Polymerase Chain Reaction-Based Prevalence of Serogroups of Escherichia coli Known to Carry Shiga Toxin Genes in Feces of Finisher Pigs.

Shiga toxin-producing Escherichia coli (STEC) are major foodborne pathogens and seven serogroups, O26, O45, O103, O111, O121, O145, and O157, that account for the majority of the STEC-associated illness in humans. Similar to cattle, swine also harbor STEC and shed them in the feces and can be a source of human STEC infections. Information on the prevalence of STEC in swine feces is limited. Therefore, our objective was to utilize polymerase chain reaction (PCR) assays to determine prevalence of major virulence genes and serogroups of STEC. Fecal samples (n = 598), collected from finisher pigs within 3 weeks before marketing in 10 pig flows located in 8 states, were included in the study. Samples enriched in E. coli broth were subjected to a real-time PCR assay targeting three virulence genes, Shiga toxin 1 (stx1), Shiga toxin 2 (stx2), and intimin (eae), which encode for Shiga toxins 1 and 2, and intimin, respectively. A novel PCR assay was designed and validated to detect serogroups, O8, O20, O59, O86, O91, O100, O120, and O174, previously reported to be commonly present in swine feces. In addition, enriched fecal samples positive for Shiga toxin genes were subjected to a multiplex PCR assay targeting O26, O45, O103, O104, O111, O121, O145, and O157 serogroups implicated in human clinical infections. Of the 598 fecal samples tested by real-time PCR, 25.9%, 65.1%, and 67% were positive for stx1, stx2, and eae, respectively. The novel eight-plex PCR assay indicated the predominant prevalence of O8 (88.6%), O86 (35.5%), O174 (24.1%), O100 (20.2%), and O91 (15.6%) serogroups. Among the seven serogroups relevant to human infections, three serogroups, O121 (17.6%), O157 (14%), and O26 (11%) were predominant. PCR-based detection indicated high prevalence of Shiga toxin genes and serogroups that are known to carry Shiga toxin genes, including serogroups commonly prevalent in cattle feces and implicated in human infections and in edema disease in swine.

Effects of Tylosin Administration Routes on the Prevalence of Antimicrobial Resistance Among Fecal Enterococci of Finishing Swine.

Antibiotics can be administered orally or parenterally in swine production, which may influence antimicrobial resistance (AMR) development in gut bacteria. A total of 40 barrows and 40 gilts were used to determine the effects of tylosin administration route on growth performance and fecal enterococcal AMR. The antibiotic treatments followed Food and Drug Administration label directions and were as follows: (1) no antibiotic (CON), (2) 110 mg tylosin per kg feed for 21 d (IN-FEED), (3) 8.82 mg tylosin per kg body weight through intramuscular injection twice daily for the first 3 d of each week for 3 weeks (IM), and (4) 66 mg tylosin per liter of drinking water (IN-WATER). Antibiotics were administered during d 0 to 21 and all pigs were then fed the CON diet from d 21 to 35. Fecal samples were collected on d 0, 21, and 35. Antimicrobial susceptibility was determined by microbroth dilution method. No evidence of route × sex interaction (p > 0.55) was observed for growth performance. From d 0 to 21, pigs receiving CON and IN-FEED had greater (p < 0.05) average daily gain (ADG) than those receiving IM, with the IN-WATER group showing intermediate ADG. Pigs receiving CON had greater (p < 0.05) gain-to-feed ratio (G:F) than IM and IN-WATER, but were not different from pigs receiving IN-FEED. Overall, enterococcal isolates collected from pigs receiving IN-FEED or IM were more resistant (p < 0.05) to erythromycin and tylosin than CON and IN-WATER groups. Regardless of administration route, the estimated probability of AMR to these two antibiotics was greater on d 21 and 35 than on d 0. In summary, IM tylosin decreased ADG and G:F in finishing pigs, which may be because of a response to the handling during injection administration. Tylosin administration through injection and feed resulted in greater probability of enterococcal AMR to erythromycin and tylosin compared with in-water treatment.

Nasal carriage of mecA-positive methicillin-resistant Staphylococcus aureus in pigs exhibits dose-response to zinc supplementation.

Zinc (Zn) is often supplemented at elevated concentrations in swine diets, particularly in piglets, to prevent enteric infections and promote growth. Previous studies from Denmark have suggested a genetic linkage and a phenotypic association between Zn resistance, encoded by czrC, and methicillin-resistance conferred by mecA in Staphylococcus aureus. Such an association has not been reported in the U.S. swine population. We conducted an analysis of the effects of Zn, supplemented as zinc oxide (ZnO), on the nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) in nursery (n=40) and finisher pigs (n=40) enrolled in a nutritional study. Nasal swabs, collected from nursery and finisher pigs, were inoculated onto MRSA CHROMagar and presumptive MRSA colonies were tested for the presence of mecA and czrC genes by polymerase chain reaction. Zinc susceptibility was determined by the agar dilution method. The prevalence of mecA-positive MRSA was 10% (4/40) and 20% (8/40) among nursery and finisher pigs, respectively. Of the 12 mecA-positive S. aureus isolates, 7 had the czrC gene (58.3%) compared to none among the 68 mecA-negative isolates. The presence of both mecA (p=0.002) and czrC (p=0.006) genes were positively associated with higher levels of Zn supplementation. The median minimum inhibitory concentrations of Zn for czrC-positive and czrC-negative isolates were 12 and 2 mM, respectively (p<0.0001). The link between czrC and mecA genes suggests the importance of elevated Zn supplementation in the co-selection and propagation of methicillin resistance among S. aureus in pigs.

Effects of In-Feed Copper, Chlortetracycline, and Tylosin on the Prevalence of Transferable Copper Resistance Gene, tcrB, Among Fecal Enterococci of Weaned Piglets.

