Growth Performance Research Articles

189 Combination of organic acid and monoglyceride blend improved growth performance in nursery pigs with and without added antibiotics and ZnO

Abstract This study was to investigate the effects of supplementing a combination of organic acid and monoglyceride additives in feed with and without added antibiotics and pharmacological levels of ZnO on growth performance of nursery pigs. Pigs (n = 1,008; 21 d of age with initial body weight (BW) = 5.8] were assigned to 4 treatments (n = 12, 21 pigs/pen, mixed sex) following 2 × 2 factorial experiment design and fed for 42 d in 4 phases (d 0-8, d 9-21, d 22-35, and d 36-42, respectively). Treatments were 1) Positive control (PC), basal diet with in-feed antibiotics in phase 1-3, and 3000 ppm of Zn in phase 1, 2000 ppm of Zn in phase 2 and 125 ppm of Zn in phase 3 and 4 (i.e., pharmacological levels); 2) PC supplemented with the combination of Acitra G20C (formic acid-based acid blend on inert carrier) and Entero-Nova 410C (blend of monoglycerides of short-chain and medium-chain fatty acids on inert carrier), Acitra G20C was added at 3 kg/MT in phase 1 diet and 1.5 kg/MT in phase 2 diet, while Entero-Nova 410C was added at 3 kg/MT in phase 1 and 2 diets, and 1 kg/MT in phase 3 and 4 diets; 3) Negative control (NC), basal diet without in-feed antibiotics and pharmacological levels of ZnO; and 4) NC supplemented with the combination of Acitra G20C and Entero-Nova 410C (same supplementation rate as Treatment 2). Diets contained nutrients meeting or exceeding NRC requirements. Growth performance was measured for each phase. Data were analyzed using JMP software with pen serving as the experimental unit and differences considered significant at P ≤ 0.05. Throughout the trial, pigs fed diets without in-feed antibiotics and pharmacological levels of ZnO had ess (P < 0.01) BW, average daily gain (ADG) and average daily feed intake (ADFI) than pigs fed diets added with antibiotics and pharmacological levels of ZnO. During the period of phase 2 and overall phase 1 and 2 of the trial, pigs fed diets supplemented with the combination of Acitra and Entero-Nova additives had greater (P < 0.05) ADG and ADFI and greater (P < 0.05) BW on d 22 of trial. In phase 3 and 4, there was no significant improvement on growth performance of pigs fed diet only supplemented with 1 kg/MT of Entero-Nova comparing with the pigs in control groups. In conclusion, under current trial conditions, the combination of Acitra G20C and Entero-Nova 410C improved growth performance of nursery pigs in phase 1 and 2 when supplemented at tested dosage comparing with pigs in control groups without the additives.

PSVI-10 Effect of sulfate or hydroxychloride forms of zinc, manganese, and copper on growth performance, weight variation, and carcass characteristics of grow-finish pigs

Abstract A total of 1,026 grow-finish pigs (337 × 1050, PIC; initially 26.0 ± 0.33 kg) were used in a 124-d trial to compare sulfate and hydrochloride forms of Zn, Mn, and Cu on growth performance, carcass characteristics, and weight variation, of grow-finish pigs. Pigs were housed in mixed gender pens with 27 pigs per pen and 19 pens per treatment. The treatments were structured as a completely randomized design and consisted of a control diet containing 150, 16, and 110 mg/kg of Cu, Mn, and Zn, respectively, from sulfate sources or provided by hydroxychloride sources. Experimental diets were corn-soybean meal-corn-dried distiller grains with solubles based and fed in meal form in phase 1 from 26 to 50 kg, phase 2 from 50 to 75 kg, phase 3 from 75 to 100 kg, and phase 4 from 100 to 136 kg. In the grower period (26 to 78 kg), pigs fed sulfate sources of Mn, Zn, and Cu had improved (P = 0.05) gain to feed ratio (G:F) compared with pigs fed hydroxychloride forms (Table). In the finisher period (78 to 136 kg), pigs fed hydroxychloride mineral sources had improved (P = 0.041) average daily gain (ADG) compared with pigs fed sulfate sources. For pig body weight variability, there was no evidence of differences (P > 0.10) in the coefficient of variation between treatments. Pigs fed hydroxychloride mineral sources tended to have greater hot carcass weight (HCW; P = 0.054) when marketed at the end of the study compared with pigs fed sulfate sources, but no evidence for differences (P > 0.10) were found in the first marketing and overall HCW or any other carcass trait at either marketing event. In conclusion, these data suggest there were no differences in overall pig growth performance or body weight (BW) variability, but pigs fed hydroxychloride sources of Zn, Mn, and Cu tended to have heavier HCW at the final marketing event.

30 Effects of using different dietary standardized ileal digestible lysine plans on growth performance and carcass characteristics of grow-finish pigs from high or low breeding value boars

Abstract The present study aimed to evaluate the impact of using different dietary standardized ileal digestible (SID) lysine (Lys) plans on growth performance and carcass characteristics of grow-finish pigs coming from high or low breeding value boars. A total of 2,080 pigs (PIC 800 × PIC Camborough) were housed in 20 mixed sex pens (26 pigs/pen), blocked by body weight (BW), and randomly allotted in a 2 × 2 factorial arrangement with boar breeding value (high or low) and nutrition Lys plan (current SID Lys curve recommendation for PIC 800 as % of PIC 337 SID Lys curve or alternative SID Lys curve). Pigs were weaned at 21 d of age (6.1 ± 0.05 kg BW) and followed during the wean-to-finish period until reach the market slaughter weight. Pigs were fed either the current recommendation or an alternative SID Lys curve for PIC 800, in a 6 phase feeding program: phase 1 (6-11 kg; 100 vs 100%, respectively); phase 2 (11-23 kg; 97 vs 100%, respectively); phase 3 (23-45 kg; 97 vs 100%, respectively); phase 4 (45-73 kg; 97 vs 95%, respectively); phase 5 (73-102 kg; 97 vs 95%, respectively); and phase 6 (102-132 kg; 97 vs 90%, respectively). Pigs were fed isoenergetic diets. Performance and carcass traits, and removals and mortality were recorded. Data were analyzed using mixed models in R, and considering pen as the experimental unit for performance traits and individual carcasses for carcass traits. There was no evidence of interaction between boar breeding value and nutrition plan factors. Overall, high breeding value pigs had greater average daily gain (ADG; 0.84 ± 0.005 g/d) compared with low breeding value pigs (0.82 ± 0.005 kg/d; P < 0.01), which was driven by increased average daily feed intake (ADFI; 1.92 ± 0.011 and 1.89 ± 0.011 kg/d, respectively; P < 0.05; Table 1). Moreover, high breeding value pigs had greater hot carcass weight (HCW; 97.8 ± 1.09 kg), carcass yield (74.1 ± 0.23%), backfat thickness (16.3 ± 0.29 mm) and lower lean meat % (57.0 ± 0.21%) compared with low breeding value pigs (96.0 ± 1.09 kg; 73.7 ± 0.23 %; 15.4 ± 0.28; 57.5 ± 0.21%, respectively; P < 0.05; Table 1). Regarding nutrition plan, no significant differences were observed for overall performance traits between pigs fed the current or alternative SID Lys curve (P > 0.05; Table 1). Nevertheless, pigs fed the alternative SID Lys curve had heavier HCW (97.3 ± 1.09 kg) compared with pigs fed the current SID Lys curve (96.6±1.09 kg; P < 0.05; Table 1). No significant differences were observed for overall removals and mortality by breeding value or nutrition Lys plan (P > 0.05). In summary, grow finish pigs from high breeding value boars have an improved productive performance. PIC 800 pigs may achieve the same productive performance with lower lysine levels at the end of the grow-finish period.

