Nursery Diets Research Articles

Impacts of replacing soybean meal with processed soybean meal on intestinal health and growth of nursery pigs challenged with F18+ Escherichia coli.

This study aimed to investigate the impact of different level of soybean meal (SBM) replaced by soy protein concentrate on intestinal health and growth performance of nursery pigs under F18+ Escherichia. coli (E. coli). Forty-eight newly weaned pigs (6.6 ± 0.3 kg) were randomly allotted to 4 treatments arranged by 2 × 2 factors using randomized complete block design with initial body weight and sex as blocks. Two factors were F18+ E. coli challenge (0 or 2.1 × 1010 CFU) and the level of SBM (24% or 12% in phase 1 and 26% or 14% in phase 2). Pigs were fed for 25 d in 2 phases (phase 1 for 11 d and phase 2 for 14 d). At the end of study, all pigs were euthanized to collect jejunal mucosa and tissues to measure parameters related to intestinal health. Data were analyzed using a MIXED procedure in SAS. The F18+ E. coli challenge decreased (p<0.05) overall average daily gain (ADG) and average daily feed intake (ADFI) and decreased (p<0.05) gain to feed ratio on d 7 to 11. The High SBM tended to have a greater overall ADG (p=0.054) and ADFI (p=0.078) compared with low SBM under F18+ E. coli challenge, but not in unchallenged conditions. The F18+ E. coli challenge increased (p<0.05) fecal score on d 7 to 18. The tumor necrosis factor-alpha and interleukin-1β in jejunal mucosa were decreased (p<0.05) in High SBM treatments. The High SBM tended to increase (p=0.085) occludin expression in jejunum. High SBM increased crypt depth in jejunum under F18+ E. coli challenge, but not in unchallenged conditions (p<0.05). High SBM in nursery diets could alleviate the detrimental effects of F18+ E. coli challenge on growth performance of pigs under compared to low SBM inclusion, which might be attributed to decreased intestinal inflammation and improved intestinal integrity.

Dietary β-mannanase reduced post-weaning diarrhea of pigs by positively modulating gut microbiota and attenuating systemic immune responses

BackgroundAfter weaning, nursery pigs have difficulty digesting non-starch polysaccharides in their diets, which can result in growth and health problems. Among non-starch polysaccharides, β-mannan is easily found in various cereal grains that form the basis of livestock diets and interferes the digestion and utilization of nutrients. Supplementation of dietary β-mannanase in nursery diet can alleviate the negative effects on nutrient utilization efficiency caused by β-mannan and improve growth and health of pigs. This study was conducted to evaluate effects of dietary β-mannanase supplementation on growth performance, nutrient digestibility, intestinal morphology, fecal microbiota, and systemic immune responses of weaned pigs.ResultsDietary β-mannanase (MAN) improved average daily gain (P = 0.053), average daily feed intake (P < 0.05), and gain to feed ratio (P = 0.077) of pigs for 3 weeks after weaning and apparent total tract digestibility of crude protein (P = 0.060) and reduced post-weaning diarrhea (P < 0.05). The MAN did not affect the ileal morphology. Pigs fed with MAN had more diverse fecal microbiota based on the results of alpha diversity [the number of operational taxonomic units (OTUs; P = 0.061), Shannon (P = 0.071), and Simpson indices (P = 0.078)] and relative abundance of phylum Bacteroidetes (P = 0.064) and genus Prevotella (P < 0.05) than pigs fed control diet (CON). As a result of beta diversity, fecal microbiota was clustered (P < 0.05) into two distinct groups between dietary treatments. The MAN decreased (P < 0.05) packed cell volume (PCV), the number of white blood cells (WBC), C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), transforming growth factor-β1 (TGF-β1), and cortisol of the pigs for 2 weeks after weaning compared with CON.ConclusionDietary β-mannanase reduced post-weaning diarrhea of pigs by positively modulating gut microbiota and attenuating systemic immune responses.

Effect of yeast probiotics in lactation and yeast cell-wall prebiotic and Bacillus subtilis probiotic in nursery on lifetime growth performance, immune response, and carcass characteristics.

Twenty-eight mixed parity sows (Line 241; DNA) and their offspring were used to evaluate live yeast supplementation during lactation with or without a pre/probiotic combination during the nursery period on lactation performance, lifetime growth performance, and immune response. On d 110 of gestation, sows were allotted to a lactation diet with or without a live yeast probiotic (0.10% Actisaf Sc 47 HR+; Phileo by Lesaffre, Milwaukee, WI). At weaning, their offspring (350 pigs; initially 6.1 ± 0.02kg) were randomly assigned in a 2 × 2 factorial with main effects of sow treatment and nursery treatment consisting of a control diet or a diet with a yeast cell-wall prebiotic and Bacillus subtilis probiotic (0.10% YB; Phileo by Lesaffre, Milwaukee, WI) fed for 42 d followed by common diets fed until marketing. Two nursery pens were combined into 1 finishing pen, such that there were 5 and 10 pigs per pen with 17 or 18 and 8 or 9 replications per treatment during the nursery and finishing periods, respectively. There were no significant effects of yeast supplementation on lactation performance (P ≥ 0.079). There was a sow × nursery diet interaction (P = 0.024) on nursery ADG. Pigs from yeast fed sows had increased ADG when fed control nursery diets compared to pigs from control sows fed the control nursery diet with pigs fed pre/probiotic nursery diets intermediate, regardless of sow diet. Pigs from yeast fed sows tended (P = 0.067) to have greater final BW (d 165). A subset of pigs was sampled throughout their lifetime to determine serum porcine circovirus type 2 (PCV2) and Mycoplasma hyopneumoniae antibody sample-to-positive (S/P) ratios and percentage inhibition of Lawsonia intracellularis. There was a tendency for a PCV2 S/P ratio sow diet × day interaction (P = 0.097) where progeny from yeast fed sows had higher PCV2 S/P ratios at 101 d of age compared to control sow progeny (P = 0.046). There was a PCV2 S/P ratio nursery diet × day interaction (P = 0.036) where pigs fed a pre/probiotic combination had reduced S/P ratios at 66, 78, and 162 d of age (P ≥ 0.022); however, at 22 d of age pigs fed a pre/probiotic combination tended to have an increased S/P ratio (P = 0.051). In conclusion, effects of combining a yeast probiotic in lactation diets and a pre/probiotic in nursery diets were not additive. However, feeding a live yeast probiotic during lactation resulted in tendencies (P ≥ 0.10) for increased progeny final BW and HCW.

