Zinc has been very efficacious in reducing post-weaning diarrhea, whereas animal-derived peptides are suggested to improve the growth performance of weaned piglets. However, the combined effect of zinc and peptides on swine production and swine gut microbiota is still largely unknown. In this study, we followed 288 nursery pigs from the age of d30 to d60 to evaluate the growth performance and gut microbiota of weanling pigs subjected to different levels of a fish-porcine-microbial peptide cocktail (0.05%, 0.25%, and 0.5%) with or without the pharmaceutical level of zinc oxide (ZnO) (2500 ppm) supplementation in a nutrient-deficient diet. Rectal swab samples were collected from pigs with body weight (BW) approach average at each pen on d30, d42, and d60 to determine gut microbiota. Average daily gain (ADG) and BW in piglets fed high zinc (HZ) increased with increasing levels of peptide. The microbiota of the HZ group also diverged from those of the standard zinc (SZ) group from d30 to d60. Adding peptide did not alter community structure regardless of zinc supplementation. Collectively, these findings demonstrated that the pharmaceutical level of zinc as ZnO conditioned the gut community to the point where peptide could effectively restore growth performance in nursery pigs fed nutrient-deficient diets.

Feed additives have been suggested to improve animal growth performance through modulating the gut microbiota. The hypothesis of this study was that the combination of two organic acids would exert synergistic effects on the growth performance and gut microbiota of weaning pigs. To test this hypothesis, we followed 398 weaning pigs from two university experiment stations (University of Illinois at Urbana-Champaign (UIUC) and University of Arkansas (UA)) to determine the effects of increasing levels (0%, 0.035%, 0.070%, and 0.105%) of sodium butyrate combined with 0.5% benzoic acid on the growth performance of nursery pigs. At the UA, an additional negative control diet was included and the gut microbiota analysis was carried out. At both universities, increasing levels of sodium butyrate in a diet containing 0.5% benzoic acid improved growth performance, which reached a plateau in the pigs fed 0.035% (SBA0.035) or 0.070% (SBA0.070) butyrate. Gut microbiota analysis revealed that pigs fed the SBA0.035 diet had more diverse microbiota and contained more potentially beneficial bacteria such as Oscillospira, Blautia, and Turicibacter and reduced levels of Veillonella and Sarcina. Results of the present study indicated that the inclusion of sodium butyrate at moderate levels in a diet containing 0.5% benzoic acid improved growth performance of weaning pigs and established potential health benefits on gut microbiota.

To evaluate the effect of bioactive peptide (P) in combination with high level of zinc (HZ) or acidifiers on growth performance, complete blood cell counts (CBC) and nutrient digestibility in nursery pigs, a total of 288 weaned pigs (PIC1050xDNA600) were stratified by initial BW within gender and allotted to 1of 7 treatments. Treatments for phase 1&2 were: 1) nutrient adequate positive control with HZ (PC), 2) nutrient deficient negative control with HZ (NC, -0.13% SID Lysine by reducing fish meal), 3) NC+0.25% peptide (0.25PZ), 4) NC+0.5% peptide (0.5PZ), 5) NC+0.25% peptide with standard zinc (0.25P), 6) NC+0.5% peptide with standard zinc (0.5P), 7) as 5 + 0.1% sodium butyrate and 0.5% benzoic acid (PSB). All pigs were fed a common low Zn diet (197 ppm) during phase 3. The whole blood was obtained from a close-to-average pen-BW pig repeatedly at weaning, and at the end of phase 2 and 3 to determine CBC. Titanium dioxide was used as an indigestible marker to determine nutrient digestibility. Data were analyzed using the Mixed procedures of SAS as a RCBD with treatment as fixed effect, and BW block as random effect. In overall phase 1&2, pigs fed PSB had similar ADG and BW when compared to pigs fed 0.25PZ and both were greater than NC pigs (Table 1). With the same inclusion rate of peptide, pigs fed a high zinc diet had greater BW and ADG than pigs fed a standard zinc diet. PSB pigs had the greatest G:F ratio and nitrogen digestibility among treatments. Increasing peptide in high zinc diets gradually decreased Neutrophil-to-lymphocyte ratio. This study indicates that the improvement in growth performance from pigs fed peptide is pharmaceutical zinc dependent and acidifiers can be an alternative to replace ZnO without affecting growth performance.

