PSIV-9 Effect of Increasing the Level of a Modified Corn Protein on Nursery Pig Growth Performance, Feed Efficiency, and Fecal Dry Matter

A total of 360 barrows (DNA Line 200×400; initially 6.1±0.05 kg) were used in a 38-d study to evaluate the effects of increasing levels of a modified corn protein product on nursery pig growth performance and fecal dry matter. Upon arrival to the nursery research facility, pigs were randomly assigned to pens (5 pigs/pen) and pens were randomly allotted to 6 dietary treatments (12 pens/treatment). Experimental diets were fed in 2 phases. Phase 1 (d 0-10) diets were formulated to contain 3, 6, 9, 12, or 15% of a modified corn protein or 6% enzymatically treated soybean meal (ESBM). Additions of the modified protein product and ESBM were reduced by 50% for phase 2 (d 10 to 25) diets and were: 1.5, 3.0, 4.5, 6.0, 7.5, and 3.0%, respectively. Nutrient loading values were provided by the supplier and diets were formulated to maximize L-Lysine HCl while keeping SID Lys:CP and SID AA:Lys similar across treatments. A common phase 3 diet was fed from d 25-38. During the experimental period (d 0-25), ADG (quadratic, P = 0.030) and ADFI (quadratic, P = 0.036) increased, and G:F worsened (linear, P = 0.006) as the amount of modified corn protein increased. For the overall experiment (d 0-38), ADG (quadratic, P = 0.028) and ADFI (quadratic, P = 0.032) increased then decreased and G:F tended to decrease (linear, P = 0.066) with increasing modified corn protein. There was a marginally significant treatment×day interaction (quadratic, P = 0.064) where fecal DM tended to increase (P = 0.051) on d 25 as the level of the modified corn protein was increased, but no evidence for change on d 10 (P > 0.10). These data suggest that the modified corn protein tested in this trial may be an alternative protein source to consider for nursery pig diets, when fed up to 12% in phase 1 and 6% in phase 2.

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53 Evaluating the Efficacy of Boot Baths with Wet and Dry Disinfectants for Porcine Epidemic Diarrhea Virus and Porcine Reproductive and Respiratory Syndrome Virus

Maintaining biosecurity between barns is challenging. Boot baths, either wet or dry, can be implemented to limit pathogen spread. The objective was to evaluate the efficacy of boot baths using wet or dry disinfectants for porcine epidemic diarrhea virus (PEDV) and porcine reproductive and respiratory syndrome virus (PRRSV). Treatments included 1) control, 2) wet disinfectant (Synergize, Neogen, Lexington, KY), and 3) dry disinfectant (Traffic C.O.P., PSP, LLC, Rainsville, AL). Prior to disinfection, 0.5 mL of both PRRSV (~1×105 TCID50/mL) and PEDV (~1×105 TCID50/mL) was placed onto a new boot with a layer of autoclaved corn dust and allowed to dry for 15 minutes. After the mixture dried, the boot was put on and stepped into its respective boot bath. After 3 seconds, the boot was lifted out of the bath and stepped onto a stainless-steel coupon to simulate walking through a facility. Both boot and coupon were allowed to dry for 1 minute before swabs were taken from both surfaces. Samples were analyzed in a duplex PCR at the Kansas State Veterinary Diagnostic Laboratory. Cycle threshold values were analyzed using SAS GLIMMIX v 9.4 (SAS, Inc., Cary, NC). There was no evidence of a treatment×surface×virus interaction (P > 0.10). The interaction between treatment×surface impacted (P < 0.05) the quantity of detectable RNA. The control had greater concentration of virus on the coupon than the boot. The reverse was true for boots treated with wet disinfectant, where the boot had a greater concentration of virus than the coupon. Treatment×virus also impacted detectable RNA (P < 0.05), where wet and control boots had greater quantities of PEDV RNA than PRRSV. There was no detectable virus when dry disinfectant was used. For this trial, dry disinfectant was the most efficacious in reducing the viral RNA on both boots and subsequent surfaces; however, further research in commercial settings is warranted.

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104 Effect of Mat Feeding on the Growth Performance and Morbidity and Mortality of Pigs After Weaning

Three experiments were conducted using 9,403 pigs to determine the effect of mat feeding on growth performance and morbidity and mortality of pigs after weaning. At weaning, pigs were randomized to 96 pens (48 feeders) with 30 to 35 pigs/pen. Feeder (2 pens) was the experimental unit. For each experiment, mat feed was provided 3 times daily for 10 d and was included in calculation of post-weaning ADFI and G:F. In Exp. 1, treatments consisted of mat verses no mat feeding. Overall, mat fed pigs tended to have decreased (P = 0.056) ADG compared with the control, which resulted in decreased (P < 0.026) final body weights. No differences were observed in ADFI or G:F. However, mat fed pigs had reduced total mortality and removals (P = 0.019). In Exp. 2, treatments were arranged in a 2×2 factorial with main effects of diet form (pellet or crumble) and mat feeding (without or with). Overall, no interactions between diet form and mat feeding were observed. No differences were observed in growth performance by mat feeding. However, pigs receiving pelleted feed had decreased overall ADFI (P = 0.013) and increased G:F (P < 0.001). Differences in total mortality and removals were not significant. In Exp. 3, treatments consisted of mat feeding small (0.32 cm) or large (1.27 cm) pellets, or no mat feeding. No differences were observed in overall ADG or G:F; however, mat fed pigs had increased ADFI (P < 0.05), regardless of pellet size. Differences in total mortality and removals were not significant. When combining removal and mortality data for the 3 experiments, mat fed pigs had fewer total removals (P = 0.025) compared with the control. In summary, mat feeding has limited effects on growth performance of pigs after weaning; however, mat feeding may encourage earlier feed intake reducing the fall out rate of pigs as indicated by the decreased removals.

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129 The Effect of Live Yeast and Yeast Extracts Included in Lactation and Nursery Diets on Nursery Pig Growth Performance

Two experiments were conducted to determine the impact of diets with yeast-based direct fed microbials (DFM) in nursery pigs weaned from sows fed lactation diets with or without yeast additives. Treatment descriptions for both experiments are reviewed in Table 1. There was no evidence of sow and nursery treatment interactions for either experiment (P > 0.05). In Exp. 1, 340 weaned pigs, initially 5.1 kg ± 0.02, were used to evaluate previous sow treatment (control vs yeast additives; Phileo by Lesaffre, Milwaukee, WI) and nursery diets with or without DFM. Treatments were a 2×2 factorial with main effects of sow treatment and nursery treatment (control vs. yeast-based pre- and probiotic diet) with 5 pigs/pen and 17 replications/treatment. Progeny from sows fed yeast additives had increased (P < 0.05) ADG from d 0-24 and d 0-45. However, pigs that were fed yeast additives for the first 24 d in the nursery tended to have decreased d 0-45 ADG (P = 0.079). In Exp. 2, 330 weaned pigs, initially 5.8 kg ± 0.03, were used to evaluate diets with combinations of DFM. Treatments were arranged in a 2×3 with main effects of sow (same as Exp. 1) and nursery treatment with 6 pigs/pen and 8 to 10 replications/treatment. From d 0-10 post-weaning, progeny of sows fed yeast additives had increased (P < 0.05) ADG and G:F. From d 24-38 when pigs were fed common diets with no added yeast-based products, ADG for pigs previously fed DFM2 was greater (P < 0.05) than control. In conclusion, feeding sows yeast during lactation improved offspring nursery growth performance in both studies. Interestingly, feeding live yeast and yeast extracts reduced nursery pig performance in Exp. 1; however, feeding DFM 2 improved growth later in the nursery in Exp. 2.

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242 Effects of Providing a Liquid Sensory Attractant to Suckling Pigs in Lactation and After Weaning on Post-Weaning Pig Performance

A total of 28 litters corresponding with 355 nursery pigs were used in a 42-d trial to determine the effect of a liquid sensory attractant (BlueLite Pro2Lyte; TechMix Global; Stewart, MN) pre- and post-weaning on the feed intake and growth of pigs after weaning. Treatments were arranged in a 2x2x2 factorial with main effects of: 1) pre-weaning treatment (without/with attractant), 2) post-weaning treatment (without/with attractant), and 3) body weight category (light/heavy). Litters that received liquid attractant pre-weaning were provided approximately 88 mL per d, divided into 2 applications, sprayed on the underline of sows for 2-d beginning the morning after farrowing and 2-d prior to weaning. In total, pigs received attractant for 4-d pre-weaning. After weaning, pens of pigs that received liquid attractant were offered approximately 56 mL per d, divided into 3 applications, sprayed on the feed in the feeder pan for 3-d post-weaning. Overall, pre and post-weaning liquid sensory attractant did not have a significant effect (P > 0.10) on growth performance of pigs after weaning. For the percentage of pigs that lost weight by d 3 after weaning, a 3-way interaction was observed (P = 0.016). Sensory attractant pre- or post-weaning reduced the percentage of heavyweight pigs that lost weight after weaning; however, for lightweight pigs, providing the attractant only pre-weaning increased the percentage of pigs that lost weight after weaning. Additionally, a greater percentage of heavyweight pigs lost weight on d 3 (P = 0.007) and d 7 (P = 0.051) compared with lightweight pigs. In summary, liquid sensory attractant application pre- and post-weaning had limited effects on the growth performance of pigs; however, varying responses were observed for the percentage of pigs that lost weight immediately after weaning. Strategies to reduce the number of pigs that lose weight after weaning warrant further investigation.

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157 Effects of Standardized Ileal Digestible Lysine Level on Growth Performance in 75 to 130 Kg DNA Finishing Pigs

Two studies were conducted to estimate the SID Lys requirement for growth and feed efficiency of 70-130-kg DNA finishing pigs. In Exp. 1, 616 pigs (600×241, DNA; initially 76.4±1.25 kg) were used from 70-100-kg and in Exp. 2, 679 pigs (600×241, DNA; initially 103.8±1.32 kg) were used from 100-130 kg. Pens of pigs were blocked by BW and randomly allotted to dietary treatments with 8-10 pigs/pen in a randomized complete block design. Diets were corn-soybean meal based and SID Lys increased by increasing soybean meal and feed-grade amino acids while maintaining minimum ratios for other amino acids. From 70-100 kg, ADG, G:F, Lys intake/d, and Lys intake/kg of gain all increased, (linear, P < 0.05) with increasing SID Lys. From 100-130 kg, ADG, Lys intake/d, and Lys intake/kg of gain increased (linear, P < 0.05) with increasing SID Lys, while G:F increased (quadratic, P = 0.032). At current ingredient and pig prices, there were no statistical differences in income over feed cost (IOFC) from 70-100 kg. From 100-130 kg, increasing SID Lys increased (quadratic, P = 0.001) IOFC. A broken-line linear (BLL) model predicted optimal ADG at 0.83% SID Lys, while a quadratic polynomial (QP) model predicted a requirement of 0.90% for G:F from 75-100 kg. A QP model predicted maximum IOFC at 0.78% SID Lys from 75-100 kg. From 100-130 kg, BLL models predicted optimal ADG and G:F at 0.64 and 0.59% SID Lys, respectively. A QP model predicted maximum IOFC at 0.64% SID Lys. In summary, these results suggest the optimal SID Lys level for 75-100 kg DNA finishing pigs for growth performance is between 0.83 and 0.90% SID Lys, and 0.78% SID Lys for maximum IOFC. The optimal SID Lys level in 100-130 kg DNA finishing pigs depends upon the response criteria, with growth performance and IOFC maximized between 0.59 and 0.64% SID Lys.