259 Effect of very low calcium diet supplemented with microbial phytase in post-weaning piglets

Abstract Young piglets have an immature intestine that provides limited gastric acidity to digest nutrients compared with later stages of growth. Food has the intrinsic capacity to modify gastric acidity, particularly in relation to their concentrations of limestone, the ingredient with the greatest capacity to bind to acid. An experiment was conducted to evaluate the impacts of reducing dietary calcium (Ca) by reducing calcium supplementation immediately after weaning; compared with the recommendations of the NRC (2012), in association with phytase supplementation. The treatments were distributed during 3 phases [Phase 1 (P1, d 0-9), 2 (P2, d 10-16) and 3 (P3, d 17-35)]. Treatments were: 1) a diet low Ca that did not contained limestone during phase 1 (LowCa), P1 to P3 respectively, 0.51-0.60-0.65 % Ca and 0.48-0.43-0.38 % standardized ileal digestible P (STTD P), 2), diet 1 with microbial phytase (LowCa+PhytM); P1 to P3 respectively, 0.51-0.60-0.65 % Ca and 0.48-0.43-0.38% STTD P with 750 FTU phytase, and 3) a diet fulfilling requirement (NormalCa+PhytM) P1 to P3 respectively, 0.85-0.80-0.70 % Ca and 0.48-0.43-0.38 % STTD P with 750 FTU phytase. Piglets (n = 120) were allocated to 6 pens of 5 piglets per treatment in function of initial body weight (BW; 6.12 ± 0.028 kg). On d 0, 15 and 36, dual X-ray (DXA) bone densitometry was used to measure body fat, lean and mineral content (BMC) compositions using 8 piglets per treatment. At the end of phase 1 (d 9) a blood sample was collected. Data were analyzed using the SAS MIXED procedure with Tukey’s test to compare means. No differences were observed in growth performance or DXA measurements during the first phase. On d 9, LowCa piglets showed signs of hypocalcaemia with reduced plasma Ca (P = 0.03), increased plasma P (P = 0.02) and a lower Ca:P ratio in plasma (P = 0.04). From d 9-15, piglets that had received LowCa+PhytM showed greater average daily gain (ADG; P = 0.002) while other criteria did not differ between treatments. On d 15, the body composition evaluated by DXA showed no difference among dietary treatments. During phase 3, final BW and average daily feed intake were not modified by dietary treatments, while average daily gain and feed efficiency were greater in LowCa than in NormalCa+PhytM (+7.3 and 6.7%, respectively), and LowCa+PhytM was intermediate. Body composition on d 35 showed no difference among treatments while a tendency (P = 0.095) for greater BMC deposition (g/d) in LowCa in comparison with NormalCa+PhytM (+1.3 %). The implemented LowCa strategy resulted in momentary hypocalcemia which probably activated homeostatic mechanisms allowing piglets to be more efficient in using minerals and possibly other nutrients leading to better growth performance, without impact on bone mineralization.

69 Effect evaluation of two sources of zinc at EU-authorized level on growth performance and gut health of piglets with a low or normal birth weight

Abstract This study aimed to investigate the effect of ZnSO4 or a porous form of ZnO, at EU-authorized level, on growth performance, gut health and colon microbiota in low and normal birth body weight (BBW) piglets. At birth, 64 piglets were chosen by their BBW and divided into low BBW (LBBW < 1 kg; 32 piglets) and normal BBW (NBBW > 1 kg; 32 piglets). At weaning, 25 d old (d 0), piglets were allocated into four groups (8 piglets/group, 2 pigs/replicate) and fed a standard diet plus 120 ppm of Zn from ZnSO4 or from a porous source of Zn (HZ - HiZox, Animine, France). Groups were balanced for litter of origin and category of BBW. Piglets were weighed weekly until d 21 post-weaning. The prevalence of diarrhea was determined by the fecal index (percentage of animals with fecal score > 3), and feed intake per pen was recorded daily. On d 9 and d 21, one piglet/replicate was slaughtered, and jejunum tissue was collected for morphology, colon content for microbiota analyzes, and distal jejunum pH was measured. Performance, pH, and morphometric parameters were analyzed using a linear mixed model, fecal index using a generalized linear mixed model with a Poisson distribution, including treatment, class of BBW and their interaction as fixed factors, and the litter as random factor. The statistical analysis on alpha, beta diversity and taxonomic composition were carried out using phyloseq, vegan and microbiomeMarker packages. Piglets in the NBBW group had greater BW throughout the study (P < 0.01). The treatment HZ tended to increase the average daily gain (ADG) at d 9-14 (P < 0.10), and significantly increased the gain to feed ratio (G:F) ratio (P < 0.05) at d 0-14. The HZ-fed piglets had a greater G:F in the overall period (P = 0.04). Additionally, the jejunum pH of the HZ-fed piglets was reduced (P = 0.02) at d 21. An interaction was observed between treatment and BBW for fecal index during d 0-14 and d 0-21 (P < 0.01), in which HZ decreased the index in LBBW. An interaction was also observed in villus height (P = 0.05) and absorptive mucosal surface (P = 0.02) on d 21, that resulted greater in NBBW piglets fed ZnSO4. For Beta diversity, using the Adonis test, BBW category tended to affect the microbial structure at d 9 (R2 = 0.04; P = 0.07) and significantly affected the bacterial structure (R2 = 0.05, P = 0.03) at d 21. At d 21, the NBBW piglets fed ZnSO4 had a greater abundance of Succinivibrio which is able to degrade complex carbohydrates, while the NBBW piglets fed HZ had a greater abundance of Ruminococcus gauvreauii which is linked to the production of short chain fatty acids (SCFAs). The use of HZ seems can be a part of the strategy to replace the pharmacological level of ZnO.

