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.

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.

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.

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.

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.

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).

Polyphenols as a partial replacement for vitamin E in nursery pig diets.

A total of 300 pigs (241 × 600; DNA, Columbus, NE; initially 6.0 ±â€…0.01 kg) were used in a 42-d trial to determine the effects of vitamin E levels and partially replacing vitamin E with a polyphenol (Cabanin CSD, R2 Argo, Denmark) on growth performance, complete blood count, serum thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD), and cytokine panel. Sixty pens of pigs were weighed and allotted to one of the five dietary treatments in a completely randomized design with 12 pens per treatment. A control treatment was formulated to provide 15 IU/kg of vitamin E equivalence from vitamin E. This control treatment was then used as a base for three replacement strategy diets to determine the effects of replacing an additional 60 IU/kg of vitamin E with polyphenol in diets containing a basal level of vitamin E requirement estimate (15 IU/kg). First, an additional 60 IU/kg of vitamin E was added for a total of 75 IU/kg of vitamin E equivalence. Second, 50% of the additional vitamin E (30 IU/kg) was replaced with the equivalency of polyphenol. Third, all 60 IU/kg of the additional vitamin E was replaced with the equivalency of polyphenol. To evaluate whether there are negative effects of feeding nursery pigs a high level of polyphenol, a fifth treatment was formulated to provide 575 IU/kg of vitamin E equivalence with 75 IU/kg from vitamin E and 500 IU/kg from polyphenol. Whole blood and serum samples were collected on days 10 and 42, and pig weights and feed disappearance were measured on days 10, 21, 31, 38, and 42. For growth performance, increasing vitamin E equivalence tended to improve (quadratic, P < 0.10) gain-to-feed ratio (G:F) from days 10 to 21, and tended to improve (linear, P < 0.10) G:F from days 21 to 42 and 0 to 42. There was a vitamin E equivalence × day interaction (P = 0.050) for serum SOD activity. Increasing vitamin E equivalence increased (linear, P < 0.05) serum SOD activity on day 42 but not on days 10 (P > 0.10). For serum cytokines, there was no evidence of differences (P > 0.10) between treatments and vitamin E equivalence. Moreover, there was no evidence of differences (P > 0.10) in all response variables between the three replacement strategies throughout the entire periods. In summary, increasing vitamin E equivalence tended to improve G:F, which may be related to the improved SOD activity. Furthermore, polyphenol can effectively replace vitamin E provided above the vitamin E requirement to provide similar benefits from increasing vitamin E equivalence.

The effect of bone and analytical methods on the assessment of bone mineralization response to dietary phosphorus, phytase, and vitamin D in nursery pigs.

A total of 360 pigs (DNA 600 × 241, DNA; initially 11.9 ±â€…0.56 kg) were used in a 28-d trial to evaluate the effects of different bones and analytical methods on the assessment of bone mineralization response to dietary P, vitamin D, and phytase in nursery pigs. Pens of pigs (six pigs per pen) were randomized to six dietary treatments in a randomized complete block design with 10 pens per treatment. Dietary treatments were designed to create differences in bone mineralization and included: (1) 0.19% standardized total tract digestibility (STTD) P (deficient), (2) 0.33% STTD P (NRC [2012] requirement) using monocalcium phosphate, (3) 0.33% STTD P including 0.14% release from phytase (Ronozyme HiPhos 2700, DSM Nutritional Products, Parsippany, NJ), (4) 0.44% STTD P using monocalcium phosphate, phytase, and no vitamin D, (5) diet 4 with vitamin D (1,653 IU/kg), and (6) diet 5 with an additional 50 µg/kg of 25(OH)D3 (HyD, DSM Nutritional Products, Parsippany, NJ) estimated to provide an additional 2,000 IU/kg of vitamin D3. After 28 d on feed, eight pigs per treatment were euthanized for bone (metacarpal, 2nd rib, 10th rib, and fibula), blood, and urine analysis. The response to treatment for bone density and ash was dependent upon the bone analyzed (treatment × bone interaction for bone density, P = 0.044; non-defatted bone ash, P = 0.060; defatted bone ash, P = 0.068). Thus, the response related to dietary treatment differed depending on which bone (metacarpal, fibula, 2nd rib, or 10th rib) was measured. Pigs fed 0.19% STTD P had decreased (P < 0.05) bone density and ash (non-defatted and defatted) for all bones compared to 0.44% STTD P, with 0.33% STTD P generally intermediate or similar to 0.44% STTD P. Pigs fed 0.44% STTD P with no vitamin D had greater (P < 0.05) non-defatted fibula ash compared to all treatments other than 0.44% STTD P with added 25(OH)D3. Pigs fed diets with 0.44% STTD P had greater (P < 0.05) defatted second rib ash compared to pigs fed 0.19% STTD P or 0.33% STTD P with no phytase. In summary, bone density and ash responses varied depending on bone analyzed. Differences in bone density and ash in response to P and vitamin D were most apparent with fibulas and second ribs. There were apparent differences in the bone ash percentage between defatted and non-defatted bone. However, differences between the treatments remain consistent regardless of the analytic procedure. For histopathology, 10th ribs were more sensitive than 2nd ribs or fibulas for the detection of lesions.