Heavy metals, such as copper, are increasingly supplemented in swine diets as an alternative to antibiotics to promote growth. Enterococci, a common gut commensal, acquire plasmid-borne, transferable copper resistance (tcrB) gene-mediated resistance to copper. The plasmid also carried resistance genes to tetracyclines and macrolides. The potential genetic link between copper and antibiotic resistance suggests that copper supplementation may exert a selection pressure for antimicrobial resistance. Therefore, a longitudinal study was conducted to investigate the effects of in-feed copper, chlortetracycline, and tylosin alone or in combination on the selection and co-selection of antimicrobial-resistant enterococci. The study included 240 weaned piglets assigned randomly to 6 dietary treatment groups: control, copper, chlortetracycline, tylosin, copper and chlortetracycline, and copper and tylosin. Feces were collected before (day 0), during (days 7, 14, 21), and after (days 28 and 35) initiating treatment, and enterococcal isolates were obtained from each fecal sample and tested for genotypic and phenotypic resistance to copper and antibiotics. A total of 2592 enterococcal isolates were tested for tcrB by polymerase chain reaction. The overall prevalence of tcrB-positive enterococci was 14.3% (372/2592). Among the tcrB-positive isolates, 331 were Enterococcus faecium and 41 were E. faecalis. All tcrB-positive isolates contained both erm(B) and tet(M) genes. The median minimum inhibitory concentration of copper for tcrB-negative and tcrB-positive enterococci was 6 and 18 mM, respectively. The majority of isolates (95/100) were resistant to multiple antibiotics. In conclusion, supplementing copper or antibiotics alone did not increase copper-resistant enterococci; however, supplementing antibiotics with copper increased the prevalence of the tcrB gene among fecal enterococci of piglets.

A review of calcium and phosphorus requirement estimates for gestating and lactating sows.

Calcium (Ca) and phosphorus (P) are minerals involved in biological functions and essential structural components of the skeleton. The body tightly regulates Ca and P to maintain homeostasis. Maternal needs for Ca and P increase during gestation and lactation to support conceptus growth and milk synthesis. Litter size and litter average daily gain (ADG) have a large effect on Ca and P requirements for sows because as they increase, the requirements increase due to a greater need from the sow. The objective of this review was to summarize published literature on Ca and P requirements in gestating and lactating sows derived from empirical data and factorial models. A total of nine empirical studies and seven factorial models were reviewed for determining the Ca and P requirements in gestation. For lactation, there were six empirical studies and seven factorial models reviewed. Empirical studies determined requirements based on the observed effect of Ca and P on bone mineralization, sow and litter performance, and milk characteristics. Factorial models generated equations to estimate Ca and P requirements using the main components of maintenance, fetal and placental growth, and maternal retention in gestation. The main components for factorial equations in lactation include maintenance and milk production. In gestation, the standardized total tract digestible phosphorus (STTD P) requirement estimates from empirical studies range from 5.4 to 9.5 g/d with total Ca ranging from 12.9 to 18.6 g/d to maximize bone measurements or performance criteria. According to the factorial models, the requirements increase throughout gestation to meet the needs of the growing fetuses and range from 7.6 to 10.6 g/d and 18.4 to 38.2 g/d of STTD P and total Ca, respectively, on day 114 of gestation for parity 1 sows. During lactation, STTD P requirement estimates from empirical studies ranged from 8.5 to 22.1 g/d and total Ca ranged from 21.2 to 50.4 g/d. For the lactation factorial models, STTD P requirements ranged from 14.2 to 25.1 g/d for STTD P and 28.4 to 55.6 g/d for total Ca for parity 1 sows with a litter size of 15 pigs. The large variation in requirement estimates makes it difficult to define Ca and P requirements; however, a minimum level of 6.0 and 22.1 g/d of STTD P during gestation and lactation, respectively, appears to be adequate to meet basal requirements. The limited data and high variation indicate a need for future research evaluating Ca and P requirements for gestating and lactating sows.

Technical note: utilization of various allotment strategies to evaluate variation and replications required to detect statistical significance in nursery pig research.

A total of 720 barrows (line 200 × 400, DNA genetics) were used in two 42-d nursery trials (initially 6.20 ±â€…0.12 kg and 5.63 ±â€…0.16 kg, respectively) to evaluate strategies for allotting pigs to pens in randomized controlled trials. At placement, the population was split into three cohorts with similar average weight and standard deviation and randomly assigned to one of the three allotment strategies. Strategy 1 (random) utilized a simple randomization strategy with each pig randomized to pens independent of all other pigs. Strategy 2 (body weight [BW] distribution) sorted each pig within the cohort into one of the five BW groups. One pig from each weight group was then randomly assigned to a pen such that distribution of BW within pen was uniform across pens. Strategy 3 (BW grouping) sorted pigs within the cohort into 3 BW categories: light, medium, and heavy. Within each BW category, pigs were randomized to pen to create pens of pigs from each BW category. Within each experiment, there were 72 pens with five pigs per pen and 24 pens per allotment strategy. For all strategies, once pigs were allotted to pens, pens were allotted to one of the two treatments for a concurrent trial. In experiment 1, environmental enrichment using ropes tied near the pan of the feeder was compared to a control with no enrichment. In experiment 2, treatment diets consisted of basal levels of Zn and Cu from the trace mineral premix for the duration of the study (110 and 17 mg/kg, respectively; control), or diets (supplemented control) with carbadox (50 g/ton; Mecadox, Phibro Animal Health, Teaneck, NJ) fed in phase 1 (days 0 to 22) and 2 (days 22 to 43), pharmacological levels of Zn and Cu (2,414 mg/kg Zn from ZnO; 168 mg/kg Cu from CuSO4) fed in phase 1, and only pharmacological levels of Cu (168 mg/kg Cu from CuSO4) fed in phase 2. These treatment designs were used to determine the impact on coefficient of variation (CV) and to estimate the number of replications required to find significant treatment differences based on allotment strategy. There were no meaningful allotment strategy × treatment interactions for either study. For between-pen CV, pigs allotted using BW distribution and BW grouping strategies had the lowest CV at allotment and final weight in both trials. For overall average daily gain in experiments 1 and 2 in experiment 2, the BW distribution strategy required the fewest replications to detect differences in performance. However, there is no meaningful difference between allotment strategies in replications required to detect significant differences for gain:feed ratio.