192 Effects of inclusion of a probiotic and/or a postbiotic in diets containing a phytogenic feed additive on growth performance and fecal microbiome composition and function of nursery pigs

Abstract This study investigated the effects of inclusion of a Bacillus-based probiotic and a postbiotic from Lactobacillus acidophilus fermentation (Dia-V Nursery, Diamond V, IA) in diets containing a phytogenic feed additive (Fresta Protect, Delacon, Austria) on growth performance and fecal microbiome of pigs. Weaned pigs [n = 1,840; 19 d old; initial body weight (BW) = 6.1 ± 0.2 kg] were allotted to 16 replicate pens/ treatment (23 pigs/pen) in 2 barns. Pens were blocked by location within barn and randomly allotted to 5 treatments: 1) Basal diet (NC), 2) NC without specialty fats (soy oil blend and medium chain fatty acid blend) + 0.1% phytogenic (PC), 3) PC + 0.05% probiotic (1.1 x 106 CFU/kg of complete feed; PC+Prob), 4) PC + 0.2% postbiotic (PC+Post), and 5) PC + 0.05% probiotic + 0.2% postbiotic (PC+Prob+Post). Pigs were fed experimental diets during phase 1 (d 0-10) and 2 (d 10-23). Pig and feed weights were recorded at the beginning and end of each phase. Fecal samples were collected from 2 pigs/pen (n = 32/treatment) on d 7 and 25 post-wean and subjected to DNA extraction and shotgun metagenomics to evaluate gut microbiome. Performance data were analyzed using the lme4 package of R with treatment as fixed effect and barn and pen location within barn as random effects. Microbiome data were center-log-ratio transformed and analyzed for alpha- and beta-diversity, differentially abundant taxa and genes, microbial network, and carbohydrate active enzymes (CAZy). No differences on performance, mortality or removals were observed during phase 1, phase 2, or overall among treatments (Table 1). Microbiome features were similar between NC and PC. The PC+Prob did not affect alpha- and beta-diversities of microbiome. The PC+Post reduced (P < 0.05) alpha-diversity on d 7 compared with PC and affected (P < 0.05) beta-diversity on both timepoints. The PC+Post had the greatest number of differentially abundant taxa (P < 0.05) compared with PC both on d 7 (27 taxa) and 25 (14 taxa). The PC+Post had greater (P < 0.05) presence of CAZy including glycoside hydrolases, glycosyltransferases and carbohydrate-binding modules on both timepoints. Inclusion of probiotic and postbiotic separately or in combination reduced (P < 0.05) the number of positive connections within the microbial network suggesting these additives promoted a more competitive microbial ecosystem against opportunistic microorganisms compared with PC. Inclusion of postbiotic speeded up the progression of microbiome toward a more mature community. This resulted in reduction of diversity but increased carbohydrate enzyme capability making microbial community leaner and more effective. In conclusion, replacement of specialty fats with a phytogenic did not affect piglet performance or microbiome under non-challenge conditions and no differences in performance were observed between PC pigs and those supplemented with a probiotic or postbiotic despite the effects observed in microbiome.

72 Effect of In-feed fecal microbiota transplant on growth performance and gut microbiota dynamics of piglet subjected to post-weaning stress

Abstract Weaning is one of the most stressful events for piglets, due to diet change from sow milk to grain-based feed. This diet change causes turnover of the gut microbial which can allow proliferation of pathogens leading to diarrhea. Antibiotics are administered to treat or prevent post-weaning diarrhea (PWD). Increased occurrence of antimicrobial resistance has increased incentives to develop viable antibiotic alternatives. PWD is most often caused by enterotoxigenic Escherichia coli. Similarly, in humans, severe diarrhea can be caused by Clostridium difficile colonization. Use of fecal microbiota transplants (FMT) has been shown to resolve C. difficile-induced diarrhea in 80 to 90% of human cases which may suggest FMT as a potential therapeutic option for post weaning diarrhea. We previously have shown that in feed fecal microbiota transplant (FMT) improved body weight (BW) gain in newly weaned piglets but it is not clear if this benefit will be replicated in piglets subjected to weaning stress. We hypothesize that FMT (in-feed) will increase colonization efficiency, improve growth performance and reduce diarrhea incidence compared with control in piglets subjected to post weaning stress. The objective of this study was to determine the effect of In-feed FMT of diarrhea index, growth performance and gut microbiota dynamics. Piglets (n = 240) subjected to physiological and transport weaning stress were allotted to 5 treatments: In-feed FMT (FMT1), doubles dose of In-feed FMT1 (FMT2), Oral gavage (FMT3), Antibiotic (positive control), and no supplementation (negative control). The donor material was screened for enterotoxigenic E. coli (F18 and F4). FMT was carried out for 14 d. Diarrhea index was observed for the first 14 d and animal BW, and fecal microbiota was collected by rectal swab on d 0, 3, 5, 7, 14, 21, 28 and 32 for analysis of microbiota composition. DNA was extracted from fecal samples and 16S rRNA gene libraries (V4 region) were prepared for bacterial community analysis. Data were analyzed with one-way ANOVA in R. Only positive control had significantly decrease in diarrhea index and significant increase BW gain on d 14, 21, and 28 (P < 0.05) but there was no effect of FMT (P > 0.05). In conclusion, antibiotics but not FMT was efficient in alleviating the negative performance effect in piglets subjected to post-weaning stress.

176 Impact of dietary crude protein level and water-based arginine on piglet growth and scouring with an Enterotoxigenic Escherichia coli F18 challenge