Lameness is defined as impaired movement or deviation from normal gait. There are many factors that can contribute to lameness, including but not limited to: infectious disease, genetic and conformational anomaly, and toxicity that affects the bone, muscle, and nervous systems. Metabolic bone disease is another cause of lameness in swine production and can be caused by inappropriate levels of essential vitamins or minerals. To understand and evaluate bone mineralization, it is important to understand the differences in diagnostic results between different bones and analytical techniques. Historically, percentage bone ash has been used as one of the procedures to assess metabolic bone disease as it measures the level of bone mineralization; however, procedures and results vary depending on the methodology and type of bone measured. Differences in bone density and ash in response to dietary P and vitamin D were most apparent in the fibulas and second ribs. There were apparent differences in the percentage of bone ash between defatted and non-defatted bone; however, the differences between the treatments remain consistent regardless of the analytic procedure. For histopathology, 10th ribs were more sensitive than 2nd ribs or fibulas for detection of lesions associated with metabolic bone disease.

Evaluation of a novel phytase derived from Citrobacter braakii and expressed in Aspergillis oryzae on growth performance and bone mineralization indicators in nursery pigs.

A total of 297 pigs (DNA 241 × 600; initially 8.64 ±â€…0.181 kg) were used in a 21-d trial to determine the efficacy of a novel phytase derived from Citrobacter braakii and expressed in Aspergillis oryzae (HiPhorius; DSM Nutritional Products, Animal Nutrition & Health, Parsippany, NJ) on pig growth and bone mineralization indicators. Pens of pigs were assigned to 1 of 5 dietary treatments in a randomized complete block design with 5 pigs per pen and 12 pens per treatment. The trial was initiated 14-d after weaning. The first three treatments were formulated to contain 0.09% aP; without added phytase (control), or the control diet with 600 or 1,000 FYT/kg of added phytase (considering a release of 0.15% or 0.18% aP, respectively). The remaining two treatments were formulated to contain 0.27% aP, one without added phytase and the other with 1,000 FYT/kg. From days 0 to 21, pigs fed increasing phytase in diets containing 0.09% aP had increased (linear, P ≤ 0.002) ADG, ADFI, and G:F, but added phytase in the 0.27% aP diet did not impact growth performance. Increasing phytase in diets containing 0.09% aP increased percentage bone ash in metacarpals and 10th ribs (linear, P < 0.001; quadratic, P = 0.004, respectively), and increased grams of Ca and P in metacarpals, 10th ribs, and fibulas (linear, P ≤ 0.027). Adding 1,000 FYT/kg phytase in diets with 0.27% aP increased (P ≤ 0.05) percentage bone ash and grams of Ca and P in fibulas and 10th ribs compared with pigs fed 0.27% aP without added phytase. Increasing aP from 0.09% to 0.27% in diets without added phytase increased (P < 0.001) ADG, ADFI, and G:F. Increasing aP from 0.09% to 0.27% in diets without added phytase increased bone density (P ≤ 0.002) in fibulas and metacarpals, percentage bone ash in all bones (P ≤ 0.074), and increased (P < 0.05) grams of Ca and P in fibulas and 10th ribs. Pigs fed diets containing 0.09 or 0.27% aP, both with 1,000 FYT added phytase, had increased (P < 0.05) bone density in fibulas and metacarpals, percentage bone ash in all bones, and increased grams of Ca and P in fibulas and 10th ribs. For growth performance (average of ADG and G:F), aP release was calculated to be 0.170% for 600 FYT/kg and 0.206% for 1,000 FYT/kg. For the average of all bone measurements (average of 3 bones for both bone density and percentage bone ash), aP release was calculated to be 0.120% and 0.125% for 600 and 1,000 FYT/kg, respectively.