PSIV-19 The use of microencapsulated zinc oxide improves the growth performance and intestinal health of newly weaned piglets

Abstract The application of microencapsulation technology to protect zinc may support inclusion of reduced levels with similar benefits to elevated doses of free zinc oxide. This study aimed to compare the effects of different doses of a microencapsulated ZnO (Zinco-Plus S) and free ZnO in nursery diets on growth performance and intestinal health of pigs. A total of 480 newly weaned piglets [26 d of age, initial body weight (BW) = 7.39 kg] were randomly assigned to one of four dietary treatments for 35d. Treatments were as follow: free ZnO (3,000, 1,500, and 0 ppm at phase 1, 2, and 3, respectively) or one of three doses of the microencapsulated ZnO (400, 600, and 800 ppm) maintained consistently across all 3 nursery phases (total amount of zinc in diets were within limits allowed by Canadian regulation). Each dietary treatment had 10 replicates, with 12 pigs/pen, gender balanced. All treatments had protease (Jefo Protease; 125 g/t), xylanase (Belfeed Xylanase; 100 g/t) and protected organic acids and essential oils (Porcinat+; 2 kg/t in phase 1 and 2, 1 kg/t in phase 3). Body weight, BW gain and feed intake were measured to determine feed conversion. At the end of phase 1, fecal sample was collected (pooled of 4 samples/pen) to determine zinc excretion. At the end of phase 2, blood serum was collected (1 pig/pen) to measure calprotectin and diamine oxidase concentrations and, ileal tissue was collected (1 pig/pen) to measure expression of zonular occludens (ZO) -1. Data were submitted to ANOVA and Fisher test with significance set at P &amp;lt; 0.05. There was no difference (P &amp;gt; 0.05) in final BW of pigs across all treatments. Nonetheless, piglets receiving 800 ppm of the microencapsulated ZnO had improved (P &amp;lt; 0.05) feed conversion ratio compared with pigs fed diet containing free ZnO. There was no difference (P &amp;gt; 0.05) in serum concentrations of calprotectin and diamine oxidase across all treatments, indicating improved intestinal health regardless of the form of ZnO. Piglets supplemented with microencapsulated ZnO at 800 ppm had an increased (P &amp;lt; 0.05) intestinal expression of ZO-1 in comparison with piglets receiving free ZnO, indicating better intestinal integrity. Fecal zinc concentrations were reduced (P &amp;lt; 0.05) by 75 % with the inclusion of microencapsulated ZnO compared with free ZnO. Piglets supplemented with microencapsulated ZnO at 800 ppm improved (P &amp;lt; 0.05) feed cost per kg BW gain by 10.7 % when compared with free ZnO. These findings show that supplementing lower levels of zinc in nursery diets via microencapsulation technology improves growth performance and supports intestinal health at levels comparable with increased free ZnO supplementation. Moreover, the utilization of microencapsulated zinc oxide has the additional advantage of minimizing environmental impact through the reduction of zinc wastage.

PSLBII-4 The effect of standardized ileal digestible sulfur amino acid intake during late gestation on gilt whole-body nitrogen retention and subsequent litter performance

Abstract Gestating gilts [n = 27; body weight (BW) = 158 ± 5.5 kg] were used to determine the effect of standardized ileal digestible (SID) sulfur amino acid (SAA) intake during late gestation on whole-body nitrogen (N) retention and subsequent litter performance. Gilts were assigned to one of two experimental diets that provided SAA at 60 or 200 % of estimated requirements during late gestation (0.29 and 0.92 % SID SAA, respectively; n = 15 and 12, respectively; Table 1 and 2). Each gilt received 2.53 kg of the assigned diet between gestation d 90 and farrowing; standard lactation and nursery diets were provided to gilts after farrowing and offspring after weaning, respectively. Gilt whole-body N balance was determined between d 107 and 109 of gestation using total urine collection and fecal grab-sampling. After farrowing, litters were standardized to 13 piglets and were not offered creep feed. Whole-body N retention was greater in gilts fed the diet containing 0.92 vs. 0.29 % SID SAA in late gestation (27.2 vs. 19.3 ± 1.8 g/d; P &amp;lt; 0.05; Table 3), but the number of piglets born alive, litter birth weight, subsequent piglet growth rates, and litter size at weaning were not different between treatment groups. The post-weaning growth performance of offspring was also not influenced by maternal dietary treatment in late gestation (Table 4). At farrowing, the post-absorptive plasma concentration of Cys tended to be less (P = 0.072) and taurine was greater (P &amp;lt; 0.01) for gilts fed 0.92 vs. 0.29 % SID SAA in late gestation; however, there were no differences in plasma SAA metabolites concentrations for gilts at weaning or offspring at birth (Table 5. At weaning, offspring from gilts fed 0.92 % SID SAA had greater plasma homocysteine (P &amp;lt; 0.05) and plasma Cys concentrations (tendency; P = 0.072) vs. offspring from gilts fed 0.29 % SID SAA in late gestation. Three weeks after weaning, plasma taurine concentration was less (P &amp;lt; 0.05) for offspring from gilts fed 0.92 vs. 0.29 % SID SAA in late gestation (Table 6). Six weeks after weaning, plasma glutathione concentration tended to be less (P = 0.057) for offspring from gilts fed 0.92 vs 0.29 % SID SAA in late gestation. When SAA were fed below estimated requirements during late gestation, whole-body N retention was reduced, but fetal growth appeared to be maintained, likely at the expense of maternal N retention. Such divergences in dietary SAA supply in late gestation had no effect on subsequent offspring growth performance, but it appeared that offspring SAA metabolism was impacted until at least 6 wk after weaning. The influence of differences in sulfur AA metabolites on offspring performance beyond the nursery phase remains unknown. Therefore, carry-over effects of maternal SAA supply in late gestation should be considered when developing feeding recommendations for gestating gilts.