Abstract The objective of this experiment was to evaluate the impact of dietary crude protein (CP) level and water-based arginine (Arg) on the growth performance and scouring of piglets post wean and following an enterotoxigenic Escherichia coli F18 infection (ETEC). A total of 240 pigs (PIC 337 x 1050, Genus, Henderson, TN) were randomly assigned to 40 mixed-sex pens (6 pigs/pen) for a 6-wk experiment. At arrival, all pigs were genotyped for fructosyltransferase (FUT1). Pens were assigned to one of four treatments in a 2 x 2 factorial, with two crude protein levels (standard: 23% vs. low: 19.5%, for period 1) and two water treatments (absence or presence (8, 6, and 4% stock dosed through 1:128 proportioner for wk 1, 2, and 3, respectively) of Arg in water. Pig body weight (BW), feed disappearance (average daily feed intake; ADFI), and feed conversion (gain to feed ratio; G:F) were evaluated for four periods: d 0-7, 7-14, 14-21, and 21-42. Scour scores were recorded daily for the first 28 d to calculate weekly percentage of days scouring (scouring percentage). On d 21, water and dietary treatments ceased, and pigs received a common diet. All pigs were orally inoculated with a field strain of ETEC for two consecutive days on d 15 and 16 of the experiment. One pig per pen had blood collected (8mL via jugular) and was euthanized on d 14 before ETEC. Blood was collected via a jugular vein from another pig confirmed to be susceptible to ETEC on d 15, 17, and 22. The same pig was euthanized for tissue collection on d 22. Fecal swabs from 1 susceptible pig per pen were collected on d 15, 17, 19, and 22 for measurement of ETEC shedding. Blood samples were analyzed for inflammatory markers, and villi: crypt within the ileum were measured. Data were analyzed using mixed model methods (SAS 9.4, Cary, NC) with pen as the experimental unit. Growth performance and scouring percentage included the fixed effects of CP level, water treatment, experimental period, and their interactions. Reducing the CP of diets reduced the overall G:F of pigs (P < 0.01, standard: 0.73, low: 0.71). The percentage of days scouring tended to be influenced by the interaction between water and period (P = 0.06); specifically, when arginine (Arg) was present in the water, there was a numerically greater scouring percentage for all periods, except for the final period (d 21-28). Confirming the success of the ETEC challenge, period significantly impacted scouring percentage (P < 0.01), where piglets experienced the greatest scouring percentage (59%) during the week following ETEC inoculation, compared with the least in the week preceding inoculation (22%). In conclusion, low CP diets reduced overall G:F, but neither CP or Arg showed benefit in terms of scouring.

PSV-4 Exposure to prenatal tributyrin improved pre-weaning growth performance and reduced fat deposition in the muscle of market age pigs

Abstract Organic acids, including short chain fatty acids, medium chain fatty acids, and tricarboxylic acid, are used as alternatives to antibiotics for the purpose of growth promotion in livestock species. Butyric acid has been used extensively for its various functions in intestinal health and barrier function, as well as its actions as a histone deacetylase inhibitor. Many of the issues relating to using butyric acid as a feed supplement are overcome by utilizing tributyrin (TB), a butyrate prodrug. Dietary supplementation of TB to sows during gestation was able to improve pre-weaning litter performance. Sows (n = 52, 42 gestational days) were randomly assigned to either a control diet or control diet supplemented with 2% TB. All diets were made isocaloric with the addition of oil and wheat flour. Dietary treatments continued until 112 d of gestation. After farrowing, piglet growth performance was monitored. Once offspring reached 6 mo of age, 30 gilts from the most median performing litters were identified for tissue collection and evaluation of meat characteristics. Sows that received tributyrin during gestation tended to have greater total litter weights at birth (P < 0.1); however, average individual birthweights were not statistically different between control and TB litters. The TB piglets tended to be heavier at weaning (P < 0.1). Pre-weaning average daily gains were higher in piglets exposed to prenatal TB (P < 0.01). Body weights and hot carcass weights did not differ significantly in gilts at market age. There was, however, a trend of increased dressing percentage from TB treated offspring, accompanied by significantly reduced back fat at the 10th rib (P < 0.1 and P < 0.05 respectively). These data suggest that TB supplementation results in both temporary and permanent improvements to growth and development. This study provides further evidence that prenatal TB can have long term effects on muscle growth and meat quality. Further studies are needed to ultimately determine whether prenatal or postnatal supplementation is ideal for improving long-term growth performance.

103 Effects of partial or total replacement of dried distiller’s grain with soybean meal on growth performance, carcass characteristics, sera urea nitrogen, and net energy utilization in finishing beef steers

Abstract The objective of this study was to determine if partial or complete replacement of dried distiller’s grains plus solubles (DDGS) with solvent-extracted soybean meal (SBM) influences growth performance, efficiency of dietary net energy utilization, sera urea-N (SUN) concentrations, or carcass traits in finishing beef steers. Continental × British steers [initial shrunk body weight (BW) = 382 ± 37 kg] were used in a 139-d experiment. Treatments included: DDGS fed at 20% DM (13.4% CP; DDGS), SBM replacing 50% of DDGS (14.4% CP; SBM50), and SBM replacing 100% of DDGS (15.4% CP; SBM100). Steers (n = 189) were weighed and allotted to 1 of 24 pens (n = 8 steers per pen; 8 pens per treatment) at the Ruminant Nutrition Center near Brookings, SD. Whole blood was collected and harvested as sera on d 77, 105, and 139 to determine SUN concentration. Growth and carcass data were analyzed as a randomized complete block design using the GLIMMIX procedure of SAS 9.4 with treatment and block (initial BW grouping) as fixed effects; SUN data were analyzed using repeated measures, pen was the experimental unit. Inclusion level was evaluated for linear and quadratic components by the method of orthogonal polynomials. Final BW was calculated by dividing hot carcass weight (HCW) by 0.625. No differences were noted (P ≥ 0.18) for final BW, average daily gain, dry matter intake, or feed efficiency. Dietary treatment tended to affect gain to feed ratio (G:F; quadratic; P = 0.10) and SBM increased the apparent efficiency of energy capture. Treatment had no effect (P ≥ 0.22) on HCW, rib fat, marbling score, USDA yield grade, or final BW adjusted to 28% empty body fat. Complete replacement of DDGS with SBM increased rib eye area by 1% (linear; P = 0.02), but decreased dressing percentage (linear, P = 0.03). Distribution of USDA quality or yield grades were unaffected by treatment (P ≥ 0.36). No treatment × day interaction was observed for SUN (P = 0.20). However, day (P < 0.01) and treatment (P < 0.01) effects were observed. Initial samples (d 77) differed between DDGS and SBM treatments, with the latter having greater SUN values (P < 0.01). On d 105, the SBM100 treatment had greater SUN than DDGS, and SBM50 was intermediate (P < 0.01). On d 139, steers from SBM100 had elevated increased SUN compared with SBM50 and DDGS treatments (P < 0.01). Net energy values calculated from animal performance for DDGS agreed closely with tabular estimates. In this experiment, replacement of DDGS with SBM increased the observed to expected ratio of dietary NE, increased muscularity and tended to decrease DP with no other observed effects on growth performance or carcass traits.