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PSVIII-1 Evaluating the Efficacy of Acidifiers Used in Nursery Diets in Reducing Bacterial Loads in Both Non-Inoculated and Inoculated Complete Feed

Acidifiers are used in nursery pig diets to reduce the incidence of diarrhea, improve growth performance, and act as a feed preservative. The objective was to evaluate whether acidifiers were able to reduce bacteria presence in non-inoculated feed and reduce bacteria growth in feed inoculated with Escherichia coli and Enterococcus faecium. Each culture media was arranged in a 2×5 factorial with 2 phases and 5 diets. The diets were 1) control – no antibiotics, 2) ZnO (Phase 1: 3,000 ppm Zn and Phase 2: 2,000 ppm Zn), 3) formic acid at 0.7% of the diet (Amasil-NA; BASF Corp. Florham, NJ), 4) glycerol monolaurate – GML at 0.18% of the diet (Natural Biologics, Newfield, NY), and 5) FORMI-3G at 1.0% of the diet (Addcon Gmbh, Bitterfeld-Wolfen, Germany). Non-inoculated feed was plated onto Aerobic Count, E. coli/Coliform, and Enterobacteriaceae petrifilm (3M, St. Paul, MN). Inoculated feed was initially contaminated with E. coli or E. faecium and allowed to incubate prior to plating on MacConkey. There was no difference (P > 0.05) in quantity of bacteria for the diets inoculated with E. coli. There was no difference (P > 0.05) between the diets inoculated with E. faecium for phase 1; however, the formic acid diet had reduced (P < 0.05) quantities of bacteria compared with control, ZnO, and GML diets. The control and ZnO phase 1 non-inoculated diets had reduced (P < 0.05) quantities of aerobic bacteria, coliforms, and Enterobacteriaceae compared with GML. In phase 2 only the control had reduced (P < 0.05) quantities of Enterobacteriaceae compared with the ZnO and formic acid diets. Formic acid was able to reduce E. faecium quantities in phase 2, while the control and ZnO had decreased overall bacterial loads in phase 1.

PSVI-20 Effects of Adding Potassium Bicarbonate to Diets with High or and Low Crystalline Lysine as a Way to Influence DCAD on Finishing Pig Growth Performance

This experiment was conducted to evaluate the effect of balancing dietary cation-anion difference (DCAD), via added potassium bicarbonate (KHCO3), in diets containing low or high levels of L-Lys HCl on growth performance of growing-finishing pigs. A total of 1,944 pigs (PIC L337 × 1050, initially 35.2±0.85 kg) were used in a 120-d study. Pens of pigs were blocked by BW and randomly allotted to 1 of 4 dietary treatments in a randomized complete block design arranged in a 2×2 factorial with main effects of KHCO3 (0 vs 0.4%), and L-Lys HCl level (low vs. high), with 27 pigs/pen and 18 replicates/treatment. Diets were corn-soybean meal-based and formulated in 4 dietary phases (d 0-20, 30-58, 58-86, and 86-120). Diets were formulated in each phase such that the diet containing a low level of L-Lys HCl (0.14-0.21% depending on phase) without KHCO3, had similar calculated DCAD as the diet containing a high level of L-Lys HCl (0.36 to 0.43% depending on phase) with KHCO3. The DCAD for these 2 treatments were approximately 230, 200, 184, and 169 mEq/kg (phase 1, 2, 3, 4, respectively). The diets with low levels of L-Lys HCl with KHCO3 had the greatest DCAD in each phase (approximately 50 mEq/kg above the low L-Lys HCl without KHCO3 diet), while the diet with a high level of L-Lys HCl without KHCO3 had the least DCAD (approximately 50 mEq/kg below the high L-Lys HCl with KHCO3 diet). Overall, there was no evidence (P > 0.10) for a KHCO3 × L-Lys HCl interaction or main effect for any observed growth responses or carcass characteristics. The results of this study suggest that supplementing KHCO3 to finishing pig diets with either high or low levels of L-Lys HCl and the corresponding changes in DCAD values did not impact growth performance or carcass characteristics.

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PSII-13 Effect of Body Weight, Body Temperature, and Blood Glucose on the Survivability of Pull Pigs After Removal

A total of 988 nursery pigs were used to determine the effect of body weight, body temperature, and blood glucose on the survivability of pull pigs after removal. At weaning, pigs were transported to a 24,000 head hotel-style nursery and placed in rooms based on sow source. Over a 4-week period post-placement, every other pig removed from the general population for welfare considerations (lameness, sick, or fallback) were tagged, weighed, and their body temperature and blood glucose measured. Mortality was tracked through the end of the nursery or approximately 38 d post-placement. Data were analyzed as a completely randomized design with room as a random effect. The predictor variables of body weight, body temperature, and blood glucose were categorized into biologically significant categories and LSMeans were determined using a binary model with mortality as the outcome. Pigs with a body weight under 4.5 kg at removal had increased mortality rate (32.4%; P< 0.001) compared with pigs with a body weight between 4.5 and 5.4 kg (20.8%) or greater than 5.4 kg (14.6%) at removal. Pigs with a body temperature below 38.6°C or above 39.7°C at removal had increased mortality rate (33.4 or 26.8%, respectively; P < 0.001) compared with pigs with a body temperature between 38.6 and 39.7°C (17.7%) at removal. Pigs with a blood glucose greater than 120 mg/dL at removal had increased mortality rate (43.5%; P < 0.001) compared with pigs with a blood glucose less than 70 mg/dL (23.0%) or between 70 and 120 (17.9%) at removal. In summary, pull pigs with low bodyweight, high or low body temperature, or high blood glucose had decreased survivability. The results of this study indicate that there are metabolic differences between nursery pigs at the time of removal and that these differences may influence survivability.

61 Persistence and Distribution of African Swine Fever Virus in Feed and Feed Mill Environment Over Time After Manufacture of Experimentally Inoculated Feed and Subsequent Manufactured Batches of Feed

To reduce the risk of feed-based pathogens causing disease, some feed manufacturers quarantine high-risk ingredients before their inclusion in feed. Data exists that confirms this practice is effective, but there is no information about swine pathogen survival in mill environments. This objective of the study was to determine survival of African swine fever virus (ASFV) in swine feed and mill surfaces. A pilot-scale feed mill manufactured a batch of ASFV-free feed (Batch 1), followed by a batch inoculated with ASFV (5.6×104 TCID50/gram; Batch 2). Then 4 subsequent ASFV-free batches were manufactured (Batch 3-6). After each batch,10 feed samples were aseptically collected in a double ‘X’ pattern. During feed manufacturing, 24 steel coupons were placed on the floor of the manufacturing area and feed dust settled on them during the milling process and overnight. Feed samples and steel coupons were stored at room temperature. Three of each were randomly selected and analyzed for ASFV DNA on d 1, 3, 7, 14, 28, 60, 90, and 180. The interaction of batch and day impacted (P = 0.023) the number of genomic copies detected per gram of feed. There were no differences of genomic copies/g in early batches; but the quantity of detectable ASFV decreased with increasing storage time after collection. In Batches 4-6, the greatest quantity of ASFV was detected on d 1, but the lowest quantity was detected on d 7, 60, and 28 or 180 for Batches 5, 6, and 7, respectively. There was no evidence (P = 0.433) of ASFV degradation on environmental coupons over the 180-d storage period. This study found that quarantine time can help reduce, but not eliminate ASFV in feed over time. However, ASFV survives on feed manufacturing surfaces for at least 180 d. Additional research is necessary to evaluate the viability of detected virus to cause illness.

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141 Evaluation of a Fermented Corn Protein Source on Growth Performance of Nursery Pigs

Two experiments were conducted to determine if fermented corn protein (FCP) can serve as a replacement to enzymatically treated soybean meal (ESBM) in 6.0 to 15.8 kg or as a replacement for soybean meal in 12.1 to 24.7 kg pig nursery diets. In Exp. 1, 350 barrows (initially 6.0 kg) were randomly allotted to 5 treatments with 5 pigs/pen and 14 replications/treatment. Dietary treatments were arranged in a 2×2 + 1 factorial with a control diet or diets with 5 or 10% FCP or ESBM. Newly weaned pigs were fed phase 1 diets for 10-d followed by phase 2 diets for 21-d. There were no interactions throughout the experiment. Overall (d 0-31), pigs fed increasing FCP had decreased (linear, P ≤ 0.026) ADG and ADFI with no differences in G:F, whereas increasing ESBM had no effect on growth performance (Table). Pigs fed ESBM had increased (P ≤ 0.034) ADG and G:F compared with pigs fed FCP with no effect on ADFI. In Exp 2, 350 pigs (initially 12.1 kg) were randomly assigned to pens with 5 pigs/pen and 14 replications/treatment. On d 24 after weaning (d 0 of trial), pens of pigs were weighed and assigned to 5 dietary treatments. Dietary treatments were arranged in a 2×2 + 1 factorial with a control diet or diets with 10 or 20% FCP with either high or low Val+Ile:Leu ratios. There were no interactions observed throughout the experiment. Overall (d 0-21), ADG, ADFI, and G:F worsened (linear, P < 0.001) as FCP increased. High Val+Ile:Leu ratios improved (P = 0.017) G:F compared with low Val+Ile:Leu ratios with no effect on ADG and ADFI. In summary, using FCP to replace ESBM for nursery pigs weighing 6.0 to 15.8 kg had decreased growth performance. Increasing concentrations of FCP in diets for pigs weighting 12.1 to 24.7 kg worsened growth and increasing Val+Ile:Leu ratios only improved G:F.

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PSV-5 Effects of Benzoic Acid and an Essential Oils Blend on Detection of Swine Viruses in Inoculated Swine Feed and Premix

Feed has been shown to harbor viable viruses over an extended period. This study investigated the use of benzoic acid (BA) and an essential oils blend (EO) to mitigate the presence of porcine epidemic diarrhea virus (PEDV), porcine reproductive and respiratory syndrome virus (PRRSV), and Senecavirus A (SVA) in a complete diet (Exp. 1) and a vitamin premix (Exp. 2). Experiment 1 consisted of a control with no additive, 0.5% BA, 0.5% BA and 200 ppm EO, 0.3% BA and 120 ppm EO, and 0.25% BA and 100 ppm EO. Feed samples were inoculated with PEDV, PRRSV, and SVA. For Exp. 2, the control contained no additive, and treatment had 2.68% EO included to mitigate PEDV. Inoculated feed or premix was stored at room temperature with sampling points at 2, 5, and 15 d post-inoculation (dpi). Samples were analyzed using triplex qRT-PCR to detect changes in RNA quantities for all viruses. Detectible PRRSV in the feed demonstrated a quadratic decrease over time (P = 0.038). A significant treatment × day interaction was observed in the feed for both PEDV (P = 0.008) and SVA (P < 0.001). The 0.5% BA treatment had greater (P < 0.05) amounts of detectible PEDV on d 2 and 5 and decreased detectible PEDV on d 15 compared with control. The 0.5% BA treated feed demonstrated decreased (P < 0.05) detectable SVA at 2 dpi but greater detectible SVA at 15 dpi compared with control. Both PEDV and SVA demonstrated viral degradation over time. The use of the EO in the vitamin premix had no evidence of main or interactive effects. In conclusion, 0.5% BA decreased PEDV at 15 dpi, but BA and EO mitigation in this model did not provide consistent evidence for increased viral degradation. However, time decreased detectability of all three viruses.

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PSVI-1 Effect of Dietary Sodium and Pharmacological Zinc Levels on Growth Performance of Nursery Pigs

A total of 360 pigs (initially 5.7±0.2 kg) were used to determine the effect of pharmacological levels of Zn and dietary Na concentration on nursey pig growth performance. The experiment compared NRC (2012) and European CVB (2020) Na estimates for this weight range (0.35% and 0.24%, respectively), with or without added Zn from ZnO. At weaning, pigs were randomly allotted to pens (6 pigs/pen) and fed a common diet for 7 d. On d-7 after weaning (d-0 of trial), pigs were assigned to 6 dietary treatments with 10 replications/treatment. Dietary treatments were arranged in a 2×3 factorial with main effects of Zn (0 or 2,000 ppm from ZnO) and Na (0.13, 0.24, or 0.35% from salt). All diets contained 110 ppm of Zn from the trace mineral premix. Following a 14-d experimental period, pigs were fed a common phase 3 diet for 21-d. There were no Zn×Na interactions for ADG or ADFI (P >0.05). From d 0-14, adding dietary ZnO or increasing Na increased (linear, P < 0.05) ADG and ADFI. An interaction for G:F (linear, P = 0.019) was observed where increasing Na up to 0.35% improved G:F when pharmacological levels of Zn were fed, but pigs fed diets without ZnO had a quadratic response (P =0.024) with maximum G:F at 0.24% dietary Na. From d 14-35 and overall, an interaction was observed (linear, P < 0.05) for G:F. Within the interaction, pigs previously fed diets without ZnO observed a linear decrease in G:F as Na level increased (linear, P =0.001), but pigs previously fed diets with ZnO observed no difference in G:F with increasing Na. In summary, increasing dietary Na and the addition of 2,000 ppm Zn from ZnO independently improved daily gain and feed intake in nursery pigs, but an improvement in G:F from increasing Na up to 0.35% was only observed when pharmacological ZnO was present.