490 Lifetime growth performance and carcass composition of offspring when inactivated Saccharomyces cerevisiae was included in gestating and lactating gilt diets and/or offspring nursery diets

Abstract Gilts [n = 90; initial body weight (BW) = 189.1 ± 3.9 kg] were used to determine the effect of feeding a yeast additive (Saccharomyces cerevisiae inactivated through hydrolyzation; HY) to gestating and lactating gilts and/or the offspring during the nursery period on lifetime offspring growth performance. Gilts were randomly assigned to one of three dietary treatments (n = 30/treatment): standard gestation and lactation diets (GHY0) or supplemented with 0.25% (GHY0.25) or 1% (GHY1.0) HY. Diets were fed between d 85 of gestation until weaning at d 21 (2.6 kg/d in gestation, ad libitum in lactation). At weaning, 8 piglets/litter were placed in nursery pens and pens were randomly assigned to a control (NO) or a HY-supplemented diet (NHY), apart from GHY1.0 offspring who were only provided NO during the nursery period (n = 12). In nursery phases 1, 2 and 3, HY was included at 0.75, 0.50, and 0.25% respectively. Thereafter, pigs received standard grower and finisher rations until slaughter (160 d of age). Data were analyzed in SAS using GLIMMIX with gilt treatment as the main effect (pre-weaning); post-weaning performance used gilt and nursery treatments as the main effects, and interactive effects were tested separately due to the incomplete 3 × 2 factorial design. Mean comparisons were conducted using the Tukey-Kramer test to separate LSmeans. Gilt BW was unaffected by gilt treatment, but gilts fed GHY1.0 had greater total lactation feed intake versus GHY0.25 (128.6 vs. 109.4 ± 7.7 kg; P &amp;lt; 0.01). At birth, GHY0.25 offspring were 70 g heavier than pigs from GHY0 (P &amp;lt; 0.001) with GHY1.0 intermediate. At weaning, GHY0.25 and GHY1.0 offspring were heavier than GHY0 offspring (5.9 vs. 5.6 kg; P &amp;lt; 0.001). After weaning, neither gilt nor nursery diet influenced offspring BW. Pigs fed GHY1.0-NO had greater ADFI versus all other treatments in the nursery (interaction; P &amp;lt; 0.001), GHY0.25-NHY had greater ADFI than GHY0.25-NO and GHY1.0-NO in the grower (interaction; P = 0.005), and NHY consumed more feed than NO in the finisher phase (main effect; P &amp;lt; 0.001). In the nursery, NHY had less average daily feed intake (ADFI) than NO (main effect; P &amp;lt; 0.05), but in grower and finisher, NHY had greater ADFI than NO pigs (main effect; P &amp;lt; 0.001). In the nursery, gain to feed (G:F) was greater for GHY0-NHY versus GHY0.25-NHY and GHY1.0-NO, and greater for GHY0-NO versus GHY0.25-NHY with all other treatments intermediate (interaction; P &amp;lt; 0.05). In the grower phase, G:F was unaffected by maternal or nursery diet, but in the finisher phase, G:F was less for pigs fed NHY versus NO during the nursery phase (main effect; P &amp;lt; 0.05). Slaughter BW, hot carcass weight, and fat and lean percents were not influenced by gilt or nursery diet. Therefore, HY provided to gilts during gestation and lactation, improved pre-weaning offspring growth, but HY supplemented to pigs during the nursery period had greater positive effects on lifetime growth performance.

Efficacy of Saccharomyces yeast postbiotics on cell turnover, immune responses, and oxidative stress in the jejunal mucosa of young pigs

This study aimed to determine the effects of Saccharomyces yeast postbiotics on cell turnover, immune responses, and oxidative stress in the jejunal mucosa of pigs. Thirty-two newly weaned pigs at 6.05 ± 0.24 kg were assigned to two dietary treatments based on a randomized complete block design. The treatments were control group receiving a basal diet and a group supplemented with Saccharomyces yeast postbiotics (175 g/ton diet) in the basal diet. After 35 d of the study, pigs were euthanized and jejunal mucosa were collected to assess immune status, oxidative stress, barrier markers, cell proliferation, and apoptosis. Saccharomyces yeast postbiotics reduced (P < 0.05) the fecal score from d 3 to d 7 and tended to increase the gene expression of interferon-γ (IFN-γ) (P = 0.071) and mammalian/mechanistic target of rapamycin (mTOR) (P = 0.080), decrease the gene expression of B-cell lymphoma 2-associated X protein 1 (BAX1) (P < 0.05), tended to decrease the gene expression of serum and glucocorticoid-induced protein kinase 1 (SGK1) (P = 0.066), increased (P < 0.05) cell proliferation in the crypts, and tended to increase the villus height (P = 0.078) and crypt depth (P = 0.052) in the jejunum. In conclusion, the supplementation of Saccharomyces yeast postbiotics in nursery diets reduced diarrhea within the first week after weaning and provided protection to the villi in the jejunum by enhancing the immune responses of nursery pigs, promoting crypt cell proliferation, and reducing the expression of genes associated with apoptosis without affecting inflammatory and oxidative stress status in the jejunum of the nursery pigs.

Prebiotic galactooligosaccharide improves piglet growth performance and intestinal health associated with alterations of the hindgut microbiota during the peri-weaning period

BackgroundWeaning stress reduces growth performance and health of young pigs due in part to an abrupt change in diets from highly digestible milk to fibrous plant-based feedstuffs. This study investigated whether dietary galactooligosaccharide (GOS), supplemented both pre- and post-weaning, could improve growth performance and intestinal health via alterations in the hindgut microbial community.MethodsUsing a 3 × 2 factorial design, during farrowing 288 piglets from 24 litters received either no creep feed (FC), creep without GOS (FG–) or creep with 5% GOS (FG+) followed by a phase 1 nursery diet without (NG–) or with 3.8% GOS (NG+). Pigs were sampled pre- (D22) and post-weaning (D31) to assess intestinal measures.ResultsCreep fed pigs grew 19% faster than controls (P < 0.01) prior to weaning, and by the end of the nursery phase (D58), pigs fed GOS pre-farrowing (FG+) were 1.85 kg heavier than controls (P < 0.05). Furthermore, pigs fed GOS in phase 1 of the nursery grew 34% faster (P < 0.04), with greater feed intake and efficiency. Cecal microbial communities clustered distinctly in pre- vs. post-weaned pigs, based on principal coordinate analysis (P < 0.01). No effects of GOS were detected pre-weaning, but gruel creep feeding increased Chao1 α-diversity and altered several genera in the cecal microbiota (P < 0.05). Post-weaning, GOS supplementation increased some genera such as Fusicatenibacter and Collinsella, whereas others decreased such as Campylobacter and Frisingicoccus (P < 0.05). Changes were accompanied by higher molar proportions of butyrate in the cecum of GOS-fed pigs (P < 0.05).ConclusionsGruel creep feeding effectively improves suckling pig growth regardless of GOS treatment. When supplemented post-weaning, prebiotic GOS improves piglet growth performance associated with changes in hindgut microbial composition.