53 Evaluation of the impact of high doses of phytase and marketing strategy on performance and carcass characteristics of late finishing pigs in commercial settings

Abstract As late finishing pigs reach market weight, space allowance per unit of body weight (BW) is reduced, which negatively impacts growth performance. Supplementing high doses of phytase results in the near complete destruction of phytic acid resulting in increased levels of lower inositol esters and inositol, which have been associated with a decreased stress response as well as having insulin-like effects. This study evaluated the impacts of high doses of phytase and two marketing strategies on growth performance and carcass characteristics of late finishing pigs. Pigs (n = 2,200; initial BW = 89.64 ± 3.08 kg) were randomly distributed to 96 pens using two commercial research barns, with 18 to 24 pigs per pen, balanced for gilts and barrows. Two phytase supplementation doses (super-dosing control of 2,250 FTU/kg and hyper-dosing at 4,500 FTU/kg) and two marketing strategies (Standard or Late) were combined to create 4 treatments in a 2×2 factorial arrangement. The first marketing event occurred at an average BW of 123.3 kg on d 22 for the Standard group and at 145.3 kg on d 44 for the Late group, marketing the heaviest 1 to 5 pigs per pen (13.2% of pigs). The second group (15.4% of pigs; BW of 147.3 and 144.8 kg for Standard and Late marketing) was marketed on d 50 and marketing of all remaining pigs occurred on d 63 for both treatments. Finisher diets contained 0.74% SID lysine, 0.60% Ca, and 0.37% available P. Regardless of the dose, phytase was given the same matrix values for nutrients and metabolizable energy. No interactions were observed between marketing strategy and phytase supplementation (P > 0.22), and no effect of phytase was observed (P > 0.09). Average BW of all pigs marketed was greater (P < 0.001) for the Late compared with the Standard marketing strategy (143.8 vs. 141.7 kg/d). Days to market was greater for Late marketing (59.7 vs. 56.8 d) as a result of the extra 22 d before the first marketing compared with the Standard strategy. Thus, average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio were not impacted (P ≥ 0.486) by marketing treatments. Hot carcass weight (103.83 vs. 101.44 kg) and yield (78.10 vs. 77.73%) were greater (P < 0.001) for Late marketing. Fat cover was greater and percent lean was less (P < 0.05) for the Late marketing treatment, but loin depth and marbling were not different (P > 0.09). All primal cuts were heavier (P < 0.001), resulting in a total primal weight of 89.44 and 87.54 kg (P < 0.001) for Late and Standard marketing, respectively. Results suggest that delaying the first marketing improved final BW, yield, and weight of primal cuts and that supplementing phytase above super-dosing levels in late finishing pigs did not improve growth performance or carcass value, regardless of marketing strategy.

113 Evaluation of high soybean meal diets with inclusion of dietary enzymes on the effect of growth performance and greenhouse gas emissions

Abstract Crossbred gilts [n = 48; initial body weight (BW) = 52.55 ± 4.12 kg] were used to evaluate the effects of high soybean meal (SBM) inclusion with dietary enzymes on the growth performance, nitrogen balance, and gas emissions of growing pigs. This study consisted of two replicates of 24 gilts placed in individual metabolism stalls. Pigs were randomly assigned to one of six dietary treatments and blocked by BW (4 pigs•treatment-1•replicate-1). Pigs were fed a common diet from d 0 to 12, the experimental diets were fed in two phased (d 12 to 24 and d 24 to 36). The experiment consisted of 3 collection periods, with each period subdivided into two subperiods to collect samples for gas emissions and nutrient balance. Manure samples were collected for 72 h. Twice daily, urine and feces were weighed, and a ratio of the excreta were subsampled to measure gas emissions. Measurement of nutrient digestibility and retention consisted of urine and feces collections over a 72 h-period. The six dietary treatments include: 1) basal control diet (NC) corn-soy diet supplemented with synthetic amino acids, 2) high soybean meal (HSBM) diet (PC) formulated to replace all synthetic lysine, 3) HSBM diet with xylanase (Ronozyme WX 5000; DM; WX), 4) HSBM diet with inclusion of a multi-enzyme additive including hemicellulase and pectinase (Ronozyme VP, DM; VP), 5) HSBM diet with inclusion of xylanase (Ronozyme WX 5000, DM) and multi-enzyme additive including hemicellulase and pectinase (Ronozyme VP, DM; WXVP), and 6) HSBM diet with 1,500 FYT/kg of phytase (HiPhorious, DM; SD). The NC, PC, WX, VP, and WXVP diets contained phytase (HiPhorious, DM Nutritional Products, Parsippany, NJ) to provide 600 phytase units (FTU) per kg of diet and was assumed to release 0.15% available phosphorous. The SD diet contained 1,500 FTU/kg and was assumed to release 0.21% available phosphorous. Additionally, high soybean meal diets within each phase were isocaloric. Data were analyzed as repeated measures in SAS 9.4 (Inst., Cary, NC) with fixed effects of treatment, collection period, and block. Pig was the experimental unit, and results were considered significant at P ≤ 0.05 and a tendency at 0.05 < P ≤ 0.10. Pigs fed VP had the greatest average daily gain (ADG) compared with pigs fed SD (P = 0.865; Table 1). Pigs fed VP had the greatest gain to feed ratio (GF) efficiency compared with pigs fed WXVP (P = 0.3544). Manure pH, urine pH and hydrogen sulfide tended to decrease in all treatments from phase 2 to phase 3. Pigs fed PC had the lowest manure pH compared with pigs fed SD (P = 0.0826; Table 2). In conclusion, the feeding of HSBM or adding select enzymes did not alter gas emissions or growth performance metrics.

31 Effects of dietary standardized ileal digestible (SID) lysine (Lys) levels and dietary SID tryptophan to Lys ratios on growth performance and behavior of late-nursery to finish maternal barrows