Decreasing variation between experimental units increases the likelihood of finding a statistically significant difference if one exists. Assignment of animals to experimental units (pens) may contribute to that variation. Therefore, the purpose of this trial was to investigate the effect that different methods of allotting pigs to pens (experimental unit) have on variation and in turn, the number of replications required to detect a significant difference of a given amount between treatments. The random strategy assigned pigs to pens in a completely random fashion. The body weight (BW) distribution strategy ordered pigs from lightest to heaviest and created five groups based on BW. Each pen was randomly assigned one pig from each of the five groups. The BW grouping strategy again ordered pigs from lightest to heaviest but split pigs into three groups based on BW and each pen was randomly assigned pigs from only one BW group such that there were pens of light pigs, pens of medium pigs, and pens of heavy pigs. Ultimately, the best allotment strategy depends on the parameter of interest. For final BW and overall ADG, the BW grouping method required the fewest pens to detect statistically significant differences.

A review of soybean processing byproducts and their use in swine and poultry diets.

Due to its importance in animal feed, soybean meal has been extensively studied to optimize its use in livestock diets. Despite extensive research, the industry has not fully characterized specific areas of soybean processing such as the inclusion of soybean byproducts added back to soybean meal during processing. Soybean processing byproducts can encompass a large variety of materials including weeds and foreign material, soybean hulls, gums, soapstocks, lecithins, spent bleaching clays, and deodorizer distillates. Despite the potential for being added back to soybean meal when a crushing plant is integrated with an oil refinery, there is currently limited information on the composition of many of these soybean processing byproducts and their subsequent effects on soybean meal quality and animal performance. Therefore, there may be opportunities for a new area of research focused on soybean processing byproducts and their optimal use within the livestock feed industry. This review summarizes the current information on soybean byproducts with a focus on identifying the areas with the greatest potential for future research in swine and poultry nutrition.

Determining the phosphorus release curve for Sunphase HT phytase in nursery pig diets.

A total of 280 pigs (DNA 241 × 600, initially 10.4 ±â€…0.24 kg) were used in a 21-d study to determine the available P (aP) release curve for Sunphase HT phytase (Wuhan Sunhy Biology Co., Ltd., Wuhan, P.R. China) when fed diets with a high phytate concentration. On day 21 post-weaning, considered day 0 of the study, pigs were blocked by average pen body weight (BW) and randomly allotted to 1 of 7 dietary treatments with 5 pigs per pen and 8 pens per treatment. Dietary treatments were derived from a single basal diet, and ingredients including phytase, monocalcium P, limestone, and sand were added to create the treatment diets. Treatments included three diets with increasing (0.11%, 0.19%, and 0.27%) aP from monocalcium P, or four diets with increasing phytase (250, 500, 1,000, or 2,000 phytase unit (FTU)/kg) added to the diet formulated to 0.11% aP. All diets were corn-soybean meal-canola meal-based and were formulated to contain 1.24% SID Lys, a 1.10:1 total calcium-to-phosphorus ratio, and a calculated 0.32% phytate P. Prior to the beginning of the study, all pigs were fed a diet containing 0.11% aP from days 18 to 21 post-weaning. At the conclusion of the study, 1 pig, closest to the mean weight of each pen, was euthanized, and the right fibula, 10th rib, and metacarpal were collected to determine bone ash and density. After cleaning, bones were submerged in ultra-purified water under a vacuum for 4 h and then weighed to calculate the density (Archimedes principle). For bone ash, bones were processed using the non-defatted method. From days 0 to 21, increasing aP from monocalcium P increased (linear, P ≤ 0.014) average daily gain (ADG), gain-to-feed (G:F), and final BW. Pigs fed increasing phytase had increased (linear, P ≤ 0.045) ADG, final BW, and plasma inositol concentration as well as improved (quadratic, P = 0.023) G:F. For bone characteristics, pigs fed increasing aP from inorganic P had a linear improvement (P ≤ 0.019) in fibula bone ash weight and percentage bone ash, rib bone ash weight and bone density, and all metacarpal bone properties, with a quadratic response (P ≤ 0.030) for fibula bone density and rib percentage ash. Additionally, pigs fed increasing phytase had increased (P < 0.05) bone ash weight, percentage bone ash, and bone density in either a linear or quadratic fashion depending on the bone analyzed. The available P release curve generated for Sunphase HT phytase for percentage bone ash combining values from the right fibula, 10th rib, and metacarpal is aP release, % = (0.360 × FTU) ÷ (2,330.250 + FTU).

Diagnostic survey of analytical methods used to determine bone mineralization in pigs.

Pigs from 64 commercial sites across 14 production systems in the Midwest United States were evaluated for baseline biological measurements used to determine bone mineralization. There were three pigs selected from each commercial site representing: 1) a clinically normal pig (healthy), 2) a pig with evidence of clinical lameness (lame), and 3) a pig from a hospital pen that was assumed to have recent low feed intake (unhealthy). Pigs ranged in age from nursery to market weight, with the three pigs sampled from each site representing the same age or phase of production. Blood, urine, metacarpal, fibula, 2nd rib, and 10th rib were collected and analyzed. Each bone was measured for density and ash (defatted and non-defatted technique). A bone × pig type interaction (P < 0.001) was observed for defatted and non-defatted bone ash and density. For defatted bone ash, there were no differences among pig types for the fibulas, 2nd rib, and 10th rib (P > 0.10), but metacarpals from healthy pigs had greater (P < 0.05) percentage bone ash compared to unhealthy pigs, with the lame pigs intermediate. For non-defatted bone ash, there were no differences among pig types for metacarpals and fibulas (P > 0.10), but unhealthy pigs had greater (P < 0.05) non-defatted percentage bone ash for 2nd and 10th ribs compared to healthy pigs, with lame pigs intermediate. Healthy and lame pigs had greater (P < 0.05) bone density than unhealthy pigs for metacarpals and fibulas, with no difference observed for ribs (P > 0.10). Healthy pigs had greater (P < 0.05) serum Ca and 25(OH)D3 compared to unhealthy pigs, with lame pigs intermediate. Healthy pigs had greater (P < 0.05) serum P compared to unhealthy and lame pigs, with no differences between the unhealthy and lame pigs. Unhealthy pigs excreted significantly more (P < 0.05) P and creatinine in the urine compared to healthy pigs with lame pigs intermediate. In summary, there are differences in serum Ca, P, and vitamin D among healthy, lame, and unhealthy pigs. Differences in bone mineralization among pig types varied depending on the analytical procedure and bone, with a considerable range in values within pig type across the 14 production systems sampled.

