H. E. Williams

Effects of dietary supplementation of formaldehyde and crystalline amino acids on gut microbial composition of nursery pigs

Formaldehyde-based feed additives are approved in the US for Salmonella control and reducing bacterial contamination in animal feed. However, we hypothesize formaldehyde inclusion in swine diets may influence gut microbial composition due to its antimicrobial properties which might negatively influence microbial populations and pig growth performance. Also, formaldehyde inclusion in diets is known to reduce the dietary availability of amino acids. Therefore, our study was conducted to characterize if the effects of feed formaldehyde-treatment are due to influences on microbial population or diet amino acid (AA) sources. Dietary treatments were arranged in a (2 × 2) + 1 factorial with formaldehyde treatment (none vs. 1000 ppm formaldehyde) and crystalline AA inclusion (low vs. high) with deficient AA content plus a positive control diet to contain adequate AA content without dietary formaldehyde. Treating diets with formaldehyde reduced growth rate (P = 0.001) while the AA inclusion had no evidence of impact. Formaldehyde reduced feed bacterial content and altered fecal microbial communities (P < 0.05). Therefore, we conclude that the negative influence on growth was due to the impact on the fecal microbial community. Implications are that strategies for feed pathogen control need to take into account potential negative impacts on the gut microbial community.

Effects of chlortetracycline alone or in combination with direct fed microbials on nursery pig growth performance and antimicrobial resistance of fecal Escherichia coli1

A total of 300 nursery pigs (initially 5.9 ± 0.05 kg BW) were used in a 42-d growth trial to evaluate the effects of feeding a therapeutic level of chlortetracycline (CTC) with or without direct fed microbials (DFM) on growth performance and antimicrobial resistance (AMR) of fecal Escherichia coli. CTC is a broad-spectrum in-feed antibiotic commonly used in the swine industry. Weaned pigs (~21 d of age) were allotted to pens based on initial BW and fed a common starter diet for 4 d. Pens were then blocked by BW and allotted to dietary treatments in a completely randomized block design. Dietary treatments were arranged in a 2 × 3 factorial consisting of combinations of CTC (none vs. 400 mg/kg from days 0 to 42) and DFM (0 vs. 0.05% DFM 1 vs. 0.05% DFM 2). Fecal samples were collected from three randomly selected pigs from each pen on days 0, 21, and 42 for E. coli isolation and AMR determination. Overall, pigs fed diets containing CTC had improved (P < 0.001) ADG, ADFI, and BW compared to those not fed CTC with no evidence for any effect of either DFM 1 or DFM 2. Regardless of CTC, inclusion of DFM 2 in diets improved (P < 0.05) ADFI from days 0 to 14 and on day 14 BW compared to diets that did not include DFM 2. The addition of CTC with or without DFMs to nursery pig diets increased (P < 0.05) the probability of AMR to tetracycline and ceftiofur of fecal E. coli isolates, but this resistance generally decreased (P < 0.05) over time. A decrease (P < 0.05) in AMR to ampicillin and tetracycline (TET) throughout the trial was observed, while resistance to ceftriaxone decreased (P < 0.020) from days 0 to 21 and increased from days 21 to 42 amongst dietary treatments regardless of CTC or DFM inclusion in the diet. A CTC × DFM × day interaction (P < 0.015) was observed for streptomycin, whereby from days 21 to 42 AMR increased in diets containing either CTC or DFM 1 alone, but the combination decreased resistance. There was no evidence for any effect of DFMs on AMR of fecal E. coli isolates to any other antibiotics evaluated. In conclusion, therapeutic levels of added CTC with or without DFM inclusion improved nursery pig performance, but increased AMR of fecal E. coli isolates to TET and ceftiofur. A moderate improvement in intake and day 14 BW was observed when DFM 2 was included in the diet with or without CTC, but, except for streptomycin, there was no evidence that added dietary DFMs affected resistance of fecal E. coli to antibiotics.

Evaluation of Elarom SES with or without Tri-basic Copper Chloride on Nursery Pig Growth Performance

A total of 360 weanling pigs (DNA 200 × 400; initially 11.5 lb BW) were used in a 42-d study evaluating the effects of feeding Elarom SES in combination with increasing tri-basic copper chloride on nursery pig performance and fecal consistency. Elarom SES (Trouw Nutrition USA, Highland, IL) is a specialty feed ingredient containing a blend of active ingredients designed to enhance growth performance and gut health. Tri-basic copper chloride (TBCC, Intellibond C, Micronutrients USA, LLC., Indianapolis, IN) is a form of copper (Cu) that has the potential for improved bioavailability and enhanced growth performance. Pigs were weaned at approximately 21 d and allotted to pens based on initial BW in a completely randomized design. Experimental diets were fed in 3 phases (phase 1, d 0 to 7; phase 2, d 7 to 21; and phase 3, d 21 to 42 post-weaning) in meal form. Experimental treatments were arranged as a 2 × 3 factorial with main effects of Elarom SES (none vs. 0.2% in all phases) and TBCC (none, 108, or 183 ppm of Cu in phase 3 only). Fecal consistency was determined by visual appraisal of pen floors on d 0, 4,7, 14, 21, 28, 35, and 42 on a scale from 1-5. A score of 1 indicated hard, pellet type feces and a score of 5 indicated watery, liquid feces. Overall, there was no evidence for treatment differences observed for ADG, ADFI, or fecal consistency; however, a tendency for an Elarom SES × TBCC interaction was observed for F/G (quadratic, P = 0.061). This was the result of F/G improving at the intermediate level of TBCC without Elarom SES, yet F/G was improved at the highest level of TBCC when Elarom SES was present. Overall, no consistent benefit was observed from feeding Elarom SES or different levels of TBCC on growth performance or fecal consistency of weaned pigs.