Abstract The objective was to determine the effects of dietary standardized ileal digestible (SID) lysine (Lys) levels and SID tryptophan (Trp) to Lys ratios on growth performance and behavior of late-nursery to finish maternal barrows. A total of 2,293 barrows (PIC Camborough, initially 11.9 ± 0.35 kg) were used in this trial with 96 mixed-sex pens and 23 to 25 pigs/pen. There was a total of 6 dietary phases: P1:11.9-29.5 kg; P2:29.5-49.6 kg; P3:49.6-62.6 kg; P4:62.6-80.3 kg; P5:80.3-103.3 kg; and P6:103.3-137.8 kg. Pens were blocked by body weight and randomly allotted to 1 of 6 treatments:T1: 100% Lys (dietary SID Lys levels meet PIC SID Lys recommendation) and 21.0% of SID Trp:Lys ratio; T2: 100% Lys and 18.5% of SID Trp:Lys ratio; T3: 100% Lys and 16.0% of SID Trp:Lys ratio; T4: 80% Lys (dietary SID Lys levels meet 80% of PIC SID Lys recommendation) and 21.0% of SID Trp:Lys ratio; T5: 80% Lys and 18.5% of SID Trp:Lys ratio; and T6: 80% Lys and 16.0% of SID Trp:Lys ratio for P1-P2 and then 100% Lys and 18.5% of SID Trp:Lys ratio for P3-P6. Ear lesion (EL) was monitored during P2-P5. Data were analyzed using a linear mixed model in R Studio (Version 3.5.2, R Core Team; Vienna, Austria). Pigs fed T1 and T2 showed improved average daily gain than T6 (P < 0.05), with other treatments intermediate (Table 1). Pigs fed T2 showed improved average daily feed intake as compared with T6 (P < 0.05), with other treatments intermediate. There was no evidence for significant difference on feed-to-gain ratio or mortality. Removal was significantly greater for pigs fed T6 compared with all other treatments (P < 0.05). Pigs fed T2 had significantly greater hot carcass weight than T4, with other treatments intermediate. There was no evidence for significant differences on carcass yield or lean percentage. Pig fed T6 had significantly greater incidence of EL in P2 than all other treatments (P < 0.05). Pigs fed T4 and T6 had greater incidence of EL in P3 than T1 (P < 0.05), with other treatments intermediate. Pigs fed T5 and T6 had significantly greater incidence of EL in P4 than T1, T2, and T3 (P < 0.05), with T4 intermediate. During P5, pigs fed T4 and T5 had the greatest incidence of EL (P < 0.05), while pigs fed T6 had significant greater incidence of EL than T3 (P < 0.05), with T1 and T2 intermediate. In conclusion, dietary SID Lys and SID Trp:Lys ratio less than PIC recommendation during late-nursery-to-grower phase resulted in compromised overall growth performance of maternal barrows, even with restored dietary SID Lys and SID Trp:Lys levels in finish phase. Dietary SID Lys level and/or SID Trp:Lys ratios lower than PIC recommendation may result in greater incidence of aggression behavior in maternal barrows.

198 Evaluation of zinc source and concentration on growth performance of nursery swine

Abstract Trace minerals (TM) supplementation in swine diets can negatively interact with other nutrients. Zinc (Zn) and copper (Cu) mutually inhibit their intestinal absorption; thus, limiting their bioavailability. Recent peer-reviewed work has suggested that nursery pigs fed a diet supplemented with increased Zn experienced impaired Cu metabolism, negatively impacting growth performance. However, it has been demonstrated that mitigation of antagonisms might be possible with the use of organic TM supplemented at decreased concentrations. To validate these findings, a total of 2,629 pigs [initial body weight (BW) = 6.2 kg] were used in a 37-d experiment. Pens of 36 pigs were randomly allotted to 1 of 8 dietary treatments with 9 replications per treatment. Dietary treatments were formulated to contain 1 of 4 Zn sources: Zn Sulfate, Zn Hydroxychloride A (Intellibond Zn [Micronutrients Inc., Indianapolis, IN), Zn Hydroxychloride B [Zn Hydroxychloride (Alltech, Inc., Nicholasville, KY)] or Organic Zn [Bioplex Zn (Alltech, Inc)] at 1 of 2 concentrations: 125 or 250 ppm. The concentrations utilized for Organic Zn treatment were 62.5 or 125 ppm per published recommendations. Experimental diets were fed in two phases: phase 1 from d 0 to 21 and phase 2 from d 22 to 37. Added Cu in both dietary phases was 10 ppm. At d 37, serum and liver samples (data not showed) were collected from 1 barrow per pen and submitted to Michigan State University Veterinary Diagnostic Laboratory to determine Zn and Cu concentration. No significant source × concentration interactions were observed for growth performance in this study. From d 0 to 37, pigs fed the greatest Zn concentration had less (P = 0.040) average daily feed intake (ADFI) and marginally decreased (P = 0.060) average daily gain (ADG), despite Zn source (Table 1). In addition, a marginal improvement (P = 0.070) in gain to feed ratio (G:F) was observed in pigs fed diets containing Organic Zn, regardless of concentration. For mineral concentrations in serum, there was a marginally significant source × concentration interaction (P = 0.078), where pigs fed diets with 125 ppm of Zn Hydroxychloride B had one of the greatest Zn concentrations, yet it was drastically reduced when pigs were fed diets with 250 ppm. Furthermore, Cu concentration in serum was decreased (P = 0.045) in pigs fed the greatest concentration of Zn, despite source. In conclusion, these results suggest that greater dietary Zn concentration impaired Cu absorption, reduced feed intake, and marginally decreased growth. Organic Zn, included at 50% reduced concentrations, marginally improved feed efficiency.

45 Awardee Talk: Investigation of the nutritional and functional roles of a combinational use of xylanase and β-glucanase on intestinal health and growth of nursery pigs

Abstract The objective of this study was to evaluate the intestinal health and growth performance of nursery pigs affected by dietary supplementation of increasing levels of xylanase and b-glucanase combinations. Pigs [n = 40; initial body weight (BW) = 6.5 ± 0.4 kg] were assigned to 5 dietary treatments and fed for 35 d in 3 phases (11, 9, and 15 d, respectively). Basal diets mainly included corn, soybean meal, and distiller’s dried grains with solubles with phytase (750 FTU/kg) supplemented with 5 levels of xylanase and b-glucanase combinations (NSPase) at 1) 0, 2) 280 TXU/kg xylanase and 125 TGU/kg b-glucanase, 3) 560 and 250, 4) 840 and 375, or 5) 1,120 and 500, respectively. Growth performance and fecal score were measured for each phase. On d 35, all pigs were euthanized and collected jejunal mucosa, jejunal digesta, jejunal tissues, and ileal digesta to determine the effects of increasing NSPase levels (%) and NSPase intake on jejunal mucosa-associated microbiota, jejunal digesta viscosity, immune responses, intestinal morphology, feed digestibility, and growth performance. Increasing NSPase level quadratically decreased (P < 0.05) Bacteroidetes (min: 0.7% at 636 TXU/kg and 284 TGU/kg), Prevotellaceae (min: 0.6% at 630 TXU/kg and 281 TGU/kg) in the jejunal mucosa. Increasing NSPase intake quadratically increased (P < 0.05) Firmicutes (max: 72.7% at 604 TXU/kg and 270 TGU/kg), Lactobacillaceae (max: 40.3% at 608 TXU/kg and 271 TGU/kg), and Lactobacillus (max: 40.3% at 608 TXU/kg and 271 TGU/kg) in the jejunal mucosa. Increasing NSPase intake also quadratically decreased (P < 0.05) Proteobacteria (min: 3.8% at 562 TXU/kg and 251 TGU/kg), Helicobacteraceae (min: 1.6% at 560 TXU/kg and 250 TGU/kg), and Helicobacter (min: 1.6% at 560 TXU/kg and 250 TGU/kg) in the jejunal mucosa. Increasing NSPase intake tended to quadratically decrease (P = 0.059) viscosity of jejunal digesta reaching the minimum (1.74 mPa·s) at 751 TXU/kg and 335 TGU/kg. Increasing NSPase level tended to linearly decrease (P = 0.073) jejunal IgG and tended to quadratically increase (P = 0.085) jejunal villus height to crypt depth ratio reaching the maximum (2.62) at 560 TXU/kg and 250 TGU/kg. Increasing NSPase intake tended to linearly increase the apparent ileal digestibility of dry matter (P = 0.087) and ether extract (P = 0.065). Increasing NSPase intake linearly increased (P < 0.05) average daily gain (ADG). In conclusion, increasing the combinational use of xylanase and β-glucanase positively modulated jejunal mucosa-associated microbiota, reduced jejunal digesta viscosity, reduced intestinal humoral immune response, enhanced villus morphology, increased ileal digestibility of nutrients, and increased growth of nursery pigs. The beneficial effects were maximized when xylanase and β-glucanase were supplemented at a range of 550 to 800 TXU/kg and 246 to 357 TGU/kg, respectively.