Approximately 60% to 80% of phosphorus (P) in feedstuffs of plant origin is stored in the form of phytic acid. Phytase is an enzyme used in swine diets to improve the digestibility of phytate-bound P. As phytase sources continue to advance, their efficacy must be evaluated. In this study, nursery pigs (9 kg) were used to determine the efficacy of a novel phytase derived from Citrobacter braakii and expressed in Aspergillis oryzae in releasing phytate-bound P. Increasing phytase added to diets deficient in aP improved growth performance and bone mineralization. Adding phytase to a diet already adequate in aP did not affect growth performance, but improved bone mineralization indicators. Available P release attributed to phytase was estimated using growth performance and found to be 0.170% for 600 FYT/kg and 0.206% for 1,000 FYT/kg. For the average of all bone measures, the estimated aP release was 0.120% for 600 FYT/kg and 0.125% for 1,000 FYT/kg. Results of this study indicate an increasing release of phytate-bound P with increasing additions of the novel phytase tested in nursery diets and confirm that additional P is needed for bone development compared to growth.

Summary of methodology used in enterotoxigenic Escherichia coli (ETEC) challenge experiments in weanling pigs and quantitative assessment of observed variability.

Postweaning diarrhea in pigs is often caused by the F4 or F18 strains of enterotoxigenic Escherichia coli (ETEC). To evaluate interventions for ETEC, experimental infection via a challenge model is critical. Others have reviewed ETEC challenge studies, but there is a lack of explanation for the variability in responses observed. Our objective was to quantitatively summarize the responses and variability among ETEC challenge studies and develop a tool for sample size calculation. The most widely evaluated response criteria across ETEC challenge studies consist of growth performance, fecal consistency, immunoglobulins, pro-inflammatory cytokines, and small intestinal morphology. However, there is variation in the responses seen following ETEC infection as well as the variability within each response criteria. Contributing factors include the type of ETEC studied, dose and timing of inoculation, and the number of replications. Generally, a reduction in average daily gain and average daily feed intake are seen following ETEC challenge as well as a rapid increase in diarrhea. The magnitude of response in growth performance varies, and methodologies used to characterize fecal consistency are not standardized. Likewise, fecal bacterial shedding is a common indicator of ETEC infection, but the responses seen across the literature are not consistent due to differences in bacterial enumeration procedures. Emphasis should also be placed on the piglet's immune response to ETEC, which is commonly assessed by quantifying levels of immunoglobulins and pro-inflammatory cytokines. Again, there is variability in these responses across published work due to differences in the timing of sample collection, dose of ETEC pigs are challenged with, and laboratory practices. Small intestinal morphology is drastically altered following infection with ETEC and appears to be a less variable response criterion to evaluate. For each of these outcome variables, we have provided quantitative estimates of the responses seen across the literature as well as the variability within them. While there is a large degree of variability across ETEC challenge experiments, we have provided a quantitative summary of these studies and a Microsoft Excel-based tool was created to calculate sample sizes for future studies that can aid researchers in designing future work.

Determining the phosphorus release curve for Smizyme TS G5 2,500 phytase from 500 to 2,500 FTU/kg in nursery pig diets.

A total of 320 pigs (Line 241 × 600, DNA, Columbus, NE; initially 11.9 ±â€…0.22 kg) were used in a 21-d growth study to determine the available P (aP) release curve for Smizyme TS G5 2,500 (Barentz, Woodbury, MN). At approximately 19 d of age, pigs were weaned, randomly allotted to pens, and fed common starter diets. Pigs were blocked by average pen body weight (BW) and randomly allotted to one of eight dietary treatments on day 18 postweaning, considered day 0 of the study. 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 containing increasing inorganic P from monocalcium P (0.11%, 0.20%, and 0.28% aP), or five diets with increasing phytase (500, 1,000, 1,500, 2,000, or 2,500 FTU/kg) added to the diet containing 0.11% aP. All diets were corn-soybean meal-canola meal-based and were formulated to contain 1.24% standardized ileal digestibility Lys, 0.30% phytate P, and an analyzed Ca:P ratio of 1.10:1. Prior to the beginning of the study, all pigs were fed a diet containing 0.11% aP for a 2-d period (days 16 to 18 postweaning). At the conclusion of the study, one pig, closest to the mean weight of each pen, was euthanized and the right fibula, rib, and metacarpal were collected to determine bone ash, density, and total bone P. Bones were weighed while suspended in a vessel of water and the weights used to calculate bone density (Archimedes' principle). For bone ash, bones were processed using the non-defatted method. For the overall experimental period, pigs fed increasing inorganic P had increased (quadratic, P ≤ 0.033) average daily gain (ADG), average daily feed intake (ADFI), and final BW and a tendency for increased (quadratic, P ≤ 0.090) gain:feed ratio (G:F). Pigs fed increasing phytase had increased (quadratic, P ≤ 0.004) ADG, G:F, and final BW and increased (linear, P = 0.019) ADFI. For fibula, rib, and metacarpal characteristics, pigs fed increasing aP from inorganic P had increased (linear, P < 0.001) bone ash weight, percentage bone ash, bone density, and bone P concentration. Additionally, pigs fed increasing phytase had increased (linear or quadratic, P < 0.05) bone ash weight, percentage bone ash, bone density, and bone P. TheaP release curve generated for Smizyme TS G5 2,500 for percentage bone ash using data generated from all three bones is aP = (0.228 × FTU/kg) ÷ (998.065 + FTU/kg).