Impact of Added Copper and Chlortetracycline on Growth Performance of Nursery Pigs

A total of 320 nursery pigs (DNA 200 × 400 barrows; initially 16.3 lb BW) were used in a 28-d trial to determine the effect of copper (Cu) and chlortetracycline (CTC), fed alone or in combination, on growth performance of weanling pigs. Pigs were weaned at approximately 21 d of age and fed a common pelleted starter diet (non-medicated) for 7 d after weaning. Pigs were allotted to dietary treatments based on BW and location in a randomized complete block design. Dietary treatments were arranged as a 2 × 2 factorial with main effects of added Cu (0 vs. 200 ppm Cu from copper sulfate) and CTC (0 vs. 440 ppm CTC). Experimental diets were corn-soybean meal-based and were fed in one phase for 28 d in meal form. There were 5 pigs per pen and 8 replications per treatment with each replication consisting of a pair of adjoining pens. The results showed no evidence for an interactive effect of Cu and CTC for any of the performance and economic variables (P > 0.05). From d 0 to 14, added Cu increased (P < 0.05) ADG and ADFI and added CTC improved (P < 0.05) ADG, ADFI, and F/G. From d 14 to 28, the addition of CTC to the diet improved (P < 0.05) ADG and ADFI, but there was no evidence for a Cu effect. For the overall experimental period (d 0 to 28), pigs fed diets with CTC had improved (P < 0.05) ADG, ADFI, and F/G, but there was no evidence for a Cu effect. The inclusion of either Cu or CTC increased (P < 0.05) BW on d 14 and 28. Regarding the economics, added dietary Cu increased (P < 0.05) feed cost per pig and value of gain per pig, but not income over feed cost (IOFC). The addition of CTC to the diet increased (P < 0.05) feed cost per pig, value of gain per pig, and IOFC. In conclusion, the findings of the present study characterize a beneficial effect of feeding Cu for 14 d on growth performance of young pigs (16 to 25 lb) and a positive effect of including CTC in nursery diets. The lack of interactive effects between Cu and CTC suggests that the responses of Cu and CTC on growth performance of nursery pigs are as efficacious when fed alone or in combination.

Effects of Crystalline Amino Acid Concentrations With or Without Formaldehyde Treatment of Diets on Nursery Pig Growth Performance and Fecal Bacterial Concentration

A total of 1,235 nursery pigs (PIC 359 × 1050; initially 26.9 lb BW) were used in a 28-d study evaluating the effects of crystalline amino acid concentrations with or without formaldehyde treatment of diets on nursery pig growth performance, feed bacteria concentration, lysine content, and fecal microbial diversity. Sal CURB (Kemin Industries Inc., Des Moines, IA) is a commercial formaldehyde product that is commonly utilized in the poultry industry for Salmonella control in feed but has also been shown to reduce PEDV infectivity in swine diets. Pigs were weaned at approximately 21 d, fed a common starter diet for 10 d, and allotted to pens based on BW in a completely randomized design. Experimental diets were fed in 2 phases (phase 1, d 0 to 12; and phase 2, 12 to 28 post-weaning) in meal form. Experimental treatments were arranged as a 2 × 2 + 1 factorial with main effects of formaldehyde (none vs. 0.30% in all phases) and crystalline AA concentration (low vs. high) plus a positive control. The positive control represented this current production system’s formulated Lys requirement needed to maximize performance, whereas treatment diets were formulated at 80% of the positive control’s lysine concentration. Feed bacterial concentration was determined by performing aerobic plate, Enterobacteriaceae, and total coliform counts on composited feed samples collected from each batch of feed manufactured at the feed mill and directly from feeders at the farm. Total, available, and free Lys analyses were conducted on composited feed samples collected from each phase of the study to determine Lys content. A composite fecal sample was collected from 3 randomly selected pigs per pen on d 28 for each treatment, DNA isolated, and each sample assessed for bacterial community analysis. Overall, a significant crystalline AA × formaldehyde interaction (P < 0.05) was observed for ADFI and F/G. The interaction for ADFI was because added formaldehyde in high crystalline AA diets decreased feed intake; however, in low crystalline AA diets, ADFI was unchanged. For F/G, pigs had improved F/G in low crystalline AA diets without formaldehyde, but no difference was observed in high crystalline AA diets. Despite the interaction for ADFI and F/G, formaldehyde-treated diets reduced (P < 0.05) ADG, ADFI, and resulted in poorer F/G. Crystalline AA concentration did not impact performance. Added formaldehyde reduced or eliminated bacterial concentration of complete feed in phase 1 of the study. Formaldehyde reduced total and available Lys in both low and high crystalline AA diets, with a greater reduction occurring in low crystalline AA diets, but had no effect on free Lys. Added formaldehyde reduced (P = 0.001) Lactobacillaceae bacterial species, but increased (P = 0.001) Clostridiaceae bacterial species in fecal microbial samples. As expected, formaldehyde treatment reduced bacterial microflora of complete feeds. Overall, the level of crystalline AA did not impact performance while the nursery diet formaldehyde addition negatively influenced growth performance, AA utilization, and fecal microbial diversity.