There is little literature or data comparing bone diagnostic results for healthy, lame, and unhealthy pigs. Typically, diagnosticians assessing clinical lameness cases in pigs will measure bone mineralization along with histopathological evaluation to diagnose and assess the severity of metabolic bone disease. Bone ash is the primary method to determine bone mineralization, with the removal of the lipid in the bone (defatting) before the bone is ashed, compared to not removing the lipid before the ashing (non-defatted). Defatting the bone reduces the amount of variation across the bones compared to non-defatting. In this diagnostic survey, there was no difference among the healthy, lame, or unhealthy pigs when comparing defatted bone ash, however, unhealthy pigs had an increased bone ash percentage compared to the healthy and lame pigs when the bones were assessed using the non-defatted procedure. There was variation across production systems and pig types for serum vitamin D. When comparing the pig types, healthy pigs had increased serum Ca, P, and vitamin D [25(OH)D3] compared to the unhealthy pigs, with the lame pigs intermediate.

A meta-regression analysis to evaluate the effects of narasin on grow-finish pig performance.

Ionophores are feed additives that decrease gram-positive microbial populations by disrupting the ion transfer across cell membranes resulting in improved growth performance. Narasin (Skycis; Elanco Animal Health, Greenfield, IN) is an FDA-approved ionophore utilized for increased rate of weight gain and improved feed efficiency in growing-finishing pigs. A meta-regression analysis was conducted to evaluate the effects of added narasin in growing-finishing pig diets to predict its influence on average daily gain (ADG), feed efficiency (G:F), and carcass yield. A database was developed containing 21 technical reports, abstracts, and refereed papers from 2012 to 2021 representing 35 observations for growth performance data in studies ranging from 35 to 116 d in length (overall data). In addition, within these 35 observations, individual period data were evaluated (143 observations) using weekly, bi-weekly, or monthly performance intervals (period data). Regression model equations were developed, and predictor variables were assessed with a stepwise manual forward selection procedure. The ADG model using the overall data included ADG, ADFI, and G:F of the control group, added narasin dose, and narasin feeding duration categorized as longer or shorter than 65 d. Predictor variables included in the G:F model using overall data were ADG, ADFI, and G:F of the control group and added narasin dose. For carcass yield, the final model included ADFI and G:F of the control group, added narasin dose, and narasin feeding duration of longer than 65 d. In the period model for ADG, the predictors included ADG, ADFI, and G:F of the control group, added narasin dose, and average BW of the control group categorized into greater than or less than 105 kg. For period data for G:F, the model selected ADG, ADFI, and G:F of the control group and added narasin dose. Based on the results, the overall response to added narasin for ADG and G:F was quadratic and tended to decrease as ADG and G:F increased. A similar quadratic response was observed for the individual period data. In summary, using median values from the database for predictor variables, this meta-analysis demonstrated narasin would be expected to improve ADG between 1.06% and 1.65%, G:F between 0.71% and 1.71%, and carcass yield by 0.31% when fed continuously for longer than 65 d.

Effects of increasing omega-3 fatty acids on growth performance, immune response, and mortality in nursery pigs.

Three experiments evaluated omega-3 fatty acids, provided by O3 trial feed, on nursery pig growth performance, mortality, and response to an LPS immune challenge or natural Porcine reproductive and respiratory virus (PRRSV) outbreak. In experiment 1, 350 pigs (241 × 600, DNA; initially 5.8 kg) were used. Pens of pigs were randomly assigned to one of the five dietary treatments containing increasing omega-3 fatty acids (0%, 1%, 2%, 3%, and 4% O3 trial feed) with 14 replications per treatment. On day 25, two pigs per pen were injected intramuscularly with 20 µg Escherichia coli LPS per kg BW and one pig per pen was injected with saline as a control. Body temperature was taken from all three pigs prior to and 2, 4, 6, and 12 h post-LPS challenge. Serum IL-1ß and TNF-α concentrations were determined in LPS-challenged pigs 24 h prior and 4 h post-LPS challenge. There was no interaction between treatment and time for change in body temperature (P > 0.10). Overall, increasing the O3 trial feed did not affect (P > 0.10) ADG, ADFI, G:F, IL-1ß, or TNF-α. In experiment 2, 1,056 pigs (PIC TR4 × [Fast LW × PIC L02] initially 7.3 kg) were used. Pens of pigs were randomly assigned to one of the four dietary treatments containing increasing omega-3 fatty acids (0%, 0.75%, 1.5%, and 3% O3 trial feed) with 12 replications per treatment. Oral fluids tested negative on days 7 and 14, but then positive for North American PRRSV virus via PCR on days 21, 28, 35, and 42. Overall, increasing O3 trial feed increased (linear, P < 0.001) ADG, ADFI, and G:F and decreased (linear, P = 0.027) total removals and mortality. In experiment 3, 91,140 pigs (DNA 600 × PIC 1050; initially 5.1 kg), originating from PRRSV-positive sow farms, were used across eight nursery sites. Each site contained five barns with two rooms per barn and ~1,100 pigs per room. Rooms of pigs were blocked by nursery site and allocated within sow source to one of the two dietary treatments (control or 3% O3 trial feed) with 40 replications per treatment. Oral fluids from 61 of the 80 rooms tested positive for North American PRRSV virus 1 wk postweaning and 78 of the 80 rooms tested positive 3 wk after weaning. Overall, O3 trial feed did not affect ADG, ADFI, or G:F but increased (P < 0.001) total removals and mortalities. In summary, increasing omega-3 fatty acids, sourced by O3 trial feed, did not improve growth performance or immune response in healthy pigs given an LPS challenge. However, it appears that if omega-3 fatty acids are fed prior to a natural PRRSV break (as in experiment 2), growth performance may be improved, and mortality reduced.

Evaluating increasing levels of sodium diformate in diets for nursery and finishing pigs on growth performance, fecal dry matter, and carcass characteristics.