138 Growth performance and physiological response of nursery pigs fed a high canola meal diet with acidifiers

Abstract This study investigated the impact of feed additives aimed at reducing gut pH on the growth performance and physiological responses of nursery pigs when fed a high canola meal (CM) diet. A total of 315 nursery pigs, 6.0 ± 1.2 kg body weight (BW), were allotted to one of five dietary treatments with 9 replicates (7 pigs/pen) in a randomized complete block design. Dietary treatments were PC: corn-soybean meal-based diet with 20% CM, NC: corn-soybean meal-based diet with 40% CM; NC+A: NC diet with acidifier at 1,500 ppm, NC+B: NC diet with encapsulated butyrate at 500 ppm, and NC+A+B: NC diet with acidifier and encapsulated butyrate. All diets were formulated to meet or exceed the nutrient requirements of NRC (2012). All pigs received a common Phase 1 nursery diet during week 1 following weaning. Experimental diets were provided in Phase 2 (wk 2 and 3) and Phase 3 (wk 4 to 6). Individual pig BW and pen feed consumption were measured for each phase to calculate growth performance. At the conclusion of each phase, blood samples were collected from one pig per pen for analysis of serum triiodothyronine (T3) and thyroxine (T4) concentrations. The selected pig was euthanized within 24 h, and its organ weights and pH of digesta were measured. The results were analyzed using MIXED procedure in SAS with the pen as an experimental unit. There was no difference in BW and average daily gain throughout the overall period. However, PC treatment exhibited greater (P < 0.05) average daily feed intake in phase 3 by 18.2% and overall period by 13.4% compared with NC treatment and no difference with NC+A+B treatment. The NC+A and NC+A+B treatments tended to improve (P ≤ 0.10) gain to feed ratio in phase 3 by 17.9% and overall period by 16.1% compared with PC treatment, respectively. At the end of phase 3, the PC treatment tended (P < 0.10) to have greater serum T4 concentrations compared with NC and NC+A treatments (3.2 vs 2.5 and 2.4 ug/dL, respectively), whereas there was no difference between PC and NC+A+B treatments. In phase 3, the thyroid gland weight for PC treatment was less (P < 0.05) than for NC treatment (0.156 vs 0.202 g/kg), whereas there was no difference among PC, NC+B, and NC+A+B treatments. In phase 3, dietary encapsulated butyrate decreased (P < 0.05) the pH of jejunal digesta compared with PC treatment (6.28 vs 7.01), and dietary encapsulated butyrate treatments (NC+B and NC+A+B) tended to decrease (P < 0.10) the pH of hind-colonic digesta compared with the pH of PC treatment by 6.2% and 7.2%. In conclusion, dietary encapsulated butyrate in combination with acidifier may alleviate thyroid dysfunction that is anti-nutritional effect of high canola meal diets.

PSVI-16 Inclusion of dietary micelle silymarin on production performance, egg quality, storage capacity, and blood profile Sin Hy-line brown laying hens

Abstract Silymarin is known to have immunomodulating, anti-inflammatory and antioxidant effects. This study aimed to investigate the effects of micelle silymarin (MS) supplementation on production performance, egg quality, egg water loss, and blood profile in Hy-line brown laying hens. For 12 wk, a total of 288, 28-wk-old laying hens were randomly allocated into one of three treatment groups. The dietary treatments were control (CON) a basal diet and a basal diet supplemented with 0.03, and 0.06% of MS. All hens were housed in an individual cage with 38 cm width × 50 cm length × 40 cm height. Growth performance was recorded at d 1, wk 6, and wk 12. The egg production and feed conversion ratio were recorded at the end of every week. The egg quality and water loss were measured at the end of wk 4, 8, and 12. At initial and at the end of wk 12, 5 mL of blood was collected to analyze aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), triglycerides, albumin, and cholesterol concentrations. All data were analyzed by the GLM procedure of SAS. The polynomial orthogonal contrasts of increasing dietary MS supplementation were examined by linear and quadratic effects. The inclusion of MS supplement in laying hen diet did not exhibit significant impact on growth performance. However, MS group showed linear improvement in egg weight, Haugh Units, and eggshell strength throughout the trial period (P < 0.05). Additionally, egg yolk color and eggshell thickness indicated linear improvements particularly at wk 4 and 8 (P < 0.05). While albumen height and egg water in MS group were linearly increased at wk 12 (P < 0.05). Compared with CON, laying hens fed MS supplement has linearly decreased the ALP and cholesterol concentrations in the serum (P < 0.05). Based on the findings, we inferred that the inclusion of 0.04 to 0.06% MS in the laying hen diet would not only increase the production performance, egg quality, and egg water loss traits but also to improve laying hens’ health.