277 Effect of yeast probiotics in lactation and nursery diets on progeny lifetime growth performance, immune response, and carcass characteristics

Abstract Mixed parity sows (n = 28; Line 241; DNA) and their offspring were used in a farrow-to-finish study to evaluate the effect of live yeast supplementation during lactation with or without yeast extract supplementation during the nursery period on sow and litter performance and lifetime growth performance, antibody titers, and carcass characteristics. Sows were blocked by parity and body weight (BW) on d 110 of gestation and allotted to 1 of 2 dietary treatments with 14 replications per treatment which consisted of a standard corn-soybean meal lactation diet with or without a yeast-based probiotic (0.10% Actisaf Sc 47 HR+; Phileo by Lesaffre, Milwaukee, WI). Following weaning, pigs (n = 350; 241×600, DNA; initial BW = 6.1 ± 0.02 kg) were randomly assigned in a 2 × 2 factorial design within sow treatment to 1 of 2 nursery diets which consisted of a control diet or a diet with pre-probiotic combination (0.10% MS309; Phileo by Lesaffre, Milwaukee, WI) fed for 42 d after weaning followed by common diets until marketing. Two nursery pens were combined in the finisher, such that there were 5 and 10 pigs/pen with 18 and 9 replications/treatment during the nursery and finishing periods, respectively. There were no significant effects of live yeast supplementation on lactation performance (P &amp;gt; 0.079). There was a sow × nursery diet interaction (P = 0.024) during the nursery period where pigs from sows fed Actisaf had increased average daily gain (ADG) when fed control nursery diets compared with pigs from control sows fed control nursery diets (Table). Pigs fed MS309 in the nursery from either sow treatment were intermediate. Pigs from sows fed Actisaf tended to be heavier at marketing (P = 0.067) with heavier hot carcass weight (HCW; P = 0.101), but there were no differences in overall finishing growth performance with the inclusion of yeast in lactation diets or nursery diets (P &amp;gt; 0.10). A subset of pigs were sampled at 7 time points to determine serum porcine circovirus type 2 (PCV2) and Mycoplasma hyopneumoniae antibody sample-to-positive (S/P) ratios and at 5 time points to ascertain percent inhibition of Lawsonia intracellularis. For all 3 immunological criteria, there were no sow diet × nursery diet × day interactions. There was a sow diet × day interaction for PCV2 S/P ratio (P = 0.097) where offspring from Actisaf sows tended to have greater PCV2 S/P ratios at 101 d of age compared with offspring from control sows (P = 0.046). There was a PCV2 S/P ratio nursery diet × day interaction (P = 0.036) where pigs fed MS309 had reduced PCV2 S/P ratios at 66, 78, and 162 d of age (P ≤ 0.022). In conclusion, feeding a pre/probiotic combination in the nursery did not affect performance or immune criteria. Conversely, feeding a live yeast probiotic during lactation resulted in tendencies for increased nursery ADG, final BW, and HCW.

301 Maxwell Lecture: Bacillus probiotics in nursery pigs: The effects of dose on gut health and performance

Abstract Weaning is one of the most stressful events in the life of a pig and critical for their health and development. To reduce the use of antibiotics and zinc oxide in nursery diets, many feed additives have been tested to demonstrate their efficacy in weaning pigs. Bacillus subtilis, a heat-resistant spore-forming bacteria, consumes oxygen in the digestive tract and can provide a favorable anaerobic environment for lactic acid-producing bacteria, resulting in their proliferation. It also produces several digestive enzymes, such as amylase, protease, and antioxidant enzymes. In addition, Bacillus species are known to alter the gut microbiome and increase the production of short-chain fatty acids in the gut. Therefore, Bacillus probiotics have been widely used in nursery diets to effectively improve growth performance and protect piglets from weaning stress and postweaning diarrhea. However, when the probiotics are supplemented in diets for weaning pigs, their efficacy is dependent on multiple factors, such as strains, the health condition of the animals, product composition, and the dose of the probiotics. There has been tremendous effort in establishing the optimal supplementation level of probiotics for nursery pigs to maximize the efficacy of their supplementation, but a high dose of probiotics could be detrimental to the gut health and microflora of nursery pigs, as it could increase the incidence of diarrhea and may have potential side effects in the immune system, antibiotic resistance, and the production of unfavorable metabolites in the gut. A study was conducted to demonstrate the effect of Bacillus probiotic supplementation for nursery pigs at the recommended and high doses (10 times greater bacterial counts than the recommended dose) compared with a control treatment with no probiotic supplementation. In the study, the Bacillus supplementation at the recommended dose did improve the early postweaning growth rate, increase the production of fecal short-chain fatty acids (acetate, propionate, and butyrate), and blood glucose concentrations, and alter the fecal microbiome. However, high-dosing probiotics in nursery diets did not show any beneficial effects that were shown in the pigs fed diets with Bacillus probiotics at the recommended dose. Bacillus-probiotic supplementation in nursery diets may enhance growth performance and benefit gut health, but a high dose of probiotics does not always lead to comparable positive effects for pigs. Therefore, it is critically important to test probiotics to optimize their efficacy and avoid unnecessary high-dosing in nursery diets, as it could be cost-ineffective and may not show benefits that can be observed with the recommended dose.