Two studies were conducted to evaluate the effects of sodium diformate in swine diets. For Exp. 1, 360 barrows (DNA 200 × 400; initially 5.9 ±â€…0.06 kg) were used in a 38-d study. At weaning, pigs were randomly assigned to pens with five pigs per pen. Each pen was allocated to one of six treatments with 12 pens per treatment. Treatments were formulated to provide none, 0.40%, 0.60%, 0.80%, 1.00%, or 1.20% sodium diformate added at the expense of corn. Diets were fed in three phases: phase 1 from weaning to day 9, phase 2 from days 9 to 24, and phase 3 from days 24 to 38. From days 0 to 24 (phases 1 and 2), increasing sodium diformate increased (linear, P = 0.001) gain-to-feed (G:F). However, sodium diformate did not affect average daily gain (ADG) or average daily feed intake (ADFI). From days 24 to 38 (phase 3) and overall (days 0 to 38), there was no evidence of differences due to increasing sodium diformate for any growth response criteria. There was no evidence for differences in fecal dry matter (DM) on day 9. However, fecal DM decreased (linear, P < 0.05; quadratic, P = 0.097) as sodium diformate increased on day 24. In Exp. 2, 2,200 pigs (Duroc sire [PIC 800 or DNA 600] × PIC Camborough; initially 24.2 ±â€…0.30 kg) were used in a 117-d growth trial. Pens of pigs (25 pigs per pen) were randomly assigned to one of four treatments with 22 pens per treatment. Treatments were formulated with additions of none, 0.25%, 0.50%, or 0.75% sodium diformate. Diets were fed in six phases from 24 to 141 kg. For period 1 (days 0 to 32), ADFI tended to decrease then increase (quadratic, P = 0.081) with increasing sodium diformate, whereas G:F increased then decreased (quadratic, P < 0.001) with increasing sodium diformate. For period 2 (days 32 to 60), there was no evidence for differences in ADG or ADFI; however, there was a tendency for G:F to increase then decrease (quadratic, P = 0.093) with increasing sodium diformate. From days 60 to 93, increasing sodium diformate increased (linear, P < 0.01) ADG and ADFI. From days 93 to 117, increasing sodium diformate increased (linear, P < 0.05) ADG, ADFI, and G:F. Overall (days 0 to 117), pigs fed increasing sodium diformate had increased (linear, P < 0.01) ADG and a tendency for increased (linear, P = 0.075) ADFI; however, there was no evidence for differences in G:F. There were no treatment differences for any carcass characteristic. In summary, increasing sodium diformate may increase G:F in the early nursery and improve ADG after day 60 (approximately 82 kg) in the finishing period.

Evaluating the effects of benzoic acid on nursery and finishing pig growth performance.

Three studies were conducted evaluating the use of benzoic acid in swine diets. In experiment 1, 350 weanling barrows (DNA 200 × 400; initially 5.9 ±â€…0.04 kg) were allotted to one of the five dietary treatments with 14 pens per treatment. Diets were fed in three phases: phase 1 from weaning to day 10, phase 2 from days 10 to 18, and phase 3 from days 18 to 38. Treatment 1 contained no benzoic acid throughout all three phases (weaning to day 42). Treatment 2 included 0.50% benzoic acid throughout all three phases. Treatment 3 contained 0.50% benzoic acid in phases 1 and 2, and 0.25% benzoic acid in phase 3. Treatment 4 contained 0.50% benzoic acid in phases 1 and 2, and no benzoic acid in phase 3. Treatment 5 contained 0.50% benzoic acid in phase 1, 0.25% benzoic acid in phase 2, and no benzoic acid in phase 3. For the overall period, pigs fed 0.50% in the first two phases and 0.25% benzoic acid in the final phase had greater (P < 0.05) average daily gain (average daily gain) than pigs fed no benzoic acid through all three phases, or pigs fed 0.50% in the first two phases and no benzoic acid in the final phase, with pigs fed the other treatments intermediate. Pigs fed 0.50% in the first two phases and 0.25% benzoic acid in the final phase had improved (P < 0.05) gain-to-feed ratio (G:F) compared with pigs fed no benzoic acid throughout all three phases, pigs fed 0.50% in the first two phases and no benzoic acid in the third phase, or pigs fed 0.50%, 0.25%, and no benzoic acid, respectively. For experiment 2, a 101-d trial was conducted using two groups of 1,053 finishing pigs (2,106 total pigs; PIC 337 × 1,050; initially 33.3 ±â€…1.9 kg). Dietary treatments were corn-soybean meal-dried distillers grains with solubles-based with the addition of none, 0.25%, or 0.50% benzoic acid. Overall, pigs fed increasing benzoic acid had a tendency for increased average daily feed intake (linear, P = 0.083) but decreased G:F (linear, P < 0.05). In experiment 3, 2,162 finishing pigs (DNA 600 × PIC 1050; initially 31.4 ±â€…2.2 kg) were used in a 109-d trial. Dietary treatments were formulated with or without 0.25% benzoic acid. For the overall experimental period, pigs fed benzoic acid had increased (P < 0.05) G:F. In summary, feeding benzoic acid elicits improved growth performance when fed throughout the entire nursery period while improved G:F in growing-finishing pigs was observed in one experiment, but not in the other.

Effect of bone and analytical method on assessment of bone mineralization in response to dietary phosphorus, phytase, and vitamin D in finishing pigs.