Effects of Evosure on Nursery Pig Performance

A total of 360 pigs (PIC C-29 × 359, initially 13.1 lb BW) were used in a 42-d growth trial evaluating the effects of Evosure on nursery pig performance. Evosure is a yeastbased technology designed to enhance weaned pig performance. Pigs were weaned at approximately 16 to 20 d and allotted to pens based on initial BW and gender in a completely randomized design. The 3 dietary treatments included a control diet, or the control diet with Evosure (NUTRIQUEST, Inc., Mason City, IA) fed at 1.0 lb/ton fed from d 0 to 21 followed by 0.5 lb/ton fed from d 21 to 42, or 1.0 lb/ton fed from d 0 to 42. Experimental diets were fed in 3 phases (Phase 1, d 0 to 7; Phase 2, d 7 to 21; and Phase 3, d 21 to 42 post-weaning) and in meal form. Overall (d 0 to 42), no differences in growth performance or final BW were observed among dietary treatments. In conclusion, under these experimental conditions, added Evosure, regardless of level, did not impact nursery pig performance.

Effects of Increasing Salt Concentration for 15 to 22 lb Nursery Pigs

A total of 325 maternal line barrows (Line 200 × 400; DNA, Columbus, NE; initially 14.6 lb BW) were used in a 14-d growth trial to determine the optimal inclusion rate of dietary salt for growth performance of nursery pigs weighing approximately 15 to 22 lb. Upon entry of the nursery, pigs were allotted by BW and fed a common starter diet (6 lb/ton added salt and 25% dried whey) for 7 d after weaning. At d 7 after weaning, considered d 0 in the trial, pigs were allotted by pen weight and assigned to 1 of 5 dietary treatments. Treatments included a diet containing 10% dried whey with no added salt, or 4, 8, 12, and 16 lb/ton of added salt. A common Phase 3 diet, containing 7 lb/ton added salt, was then fed from d 14 to d 21. From d 0 to 14, increasing salt increased (linear, P < 0.015) ADG and ADFI. Feed efficiency improved (quadratic, P < 0.034) as added salt increased from 0 to 12 lb with no further benefits observed thereafter. From d 14 to 21, when pigs were fed a common Phase 3 diet (7 lb/ton added salt), those previously fed no added salt had 20% greater ADG (linear, P < 0.013) than those previously fed 4 to 16 lb added salt. The compensatory ADG observed from d 14 to 21 resulted in no overall differences in ADG, ADFI, or F/G from d 0 to 21. In conclusion, it appears that 12 lb/ton of added salt in a diet containing 10% dried whey optimizes ADG, ADFI, and F/G in 15 to 22 lb nursery pigs.

Determination of Probiotic and/or Chlortetracycline Inclusion Effects on Nursery Pig Growth Performance

A total of 300 nursery pigs (DNA 200 × 400, Columbus, NE; initially 13.0 lb BW) were used in a 42-d study evaluating the effects of feeding chlortetracycline (CTC) in combination with probiotics on nursery pig performance. Probiotics are a class of antimicrobial alternatives designed to enhance growth performance and digestive tract health. Pigs were weaned at approximately 21 d of age and allotted to pens based on initial BW. Pigs were fed a common pelleted starter diet for 4 d and then weighed, and pens were allotted to 1 of 6 dietary treatments based on BW in a completely randomized design. The treatments were arranged in a 2 × 3 factorial with main effects of chlortetracycline (0 vs. CTC at 400 g/ ton from d 0 to 42) and probiotic (0 vs. 1 lb/ton Bioplus 2B (Chr. Hansen USA, Inc., Milwaukee, WI)) vs. 1 lb/ton Poultry Star (Biomin America, Inc., San Antonio, TX). Experimental diets were fed in 2 phases (Phase 1: d 0 to 14 and Phase 2: d 14 to 42) and fed in meal form. On d 14 and 28, CTC was removed from the diet according to FDA regulations. For overall performance, there were no interactions (P > 0.05) between added probiotics and CTC. However, pigs fed CTC had improved (P < 0.001) ADG, ADFI, and overall BW compared with those fed diets without CTC. While adding Poultry Star to the diet increased (P < 0.05) BW and ADFI on d 14, there were no consistent benefits of feeding either probiotic alone or in combination with CTC.