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PSVI-5 Effects of Added Vitamin Levels on Growth Performance of Finishing Pigs

A total of 1,080 mixed sex growing-finishing pigs (337 × 1050, PIC; initially 28.7 ±0.39 kg) were used in a 123-d growth trial to determine the effects of vitamin concentrations on finishing pig growth performance and carcass characteristics. Pens of pigs were assigned to 1 of 2 treatments in a completely randomized design. There were 20 replicate pens/treatment and 27 pigs/pen. The experimental diets were corn-soybean meal-based and were fed in 4 phases from 28 to 50, 50 to 73, 73 to 100 and 100 to 133 kg. Pigs were fed 1 of 2 levels of a vitamin premix (control and high) that contained: 1,653,468 IU vitamin A acetate; 661,387 IU vitamin D, vitamin E (17,637 mg dl-α-tocopheryl acetate), 1,323 mg vitamin K (menadione), 13.2 mg vitamin B₁₂, 19,842 mg niacin, 11,023 mg pantothenic acid, and 3,307 mg riboflavin per kg. The amount per phase was 1.36, 1.13, 0.91 and 0.07%, respectively, for the control with the added amount doubled for the high vitamin fortification. Overall, (day 0 to 123), there was no evidence for difference (P > 0.10) in ADG, ADFI and G:F. Also, no statistical difference was found (P > 0.10) for final BW, HCW or any carcass characteristic. In conclusion, the level of vitamins used in this study did not influence growth and carcass traits in finishing pigs.

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168 Evaluation of Increasing Dietary Threonine to Lysine Ratio in Corn-Soybean Meal Diets with and Without Dried Distillers Grains with Solubles (DDGS) on Growth Performance of Grow-Finish Pigs

A total of 2,160 pigs (PIC 337×1050; initial BW 35.1 kg) were used in a 112-d growth trial to evaluate the effects of normal or high SID Thr:Lys ratio in diets with and without DDGS on growth performance. Pigs were assigned to pens (27 pigs per pen) in a randomized complete block design by BW with 20 replications per treatment. Pens of pigs were allotted to 1 of 4 dietary treatments arranged in a 2×2 factorial with main effects of dietary Thr level (Normal vs High) and DDGS (with or without). Treatment diets were formulated in 4 phases from 35 to 57, 57 to 82, 82 to 105, and 105 to 136 kg BW. Diets with high DDGS were formulated to include 40% DDGS in phase 1 and 2, 30% in phase 3, and 15% in phase 4. Normal Thr diets were formulated to contain 61, 62, 63, and 65% SID Thr:Lys ratios for the 4 dietary phases, respectively. High Thr diets had SID Thr:Lys ratios of 67, 68, 69 and 72%, respectively. There were no (P>0.10) DDGS×Thr interactions. For the overall period (d 0 to 112), pigs fed diets without DDGS had increased (P < 0.001) ADG and BW, and reduced (P < 0.001) ADFI leading to improved (P < 0.001) G:F. There was no evidence for difference (P > 0.10) between diets with normal or high SID Thr:Lys ratio regardless of DDGS inclusion. In summary, the addition of high levels of DDGS reduced ADG and increased ADFI, which resulted in poorer G:F and lighter final BW, regardless of the dietary SID Thr:Lys ratio. These results indicate that addition of an insoluble fiber source, such as corn DDGS, does not increase the Thr:Lys requirement of finishing pigs.

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111 Evaluation of Dietary Mycotoxin Control Strategies on Nursery Pig Growth Performance and Blood Measures

A total of 4,318 pigs (337×1050, PIC; initially 6.5±0.08kg) were used in a 35-d trial to evaluate dietary mycotoxin control strategies on nursery pig performance and blood measures. Pigs were weaned at 21-d of age and randomly allotted to 1 of 5 dietary treatments. A total of 160 pens were used with 80 double-sided 5-hole stainless steel fence line feeders, with feeder serving as the experimental unit. For each feeder, 1 pen contained 27 gilts and 1 pen contained 27 barrows. There were 16 replications/treatment. A common phase 1 diet was fed in pelleted form for 7-d prior to treatment diets. Experimental treatments were fed from d 7 to 42 after weaning (d0 to 35 of study) and included a low deoxynivalenol (DON) diet (1.12±0.623 mg/kg), high DON diet (2.34±1.809 mg/kg), high DON+ sodium metabisulfite (SMB), high DON+ 1 of 2 mitigating products; Technology1, or Technology1+. Technology1 and 1+ are comprised of clays, yeast cell wall components and a blend of plant extracts. Technology1+ also contains SMB. Overall (d0 to 35), pigs fed high DON had decreased (P < 0.05) final BW, ADG, and ADFI compared with low DON. Additionally, pigs fed high DON+SMB had increased (P<0.05) ADG compared with all other treatments. An increase (P < 0.05) in G:F was observed in pigs fed high DON+SMB or high DON+Technology1+ compared with low DON or high DON+Technology1 with high DON intermediate. Analysis of dried blood spots collected on d 35 revealed pigs fed high DON or high DON+Technology1 had increased (P < 0.05) DON concentrations compared with low DON with high DON+SMB and high DON+Technology1+ intermediate. In summary, pigs fed high DON had reduced performance compared with low DON. Sodium metabisulfite supplementation to high DON led to ADG and G:F that exceeded low DON, whereas Technology1+ resulted in similar ADG and improved G:F compared with low DON.

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246 Awardee Talk: Evaluating the Impact of Essential Fatty Acids in Lactation Diets on Sow and Litter Performance

Two experiments were conducted to evaluate the effects of supplemental fat sources providing low and high essential fatty acids (EFA) in lactation diets on sow reproductive performance, piglet growth and survivability, and colostrum and milk composition. In Exp. 1, mixed parity sows (n = 91) were allotted to 5 experimental treatments arranged in a 2×2 + 1 factorial. Treatments were corn-soybean meal-based diets that contained no added fat or diets with 3% added fat as either beef tallow or soybean oil starting on d 107 or 112 of gestation. Sows were provided low EFA [linoleic acid (LA) and α-linolenic acid (ALA)] in diets without supplemental fat or with beef tallow or high EFA with soybean oil. Results confirmed that providing fat sources with high EFA can increase colostrum and milk LA and ALA content, regardless of pre-farrow time of diet consumption. However, supplemental fat did not influence litter growth performance (P > 0.05). In Exp. 2, mixed parity sows (n = 3,451) were assigned to 4 corn-soybean meal-wheat-based lactation diets with 0.5 (Control) or 3% choice white grease (CWG), 3% soybean oil (SO), or a combination of 3% soybean oil and 2% choice white grease (Combination) at d 112 of gestation to provide diets with low or high EFA. Lactation ADFI increased (P < 0.05) for sows fed the Combination and CWG diets compared with sows fed the Control or SO diet. Sows fed Combination and SO diets had greater (P < 0.05) LA and ALA intake, LA and ALA in colostrum and milk, litter weaning weights, and litter ADG than sows fed 0.5 or 3% CWG. Sow EFA intake did not affect (P > 0.10) piglet survivability or subsequent sow reproductive performance. In conclusion, increased LA and ALA intake provided by SO during lactation increased overall litter growth and weaning weights but did not affect piglet survivability or subsequent performance.

PSIV-17 The Effect of Live Yeast and Yeast Extracts Included in Lactation Diets on Sow and Litter Performance and Antimicrobial Susceptibility of Sow Fecal Escherichia Coli

Eighty sows (Line 241; DNA Genetics) were used to evaluate the effect of feeding live yeast and yeast extracts to lactating sows on sow and litter performance and antimicrobial resistance (AMR) patterns of sow fecal Escherichia coli. Sows were blocked by farrowing group, BW, and parity on d 110 of gestation and allotted to 1 of 2 dietary treatments. Dietary treatments consisted of a standard lactation diet or a diet that contained yeast-based pre- and probiotics (0.10% Actisaf Sc 47 HR+ and 0.025% SafMannan; Phileo by Lesaffre, Milwaukee, WI). Diets were fed from d 110 of gestation until weaning. A tendency (P = 0.073) was observed for increased feed intake through lactation when sows were fed yeast additives compared with the control (5.65 vs 5.90 kg/d). There was no evidence (P > 0.10) that treatment influenced any other sow or litter performance criteria. Fecal samples were collected from the first farrowing group (27 sows) to determine AMR patterns of E. coli upon entry into the farrowing house and at weaning. Microbroth dilution method was used to determine the minimal inhibitory concentrations (MIC) of E. coli isolates to 14 different antimicrobials. An interaction (P = 0.026) of diet × sampling day was observed for cefoxitin where fecal E. coli showed no evidence of treatment differences (P = 0.237) in MIC values at entry, but sows fed the control diet had lower (P = 0.035) MIC values at weaning compared with sows fed yeast additives. There were no diet main effects (P > 0.10) on the AMR of fecal E. coli. There was an increased (P < 0.02) trend towards resistance for 11 of the 14 antimicrobials over time (Table 1). In conclusion, feeding live yeast and yeast extracts tended to increase feed intake during lactation but did not influence sow or litter performance and had minimal impact on AMR of fecal E. coli during lactation.

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100 The Impact of Dietary Analyzed Ca to P Ratios and Standardized Total Tract Digestible P to Net Energy Ratios on Growth Performance, Bone, and Carcass Characteristics of Pigs

A total of 2,184 pigs (initially 12.4 kg) were used to evaluate effects of varying analyzed Ca:P ratios at 2 levels of standardized total tract digestible (STTD) P:NE. Pens of pigs (26 pigs/pen) were assigned to 6 dietary treatments in a randomized complete block design with 14 pens/treatment. Diets consisted of 2 levels of STTD P:NE: PIC recommendation (1.8, 1.62, 1.43, 1.25, 1.10, 0.99 g STTD P/Mcal NE from 11-22, 22-40, 40-58, 58-81, 81-104, 104-129 kg, respectively) or 75% of the PIC recommendation, and 3 analyzed Ca:P ratios: 0.90:1, 1.30:1, and 1.75:1. Diets were corn-soybean meal-based and contained phytase (Quantum Blue G, AB Vista, Marlborough, UK; 500 to 210 FTU/kg with release values from 0.13 to 0.07% STTD P). There was a Ca:P×STTD P:NE interaction (P < 0.05) observed for ADG, G:F and final BW. For ADG and final BW, when feeding 75% of PIC STTD P recommendation, increasing analyzed Ca:P ratio decreased ADG and final BW (linear, P< 0.001). But when feeding at PIC STTD P recommendation, increasing the analyzed Ca:P ratio tended to improve ADG and final BW (linear, P< 0.10). For G:F, when feeding 75% of PIC STTD P recommendation, increasing analyzed Ca:P ratio tended to decrease G:F (linear, P < 0.10), whereas in pigs fed diets that met PIC STTD P recommendations, increasing analyzed Ca:P ratio tended to improve G:F in a quadratic (P < 0.10) manner. Pigs fed at PIC STTD P recommendations had increased ADG, final BW, and G:F compared with pigs fed 75% of PIC STTD P recommendations (P < 0.001). In summary, pigs fed at PIC STTD P recommendations had improved overall ADG and G:F compared with pigs fed diets at 75% PIC STTD P recommendations. Additionally, increasing analyzed Ca:P ratio reduced ADG and G:F when STTD P was below PIC recommendations, but had marginal impacts when adequate STTD P was fed.

