, OM, NDF, ADF, and hemicellulose were increased (P < 0.01) for steers consuming the packet on average by 2.4, 2.4, 8.3, 10, and 7.5% respectively, for both digestibility phases. Regardless of treatment, a decreased rumination (P ≤ 0.03) and chewing (P ≤ 0.01) activity-variables were observed for phase 2 compared to phase 1. Steers consuming the packet spent 13% less time eating during phase 1 only (P < 0.01), and had a 14% increase in meal frequency (P = 0.02) and 12.3% reduction in mean meal size, kg of DM (P < 0.01) in phase 2 only. Steers consuming the packet also had a reduced mean meal duration in both phase 1 (P = 0.01) and phase 2 (P = 0.01). Average papillae area was increased (P = 0.02) by 30% and the total VFA tended (P = 0.09) to increase by 8% for steers consuming the packet at time of slaughter. Calf-fed steers improved gain efficiency during the initial 30 d after feedlot arrival, while superior intake, dressing percentage, nutrient digestibility, total VFA, ruminal papillae area, and eating behavior appear to last until cattle harvest.Item 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, feeding behavior, and methane emissions(2022-05) Tonelli Nardi, Kaue; Onorino Sarturi, Jhones; Crossland, Whitney L.; Henry, Darren D.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, total tract apparent nutrient digestibility, and 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) in a randomized complete block design where pen represented the experimental unit. A steam-flaked corn-based finishing diet was offered ad libitum, and the treatments were applied as follows: 1) control and 2) 30 g/steer-daily (DM-basis) of the nutritional packet. Ground corn was used as a carrier for the nutritional packet and included at 1 % of diet DM. The nutritional packet was formulated to provide 1.7 × 1010 CFU/steer-daily of Saccharomyces cerevisiae, 162 mg/steer-daily of Vitamin C; 400 mg/steer-daily of Vitamin B1; 2.4 g/steer-daily of NaCl, and 2.4 g/steer-daily of KCl. Data were analyzed using the GLIMMIX procedure of SAS. Average daily gain of BW (P = 0.89), DMI (P = 0.57), and gain efficiency (P = 0.82) were not affected by the inclusion of the nutritional packet. The 12th rib fat deposition increased (P = 0.02) by 17.5% for cattle offered the nutritional packet, followed by a also greater (P = 0.03) calculated yield grade. The NDF and ADF digestible intake (kg/day) were 7.53 and 11.9% greater (P ≤ 0.02) for treated cattle, respectively. Steers offered the nutritional packet had increased (P ≤ 0.02) digestibility of DM, OM, NDF, and ADF, while a tendency (P = 0.08) was observed for hemicellulose. Steers feeding behavior 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 offered the nutritional packet did not differ between periods, while steers offered the control treatment decreased such behavior activities on d 63. Rumination, drinking, active, chewing, and resting times were not affected (P ≥ 0.28) by treatments. The nutritional packet improved nutrient digestibility with no effect on nutrient intake which may have led an increased carcass-fat deposition. Such effect associated with no deleterious effects on growth performance, and a more stable eating behavior during the final 64 days on feed can potentially warrant less days on feed when cattle receive such nutritional packet.Item 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(2023) Rush, Camron J. (TTU); Sarturi, Jhones O. (TTU); Huerta-Leidenz, Nelson O. (TTU); Woerner, Dale R. (TTU); Crossland, Whitney L. (TTU); Henry, Darren D.; Silva, Kaliu G.S. (TTU); Lopez, Alejandra M. (TTU)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.