195 Incidence of porcine ear necrosis in nursery pigs under commercial conditions is reduced with stimbiotic

Abstract Three studies were conducted to evaluate the potential benefit of a stimbiotic on porcine ear necrosis and the fecal microbiome in nursery pigs. In experiment 1, 600 mixed-sex piglets were randomly placed in 20 pens with 30 pigs/pen (n = 10). The pigs were fed a common wheat and barley-based nursery diet (CON) or CON with stimbiotic (Signis, 0.15g/kg; STB). Incidence of ear necrosis was recorded on individual animals at 28 d post-weaning. Mortality was analyzed using ANOVA and PEN was evaluated using a chi-square test. In experiment 2, a total of 65,200 pigs were placed on trial in 8 nursery barns. Treatments were assigned to a quadrant within each barn (n = 8). Newly weaned pigs were fed a common corn-soy nursery diet (CON) or CON with stimbiotic (Signis, 0.1g/kg; STB). Ear necrosis was classified as either: 1) nominal lesions or 2) moderate to severe lesions and was recorded at 1, 3, and 5 wk post weaning. Mortality and injectable treatments were recorded. Mortality data were analyzed using a binomial regression. A Poisson regression was used to analyze the incidence of PEN and injectable treatment rate with the fixed effect of treatment and random effects of sow farm, site, and barn. In experiment 3, a total of 47,200 pigs in 10 nursery barns were randomly assigned to either a standard nursery diet (CON) or CON with stimbiotic (Signis, 0.1 g•kg-1•ton-1; STB). Mortality was recorded throughout the 6-wk trial and PEN score was recorded at d 42. Fecal samples were collected on 7, 21, and 42 d post-weaning for 16S rRNA sequencing and predictive metabolic function analysis. In experiment 1, no differences in mortality were observed (P &amp;gt; 0.10). A total of 156 pigs in the CON fed group developed PEN, whereas only 27 pigs in the STB group developed PEN (52% vs. 9%; P &amp;lt; 0.01). In experiment 2, there was no difference among treatments for mortality. Pigs fed the STB treatment required 15% fewer injectable treatments than pigs fed the control (P &amp;lt; 0.05). No differences of PEN were observed in wk 1 and 3; however, at 5 wk post-weaning, incidence of PEN was 23% less in pigs fed the STB the the control fed pigs (P &amp;lt; 0.05). In experiment 3, the pigs fed STB had decreased incidence of ear necrosis (3.09% vs 4.08%; P &amp;lt; 0.05) and mortality (2.42% vs 2.86%; P &amp;lt; 0.05), overall reducing PEN and mortality by 32% and 18%, respectively. The fecal microbiome of pigs fed CON was associated with the chondroitin sulfate degradation pathway, an important component of cartilage. In conclusion, feeding a stimbiotic appears to be beneficial in nursery pigs to help alleviate challenges with PEN, which is potentially driven by a beneficial shift in the pig’s microbiome.

181 Effects of Soy protein concentrate replacing conventional soybean meal on intestinal health and growth of newly weaned pigs challenged with F18+ Escherichia coli.

Abstract This study aims to investigate the impact of various levels of soy protein concentrate (SPC) replacing conventional soybean meal (SBM) on various parameters related to intestinal health and growth performance of nursery pigs under F18+ Escherichia coli challenge. Newly weaned pigs [n = 72; initial body weight (BW) = 6.6 ± 0.3 kg] were randomly allotted to 6 treatment groups based on randomized complete block design with initial BW and sex as blocks and fed for 25 d (P1/2 for 11/14 d, respectively). The treatment groups were 1) NC: a diet with conventional SBM, 2) PC: NC with F18+ E. coli challenge at d 7 (2.1 × 1010 CFU); 3) T1: PC with 5% SPC replacing conventional SBM; 4) T2: PC with 10% SPC replacing conventional SBM; 55) T3: NC with 10% SPC replacing conventional SBM, and 6) AGP: PC with 0.25% bacitracin methylene disalicylate. At the end of study, all pigs were euthanized to collect jejunal tissues to measure parameters related to intestinal health. Data were analyzed using MIXED procedure in SAS. The PC decreased (P &amp;lt; 0.05) average daily gain (ADG) and average daily feed intake (ADFI) on d 7 to d 25 (post-challenge) compared with NC. The T2 decreased (P &amp;lt; 0.05) ADG and ADFI on post-challenge period compared with T3. The ADG tended to linearly decrease (P = 0.067) and ADFI linearly decrease (P &amp;lt; 0.05) on post-challenge period with increasing SPC supplementation replacing SBM in the diets. The E. coli challenge increased (P &amp;lt; 0.05) fecal score in PC, and T2 treatments compared with NC, and T3, respectively. The tumor necrosis factor-alpha (TNF-α) in jejunal mucosa linearly increased (P &amp;lt; 0.05) with increasing SPC supplementation replacing SBM in nursery diets under E. coli challenge. The PC decreased (P &amp;lt; 0.05) interleukin-8 (IL-8) compared with NC. The PC (P = 0.078) and T3 (P = 0.099) tended to decrease immunoglobulin A (IgA) compared with NC. The AGP increased (P &amp;lt; 0.05) IgA compared with PC. The AGP increased (P &amp;lt; 0.05) the expression of occludin (OC) compared with PC. The expression of OC tended to linearly decrease (P = 0.099) with increasing SPC supplementation replacing SBM in nursery diets under E. coli challenge. The T2 increased (P &amp;lt; 0.05) villus height to crypt depth ratio (VH:CD) compared with T3. In conclusion, supplementation of SPC replacing SBM in the diet did not alleviate the deleterious effect of E. coli challenge on growth performance nursery pigs, which might be contributed by reduced feed intake. Additionally, supplementation of SPC seems to exacerbate the negative effect of E. coli challenge with increased intestinal inflammation and intestinal disintegration.