Evaluation of a Lactococcus lactis-based dried fermentation product administered through drinking water on nursery pig growth performance, fecal Escherichia coli virulence genes and pathotypes, antibiotic usage, and mortality.

A total of 34,749 pigs were used in two experiments to evaluate the effects of a postbiotic dried fermentation product (DFP) administered through drinking water on nursery pig growth performance, antibiotic injection frequency, morbidity, mortality, fecal consistency, and characterization of fecal Escherichia coli. The DFP is composed of bioactive molecules derived from Lactococcus lactis. In Exp. 1, 350 barrows (DNA Line 200 × 400; initial body weight [BW] 6.1 ± 0.01 kg) were used in a 42-d study with five pigs per pen and 35 pens per treatment. The DFP was supplied for 14 d at a target dosage of 24 mg/kg BW using a water medicator at a 1:128 dilution. On days 7 and 14, fecal samples were collected for dry matter (DM) and to determine, by a multiplex polymerase chain reaction (PCR) assay, prevalence of 11 virulence genes characteristic of E. coli pathotypes. There was no evidence (P > 0.10) for differences for growth, incidence of diarrhea, number of antibiotic injections, removals, or fecal DM. On both fecal collection days, E. coli virulence genes were present with day 7 samples positive for genes that encode for hemolysins (hlyA, exhA), intimin (eae), and enteroaggregative heat-stable enterotoxin (astA). Prevalence of enterotoxin genes (elt, estA, estB, astA) increased on day 14, but DFP had no effects on the prevalence of any of the virulence genes. A total of 32 out of 72 E. coli isolates were identified as enterotoxigenic pathotype and all except one were from day 14 fecal samples. Fourteen isolates were positive for F4 fimbria and one isolate was positive for F4 and F18 fimbriae. In Exp. 2, 34,399 nursery pigs (initially 5.6 kg) were used in 20 nursery barns with 10 barns per treatment (control or DFP). The target dosage of the DFP for the first 14 d was 35 mg/kg BW. Following the 14-d supplementation period, pigs continued to be monitored for approximately 31 d. There was no evidence (P > 0.05) for the DFP to influence the overall percentage of pigs that died or growth performance. From days 0 to 14, providing the DFP reduced (P < 0.05) the percentage of pigs that were euthanized. However, providing the DFP increased (P < 0.05) the overall percentage of pigs that were euthanized and total mortality. For the number of antibiotic injections (treatment interventions), providing the DFP reduced the number of injections for the common period (P < 0.001) and overall (P = 0.002). These results indicate that the DFP did not influence growth performance but providing the DFP in Exp. 2 led to increased total nursery pig mortality.

Effects of gruel feeding and oral dextrose on the survivability of pigs after weaning.

Two experiments were conducted in a 14,400 head nursery using 3,087 (experiment 1) and 988 (experiment 2) pigs to determine the effect of gruel feeding (experiment 1) and supplemental oral dextrose (experiment 2) on nursery pig survivability after weaning. Upon arrival to the nursery, for experiment 1, the smallest 10% of pigs were selected and randomly placed in pens with 61 to 108 pigs per pen. Pens of small pigs were assigned to one of two treatments in a completely randomized design. Treatments consisted of gruel feeding two or four times per day for 14 d postplacement. At each gruel feeding, approximately 1.13 kg of solid feed was added to a round bowl (Rotecna S.A., Agramunt, Spain) located at the front of each pen and water added at a decreasing rate over time. In experiment 2, every other pig removed for welfare considerations (lameness, sick, or unthrifty) from the general population or pens of small pigs received a single 10 mL oral dose of a 50% dextrose solution (Vet One, MWI Animal Health, Boise, ID), as a source of glucose, before being placed in a removal pen. All removed pigs were tagged and weighed, body temperature recorded, and blood glucose concentration measured prior to and 30 min after entering removal pens. Overall, gruel feeding small pigs two or four times per day for 14 d postplacement 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 38 d postweaning (21.4% vs. 23.4% respectively), even though blood glucose concentration increased (P < 0.001) 30 min after removal for pigs administered dextrose. An interaction was observed for blood glucose concentration and body temperature (P < 0.001) where pigs with blood glucose concentrations less than 70 mg/dL had increased mortality as body temperature increased. In contrast, pigs with a blood glucose concentration of 70 mg/dL or greater had decreased mortality as body temperature increased. Pigs weighing less than 4.5 kg also had increased mortality (P < 0.001) compared with pigs weighing greater than or equal to 4.5 kg at removal. In summary, gruel feeding four times per day vs. two times per day or providing a dextrose supplement to pigs removed from the general population did not improve the survivability of pigs after weaning. Additionally, pigs removed with decreased body weight or with body temperature or blood glucose concentrations below or above the normal range had decreased survivability.