A total of 344 weaned pigs (21 ± 2 d of age) were used at University of Arkansas (UA, n = 2 16) and University of Illinois at Urbana-Champaign (UIUC, n = 128) to evaluate increasing level of sodium butyrate (SB) on growth performance and complete blood cell count. Pigs at each facility were blocked by initial BW and randomly allotted to 1 of 4 dietary treatments with 9 replications/diet and 6 pigs/pen at UA; and 8 replications/diet and 4 pigs/pen at UIUC. Treatments included a control corn-soybean-meal based diet and 3 diets in which 0.05, 0.10, or 0.15% SB was added to the control diet. Feed was manufactured at each facility. Pigs were fed in 3 phases: 7 d, 14 d, and 14 d at UIUC and 7 d, 14 d, and 19 d at UA for phase 1, 2, and 3, respectively. At UA, blood was collected at the beginning of the experiment and at the end of each phase to determine complete blood cell count. Data for growth performance for both facilities were pooled and analysed as a RCBD using the Mixed procedure of SAS. Treatment was the fixed effect, and facility and facility by treatment interactions were random effects. Orthogonal contrasts were used to assess linear and quadratic responses to inclusion of increasing levels of SB in diets. Increasing dietary SB increased weight gain (quadratic, P < 0.05), ADFI (quadratic, P ≤ 0.05), and final BW (quadratic, P < 0.05). Total white blood cell and eosinophil cell count tended to increase with increasing SB (quadratic, P = 0.07 and P = 0.08, respectively). The lymphocyte cell count tended to decrease (linear, P = 0.09) with increasing SB. Results indicated that feeding SB during the nursery phase tended to alter blood cell count and improve growth performance.

A total of 270 weaned pigs (21-d age) were used to evaluate the effects of administering benzoic acid (BA) alone or with sodium butyrate (SB) on nutrient digestibility, fecal VFA concentrations and growth performance. At weaning (age 21-d), pigs were blocked by initial BW (4.7 ± 0.21 kg) and allotted to 1 of 5 treatments with 9 replicate pens per treatment. Pigs remained on the same treatment through three feeding phases: Phase 1 (d 0-7), Phase 2 (d 7-21), and Phase 3 (d 21-40). The treatments were the Control diet without acidifier (C), C with 0.5% BA, and BA with 0.05%, 0.1% or 0.15% of SB to form SBA0.05, SBA0.1, and SBA0.15, respectively. Titanium dioxide was added in phase 3 diets (d21-40). Diets were fed in meal form and sampled at manufacturing and pen fecal samples were collected for two consecutive days at the end (d40). Samples were analyzed for the concentration of DM, GE, N, ash, NDF, ADF, calcium, and phosphorus and the ATTD for each nutrient was calculated. Additionally, fecal VFAs were quantified via gas chromatographic technique. Data were analyzed using Mixed procedure of SAS, with treatment as a fixed effect and initial BW block as a random effect. Level of sodium butyrate was used in IML procedure to generate coefficients for orthogonal contrast for BA, SBA0.05, SBA0.1, and SBA0.15. In feces, absolute butyrate (mM) and total VFA (mM) tended (P&lt; 0.10) to increase quadratically with increasing SB supplementation. Similar to G:F ratio, pigs fed the BA diet had higher ATTD of DM, GE, N, ash, NDF, ADF, and P than pigs fed other treatments. Results suggest that the mechanism on improving growth performance differs among acidifiers.