A total of 882 pigs (PIC TR4 × [Fast LW × PIC L02]; initially 33.2 ±â€…0.31 kg) were used in a 112-d study to evaluate the effects of different bones and analytical methods on the assessment of bone mineralization response to changes in dietary P, phytase, and vitamin D in growing pigs. Pens of pigs (20 pigs per pen) were randomized to one of five dietary treatments with nine pens per treatment. Dietary treatments were designed to create differences in bone mineralization and included: 1) P at 80% of NRC (2012) standardized total tract digestible (STTD) P requirement, 2) NRC STTD P with no phytase, 3) NRC STTD P with phytase providing an assumed release of 0.14% STTD P from 2,000 FYT/kg, 4) high STTD P (128% of the NRC P) using monocalcium phosphate and phytase, and 5) diet 4 with additional vitamin D3 from 25(OH)D3. On day 112, one pig per pen was euthanized for bone, blood, and urine analysis. Additionally, 11 pigs identified as having poor body condition which indicated a history of low feed intake (unhealthy) were sampled. There were no differences between treatments for final body weight, average daily gain, average daily feed intake, gain to feed, or bone ash measurements (treatment × bone interaction) regardless of bone ash method. The response to treatment for bone density and bone mineral content was dependent upon the bone sampled (density interaction, P = 0.053; mineral interaction, P = 0.078). For 10th rib bone density, pigs fed high levels of P had increased (P < 0.05) bone density compared with pigs fed NRC levels with phytase, with pigs fed deficient P, NRC levels of P with no phytase, and high STTD P with extra 25(OH)D3 intermediate, with no differences for metacarpals, fibulas, or 2nd ribs. Pigs fed extra vitamin D from 25(OH)D3 had increased (P < 0.05) 10th rib bone mineral content compared with pigs fed deficient P and NRC levels of P with phytase, with pigs fed industry P and vitamin D, and NRC P with monocalcium intermediate. Healthy pigs had greater (P < 0.05) serum Ca, P, vitamin D concentrations, and defatted bone ash than those unhealthy, with no difference between the two health statuses for non-defatted bone ash. In summary, differences between bone ash procedures were more apparent than differences between diets. Differences in bone density and mineral content in response to dietary P and vitamin D were most apparent with 10th ribs.

Lameness is defined as impaired movement or deviation from normal gait. The evaluation of bone mineralization can be an important component of a diagnostic investigation of lameness. Lameness in growing pigs can cause an increase in morbidity and mortality, which leads to economic losses and animal welfare concerns for producers. Calcium and P are the primary minerals in skeletal tissue and their deficiency is considered to be one of the causes of lameness. To evaluate bone mineralization, it is important to know the differences between methodologies used to determine bone ash and the expected differences between the bones analyzed. Furthermore, there has been limited data comparing bone mineralization and serum Ca and P concentrations between healthy pigs and those exhibiting clinical signs of illness (unhealthy). By removing the lipid in the bone (defatting) before the bone is ashed, variation across bones is decreased compared with not removing lipid before ashing (non-defatted). The reduction in variation across bones allows for more differences to be detected among dietary treatments and health statuses of pigs. The 10th rib is more sensitive to detect dietary differences using bone density than metacarpals, fibulas, and 2nd ribs. When comparing healthy vs. unhealthy pigs exhibiting clinical signs of illness, healthy pigs have increased defatted percentage bone ash and serum Ca, P, and vitamin D.

Effects of increasing soybean meal in corn-based diets on the growth performance of late finishing pigs.

Three experiments were conducted to determine the effects of increasing soybean meal (SBM) levels by replacing feed-grade amino acids (AA) in corn, corn dried distillers grains with solubles (DDGS), and corn-wheat midds-based diets on growth performance of late finishing pigs (n = 4,406) raised in commercial facilities. Across all experiments, pens of pigs were blocked by initial bodyweight (BW) and randomly assigned to 1 of 5 dietary treatments. All diets were formulated to contain 0.70% standardized ileal digestible (SID) Lys and varying amounts of feed-grade AA. All diets were formulated to meet or exceed minimum essential AA requirement estimates as a ratio to Lys. In Exp. 1, 1,793 pigs (initially 104.9 ± 4.9 kg) were fed corn-based diets and pens of pigs were assigned treatments with increasing SBM from 5% to 20%. Overall, average daily gain (ADG) and feed efficiency (G:F) improved (linear and cubic, P ≤ 0.02) as dietary SBM increased, with the greatest improvement observed as SBM increased from 5% to 8.75% and little improvement thereafter. In Exp. 2, 1,827 pigs (initially 97.9 ± 4.3 kg) were fed diets containing 25% DDGS with SBM levels increasing from 0% to 16%. Overall, feed efficiency marginally improved (linear, P ≤ 0.10) as SBM increased, with the greatest performance observed when diets contained 8% SBM and similar performance thereafter with 12 or 16% dietary SBM. In Exp. 3, 786 pigs (initially 96.7 ± 3.2 kg) were fed diets that contained 30% wheat midds and dietary SBM from 0% to 16%. Final BW of pigs increased (linear, P < 0.05) and overall ADG and G:F improved (linear and cubic, P < 0.05) as SBM increased. The combined results of the three experiments suggest that inclusion of at least 4% to 8% dietary SBM at the expense of feed-grade amino acids in corn-based diets with or without grain coproducts can improve growth performance of late-finishing (greater than 100 kg) pigs.

Effects of providing sensory attractants to suckling pigs during lactation and after weaning on post-weaning growth performance.

Three experiments were conducted to determine the effect of sensory attractants pre- and post-weaning on the growth performance of pigs after weaning. For each experiment, treatments were arranged as a 2 × 2 × 2 factorial with main effects of pre-weaning application (without or with), post-weaning application (without or with), and body weight category (representing the lightest or heaviest 50% of the population). In Exp. 1, 356 nursery pigs (initially 5.7 kg) were used in a 28-d trial with enrichment cubes used as the sensory attractant. A greater percentage of heavy pigs (P = 0.007) or pigs offered enrichment cubes pre-weaning (P = 0.044) lost BW from weaning to d 3 compared to light pigs or pigs not offered enrichment cubes pre-weaning. From weaning to d 7, a greater percentage of pigs lost weight when not offered cubes post-weaning (P = 0.002) compared to pigs offered cubes post-weaning. In Exp. 2, 355 nursery pigs (initially 5.6 kg) were used in a 29-d trial with a powder used as the sensory attractant. Providing a powder attractant both pre- and post-weaning reduced the percentage of pigs that lost weight from weaning to d 3 as compared with providing a powder either pre- or post-weaning only (interaction, P < 0.05). In Exp. 3, 355 nursery pigs (initially 5.9 kg) were used in a 24-d trial with a liquid spray used as the sensory attractant. A greater percentage of heavy pigs that did not receive liquid attractant lost weight from weaning to d 3, whereas a greater percentage of light pigs lost weight when they received liquid attractant only pre-weaning (three-way interaction; P = 0.016). Across all three experiments, sensory attractant application had limited effects on the growth performance of pigs after weaning; however, varying responses were observed for the percentage of pigs that lost weight in the first 3 to 7 d immediately post-weaning. In summary, environmental enrichment with cubes (Exp. 1) appears to have the greatest effect when applied post-weaning whereas flavor attractants (Exp. 2 and 3) appear to have the greatest effect when applied both pre- and post-weaning.