196 Effects of zinc source and level in low ABC-4 diets on nursery pig growth performance and fecal dry matter

Abstract Incorporating pharmacological levels of Zn in nursery pig diets is a well-recognized practice for reducing post-weaning diarrhea, enhancing growth performance, and enhancing gut health. We hypnotized that the use of a specific form of ZnO (small aggregates and agglomerated particles; SAAP), which provides a greater antibacterial property than standard ZnO, could be added at reduced levels without compromising piglet performance. This study aimed to explore the effects of different levels of SAAP Zn source (HiZox, Animine, France) in low ABC-4 diets with low or high CP content. A total of 360 weanling barrows [DNA 200 × 400, initial body weight (BW) = 5.9 ± 0.4 kg] were used in a 38-d experiment. Pigs were randomly assigned to pens (5 pigs/pen) and pens assigned to 1 of 6 treatments with 12 pens/treatment. The experiment consisted of phase 1 from d 0 to 10, phase 2 from d 11 to 24, and phase 3 from d 25 to 38. Treatments consisted in a negative control (NC), which had 150 ppm of Zn (HiZox) throughout the experiment and the remaining treatments were: positive control (PC) containing 3,000 ppm (phase 1) and 2,000 ppm (phase 2) of Zn provided by ZnO; low-HiZox containing 500 ppm (phase 1) and 300 ppm (phase 2) of Zn; low-HiZox-low-CP was similar to low-HiZox but contained less CP (19.3%) than the NC, PC, low and high-HiZox diets (21.3%); high-HiZox containing 800 ppm (phase 1) and 500 ppm (phase 2) of Zn; and high-HiZox-low-CP was similar to high-HiZox but contained 19.3% CP. In phase 3, all pigs were fed a common diet containing 150 ppm of Zn (HiZox) and high CP. For the experimental period (d 0 to 24), average daily gain (ADG; quadratic, P = 0.007) and average daily feed intake (ADFI; quadratic, P = 0.018) increased as HiZox increased (Table). Pigs fed high-HiZox-low-CP had poorer gain to feed ratio (G:F; P &amp;lt; 0.05) than NC, PC, low-HiZox, and high-HiZox. Additionally, in both experimental and overall periods, pigs fed diets with low CP had decreased G:F (P = 0.043) than those fed the same Zn levels but with high CP. Overall, pigs fed high-HiZox-low-CP had decreased G:F than pigs fed high-HiZox only (732 vs. 761 g/kg, respectively; P &amp;lt; 0.05), with other treatments intermediate. For fecal dry matter (DM), pigs fed low CP diets had greater (P = 0.008) DM compared with pigs fed high CP. Thus, the inclusion of HiZox at 800 and 500 ppm in phases 1 and 2, respectively, in a low-ABC-4 diet might be a strategy to reduce the use of pharmacological levels of Zn from ZnO in nursery diets.

79 Evaluating the effects of increasing levels of sodium diformate on nursery pig performance

Abstract Organic acids, such as formic acid, are commonly used as acidifiers in swine diets. Forms of formic acid include salts of sodium, calcium, or potassium. Previous research has shown positive results using potassium diformate in swine diets including improved nutrient digestibility, growth performance, and altered gut microbiota. Additionally, recent data has shown increasing levels of sodium diformate improved growth performance in finishing pigs; however, additional data are needed in nursery pigs. The objective of this study was to investigate the effects of increasing sodium diformate in nursery diets on growth performance. Weanling barrows [n = 360; DNA 200 × 400; initial body weight (BW) = 5.9 ± 0.06 kg] were used in a 38-d study. At weaning, pigs were randomly assigned to pens with 5 pigs per pen. Each pen was randomly allocated to 1 of 6 treatments in a completely randomized design with 12 replicates per treatment. Dietary treatments were formulated to provide none, 0.40, 0.60, 0.80, 1.00, or 1.20% sodium diformate (Formi NDF, ADDCON, Nordic AS, Porsgrunn, Norway) at the expense of corn. Experimental diets were fed in 3 phases: phase 1 from weaning to d 9, phase 2 from d 9 to 24, and phase 3 from d 24 to 38. Feces was collected on d 9 and 24 from 3 pigs per pen to determine fecal dry matter (DM). All data were analyzed using a linear mixed model with treatment as a fixed effect and barn as a random intercept. Contrast statements were used to evaluate the linear and quadratic dose response to increasing sodium diformate inclusion. All statistical models were fit using the GLIMMIX procedure of SAS version 9.4 (Cary, NC). From d 0 to 24 (phase 1 and 2), gain to feed ratio (G:F) increased (linear, P = 0.001) as sodium diformate increased in the diet (Table). However, sodium diformate did not affect (P &amp;gt; 0.10) average daily gain (ADG) or average daily feed intake (ADFI). From d 24 to 38 (phase 3), there was no evidence of differences (P &amp;gt; 0.10) due to increasing sodium diformate for any growth response criteria. For the overall experimental period (d 0 to 38), increasing sodium diformate did not affect (P &amp;gt; 0.10) ADG, ADFI, or G:F. Overall mortality was 0.8% and was not influenced (P &amp;gt; 0.10) by treatment. There was no evidence for differences (P &amp;gt; 0.10) in fecal DM on d 9. However, fecal DM decreased (linear, P &amp;lt; 0.05; quadratic, P = 0.097) as sodium diformate increased in the diet on d 24 with pigs fed 0.40% sodium diformate having the greatest fecal DM. In conclusion, these data suggest increasing levels of sodium diformate has the potential to improve feed efficiency in the early nursey period but did not affect performance in the late nursery.

142 Evaluation of low SID lysine diets fed to enteric health challenged pigs on wean-to-finish performance

Abstract Producers have been adopting low crude protein or low SID Lys nursery diets to address enteric health concerns. Therefore, we evaluated the longitudinal impact of these strategies on lifetime pig performance. Weaned mixed sex pigs n = 588; initial body weight (BW) = 6.81 ± 1.34 kg] sourced from a poor enteric health flow, were randomly assigned to pens and to one of four nursery dietary treatments, fed for 7 wk. Following the nursery period, pens were then assigned to one of two grow-finish treatments, fed until marketing, to complete a 2 × 2 × 2 factorial design (n = 6 pens/treatment, 12 to 13 pigs/pen). Phase 1 nursery diets were formulated to a 1.10% or 1.40% SID Lys (nLLys or nHLys) with amino acids (AA) provided by both soybean meal (SBM) and crystalline AA or SBM only (nLSBM or nHSBM, respectively). Nursery phase 2 and 3 diets were formulated with a 0.05% decrease in SID Lys while maintaining a 0.30% differential between high and low lysine treatments. Following the nursery, grow-finish pigs were fed diets formulated to equal SID Lys:ME with either a conventional crystalline AA (gfLSBM) or high SBM diet lacking crystalline AA (gfHSBM) to meet AA requirements. During the nursery, enteric health was assessed by fecal pathogen PCRs and bacterial culture, confirming a high natural rotavirus and F18 enterotoxigenic Escherichia coli burden. Pig BW and pen feed disappearance were recorded at the beginning and end of each phase to calculate average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency (gain to feed ratio; G:F). Data were analyzed with pen as the experimental unit and the fixed effects of nursery SID Lys (nLys), nursery SBM (nSBM), grow-finish SBM (gfSBM), and the two- and three-way interactions using ANOVA. There were no three-way interactions for ADG or ADFI on final performance and no two-way interactions of nLys by nSBM in the nursery. Additionally, there was no effect of nSBM on overall nursery ADG, ADFI, and G:F (P &amp;gt; 0.05). Pigs fed nHLys-gfHSBM (0.84 kg/d) had improved overall ADG versus pigs fed nLLys-gfHSBM (0.80 kg/d; interaction; P = 0.010). Final nursery ADG (0.47 vs. 0.42 kg/d), G:F (0.70 vs. 0.63), and ending BW (30.9 vs. 28.0 kg) were greater in pens fed nHLys compared with nLLys (P &amp;lt; 0.001). Grow-finish pigs fed gfHSBM were more efficient compared with gfLSBM overall (0.457 vs. 0.449, respectively; P = 0.016). Although pigs fed nHLys had improved ending ADG compared with nLLys (0.83 vs. 0.81 kg/d; P = 0.018, respectively), there were no differences in final BW (128.0 vs. 127.0 kg) or ADFI (1.83 vs. 1.80 kg/d; P &amp;gt; 0.05). In conclusion, low SID Lys enteric diets did not improve wean-to-market pig performance in enterically challenged pigs and there was no difference between amino acid sources (crystalline vs SBM).