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PSI-2 Effect of Gruel Feeding and Oral Dextrose on the Survivability of Pigs After Weaning

Two experiments were conducted using 3,087 (Exp. 1) and 988 (Exp. 2) pigs to determine the effect of gruel feeding (Exp. 1) and oral glucose (Exp. 2) on pig survivability after weaning. Upon arrival to the nursery, the smallest 10% of pigs were selected and randomly placed in designated pens with 61 to 108 pigs/pen. Pens of small pigs were assigned to 1 of 2 treatments in a completely randomized design. Treatment consisted of gruel feeding 2 or 4 times/day for 14-d post-placement. At each gruel feeding, approximately 1.13 kg of solid feed was added to a round Rotecna bowl (Rotecna S.A., Agramunt, Spain) located at the front of the pen. Water was added at a decreasing rate over time. From d 0 to 5, 6 to 10, and 11 to 14 the ratio of water to feed was 3:1, 1:1, and 1:3, respectively. In Exp. 2, every other pig removed from general population or pens of small pigs for welfare considerations received a single 10 mL oral dose of a 50% dextrose solution and were placed in sick/fallback pens. All removed pigs were tagged and blood glucose measured prior to and 30 min after entering sick/fallback pens. Overall, gruel feeding small pigs 2 or 4 times/day for 14-d post-placement did not influence (P > 0.10) mortality from weaning to the end of gruel feeding (3.78 vs 4.25%, respectively). Likewise, dextrose administration did not influence (P > 0.10) pig mortality after removal to approximately d 38 after weaning (21.4 vs 23.4% respectively), even though blood glucose increased (P < 0.001) in those administered dextrose (11.4 vs 19.1 mg/dL). In summary, gruel feeding 4 times/d or providing sick/fallback pigs glucose supplementation does not improve survivability of pigs after weaning. More research is needed using alternative protocols to understand the value of gruel feeding on pig survival post-weaning.

103 Effect of Floor Feeding Creep Feed on the Growth Performance and Morbidity and Mortality of Pigs After Weaning

A total of 264 litters corresponding to 2,497 nursery pigs were used in a 40-d trial to determine the effect of floor feeding pelleted creep feed or lactation feed on the growth performance and morbidity and mortality of pigs after weaning. Treatments were applied in the farrowing house for 4-d prior to weaning and consisted of a control (no creep), standard (0.32 cm) creep pellet, large (1.27 cm) creep pellet, or sow lactation feed in meal form. For each treatment, approximately 227 g of creep feed per day equally divided into 2 feedings was provided on the mat in farrowing stalls. At weaning, pigs were transported to the nursery facility and randomized to pen within creep feeding treatment. A total of 96 pens (48 feeders) were used, with one barrow pen and one gilt pen per feeder. Thus, feeder (2 pens) was the experimental unit. There were 26 pigs per pen and 12 replications per treatment. During week 1 post-weaning, pigs fed standard or large pellet creep feed had increased (P < 0.001) ADG compared with pigs fed sow lactation feed or no creep feed. This was not driven by improved ADFI but rather G:F (P < 0.001). No differences in growth performance were observed throughout the remainder of the nursery period. Overall, on a per pig placed basis, pigs fed large pellet creep feed had increased ADG (P < 0.05) and improved G:F (P < 0.05) compared with pigs fed sow lactation feed, with the other 2 treatments intermediate. This response was a direct reflection of decreased (P < 0.05) total mortality and removals for pigs fed large pellet creep feed. In summary, floor feeding large pellet creep feed starting 4-d preweaning improved nursery pig growth performance and fallout rates compared with creep feeding sow lactation feed, with standard pellet creep feed or no creep feed having an intermediate effect.

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156 Effects of Standardized Ileal Digestible Lysine Level on Growth Performance in 35 to 80 Kg DNA Finishing Pigs

Two studies were conducted to estimate the SID Lys requirement for growth and feed efficiency of 35-80-kg DNA finishing pigs. In Exp. 1, 608 pigs (600 × 241, DNA; initially 36.3±0.91kg) were used to estimate the SID Lys requirement from 35-55-kg. In Exp. 2, 700 pigs (DNA 600×241; initial BW of 53.2±0.86kg) were used to estimate the SID Lys requirement form 50-80-kg. Pens of pigs were blocked by BW and randomly allotted to 1 of 6 dietary treatments with 7-10 pigs/pen in a randomized complete block design with 12 replications per treatment. Diets were corn-soybean meal-based and SID Lys increased by increasing soybean meal and feed-grade amino acids while maintaining minimum ratios for other amino acids. Increasing SID Lys increased (linear, P < 0.05) ADG in both studies. From 50-80-kg, ADFI decreased, then increased (quadratic, P = 0.004) with increasing SID Lys. Feed efficiency improved, while Lys intake/d, and Lys intake/kg of gain increased (linear, P < 0.05, 35-55-kg; quadratic, P < 0.05, 50-80-kg) with increasing SID Lys. At current ingredient and pig prices, there were no statistical differences in income over feed cost (IOFC) from 35-55 kg. From 50-80-kg, increasing SID Lys increased (linear, P < 0.001) IOFC. Linear models resulted in the best fit for ADG, G:F and IOFC from 35-55-kg, with optimum performance at 1.20% SID Lys or greater. A quadratic polynomial model predicted a requirement of 0.97% SID Lys for optimum G:F from 50-80-kg. Meanwhile, a broken-line linear model predicted optimal IOFC at 0.76% SID Lys from 50-80-kg. In summary, these results suggest that the optimal SID Lys level for 35-55-kg DNA finishing pigs is at least 1.20%. The optimal SID Lys level for 50-80-kg DNA finishing pigs depends on the response criteria, with growth performance optimized at or above 0.97% SID Lys and IOFC maximized at 0.76% SID Lys.

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169 The Effect of Increasing Valine, Isoleucine, and Tryptophan:Lysine Ratios on Growth Performance and Carcass Characteristics of Pigs Fed Diets with High Leucine:Lysine

A total of 4,076 pigs (initially 39.3 kg) were used across 2 experiments to evaluate the effect of increasing ratios of Val, Ile, and Trp:Lys in corn-soybean meal-DDGS-based diets on pig growth performance and carcass characteristics. In both experiments, the 4 dietary treatments were: 1) high soybean meal and low feed grade amino acids (control), 2) low soybean meal and high feed grade amino acids, with Val:Lys, Ile:Lys, and Trp:Lys at 67, 55, and 18, respectively, (low ratio) 3) diet 2 except Val:Lys, Ile:Lys, and Trp:Lys increased to 72, 60, and 21, respectively, (medium ratio), and 4) diet 2 except Val:Lys, Ile:Lys, and Trp:Lys at 80, 65, and 23, respectively (high ratio). The Leu:lys levels for the diets with increased synthetic amino acids ranged from 135 to 146 for the 4 phases. All diets contained 30% DDGS until 100 kg BW, and then 20% DDGS until trial completion. Because there was no experiment × treatment interactions, data from both experiments were combined. Overall, ADG and ADFI increased (AA ratio; linear, P < 0.05) as Val, Ile, and Trp:Lys ratios increased from low to high. Pigs fed the control diet exhibited increased ADG compared with pigs fed low ratio diets, while pigs fed medium and high ratio diets performed intermediate. For carcass characteristics, pigs fed the control had increased (P < 0.05) percentage lean and loin depth compared with pigs fed the medium ratio diet, with pigs fed low and high ratio intermediate. Pigs fed the medium ratio diet had increased backfat depth compared with pigs fed the control, with pigs fed the low and high ratio intermediate (P < 0.05). In summary, the soybean meal level can be reduced, and synthetic amino acid levels increased in high DDGS diets as long as ratios of Val, Ile, and Trp to Lys are increased.

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57 Effect of Calcium Carbonate Level with or without Benzoic Acid on Weanling Pig Growth Performance, Fecal Dry Matter, and Blood Ca and P Concentrations

A total of 360 barrows (DNA Line 200×400; initially 6.2 ± 0.03 kg) were used in a 38-d study to evaluate the interactive effects of added dietary calcium carbonate and benzoic acid on nursery pig growth performance, fecal dry matter, and blood Ca and P concentration. Upon arrival to the nursery research facility, pigs were randomly assigned to pens (5 pigs/pen) and pens were allotted to 1 of 6 dietary treatments (12 pens/treatment). Dietary treatments fed from d 0 to 24 were formulated to provide 0.45, 0.90, or 1.35% calcium carbonate with or without 0.5% benzoic acid (VevoVitall, DSM Nutritional Products, Parsippany, NJ). Diets were fed in 3 phases with total Ca of 0.66, 0.83, or 1.00% Ca from d 0 to 10, and 0.54, 0.72, or 0.89% from d 10 to 24. A common diet was fed from d 24 to 38 (0.68% Ca). Serum Ca and P was analyzed on d 21. There were no calcium carbonate×benzoic acid interactions observed for any response criteria (P > 0.10). For the experimental period (d 0 to 24), there was a tendency for benzoic acid to improve ADG (P = 0.056) and ADFI (P = 0.071) with no influence on G:F (P>0.10). Increasing calcium carbonate linearly reduced (P < 0.05) G:F. For serum analysis, serum Ca increased (linear, P < 0.001) as the level of dietary calcium carbonate increased. There were no differences (P > 0.010) in fecal DM. For the overall study (d 0 to 38), pigs fed benzoic acid had increased ADG (P = 0.011) and ADFI (P = 0.030) and marginally improved (P = 0.096) G:F. Calcium carbonate level did not influence overall performance. This data suggests that lower levels of calcium carbonate may improve feed efficiency in early nursey period. Adding benzoic acid to the diet for nursery pigs increased ADG and ADFI, and tended to increase G:F regardless of the calcium carbonate level.

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49 Determining the Phosphorus Release of Grainzyme Phytase in Diets for Nursery Pigs

A total of 360 pigs (Line 200 × 400, DNA, Columbus, NE, initially 9.9 ± 0.19 kg) were used in a 21-d growth study to determine the available P (aP) release curve for GraINzyme phytase (Agrivida Inc., Woburn, MA). Pigs were weaned at approximately 21-d of age, randomly allotted to pens based on initial body weight (BW) and fed common starter diets. From d 18 to 21 post-weaning, all pigs were fed a diet containing 0.11% aP. On d 21 post-weaning, considered d 0 of the study, pens were blocked by BW and randomly allotted to 1 of 8 dietary treatments with 5 pigs/pen and 9 pens/treatment. Dietary treatments were formulated to include increasing aP derived from either an inorganic P source (0.11, 0.19, or 0.27% from monocalcium P) or increasing phytase (150, 250, 500, 1,000, or 1,500 FTU/kg). Diets were corn-soybean meal-based and contained 1.24% standardized ileal digestible (SID) Lys. On d 21 of the trial, 1 pig/pen (weighing closest to the mean pen BW) was euthanized and the right fibula was collected to determine bone ash using the non-defatted processing method. Overall (d 0 to 21), pigs fed increasing aP from inorganic P or phytase had increased (linear, P < 0.002) ADG, ADFI, and G:F (quadratic, P < 0.05). Bone ash weight (g) and percentage bone ash increased (linear, P < 0.001) with increasing inorganic P or added phytase. The release equations developed for GraINzyme for ADG, G:F, bone ash weight, and percentage bone ash are: aP = (0.255 × FTU) ÷ (1,299.969 + FTU), aP = (0.233 × FTU) ÷ (1,236.428 + FTU), aP = (45,999.949 × FTU) ÷ (462,529,200 + FTU), and aP = (0.272 × FTU) ÷ (2,576.581 + FTU), respectively.

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119 A Meta-Regression Analysis to Evaluate the Influence of Branched-Chain Amino Acids in Lactation Diets on Sow and Litter Growth Performance

The branched-chain amino acids (BCAA) Ile, Leu, and Val are 3 dietary essential amino acids for lactating sows; however, effects of dietary BCAA on sow and litter growth performance in the literature are equivocal. Thus, a meta-regression analysis was conducted to evaluate effects of BCAA and their interactions in lactating sow diets to predict litter growth performance, sow bodyweight (BW) change, and sow feed intake. Thirty-four publications representing 43 trials from 1997 to 2020 were used to develop a database that contained 167 observations. Diets for each trial were reformulated using NRC (2012) nutrient loading values in an Excel-based spreadsheet. Amino acids were expressed on a standardized ileal digestible (SID) basis. Regression model equations were developed with the MIXED procedure of SAS (Version 9.4, SAS Institute, Cary, NC), and studies were weighted by the inverse of the squared SEM. Statistically significant (P < 0.05) predictor variables were assessed with a step-wise manual forward selection and required to provide an improvement of at least 2 BIC for model inclusion. Significant predictor variables within 3 equations developed for litter ADG included the count of weaned pigs per litter, dietary concentrations of NE, SID Lys, and CP, sow ADFI, Val:Lys, Ile:Lys, and Leu:Val. For sow BW change, significant predictor variables within 2 developed models included litter size at 24 h, sow ADFI, Leu:Lys, and Ile+Val:Leu. The optimum equation for sow ADFI included Leu:Trp, SID Lys, NE, CP, and Leu:Lys as significant predictor variables. Overall, the prediction equations suggest that BCAA have an important role in litter growth, sow BW change, and feed intake during lactation; however, the influence of BCAA on these criteria is much smaller than that of other dietary components such as NE, SID Lys, sow ADFI, and CP.