Comparing tryptophan:lysine ratios in dried distillers grains with solubles-based diets with and without a dried distillers grains with solubles withdrawal strategy on growth, carcass characteristics, and carcass fat iodine value of growing-finishing pigs.

A total of 6,240 finishing pigs (DNA 600 × PIC 1050; initially 22.5 ±â€…1.00 kg), divided into two groups, were used in a 119 or 120 d study comparing increasing Trp:Lys ratio in diets containing dried distillers grains with solubles (DDGS) or a DDGS withdrawal strategy (removing all DDGS from the last phase before marketing) on growth performance and carcass fat iodine value (IV). Pigs were randomly allotted to one of seven dietary treatments with 30 to 36 pigs per pen and 26 replications per treatment. Diets were fed in four phases, approximately 23 to 44, 44 to 71, 71 to 100, and 100 kg to market. Diets included a control corn-soybean meal-based diet (no DDGS) formulated to a 19% standardized ileal digestibility (SID) Trp:Lys ratio, four diets with 30% DDGS fed in all four phases and formulated to provide SID Trp:Lys ratios of 16%, 19%, 22%, or 25%, and two DDGS withdrawal strategy diets: 19% SID Trp:Lys with 30% DDGS in phases 1 through 3 and then 0% DDGS in phase 4 with either a 19% or 25% Trp:Lys ratio. Overall, body weight (BW), average daily gain (ADG), average daily feed intake (ADFI), and gain:feed ratio (G:F) increased (linear, P < 0.05) as SID Trp:Lys ratio increased in diets with 30% DDGS fed in all phases. Simultaneously, hot carcass weight (quadratic, P = 0.014), carcass yield (quadratic, P = 0.012), and backfat depth (linear, P = 0.040) increased with increasing Trp:Lys ratio. Pigs fed the 19% SID Trp:Lys ratio withdrawal strategy diet had similar ADG and ADFI as those fed the control diet, the 25% Trp:Lys withdrawal diet, or the 30% DDGS diets with 25% Trp:Lys ratio throughout the study. Pigs fed the control diet had decreased (P < 0.05) carcass fat IV compared to pigs fed the DDGS diets throughout the study, with pigs fed the two DDGS withdrawal strategy diets intermediate. In summary, increasing the SID Trp:Lys ratio in diets with 30% DDGS resulted in a linear increase in ADG, ADFI, G:F, and BW but did not influence carcass fat IV, with most of the benefits observed as diets increased from 16% to 19% Trp:Lys. Removing DDGS from the diet in the last period reduced carcass fat IV and increased growth rate during the withdrawal period compared to pigs fed with 30% DDGS throughout, indicating value in a withdrawal strategy.

Feeding high levels of dried distillers grains with solubles (DDGS) up to marketing has been found to have negative impacts on growth performance and carcass characteristics of finishing pigs, specifically carcass yield. High inclusion of DDGS has also been shown to increase iodine value (IV), a measurement of fat quality, due to increased deposition of unsaturated fatty acids. However, recent data suggested that when feeding finishing pigs diets containing DDGS, increasing the standardized ileal digestible Trp:Lys ratio well above the NRC requirement estimates can prevent or lessen some of these negative effects. This study compared removing DDGS from the final dietary phase with two levels of Trp:Lys ratio, commonly referred to as a withdrawal strategy, to increasing levels of Trp:Lys in diets containing 30% DDGS. The results of this study indicate that increasing the Trp:Lys ratio in diets containing DDGS to a 25% Trp:Lys ratio resulted in growth performance similar to the control diet and the withdrawal strategy, with most of the benefits observed when Trp:Lys is increased from a deficient to adequate status. However, feeding diets with DDGS up to market resulted in increased IV.

Effect of added calcium carbonate without and with benzoic acid on weanling pig growth performance, fecal dry matter, and blood Ca and P concentrations.

The objective of these studies was to determine the effects of increasing levels of calcium carbonate (CaCO3) with and without benzoic acid on weanling pig growth performance, fecal dry matter (DM), and blood Ca and P concentrations. In experiment 1, 695 pigs (DNA Line 200 × 400, initially 5.9 ±â€…0.02 kg) were used in a 28 d study. Pigs were weaned at approximately 21 d of age and randomly assigned to pens and then pens were allotted to one of five dietary treatments. Treatment diets were fed from weaning (day 0) to day 14, with a common diet fed from days 14 to 28. Dietary treatments were formulated to provide 0%, 0.45%, 0.90%, 1.35%, and 1.80% added CaCO3 at the expense of ground corn. From days 0 to 14 (treatment period), average daily gain (ADG) and G:F decreased (linear, P ≤ 0.01) as CaCO3 increased. From days 14 to 28 (common period) and for the overall experiment (days 0 to 28), there was no evidence of differences in growth performance between treatments. For fecal DM, there was a trend (quadratic, P = 0.091) where pigs fed with the highest CaCO3 diets had the greatest fecal DM. Experiment 2 used 360 pigs (DNA Line 200 × 400, initially 6.2 ±â€…0.03 kg) in a 38 d study. Upon arrival to the nursery facility, pigs were randomly assigned to pens and then pens were allotted to one of six dietary treatments. Dietary treatments were fed in three phases with treatment diets fed from days 0 to 10 and days 10 to 24, and a common phase 3 diet fed from days 24 to 38. Dietary treatments were formulated to provide 0.45%, 0.90%, and 1.35% added CaCO3 with or without 0.5% benzoic acid (VevoVitall, DSM Nutritional Products, Parsippany, NJ) added at the expense of ground corn. There was no evidence (P > 0.05) for any CaCO3 by benzoic acid interactions. For the experimental period (days 0 to 24), there was a tendency for benzoic acid to increase ADG (P = 0.056), average daily feed intake (ADFI; P = 0.071), and gain-to-feed ratio (G:F; linear, P = 0.014) as CaCO3 decreased. During the common period (days 24 to 38), pigs previously fed benzoic acid had increased (P = 0.045) ADG and marginally increased (P = 0.091) ADFI. For the overall study, pigs fed benzoic acid had increased ADG (P = 0.011) and ADFI (P = 0.030), marginally increased G:F (P = 0.096) and final body weight (P = 0.059). Serum Ca decreased (linear, P < 0.001) as CaCO3 decreased in the diet. These data show that decreasing the CaCO3 content in the nursery diet immediately after weaning may improve ADG and G:F. Dietary addition of benzoic acid may also provide beneficial effects on ADG and ADFI, regardless of dietary Ca level.