85 The influence of supplementing isolated or intact structural fiber on the physicochemical properties of digesta and fecal consistency of nursery pigs

Abstract In human nutrition, functional fiber refers to isolated non-digestible carbohydrates with physiological roles, while structural fiber pertains to those that are intrinsic and intact in plants. Increasing dietary fiber in post-weaning pig diets has been shown to improve gastrointestinal health and alter fecal consistency. However, minimal research has been conducted on the role of supplementing isolated functional or structural fiber that are chemically insoluble in nursery diets. The experimental objective was to evaluate the effect of functional or structural insoluble fiber supplementation on the physicochemical properties of digesta and feces during the nursery period. A total of 256 newly weaned pigs were randomly assigned to one of four treatments across two replications with 4 pigs per pen and 16 pens per treatment for a 35-d study. The average initial pig body weight (BW) was 5.13 ± 0.65 kg and same sex pens were used and balanced across treatments. Dietary treatments consisted of a control nursery diet (PC), PC with 3% soy hulls (NC), PC with 2% isolated lignocellulose (ISO), and PC with 2% structural lignocellulose (STR). Treatments were fed across phase 1 (d 0-7) and phase 2 (d 7-21) diets, and a common diet was fed in phase 3 (d 21-35). On d 7, 14, 21, 28, and 35, fresh fecal samples were collected to determine water binding capacity (WBC), water swelling capacity (WSC), and fecal dry matter (DM). Fecal scores were also evaluated using a predefined scale (1 = solid; 4 = liquid). On d 21, one pig per pen closest to the mean BW was necropsied, and ileal, cecal, and colonic digesta were collected. Continuous data were analyzed as a linear mixed model (PROC MIXED) with treatment, sex, and period as fixed effects, replicate as a random effect, and initial BW as a covariate where appropriate. Fecal scores were analyzed using a multinomial model in PROC GENMOD and FREQ. Pigs fed ISO and STR tended to have greater fecal DM (24.1%, 24.6%, 25.4%, and 26.29% for PC, NC, ISO, and STR, respectively; P = 0.071). There was a greater proportion of solid and semi-solid feces in pigs fed ISO (P = 0.039). Fecal WBC was greatest in pigs fed PC, with NC and ISO performing intermediately, and STR having the least (2.66, 2.55, 2.50, and 2.39 mL/g of DM for PC, NC, ISO, and STR, respectively; P = 0.071). Fecal WSC increased with time (P &amp;lt; 0.001), but there was no impact of treatment (P = 0.983). Ileal digesta pH was decreased in NC and STR, relative to PC and ISO, (P = 0.007). There tended to be a similar response for cecal pH (P = 0.092). Pigs fed PC tended to have the greatest colonic WBC (P = 0.058). Collectively, supplementing isolated or structural lignocellulose can alter the physicochemical properties of nursery pig feces.

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 &amp;lt; 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 &amp;lt; 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 &amp;lt; 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 &amp;lt; 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 &amp;lt; 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.

201 The effects of the supplementation of a Zinc-amino acid complex in pig nursery diets with differing pharmacological levels of zinc oxide and complexity

Abstract Diet complexity (DC), which has significance in nursery pig production, generally refers to a greater number of highly digestible ingredients. Increased DC may have even greater significance in scenarios of reduction or withdrawal of zinc oxide (ZnO) in nursery diets. The objectives were to determine 1) the impact of adding Zn-amino acid complex (Zinpro ProPath Zn) to mid- (MC) and low-complexity (LC) diets on nursery pig performance and health compared with a high complexity (HC) diet, and 2) the impact of Zinpro ProPath Zn in diets with and without pharmacologic levels of ZnO. A total of 2,400 mixed-sex weanling pigs [initial body (BW) weight = 5.79 ± 0.15 kg] were assigned to 1 of 5 dietary treatments during nursery (42 d) as follows: 1) HC; MC diet with 2) MC+ZnO) or without 3) MC-ZnO) pharmacologic ZnO; and LC diet with 4) LC+ZnO) or without 5) LC-ZnO) pharmacologic ZnO. All diets except HC were supplemented with Zinpro ProPath Zn (125 mg/kg Zn) and ZnO [3,000, 2,000, and 0 mg/kg Zn during Phases I (14 d), II (14 d) and III (14 d), respectively]. Different DC were achieved by manipulating the inclusion of spray-dried plasma, soy protein concentrate, and whey protein. Growth performance, onset of feed intake, fecal dry matter, number of injectable treatments administered, and serum acute-phase response were assessed. Pigs fed HC (20.0 kg) had greater final BW (FBW) compared with pigs fed MC-ZnO (18.8 kg), which had greater FBW compared with pigs fed LC-ZnO (17.5 kg; SEM = 0.34; P &amp;lt; 0.05). Average daily feed intake (ADFI) was greater in pigs fed HC (0.46 kg/d) compared with MC-ZnO (0.43 kg/d) and LC+ZnO (0.42 kg/d), which had greater ADFI compared with LC-ZnO (0.39 kg/d; SEM = 0.01; P &amp;lt; 0.05). Similarly, average daily gain (ADG) and gain to feed ratio (G:F) were greater in pigs fed HC (0.33 kg/d, 0.72 kg/kg, respectively) compared with pigs fed LC (0.27 kg/d, 0.67 kg/kg, respectively), regardless of ZnO (SEM = 0.01; P &amp;lt; 0.05). There was no effect of dietary treatments on the fecal dry matter or on the onset of feed intake of pigs (P &amp;gt; 0.10). The number of injectable treatments administered was greatest in LC-ZnO (62.7%), followed by LC+ZnO (50.6%), MC regardless of ZnO (44.0%), and HC (36.7%; SEM = 1.04; P &amp;lt; 0.05). Serum alkaline phosphatase was less in LC-ZnO than the other groups (229.8 vs. 280.9 ± 11.9 IU/L; P &amp;lt; 0.05). Taken together, feeding HC diets during the nursery appears to be effective in improving performance and health of pigs, particularly when compared with MC and LC diets without ZnO. Moreover, the addition of Zinpro ProPath Zn may partially attenuate the negative effects of ZnO removal in MC, but not LC, diets.