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PSIII-19 Effect of Sensory Attractants Before and After Weaning on Nursery Pig Performance

Two experiments were conducted using 48 litters and 711 nursery pigs to determine the effect of a powder sensory attractant (Exp. 1; Baby Pig Restart APF; TechMix Global; Stewart, MN) or enrichment cube (Exp. 2; supersized pellets resembling cattle cubes) pre- and post-weaning on feed intake and growth. Treatments were arranged in a 2x2x2 factorial with main effects of pre-weaning treatment (without/with attractant), post-weaning treatment (without/with attractant), and BW category (light/heavy). Pre-weaning treatments were assigned in a RCBD and post-weaning treatments were assigned in a CRD. Litters receiving attractant pre-weaning were provided 90 g/d of powder, divided into 2 feedings, in the pan of rotary creep feeders (Exp. 1) or 100 g of cubes once daily on the floor of farrowing stalls (Exp. 2) for 4-d prior to weaning. After weaning, pens of pigs that received attractant were offered 45 g/d of powder, divided into 2 feedings/d for 2-d (Exp. 1), or 100 g of cubes once daily (Exp. 2) top-dressed on feed in the feeder pan for 3-d post-weaning. In both experiments, pre- and post-weaning attractant had limited effects on the growth performance of pigs after weaning. In Exp. 1, the percentage of pigs that lost weight 3-d post-weaning decreased by approximately 20 percentage points when pigs were provided powder both pre- and post-weaning compared with the other 3 treatment combinations (P = 0.015). No differences were observed for BW category. In Exp. 2, the percentage of pigs that lost weight 7-d post-weaning decreased by 11.7 percentage points when pigs were offered cubes compared with no cubes (P = 0.002). On d 3, more heavyweight pigs lost weight (P = 0.007) than lightweight pigs; however, this effect was diminished by d 7. In summary, sensory attractants reduced the percentage of pigs that lost weight immediately after weaning which may be due to encouraged activity around the feeder.

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140 Effects of Calcium Carbonate Level on Weanling Pig Growth Performance and Fecal Dry Matter

A total of 695 barrows (DNA 200×400; initially 5.9 ± 0.02 kg) were used in 2 groups in a 28-d study to evaluate the effects of dietary calcium carbonate level on nursery pig growth performance and fecal dry matter. Upon arrival to the research facility, pigs were randomly assigned to pens with 5 pigs/pen, and pens were allotted to 1 of 5 dietary treatments with 27 or 28 pens/treatment. Dietary treatments were formulated to provide 0, 0.45, 0.90, 1.35, and 1.80% calcium carbonate added at the expense of corn, which resulted in total Ca of 0.49, 0.66, 0.84, 1.01 and 1.18%, respectively. All diets were formulated to contain 0.68% total P and 0.59% STTD P. Diets were fed in 2 phases with treatment diets fed from d 0 to 14 and a common diet fed from d 14 to 28. Treatment diets were fed in meal (group 1) and pellet (group 2) form. Feces were collected from 3 pigs/pen and dried to calculate fecal dry matter. There was no evidence for a treatment×group interaction and thus, groups were combined. From d 0 to 14 (treatment period), ADG (P = 0.010), d 14 BW (P = 0.006), and G:F (P = 0.010) decreased linearly as calcium carbonate increased. There was no evidence for a difference in ADFI (P > 0.10) between treatments. For fecal dry matter, there was a tendency for a quadratic response (P = 0.091) with the highest and lowest calcium carbonate diets having the greatest dry matter. Subsequent performance from d 14 to 28 was not influenced by previous treatment (P > 0.10). In summary, increasing dietary calcium carbonate from 0 to 1.80% decreased ADG and G:F in pigs the first 14-d after weaning.

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65 Evaluation of Essential Fatty Acids in Lactating Sow Diets on Sow Reproductive Performance, Colostrum and Milk Composition, and Pre-Weaning Litter Growth and Survivability

Mixed parity sows (n = 3,451; PIC, Hendersonville, TN) and their litters were used to evaluate the effects of essential fatty acid (EFA) intake on sow reproductive performance, piglet growth and survivability, and colostrum and milk composition. At approximately d 112 of gestation, sows were randomly assigned to 1 of 4 corn-soybean meal-wheat-based lactation diets with 0.5 (Control) or 3% choice white grease (CWG), 3% soybean oil (SO), or a combination of 3% soybean oil and 2% choice white grease (Combination). Thus, sows were provided diets with low EFA [linoleic acid (LA) and α-linolenic acid (ALA)] in diets with CWG or high EFA in diets with SO. Lactation ADFI increased (P < 0.05) for sows fed the Combination and CWG diets compared with sows fed the Control or SO diet. Daily LA and ALA intake of sows fed the Combination and SO diets were greater (P < 0.05) than sows fed 0.5 or 3% CWG. Overall, sows consuming high EFA from the Combination or SO diets produced litters with heavier (P < 0.05) piglet weaning weights and greater (P < 0.05) litter ADG when compared with litters from sows fed diets with low EFA provided through CWG. There was no effect of sow EFA intake on piglet survivability (P > 0.10). Lactation diet EFA concentration did not influence colostrum or milk dry matter, crude protein, or crude fat content (P>0.10). However, LA and ALA content in colostrum and milk at weaning increased (P < 0.05) in response to elevated dietary EFA from SO. There was no evidence for differences (P > 0.10) in subsequent sow reproductive or litter performance due to previous lactation EFA intake. In conclusion, increased LA and ALA intake provided by SO during lactation increased overall litter growth and pig weaning weights but did not affect piglet survivability or subsequent performance.

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PSIV-13 Effects of Increasing Dietary Alpha-Linolenic Acid on Nursery Pig Growth Performance and Response to Immune Challenge

A total of 350 weanling pigs (Line 241 × 600, DNA; initially 5.8 ± 0.1 lb BW) were used in a 41-d study to evaluate growth performance and immune response of nursery pigs fed diets containing increasing levels of O3 Trial Feed, a source of omega-3 fatty acids (alpha-linolenic acid). At weaning, pigs were randomly assigned to 1 of 5 dietary treatments in a completely randomized design with 5 pigs per pen and 14 replications per treatment. The dietary treatments included increasing percentages of O3 Trial Feed (0, 1, 2, 3, and 4%). Omega-6:3 ratios for the 5 treatments within each phase were: Phase 1 (27.3:1, 11.6:1, 7.4:1, 5.4:1, 4.3:1); Phase 2 (23.0:1, 9.6:1, 6.1:1, 4.5:1, 3.6:1); and Phase 3 (24.4:1, 10.2:1, 6.5:1, 4.8:1, 3.8:1), respectively. On d 25, two pigs per pen were injected with 20 µg of Escherichia coli (E. coli) lipopolysaccharide (LPS) per kg BW and 1 pig per pen was injected with saline to serve as a control. Body temperature was recorded from the 3 pigs per pen prior to the injection (hour 0) and 2, 4, 6, and 12 h after injection. On d 25 a blood sample was collected 4 h post injection from pigs injected with the LPS challenge to determine IL-1β levels in serum. For overall growth performance, there were no differences observed in ADG, ADFI, or G:F (P > 0.05). Temperature increased at 2 h post LPS injection, then decreased as time from the LPS injection increased (main effect of time, P < 0.0001). Dietary treatment did not influence change in body temperature or IL-1β (P > 0.05). In this study, dietary alpha-linolenic acid levels did not influence growth performance or immune response to a LPS challenge.

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PSIV-20 The Effect of Live Yeast and Yeast Extracts Included in Lactation and Nursery Diets on Nursery Pig Fecal Antimicrobial Resistance

A 45-d study used 340 weaned pigs (Line 241×600, DNA) to evaluate yeast additives in sow diets and yeast-based pre- and probiotics (Phileo by Lesaffre, Milwaukee, WI) in nursery diets on antimicrobial resistance (AMR) of fecal Escherichia coli. At weaning, pigs were penned based on sow diet and randomly assigned to 2 treatments with 5 pigs/pen and 17 pens/treatment. Treatments were a 2×2 factorial of sow treatment (control vs. yeast-based pre- and probiotic diet; 0.10% ActiSaf Sc47HR+ and 0.025% SafMannan) and nursery treatment (control vs. yeast-based pre- and probiotic diet; 0.10% ActiSaf Sc47HR+, 0.05% SafMannan, and 0.05% NucleoSaf from d 0-7, then levels reduced 50% from d 7-24). A common diet was fed from d 24-45. Microbroth dilutions were used to determine minimum inhibitory concentrations (MIC) of E. coli isolates to 14 antimicrobials. A 3-way interaction of sow treatment×nursery treatment×sampling day was observed (P < 0.05) for ciprofloxacin, gentamicin, sulfisoxazole, and trimethoprim/sulfamethoxazole (Table 1). For ciprofloxacin, MIC was reduced (P = 0.044) on d 45 for the yeast-fed sow, yeast-fed nursery group compared with pigs from the yeast-fed sow, control-fed nursery group. The MIC values for the yeast-fed sow, yeast-fed nursery treatment were greater (P = 0.021) for gentamicin on d 5 but less (P = 0.018) than on d 24 compared with the yeast-fed sow, control-fed nursery treatment. On d 45, progeny of the control sows fed yeast in the nursery had less (P = 0.005) MIC to sulfisoxazole than control-fed sow, control-fed nursery treatment. Fecal E. coli had decreased (P = 0.004) MIC on d 5 to trimethoprim/sulfamethoxazole from the control-fed sow, yeast-fed nursery treatment compared with the control-fed sow, control-fed nursery treatment. All fecal E. coli isolates were susceptible to all antimicrobials except tetracycline on d 5. In conclusion, feeding sows live yeast and yeast extracts impacted fecal E. coli AMR in their progeny and this impact depends on nursery diet and post-weaning sampling day.

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114 Evaluation of Selenium Source on Nursery Pig Growth Performance, Serum and Tissue Selenium Concentrations, and Serum Antioxidant Status

A total of 3,888 pigs (337×1050, PIC, Hendersonville, TN; 6.0 kg at weaning) were used in a 42-d study to determine the influence of Se source on nursery pig selenium status and growth performance. At placement, pens of pigs were weighed and allotted to 1 of 3 dietary treatments in a randomized complete block design with blocking structure including sow farm origin, date of entry, and average pen BW. A total of 144 pens were used with 72 double-sided 5-hole stainless steel, fence-line feeders, with feeder serving as the experimental unit. For each feeder, 1 pen contained 27 gilts and the other 27 barrows. There were 24 replicates per treatment. Diets were fed in 3 phases, and all contained 0.3 ppm added Se. A common phase 1 diet contained added Se from sodium selenite and was fed in pelleted form to all pigs for 7 d prior to initiation of treatment diets. Three Se sources [sodium selenite; Se yeast; and hydroxy-selenomethionine (OH-SeMet)] were used to formulate 3 experimental treatments in meal form for phase 2 (d 7 to 21) and phase 3 (d 21 to 42). During the common phase 1 period, ADFI tended (P < 0.10) to be different (107, 103, and 102 g/d) for sodium selenite, Se yeast, and OH-SeMet, respectively. From d 7 to 42 (treatment period), pigs fed OH-SeMet tended to have decreased ADG (P < 0.10) and had increased (P < 0.05) serum, liver, and muscle selenium concentration compared with other treatments. There was no difference (P > 0.05) in antioxidant status as measured by serum GSH-Px or TBARS. In summary, compared with sodium selenite and selenium yeast, OH-SeMet had greater bioavailability as indicated by increased serum and tissue selenium concentration; however, antioxidant status was similar between treatments and OH-SeMet tended to reduce growth performance compared with pigs fed sodium selenite.