Evaluation of supplemental fat sources and pre-farrow essential fatty acid intake on lactating sow performance and essential fatty acid composition of colostrum, milk, and adipose tissue.

A total of 91 sows (Line 241, DNA Genetics) were used to evaluate the effects of supplemental fat sources and essential fatty acid intake on sow farrowing performance, litter growth performance, and essential fatty acid composition of colostrum, milk, and adipose tissue. At approximatelyday 107 of gestation, sows were blocked by body weight and parity, then allotted to 1 of 5 experimental treatments as part of a 2 × 2 + 1 factorial arrangement. Experimental diets were corn-soybean meal-based with a control diet that contained no added fat or diets with 3% added fat as either beef tallow or soybean oil, with consumption of the added fat diets starting on day 107 or 112 of gestation and fed until weaning. Thus, sows were provided low essential fatty acids (EFA; as linoleic and α-linolenic acid) without supplemental fat or with beef tallow or high EFA with soybean oil. Sows were provided approximately 2.8 kg/d of their assigned lactation diet pre-farrow and then provided ad libitum access after parturition. Sows consuming diets with beef tallow had greater lactation ADFI (fat source, P = 0.030), but lower daily linoleic acid (LA) and α-linolenic acid (ALA) intake than sows that consumed diets with soybean oil (fat source, P < 0.001). Supplemental fat sources providing either low or high EFA did not influence litter growth performance (fat source, P > 0.05). Sows fed diets with beef tallow did not influence the LA composition of colostrum; however, lactation diets with high EFA provided by soybean oil on day 107 of gestation increased colostrum LA concentration compared to providing diets on day 112 of gestation (fat source × time, P = 0.084; time, P < 0.001). Additionally, regardless of pre-farrow timing, ALA concentration of colostrum increased when sows consumed diets with soybean oil compared to beef tallow (fat source, P < 0.001). Both LA and ALA concentrations of milk at weaning were greater for sows that consumed diets with soybean oil compared to beef tallow (fat source, P < 0.001). Furthermore, concentrations of LA and ALA within adipose tissue were greater at weaning when sows consumed diets with high EFA compared to low EFA (fat source, P < 0.05). These responses suggest that providing dietary fat sources with high concentrations of EFA can increase backfat, colostrum, and milk LA and ALA. However, in this experiment, changes in colostrum and milk composition did not influence litter growth performance.

The lactating sow secretes essential fatty acids (EFA) in colostrum and milk to support litter growth and if dietary linoleic (LA) and alpha-linolenic acid (ALA) intake during lactation are limited, subsequent reproductive function of sows may be impaired. However, the inclusion of dietary fat sources with varying EFA composition in lactation diets provided shortly prior to farrowing can increase the energy density of the diet and modify colostrum and milk fatty acid profiles that may influence litter growth performance and survivability. The first objective of this trial was to evaluate the impact of providing sows lactation diets with dietary fat sources that provide low or high EFA on colostrum, milk, and sow adipose tissue fatty acid composition. A second objective was to evaluate the timing of feeding low- or high-EFA diets within the last week of gestation on colostrum and milk EFA composition. Overall, providing dietary fat sources with high concentrations of EFA shortly prior to farrowing altered fatty acid profiles of colostrum, milk, and backfat resulting in increased LA and ALA when compared to providing sows diets with low EFA. However, changes in colostrum and milk composition did not alter litter growth performance.

Industry survey of added vitamins and trace minerals in U.S. swine diets.

From November 2021 to February 2022, 37 swine nutritionists representing 29 production systems and 8 nutrition supplier companies in the United States were surveyed about added vitamin and trace mineral concentrations in swine diets. Respondents were asked to provide vitamin premix and trace mineral concentrations, inclusion rates, and weight ranges associated with feeding phases. Survey participants represented 4.38 million sows, or 72% of the U.S. industry. Data were compiled into three nursery phases (phase 1, weaning to 7 kg; phase 2, 7 to 11 kg; and phase 3, 11 to 23 kg), three finishing phases (23 to 55 kg; 55 to 100 kg; 100 kg to market), gilt development, gestation, lactation, and boar. Within each dietary phase, the vitamins and trace minerals of interest included: vitamins A, D, E, and K, thiamin, riboflavin, niacin, pantothenic acid, pyridoxine, biotin, folic acid, vitamin B12, choline, vitamin C, carnitine, copper, iodine, iron, manganese, selenium, zinc, cobalt, and chromium. Descriptive statistics used included: average, weighted average (determined by the total number of sows represented), median, minimum, maximum, 25th percentile (lowest quartile), and 75th percentile (highest quartile). In addition, all average supplementation rates for vitamins and trace minerals within each phase of production were compared to the requirement estimates reported in the NRC (2012). Nutritionists generally supplemented vitamins and trace minerals well above the NRC (2012) requirement estimates. However, great variation among respondents was observed in all vitamins and trace minerals, particularly in the fat-soluble vitamins. Also, the use of alternative sources of vitamin D [25(OH)D3], E (natural, d-alpha-tocopherol), and organic or chelated minerals like copper, manganese, selenium, and zinc were being used by approximately 40% of the respondents, primarily in breeding herd and nursery diets. Understanding current supplementation practices may help develop research trials to test different vitamin and trace mineral inclusions and provide an industry benchmark of vitamin and trace mineral usage.