110 Effects of increasing levels of soybean meal in nursery diets on growth performance and fecal dry matter of 10 to 25 kg pigs

Abstract With the recent Renewable Fuel Standard Program developed by the Environmental Protection Agency, soybean oil is expected to be in record demand by the fuel energy industry. As a result, there will be the potential opportunity for increased usage of soybean meal (SBM) in swine diets. Therefore, the objective of this study was to evaluate the effect of different levels of SBM in late nursery diets on growth performance and fecal dry matter (DM). In Exp. pigs [n = 1,266; DNA 241 × 600; initial body weight (BW) = 10.1 ± 0.27 kg] were fed 1 of 4 dietary treatments which were corn-based with SBM levels of 25.0, 28.9, 32.5, or 36.2%. In Exp. pigs (n = 2,340; DNA 241 × 600; initial BW = 13.5 ± 0.29 kg) were fed 1 of 5 dietary treatments which were corn-based with SBM levels of 25.0, 28.9, 32.5, 36.2, or 40.0%. Both experiments lasted 21 d with 14 replicate pens/treatment and 4 or 5 pigs/pen. At d 21 and 26 postweaning for Exp. 1 and 2, respectively, pens of pigs were randomly allotted to treatments in a randomized complete block design with BW as the blocking factor. Additions of SBM replaced feed-grade amino acids to form experimental diets, and all diets were formulated to be nearly isocaloric with SBM NE considered to be 100% of corn NE. Dietary additions of feed-grade AA were adjusted to meet or exceed NRC (2012) AA requirements in relation to Lys for Ile, Met, Cys, Thr, Trp, and Val. In Exp. 1, increasing SBM from 25.0 to 36.2% decreased average daily gain (ADG; linear, P = 0.012), average daily feed intake (ADFI; linear, P &amp;lt; 0.001), and final BW (linear, P = 0.021), with the greatest change occurring when SBM increased from 28.9 to 32.5% (Table). No evidence for difference between treatments was observed for gain to feed ratio (G:F; P = 0.729). Fecal DM decreased (linear, P &amp;lt; 0.006) as SBM increased in the diet at d 7, but not on d 21. In Exp. 2, starting with a heavier initial BW, increasing SBM from 25.0 to 40.0% decreased ADFI (linear, P = 0.017), with the greatest change occurring when SBM increased from 32.5 to 36.2%. However, no evidence for treatment differences (P ≥ 0.198) was observed for ADG, final BW, or G:F. Fecal DM decreased (linear, P ≤ 0.046) at d 7 and 21 as SBM increased in the diet. In conclusion, feeding greater than 28.9% SBM for nursery pigs starting at 10 kg BW does compromise performance, but when pigs are closer to 13.5 kg BW, greater SBM diets did not affect ADG or G:F. Also, increasing the level of SBM reduced fecal DM more markedly a week after the transition to high SBM diets compared with 3 wk after the start of treatment feeding.

139 Effect of dietary crude protein concentration and sensory feed additive on nursery pig growth performance

Abstract Maximizing growth performance and feed intake for nursery pig diets is an ongoing challenge in the US swine industry. Using sensory feed additives is one strategy to optimize feed intake and growth rates of pigs. Weanling pigs (n = 416; average age = 19.8 d) were used to test the effects of sensory feed additive (SA; Luctamax Piglet, Lucta, Mahwah, NJ) addition to control (CON) and low crude protein (LCP; decreased 4% CP) nursery diets in a 2 x 2 factorial design (CON, CON+SA, LCP, LCP+SA). Decreased dietary CP was achieved by removing or decreasing fish meal and soy concentrate in phases 1 and 2 and reducing soybean meal in phase 3 and adding synthetic amino acids to maintain amino acid ratios (NRC 2012). Nursery treatments were fed in three phases; phase 1 (PH1, d 0-7, 0.10% SA), phase 2 (PH2, d 7-21, 0.10% SA), and phase 3 (PH3, d 21-36, 0.05% SA). Pigs were blocked by initial body weight (BW), sex, ancestry, and housed at 6 or 7 pigs/pen with 15 pens/treatment. Weekly pig BW and feed intake were used to calculate pen average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio (G:F). Data were analyzed using GLM procedure of SAS 9.4. During PH1 pigs receiving the CON diets tended (P = 0.065) to have a greater G:F compared with pigs receiving LCP diets. For the remainder of this study there were consistent interactions between dietary CP and SA. When SA was added to the LCP diet ADFI increased but when SA was added to CON diet ADFI decreased and these changes in feed intake often led to similar dietary interactions in ADG. During PH2, pigs fed CON or LCP+SA diets had greater ADFI (P = 0.032) and tended to have a greater ADG (P = 0.094) but reduced G:F (P = 0.100) compared with pigs fed CON+SA or LCP diets. In PH3, pigs fed CON or LCP+SA diets had a greater ADG (P = 0.027) and ADFI (P = 0.011) compared with CON+SA or LCP diets. Pigs fed LCP diets had greater ADFI (P = 0.001) but reduced G:F (P = 0.0001) than pigs fed CON diets. Overall, pigs fed CON or LCP+SA diets had greater ADFI (P = 0.016) and tended to have a greater ADG (P = 0.059) but reduced G:F (P = 0.067) compared with pigs fed CON+SA or LCP diets. Pigs fed CON diets had a greater G:F (P &amp;lt; 0.001) compared with pigs fed LCP diets, while LCP pigs tended to have a greater ADFI (P = 0.054) compared with CON pigs. Inclusion of SA to LCP diet mitigated the adverse impact of replacing whole dietary proteins with high inclusion of synthetic amino acids. Careful consideration is needed when using sensory feed additives so as not to impede growth performance in diets containing traditionally greater levels of crude protein.