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148 Use of an Alpha-Linolenic Acid Source to Reduce Omega-6:3 Ratio in Prrs-Virus Challenged Nursery Pigs

A total of 1,056 pigs [PIC TR4 × (Fast LW × PIC L02)], originating from an active PRRSV-positive sow farm, were used in a 46-d study to evaluate growth performance and mortality and removals of nursery pigs. Pigs were fed diets containing increasing levels of O3 Trial Feed (NBO3, Manhattan KS), a source of omega-3 fatty acids (alpha-linolenic acid). At placement in the nursery, pens of pigs were randomly assigned 1 of 4 dietary treatments in a completely randomized design with 22 pigs per pen and 12 replications per treatment. The dietary treatments included increasing percentages of O3 Trial Feed (0, 0.75, 1.5, and 3%). Omega-6:3 ratios for the 4 treatments within each phase were: Phase 1 (15.1:1, 8.4:1, 5.9:1, 3.7:1); Phase 2 (16.5:1, 9.2:1, 6.4:1, 4.0:1); Phase 3 (20.8:1, 10.4:1, 7.0:1, 4.2:1); and Phase 4 (25.3:1, 12.5:1, 8.3:1, 5.0:1), respectively. Pigs remained on treatments throughout the 4 dietary phases over the 46-d study. Overall, pigs fed increased O3 Trial Feed had increased (linear, P < 0.001) ADG, ADFI and G:F. The greatest impact on growth due to dietary treatment began when pigs tested positive for PRRSV during week 3 of the study. This was confirmed by testing oral fluids, collected on a weekly basis, for PRRSV using a PCR test. Pigs fed increasing O3 Trial Feed also had decreased (linear, P = 0.027) total removals and mortalities. In summary, adding O3 Trial Feed to reduce the Omega 6-3 ratio improved growth performance and reduced mortality in nursery pigs with an active PRRSV challenge.

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PSIII-18 Effect of Increasing L-Lysine-HCl and Amino Acid Ratios on Performance of Finishing Pigs from 109 to 129 Kg

A total of 1,789 pigs (PIC; 337×1050; initial BW 108.9 ± 1.14 kg) were used to determine the effects of increasing L-Lys-HCl and AA ratios on performance of late finishing pigs fed corn-soybean meal diets without DDGS. The study used 2 groups of pigs and each study lasted 18 and 27 d, respectively. Pigs were housed in mixed gender pens with 20 to 25 pigs/pen and 19 replications/treatment (10 and 9 replications/group, respectively). Pens of pigs were blocked by BW and randomly allotted to 1 of 4 dietary treatments. Treatment diets were formulated to 0.70% digestible Lys and consisted of low, medium, or high levels of feed-grade AA and moderate or high AA ratios relative to Lys. Low, medium and high feed-grade AA treatments had increased L-Lys-HCl (0.15, 0.30 and 0.39%) replacing soybean meal to achieve CP levels of 13.6, 12.0, and 11.0. Minimum AA:Lys ratios were 53% Ile, 128% Leu, 58% Met&Cys, 66% Thr, 18.5% Trp, 68% Val, and 34% His in Moderate AA ratio diets and 60% Ile, 128% Leu, 60% Met&Cys, 70% Thr, 21.2% Trp, 72% Val, and 33% His for the high AA ratio treatment. Overall, there was a marginally significant increase in ADFI (quadratic, P = 0.097) observed in pigs fed medium feed-grade AA and moderate AA ratios. Treatment diets had no effect on ADG or G:F. At the end of group 2, carcass data was collected with no differences (P > 0.10) observed for HCW, carcass yield, backfat depth, loin depth or percentage lean. In summary, differing levels of feed-grade AA and AA ratios used in this study did not impact growth performance or carcass characteristics of late finishing pigs with the exception of a marginally significant increase in ADFI.

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PSVI-10 Evaluation of Vegetable Protein Sources on Nursery Pig Performance in a Commercial Environment

This experiment was conducted to evaluate the influence of vegetable protein sources on growth performance of nursery pigs in a commercial research environment. A total of 2,592 pigs (L337 × 1050, PIC; initial BW of 5.3 ± 0.05 kg) were used in a 42-d study. Pens of pigs were blocked by BW and weaning date and allotted to 1 of 6 dietary treatments in a randomized complete block design with 27 pigs/pen and 16 replications/treatment. A corn-soybean meal control diet with no specialty vegetable protein source was used to compare performance against 5 diets containing either 1 of 2 soy protein concentrates (XSoy 600; CJ America-Bio, Downers Grove, IL; 5.0 and 2.5%, phase 1 and 2, respectively or Soytide; CJ America-Bio, Downers Grove, IL; 5.5 and 2.75%, phase 1 and 2, respectively), enzyme-treated soybean meal (HP 300; Hamlet Protein, Findlay, OH; 5.7 and 2.83%, phase 1 and 2, respectively), fermented soybean meal (Fermex 200; Purina Animal Nutrition, Shoreview, MN; 6.7 and 3.35%, phase 1 and 2, respectively), or high-protein corn DDGs (NexPro; Poet, Wichita, KS; 7.5 and 3.75%, phase 1 and 2, respectively). Diets were formulated in 2 dietary phases and fed at 2.27 kg/pig and 8.16 kg/pig, respectively, with a common phase 3 diet fed until d 42. The dietary level of soybean meal was held constant within phases 1 and 2 for diets 2 to 5 with protein sources replaced on a digestible lysine basis. During the experimental diet period (d 0 to 21) or overall (d 0 to 42), there was no evidence of difference (P > 0.05) for ADG, ADFI or G:F. Additionally, there was no evidence of difference (P > 0.05) for total removals, and mortality. In summary, none of the protein sources evaluated improved growth performance relative to soybean meal.

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A meta-regression analysis to evaluate the influence of branched-chain amino acids in lactation diets on sow and litter growth performance

The branched-chain amino acids (BCAA) Ile, Leu, and Val are three dietary essential amino acids for lactating sows; however, effects of dietary BCAA on sow and litter growth performance in the literature are equivocal. Thus, a meta-regression analysis was conducted to evaluate the effects of BCAA and their interactions in lactating sow diets to predict litter growth performance, sow bodyweight change, and sow feed intake. Thirty-four publications that represented 43 trials from 1997 to 2020 were used to develop a database that contained 167 observations. Diets for each trial were reformulated using NRC. 2012. Nutrient requirements of swine. 11th ed. Washington, DC: National Academies Press nutrient loading values in an Excel-based spreadsheet. Amino acids were expressed on a standardized ileal digestible (SID) basis. Regression model equations were developed with the MIXED procedure of SAS (Version 9.4, SAS Institute, Cary, NC) and utilized the inverse of reported squared SEM with the WEIGHT statement to account for heterogeneous errors across studies. Predictor variables were assessed with a step-wise manual forward selection for model inclusion. Additionally, statistically significant (P < 0.05) predictor variables were required to provide an improvement of at least 2 Bayesian information criterion units to be included in the final model. Significant predictor variables within three optimum equations developed for litter ADG included the count of weaned pigs per litter, NE, SID Lys, CP, sow ADFI, Val:Lys, Ile:Lys, and Leu:Val. For sow BW change, significant predictor variables within two developed models included litter size at 24 h, sow ADFI, Leu:Lys, and Ile + Val:Leu. The optimum equation for sow ADFI included Leu:Trp, SID Lys, NE, CP, and Leu:Lys as significant predictor variables. Overall, the prediction equations suggest that BCAA play an important role in litter growth, sow BW change, and feed intake during lactation; however, the influence of BCAA on these criteria is much smaller than that of other dietary components such as NE, SID Lys, sow ADFI, and CP.

Inoculation of Weaned Pigs by Feed, Water, and Airborne Transmission of Salmonella enterica Serotype 4,[5],12:i:

ABSTRACT

Salmonella enterica serotype 4,[5],12:i:- (STM) has become an increasing problem for food safety and has been often detected in swine products. Weanling pigs were exposed to STM-contaminated feed, water, or air to determine possible STM transmission routes. A control group of pigs was included. STM was monitored daily in feces and rectal and nasal swabs. STM colonization was most prevalent in tissues from tonsil, lower intestine, and mesenteric lymph nodes. No differences in lesion severity were observed between inoculated and control pigs. Contaminated feed, water, and aerosolized particles caused infection in weaned pigs; however, no STM colonization was observed in skeletal muscle destined for human consumption. Based on the results from this study, STM contamination in pork products most likely results from cross-contamination of meat by digesta or lymph node tissue during processing.

HIGHLIGHTS

A review of branched-chain amino acids in lactation diets on sow and litter growth performance

Branched-chain amino acids (BCAA) are three essential amino acids (AA) for lactating sows; however, the effects of dietary Leu, Val, and Ile on sow and litter performance within the literature is equivocal. The BCAA are structurally similar and share the first steps of their catabolism pathway where Leu, Val, and Ile are transaminated through BCAA aminotransferase and irreversibly decarboxylated by the branched-chain α-ketoacid dehydrogenase complex. Although these steps are shared among BCAA, Leu is recognized as the primary stimulator due to Leu’s greater affinity towards the enzymes compared to Val and Ile. Since the late 1990’s, sows are producing larger and heavier litters and generally consume diets with greater concentrations of Leu and crystalline AA, which may create imbalances among dietary BCAA. Research conducted with growing-finishing pigs confirms that high concentrations of Leu can impair BCAA utilization and growth performance. However, the effects of BCAA on lactating sow and litter performance are not as clearly understood. Within mammary tissue, BCAA uptake is greater than milk output of BCAA since Val, Ile, and Leu are catabolized to form non-essential AA, lactose, fatty acids, and other metabolites. Within the mammary gland, BCAA aminotransferase activity is much higher than within skeletal muscle, liver, or small intestine. Thus, competition among the BCAA, namely between Leu and Val, can significantly inhibit Val uptake within mammary tissue. Therefore, dietary modifications that mitigate BCAA competition may positively influence Val utilization for colostrum and milk synthesis. Little data exists on Ile and Leu requirements for modern lactating sows. Although Val requirements have been extensively researched in the last 25 years, an ideal Val:Lys has not been consistently established across experiments. Some studies concluded that total Val concentrations above 120% of Lys optimized performance whereas others determined that increasing SID Val:Lys from 55 to 136% did not improve piglet growth performance. Although increasing dietary Val positively influences fat and protein composition of colostrum and milk, litter growth during lactation is not always positively affected. Given the competition among BCAA for utilization within mammary tissue, research evaluating the Leu and Ile requirement of modern lactating sows is warranted to fully understand the influence and interactions of BCAA on reproductive and litter growth performance.

Using caloric efficiency to estimate the net energy value of expelled, extruded soybean meal relative to dehulled, solvent-extracted soybean meal and its effects on growth performance of nursery pigs

This study aimed to estimate the net energy (NE) value of expelled, extruded soybean meal (MSBM) relative to dehulled, solvent-extracted soybean meal (SSBM) and determine its effects on growth performance of late nursery pigs. A total of 297 pigs (DNA 241 × 600) were weaned (BW 5.10 kg) and placed into 60 pens (2 rooms of 30 pens) with 5 pigs per pen balanced by gender and weaning weight. Pigs were fed a common diet for 21 d. Then, pens of pigs (BW 9.3 kg) were randomly assigned to one of five treatments to provide 12 replications per treatment. Treatments consisted of increasing amounts of MSBM replacing SSBM in the diet (0%, 25%, 50%, 75%, and 100%). All diets were fed for 28 d and were formulated to 1.30% standardized ileal digestible lysine and met or exceeded requirements for amino acids, calcium, and phosphorus. The SSBM diet was formulated to 2,421 kcal/kg and NE was not balanced between diets. Analyzed values for CP, EE, CF, and total lysine for the SSBM were 47.28%, 0.47%, 3.80%, and 3.00%, whereas the MSBM contained 47.41%, 6.88%, 5.32%, and 2.99%, respectively. The MSBM had increased values for KOH solubility and trypsin inhibitor (83.62% and 7,026 TIU/g) compared to the SSBM (73.05% and 3,011 TIU/g), whereas urease activity was similar between the two (0.03 and 0.02 Δ pH, respectively). Data were analyzed using Proc GLIMMIX (SAS 9.4; Cary, NC) with pen as the experimental unit and room as the blocking factor. There was no evidence of differences in ADG and ADFI in pigs fed diets with increasing concentrations of MSBM. Pigs fed diets with increasing concentrations of MSBM had improved (linear, P < 0.001) G:F and caloric efficiency on an NE basis. Using caloric efficiency to estimate NE of the MSBM relative to SSBM, MSBM was estimated to have a value of 2,566 kcal/kg. In conclusion, MSBM contains approximately 123% of the energy of SSBM, which improved feed efficiency when fed to nursery pigs.