PSVI-21 The effects of soybean meal concentration and Yucca schidigera extract supplementation on growth performance of nursery swine

Abstract Soybean meal (SBM) is the primary plant-protein source for swine in the USA. However, SBM might not be suitable to be fed at high levels, particularly in the early post-weaning period. To offset these effects, pigs are gradually transitioning to diets with greater concentrations of SBM. Whereas, greater SBM concentrations can be detrimental, peer-reviewed studies have indicated that pigs fed diets with 30% SBM and supplemented with 125 ppm Yucca schidigera extract (YSE) from d 0-14 post-wean performed similarly to pigs fed diets with 15 and 20% SBM, from d 0-7 and d 7-14 post wean, respectively. Suggesting that pigs can be fed greater SBM concentrations without compromising performance. To confirm these findings, a total of 972 pigs [initial body weight (BW) = 5.4 kg) were used in a 38-d experiment. Pens of 27 pigs were randomly allotted to 1 of 4 dietary treatments with 9 replications per treatment. Dietary treatments were arranged in a 2 × 2 factorial with main effects of SBM concentration (15 or 31%) and YSE (0 or 125 ppm; DeOdorase Alltech, Inc., Nicholasville, KY). Pigs were fed a nursery program comprised of two phases. Phase 1 from d 0 to 21 (experimental feeding period) and Phase 2 from d 22 to -38 (common period). Phase 1 diets were formulated to contain 1.38% SID Lys and 2,600 kcal/kg NE. Phase 2 diets were formulated to contain 1.30% SID Lys and 2,565 kcal/kg NE. Data were analyzed using the GLIMMIX procedure of SAS (Cary, NC) in a randomized complete block design with pen serving as the experimental unit and initial BW serving as blocking factor. No significant SBM × YSE interactions (P > 0.10) were observed in growth performance in this study (Table 1). From d 0 to 21, pigs fed diets supplemented with YSE increased (P = 0.006) average daily feed intake (ADFI), which numerically improved (P = 0.16) average daily gain (ADG) and thus (P = 0.12) BW, despite SBM concentration. From d 21 to 38, pigs previously fed diets supplemented with YSE, maintained a marginally higher (P = 0.08) ADFI, which numerically increased (P = 0.12) ADG, resulting in marginally higher (P = 0.08) BW, despite SBM concentration. From d 0 to 38, pigs fed diets supplemented with YSE increased (P = 0.03) ADFI, which numerically improved (P = 0.10) ADG, resulting in marginally greater (P = 0.08) BW, despite SBM concentration. In conclusion, whereas pigs fed with greater SBM concentrations did not compromise performance, diet supplementation with YSE increased ADFI during the experimental and common periods, resulting in improved growth performance.

57 Effect of diet mixing strategies on growth performance and carcass characteristic in feedlot steer

Abstract Our objective was to determine the effects of a feeding management strategy on growth and carcass quality and characteristics on finishing feedlot beef cattle. Angus-Simmental steers (n = 60), blocked by body weight (BW), were housed in individual pens and randomly assigned to treatments. Treatments were total mixed ration (TMR) or a non-mixed diet (Split). The diet contained 67.5% of dry rolled corn, 18% of distiller grains with soluble, 2.5% soybean meal, 7% hay, and 5% of mineral and vitamin mixed. The diet composition for both treatments was similar, the only difference was the use of a TMR or that the concentrate was fed separately from the hay on the Split treated calves. Feed intake was monitored through slick bunk management in both treatments. For the Split assigned calves, if any hay or concentrate was left in the bunk on two consecutive days, the total feed was decreased by 5%; maintaining always the 93% concentrate and 7% forage ratio. Steers were weighed monthly and feed samples were collected for nutrient composition analysis semimonthly. Monthly weights and intakes were used to calculate average daily gain (ADG) and gain to feed ratio (G:F). Steers were slaughtered per block when the average weight of the block reached 555 kg. Carcasses were evaluated 48 h post slaughter. Carcass yield and quality factors were evaluated at the 12th/13th rib interface. Data were analyzed as randomized complete block design. Considering the fixed effect of the feeding strategy and the random effect of block. We did not observe differences (P > 0.17) in growth performance or carcass characteristics variables due to management strategy (Table 1). The lack of observed differences due to treatment might be because the ratio of concentrate and forage intake was similar for both groups, in addition to the slick bunk management in both treatments, which forced steers to eat all their ration, independent of the treatment, to continue to receive the same amount of feed.

235 Evaluation of an exogenous fibrolytic enzyme combination in forage-based growing diets fed to growing beef cattle

Abstract Crossbred steers [n = 73; 287±19 kg initial body weight (BW)] were used in an 84-d growing study to investigate the effects of feeding an exogenous xylanase and cellulase combination product (EFE) and wheat straw (WS) inclusion level on the growth performance of growing beef cattle. Treatments were arranged as a 2 × 2 factorial with two levels of WS, either 5% (low; LS) or 15% (high; HS) of diet dry matter, and two inclusion rates of exogenous fibrolytic enzymes, 0 (none; N) or 750 g/ton (enzyme; E; Bovizyme CX; Danisco Animal Nutrition and Health; Wilmington, DE) of diet. Body weights and blood samples were collected every 28 d. Individual intake data were collected using an automated feeding system (Insentec Roughage Intake Control, Hokofarm B.V., Marknesse, The Netherland). Average daily gain (ADG), dry matter intake (DMI), gain to feed ratio (G:F), plasma glucose (GLU), plasma non-esterified fatty acids (NEFA), and plasma urea nitrogen (PUN) were analyzed using PROC MIXED (SAS Ins. Inc., Cary, N.C.). Animal was the experimental unit and fixed effects included blocks of body weight (n = 3) and original source of steers (n = 2). The model included the level of WS (LS, HS), level of EFE (N or E), and WS × EFE interactions. There were no WS × EFE interactions (P ≥ 0.31) for all measured traits. Supplementing EFE resulted in no differences (P ≥ 0.16) for ending BW, ADG, DMI, G:F, NEFA, and PUN. However, within HS diet, inclusion of E numerically increased ADG by 0.05 kg/d compared with N (1.29 vs. 1.24 kg/d; HSE vs. HSN, respectively; P > 0.31). Steers consuming E diets tended to have greater GLU compared with N (4.92 vs. 4.80 µmol/L, respectively; P = 0.10). Between levels of straw inclusion, ending BW was greater for steers consuming LS diet compared with HS diet (413 vs. 393 kg, respectively; P < 0.0001). Resulting in greater ADG for steers consuming LS diet compared with HS diet (1.49 vs. 1.26 kg, respectively; P < 0.01). Dry matter intake was greater for steers consuming LS diet than HS diet (9.06 vs. 8.33 kg, respectively; P < 0.01). Therefore, G:F was improved for steers consuming LS diet compared with HS diet (0.165 vs. 0.151, respectively; P < 0.01). Steers consuming LS diet had decreased NEFA compared with HS diet (311 vs. 376 µmol/L, respectively; P < 0.01). Results from this study indicate that regardless of the inclusion level of WS, supplementing growing steers with EFE did not influence growth performance. However, replacing ten percent of corn silage with WS reduced the energy concentration of the diet, decreasing growth performance.