Assessment of soy-based imports into the United States and associated foreign animal disease status

Soy-based products are known to pose a viable risk to U.S. swine herds because of their ability to harbour and transmit virus. This publication aimed to evaluate soy imports into the United States as a whole and from foreign animal disease positive (FAD-positive) countries to determine which products are being imported in the highest quantities and observe potential trends in imports from FAD-positive countries. Import data were accessed through the United States International Trade Commission website (USITC DataWeb) and summarized using R (version 4.0.2, R core team, Vienna, Austria). Twenty-one different Harmonized Tariff Schedule (HTS) codes were queried to determine quantities (metric tonnes, MT) and breakdown of different soy product types being imported into the United States from 2015 to 2020. A total of 78 different countries exported soy products to the United States in 2019 and 2020 with top contributors being Canada (546,467 and 481,497 MT, respectively), India (397,858 and 430,621 MT, respectively) and Argentina (122,116 and 79,471 MT, respectively). Soy oilcake (582,273 MT) was imported in the largest quantities, followed by organic soybeans (270,194 MT) and soy oil (134,436 MT) for 2020. Of the 78 countries, 46 had cases of FAD reported through the World Organization for Animal Health (OIE) World Animal Health Information Database (WAHIS). Top exporters of soy products to the United States from FAD-positive countries in 2019 and 2020 were India (397,858 and 430,621 MT, respectively), Argentina (122,116 MT in 2019) and Ukraine (40,293 and 56,392 MT, respectively). The risk of FAD introduction to the United States through soy imports can fluctuate based on where FAD outbreaks are occurring, shipping methods and end usage of products. A system to monitor these factors could help make future decisions about trade and risk of FAD introduction to U.S. swine herds.

Effect of fiber source and crude protein level on nursery pig performance and fecal microbial communities

Reduction in dietary crude protein and addition of fiber could mitigate the incidence and severity of post-weaning diarrhea, a common gastrointestinal condition in newly weaned pigs. Therefore, 360 weanling pigs, initially 5.0 ± 0.10 kg, were used to evaluate the effects of crude protein (CP) level and fiber source on growth performance and fecal microbial communities. At weaning, pigs were randomly assigned to pens and allotted to 1 of 8 dietary treatments in a 2 × 4 factorial with main effects of CP (21 or 18%) and fiber source (none, coarse wheat bran, oat hulls, or cellulose). There were 5 pigs per pen and 9 pens per treatment. Experimental diets were formulated in two dietary phases from d 0 to 10 and 10 to 24, with a common post-treatment diet fed from 24 to 45. The 21% CP diets contained 1.40% standardized ileal digestible (SID) Lys in phase 1 and 1.35% SID Lys in phase 2. By using a maximum SID Lys:digestible CP ratio of 6.35%, the 18% CP diets contained 1.25% SID Lys in both phases. Diets containing a fiber source were formulated to the level of insoluble fiber provided by 4% coarse wheat bran, resulting in the addition of 1.85% oat hulls and 1.55% cellulose. No fiber source × CP level interactions (P > 0.05) were observed. Decreasing CP (and subsequently SID lysine) decreased (P = 0.05) ADG and G:F during the experimental period. From d 0 to 45, ADG decreased (P = 0.05) for pigs fed 18% CP diets compared to pigs fed 21% CP. No effect of fiber source was observed for growth performance. Fecal DM on d 17 increased (P < 0.001) for pigs fed 18% CP diets compared to pigs fed 21% CP diets. Pigs fed diets with added cellulose had increased (P < 0.05) fecal dry matter during the experimental period compared to pigs fed no fiber source or wheat bran. Bacterial community structure was investigated by sequencing the V4 region of the 16S rRNA gene. Analysis indicated a significant difference between CP content at d 24 (P = 0.023) using a Weighted UniFrac distance matrix. Further investigation identified five differential Amplicon Sequence Variants associated with CP content at d 24. In conclusion, reducing crude protein (and subsequently SID Lys) decreased growth performance but increased fecal dry matter content. The source of dietary fiber in nursery diets had no impact on growth performance; but pigs fed added cellulose had increased fecal DM compared with other treatments. Microbial analysis identified differential taxa associated with CP content.

Maintaining continuity of nutrient intake after weaning. II. Review of post-weaning strategies

Low feed consumption during the first 3 d post-weaning disrupts nutrient intake and results in what is commonly known as a post-weaning growth check. While most pigs recover from this initial reduction in feed intake (FI), some pigs fail to successfully make this transition leading to morbidity and mortality. In this review, our objective is to describe the different post-weaning strategies that can be used to minimize nutrient intake disruption and improve FI in the immediate post-weaning period. Providing weanling pigs with an environment that encourages them to search out and consume feed is important. This includes appropriate barn temperatures, resource availability, and nursery placement strategies. Research is needed to better understand the ideal environmental temperatures to encourage pen exploration and reduce time to initial FI. Likewise, mat and gruel feeding are commonly practiced throughout the industry to increase feed accessibility; however, limited research data is available to validate protocols or benefits. Nursery placement strategies include sorting light weight pigs into uniform body weight groups and average or heavy weight pigs into variable body weight groups to provide benefit to light pigs while reducing initial aggression in heavy pigs. Furthermore, water enrichment with nutrient dense products have been shown to improve growth performance and reduce morbidity and mortality in the early post-weaning period. Because young pigs are sensitive to palatability, diet form and complexity should also be considered. Weanling pigs prefer diets manufactured with coarse ground corn (700 μm) compared to fine ground corn. Additionally, weanling pigs are more attracted to large diameter pellets (12 mm) compared with small pellets. Despite these preferences, impacts on growth are relatively small. Feeding complex diets with high levels of lactose, animal protein products, or other palatable ingredients is another strategy shown to improve growth performance during the first week post-weaning; however, the initial benefits quickly diminished as pigs become older. Other strategies that warrant further investigation include the effect of crumble diets on feed preference and the concept of perinatal or social interaction flavor learning. In summary, strategic post-weaning nutrition and management practices must focus on maintaining continuity of nutrient intake in order to reduce morbidity and mortality in the immediate post-weaning period.

Evaluation of microencapsulated organic acids and botanicals on growth performance of nursery and growing-finishing pigs

A total of 1,215 pigs (L337 × 1050, PIC, Hendersonville, TN) were used to determine the effect of microencapsulated organic acids and botanicals (MOB; AviPlus; Vetagro, Inc. Chicago, IL), on growth performance from weaning to market. Pigs were weaned at approximately 21 d of age and placed in pens based on initial body weight (BW) with 27 pigs per pen in a randomized complete block design. During the 42-d nursery period, pigs were allotted to one of two treatments in an unbalanced treatment structure with 15 pens (replications) fed the control diet and 30 pens (replications) fed diets containing 0.30% MOB from days 0 to 21 and 0.10% from days 21 to 42. On day 42, pigs were transported as intact pens from the nursery to the finishing facility. During the finishing period, three treatments were applied which included: 1) pigs on the control diet in nursery remained on control diets; 2) 50% of pigs provided MOB in nursery were then fed 0.05% MOB throughout finishing, and 3) 50% of pigs provided MOB in nursery were then fed the control diet throughout finishing. All pens of pigs on treatments 2 and 3 were allotted based on ending nursery BW to the finishing treatment. There were 15 replications per treatment in the finishing period. From days 0 to 21, pigs fed diets with MOB had a tendency for increased (P < 0.058) gain:feed (G:F) when compared to pigs fed the control diet; however, there was no evidence of difference (P > 0.05) for average daily gain (ADG), average daily feed intake (ADFI), or day 21 BW. From days 21 to 42, there was no evidence of difference (P > 0.05) for ADG, ADFI, or G:F. For the overall nursery period (days 0 to 42), pigs fed diets with MOB had increased (P < 0.05) G:F (660 vs. 670 g/kg) when compared with pigs fed the control diet, but there was no evidence of difference (P > 0.05) for day 42 BW, ADG, or ADFI between treatments. From d 42 to 106, there was no evidence of difference (P > 0.05) for ADG, ADFI, and G:F. For the overall finishing period (days 42 to 156) and overall experimental period (days 0 to 156), there was no evidence of difference (P > 0.05) for BW, ADG, ADFI, or G:F. For mortality and removals, there was no evidence of difference (P > 0.05) observed during the nursery, finishing, or overall. In summary, providing MOB during the nursery phase increased G:F in the early and overall nursery phase, but there was no effect on overall wean-to-finish performance.

Live yeast and yeast extracts with and without pharmacological levels of zinc on nursery pig growth performance and antimicrobial susceptibilities of fecal Escherichia coli

A total of 360 weanling barrows (Line 200 ×400, DNA, Columbus NE; initially 5.6 ± 0.03 kg) were used in a 42-d study to evaluate yeast-based pre- and probiotics (Phileo by Lesaffre, Milwaukee, WI) in diets with or without pharmacological levels of Zn on growth performance and antimicrobial resistance (AMR) patterns of fecal Escherichia coli. Pens were assigned to 1 of 4 dietary treatments with 5 pigs per pen and 18 pens per treatment. Dietary treatments were arranged in a 2 × 2 factorial with main effects of yeast-based pre- and probiotics (none vs. 0.10% ActiSaf Sc 47 HR+, 0.05% SafMannan, and 0.05% NucleoSaf from d 0 to 7, then concentrations were lowered by 50% from d 7 to 21) and pharmacological levels of Zn (110 vs. 3,000 mg/kg from d 0 to 7, and 2,000 mg/kg from d 7 to 21 with added Zn provided by ZnO). All pigs were fed a common diet from d 21 to 42 post-weaning. There were no yeast ×Zn interactions or effects from yeast additives observed on any response criteria. From d 0 to 21, and 0 to 42, pigs fed pharmacological levels of Zn had increased (P < 0.001) ADG and ADFI. Fecal samples were collected on d 4, 21, and 42 from the same three pigs per pen for fecal dry matter (DM) and AMR patterns of E. coli. On d 4, pigs fed pharmacological levels of Zn had greater fecal DM (P = 0.043); however, no differences were observed on d 21 or 42. E. coli was isolated from fecal samples and the microbroth dilution method was used to determine the minimal inhibitory concentrations (MIC) of E. coli isolates to 14 different antimicrobials. Isolates were categorized as either susceptible, intermediate, or resistant based on Clinical and Laboratory Standards Institute (CLSI) guidelines. The addition of pharmacological levels of Zn had a tendency (P = 0.051) to increase the MIC values of ciprofloxacin; however, these MIC values were still well under the CLSI classified resistant breakpoint for Ciprofloxacin. There was no evidence for differences (P > 0.10) for yeast additives or Zn for AMR of fecal E. coli isolates to any of the remaining antibiotics. In conclusion, pharmacological levels of Zn improved ADG, ADFI, and all isolates were classified as susceptible to ciprofloxacin although the MIC of fecal E. coli tended to be increased. Thus, the short-term use of pharmacological levels of Zn did not increase antimicrobial resistance. There was no response observed from live yeast and yeast extracts for any of the growth, fecal DM, or AMR of fecal E. coli criteria.

Influence of Enogen Feed corn and conventional yellow dent corn in pelleted or meal-based diets on finishing pig performance and carcass characteristics

Genetic modification of corn has enhanced the use of different corn hybrids in animal agriculture. Enogen Feed corn, developed by Syngenta Seeds (Downers Grove, IL), has potential for use in livestock diets due to increase α-amylase enzyme in the corn thus improving starch digestibility. In addition, the pelleting process also increases starch gelatinization which increases its digestibility by the pig, increasing growth rate and improving feed efficiency. Therefore, pelleting Enogen Feed corn might prove to provide a greater response in growth performance than conventional yellow dent corn. Thus, the objective of this experiment was to determine the effects of corn source and diet form on growth performance and carcass characteristics of finishing pigs. A total of 288 pigs (53.0 ± 0.5 kg) were used with eight pigs per pen and nine pens per treatment in a 72-d study. Treatments were arranged in a 2 × 2 factorial with main effects of corn source (Enogen Feed corn or conventional yellow dent corn) and diet form (meal or pellet). For overall (d 0 to 72) performance, no interactions between corn source and diet form were observed. There was a tendency (P < 0.10) for slightly improved average daily gain (ADG) and gain:feed ratio (G:F) for pigs fed conventional yellow dent corn compared to those fed Enogen Feed corn. For feed form, pigs fed pelleted diets had increased (P < 0.001) ADG and G:F compared to pigs fed meal diets. For carcass characteristics, pigs fed pelleted diets had increased hot carcass weight compared to pigs fed meal diets (P < 0.001). In summary, feeding pelleted diets to finishing pigs increased ADG and improved feed efficiency compared to those fed meal-based diets. There were no major differences between observed corn sources or interactions between corn source and diet form on growth performance.

The effects of pharmacological levels of zinc, diet acidification, and dietary crude protein on growth performance in nursery pigs

This experiment was conducted to evaluate potential replacements for pharmacological levels of Zn (provided by Zn oxide), such as diet acidification (sodium diformate) and low dietary crude protein (CP: 21 vs 18%) on nursery pig performance and fecal dry matter (DM). A total of 360 weaned pigs (Line 200 × 400, DNA, Columbus, NE; initially 5.90 ± 0.014 kg) were used in a 42-d growth study. Pigs were weaned at approximately 21 d of age and randomly assigned to pens (five pigs per pen). Pens were then allotted to one of eight dietary treatments with nine pens per treatment. Experimental diets were fed in two phases: phase 1 from weaning to day 7 and phase 2 from days 7 to 21, with all pigs fed the same common diet from days 21 to 42. The eight treatment diets were arranged as a 2 × 2 × 2 factorial with main effects of Zn (110 mg/kg from days 0 to 21 or 3,000 mg/kg from days 0 to 7, and 2,000 mg/kg from days 7 to 21), diet acidification, (without or with 1.2% sodium diformate), and dietary CP (21% or 18%, 1.40% and 1.35% in phases 1 and 2 vs. 1.20% standardized ileal digestible Lys, respectively). Fecal samples were collected weekly from the same three pigs per pen to determine DM content. No 2- or 3-way interactions (P > 0.05) were observed throughout the 42-d study for growth performance; however, there was a Zn × acidifier × CP interaction (P < 0.05) for fecal DM on day 7 and for the overall average of the six collection periods. Reducing CP without acidification or pharmacological levels of Zn increased fecal DM, but CP had little effect when ZnO was present in the diet. From days 0 to 21, significant (P < 0.05) main effects were observed where average daily gain (ADG) and gain:feed (G:F) increased for pigs fed pharmacological levels of Zn, sodium diformate, or 21% CP (P < 0.065). In the subsequent period (days 21 to 42) after the experimental diets were fed, there was no evidence of difference in growth performance among treatments. Overall (days 0 to 42), main effect tendencies were observed (P < 0.066) for pigs fed added Zn or sodium diformate from days 0 to 21, whereas pigs fed 21% CP had greater G:F than those fed 18% CP. Pig weight on day 42 was increased by adding Zn (P < 0.05) or acidifier (P < 0.06) but not CP. In summary, none of the feed additives had a major influence on fecal DM, but dietary addition of pharmacological levels of Zn or sodium diformate independently improved nursery pig performance.

Sampling and detection of African swine fever virus within a feed manufacturing and swine production system

Transmission of biological hazards capable of causing disease in livestock can occur through a wide variety of direct and indirect routes. In swine production, there are a large number of possible routes of exposure of a pathogen into a susceptible population. African swine fever virus (ASFV) has been a significant challenge for Southeast Asia since first detected in China in 2018 and has spread through many countries within the region. In order to understand potential transmission pathways within an ASFV endemic region, a diagnostic investigation was performed to determine the level of contamination on a wide variety of surface types within a live animal production, feed manufacturing, and feed distribution system located in Vietnam. All diagnostic testing was performed locally by the production system's internal diagnostic laboratory using real‐time polymerase chain reaction (rt‐PCR) analysis. Early in the diagnostic investigation, it became clear that feed trucks were a common site of ASFV surface contamination detection. This information resulted in biosecurity‐focused actions for feed trucks arriving back at the feed mill, including decontamination of interior truck cab surfaces and washing of exterior truck surfaces with high‐pressure water prior to application of surface disinfectants. Additionally, a low number of rt‐PCR positive samples were detected within the feed production system, with the greatest number coming from transient surfaces such as high traffic areas and worker clothing. This illustrates the importance of managing employee traffic through procedures such as zoning and separation between clean–dirty areas to reduce the likelihood of pathogen transmission. In conclusion, this report illustrates the importance of routine data capture regarding efficacy of biosecurity procedures which allows for real‐time updates and improvement as biosecurity gaps are identified.

Effect of cleaning corn on mycotoxin concentration and nursery pig growth performance

Mycotoxins are naturally produced hazards that result from molds grown on cereal grains and other commodities. These molds may produce carcinogenic mycotoxins, which can be harmful to humans and animals. Removing broken kernels has been demonstrated to reduce mycotoxin concentration, but with high variability. Therefore, two experiments were conducted to quantify the magnitude of natural mycotoxin concentration that may be reduced by cleaning corn. Two loads of corn that were naturally contaminated with mycotoxins were procured. Corn for Experiment 1 was contaminated with aflatoxin (1,074 parts per billion; ppb), fumonisin (8.3 parts per million; ppm), and ochratoxin A (206 ppb), while corn for Experiment 2 was contaminated with only fumonisin (5.5 ppm). Corn was cleaned by mechanical sieving. For each experiment, corn was divided into twenty 150 kg runs. Runs were randomly assigned to 1 of 4 experimental treatments: 1) no screen 2) 12.7 mm screen, 3) 4.8 mm screen, and 4) 12.7 + 4.8-mm screen. The corn cleaner was sanitized between runs. Three 5 kg corn samples were collected from each run, and analyzed for mycotoxin concentration. In Experiment 1, cleaning reduced (P < 0.05) aflatoxin and fumonisin concentration by an average of 26% and 45%, respectively, compared to the original uncleaned corn level, but did not impact (P > 0.10) ochratoxin A. The resultant screenings had nearly four times the aflatoxin (4,224 ppb) and 7.5 times the fumonisin concentration (60.4 ppm) as the uncleaned corn. In Experiment 2, cleaning reduced (P < 0.05) fumonisin concentration by 32%. The resultant screenings had 19.6 times the fumonisin concentration (65.4 ppm) as the uncleaned corn. To determine the effect that cleaning corn may have on nursery pig growth performance, 360 nursery pigs were used in Experiment 3 to evaluate the impact of cleaning or pelleting on growth performance. Treatments were arranged in a 2 × 3 factorial with corn type (uncleaned vs. cleaned) and feed form (mash vs. pelleted from either mill A or B). Neither cleaning corn nor pellet mill type affected (P > 0.19) nursery pig growth performance. Pelleting improved (P < 0.0001) gain to feed ratio (G:F) by 7.6% compared to mash diets. These data suggest that cleaning is an effective method to legally reduce aflatoxin and fumonisin concentration, but does not impact animal growth performance. Screenings should be used cautiously when feeding to animals.

Using environmental sampling to evaluate the effectiveness of decontamination methods to reduce detection of porcine epidemic diarrhea virus RNA on feed manufacturing surfaces

Porcine epidemic diarrhea virus (PEDV) is a possible biological hazard in feed mills. If the virus enters a feed mill, it becomes widely distributed and is difficult to decontaminate from both feed contact and non-feed contact surfaces. The objective of this study was to evaluate a variety of liquid and dry decontamination treatments that could be used to reduce the amount of PEDV found on feed manufacturing surfaces. This experiment was designed as a 5 × 10 factorial with five different feed manufacturing surfaces and 10 decontamination treatments with three replicates of each combination. Surfaces included stainless steel, solid polyethylene, woven polypropylene tote bag, rubber, and sealed concrete coupons. One mL (1×10⁵ TCID₅₀/mL) of stock PEDV was applied to each surface and allowed to dry completely for 60 min. Next, for decontamination requiring surface application, the application was performed and allowed 15 min contact time. The quantity of PEDV RNA was determined using quantitative reverse transcription PCR. A decontamination treatment × surface interaction was observed (P < 0.0001), indicating the efficacy of treatment is dependent upon the surface in which it is applied. Within the cement surfaces, the sodium hypochlorite resulted in the greatest (P < 0.05) cycle threshold (Ct) value, followed by formaldehyde which had a greater (P < 0.05) Ct value compared to remaining treatments. Within polyethylene, rubber, and stainless steel surfaces, the formaldehyde treated surfaces had the greatest Ct values (P < 0.05), followed by the sodium hypochlorite treatment, with other treatments all having lower Ct values (P < 0.05). For the woven polyethylene surfaces, the formaldehyde and sodium hypochlorite treatments had greater Ct values compared to all other treatments (P < 0.05). Additional research is necessary to identify the role of decontamination treatment on PEDV infectivity and develop methods for decontamination of feed manufacturing facilities.

The influence of particle size of Enogen Feed corn and conventional yellow dent corn on nursery and finishing pig performance, carcass characteristics and stomach morphology

Enogen Feed corn is a variety developed by Syngenta Seeds (Downers Grove, IL) that has been genetically modified to contain an α-amylase enzyme trait (SYT-EFC). Originally, Enogen feed corn was developed for the ethanol industry due to its reduction in viscosity of the corn mash, thus eliminating the need to add a liquid form of the α-amylase enzyme. However, there is a potential application for Enogen Feed corn to be used in livestock diets due to the increase in α-amylase enzyme potential to increase starch digestibility. A more common method of increasing starch digestibility in corn is to finely grind it to reduce particle size. This increases the surface area and allows for greater interaction with digestive enzymes. We hypothesized that pigs fed Enogen feed corn potentially could achieve similar gain:feed ratio (G:F) at larger particle sizes than conventional corn because of the differences in starch digestibility. In experiment 1, a total of 360 pigs (DNA 200 × 400, Columbus, NE; initially 6.6 ± 0.1 kg BW) were used with five pigs per pen and 12 pens per treatment. Treatments were arranged in a 2 × 3 factorial with main effects of corn source (Enogen Feed corn or conventional yellow dent corn) and ground corn particle size (300, 600, or 900 µm). Overall, there was a corn source × particle size interaction (linear, P = 0.027) for G:F. There was no effect due to particle size when pigs were fed conventional yellow dent corn, but in pigs fed Enogen Feed corn, G:F increased with decreasing particle size. Neither corn source nor particle size affected (P > 0.05) overall average daily gain (ADG) or average daily feed intake (ADFI). In experiment 2, a total of 323 pigs (241 × 600; DNA, Columbus, NE; initially 50.0 ± 1.3 kg) were used with nine pigs per pen and six pens per treatment. Treatments were identical as experiement 1. Overall, corn source had no effect on finishing pig ADG, ADFI or G:F. For corn particle size, ADG and G:F increased (linear, P < 0.014) and ADFI decreased (P = 0.043) as particle size decreased. For stomach morphology, there was a tendency for a corn source × particle size interaction (P = 0.055) for keratinization score with keratinization increasing linearly (P = 0.001) as particle size of the corn decreased for yellow dent corn with no change in keratinization score as particle size decreased for Enogen Feed corn. In summary, reducing corn particle size improved G:F with no major differences observed between corn sources for overall pig performance.