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.

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 lactation and nursery diets supplemented with a feed flavor on sow feed intake and lactation performance and subsequent weaned pig nursery performance.

A total of 105 sows (Line 241, DNA, Columbus, NE) were used across four batch farrowing groups to evaluate the effects of feeding a feed flavor in lactation diets on sow and litter performance. Sow groups 1 and 2 farrowed in an old farrowing facility during the summer months and groups 3 and 4 farrowed in a new farrowing facility during the winter months. Sows were blocked by body weight (BW) within parity on days 110 of gestation and allotted to 1 of 2 dietary treatments. Dietary treatments were a standard corn-soy-based lactation diet (control) or the control diet with the addition of a feed flavor at 0.05% of diet (Krave AP, Adisseo, Alpharetta, GA, USA). Farrowing facility environment had a large impact and resulted in many interactions with the feed flavor treatment. From farrowing to weaning, sows fed the feed flavor in the old farrowing house tended to have a higher (P = 0.058) lactation feed intake, while no difference in average daily feed intake (ADFI) was observed in the new farrowing house. Pigs weaned from sows fed with the feed flavor in the old farrowing facility had a higher (P = 0.026) BW at weaning and piglet average daily gain (ADG) from day 2 to weaning (P = 0.001) compared to piglets from sows not fed with the feed flavor; whereas the opposite occurred in the new farrowing house. Progeny from one farrowing group in the old farrowing facility was followed into the nursery. A total of 360 weaned pigs (DNA 241 × 600: initially 5.7 kg) were used in a 2 × 2 factorial in the nursery portion of the study to evaluate the effects of previous sow feed flavoring treatment (control vs. flavor) and nursery diets formulated with or without a feed flavor on growth performance in a 38-d trial. Nursery treatments were either a control diet or a diet containing a feed flavor (Delistart #NA 21, Adisseo). Offspring from sows fed with the flavor diet were heavier at weaning (P < 0.001) which was maintained throughout the study. Overall, progeny from sows fed with a diet containing a feed flavor had greater (P < 0.05) ADG, ADFI, and final BW during the trial. The presence of a feed flavor in the nursery did not improve overall nursery performance. In conclusion, when sow lactation feed intake was increased in the old farrowing house, pigs weaned from sows fed with the flavor diet were heavier (P = 0.039) at weaning compared to pigs weaned from sows fed with the control diet. Adding the feed flavor increased sow feed intake and piglet ADG in a warm environment, but not in a cool environment.

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; initially 6.0 ± 0.23 kg) were used in a 35-d study. At the time of placement, pens of pigs were weighed and allotted to one of three dietary treatments in a randomized complete block design with a blocking structure including sow farm origin, date of entry into the facility, and average pen body weight. A total of 144 pens were used with 72 double-sided 5-hole stainless steel fence line feeders, with one feeder serving as the experimental unit. For each feeder, 1 pen contained 27 gilts, and 1 pen contained 27 barrows. There were 24 replicates per dietary treatment. Diets were fed in three phases, and all contained 0.3 mg/kg added Se. A common phase 1 diet contained added Se from sodium selenite and was fed in pelleted form to all pigs from day 7 to approximately day 0. Three Se sources sodium selenite, Se yeast, and hydroxy-selenomethionine (OH-SeMet) were used to formulate three experimental diets in meal form for phase 2 (days 0 to 14) and phase 3 (days 14 to 35). During the pre-treatment period (days 7 to 0), there was a tendency (P = 0.097) of a difference in average daily feed intake between treatments, although no significant pairwise differences were observed (P > 0.05). There were no other differences in growth performance between treatments from days 7 to 0. Clinical disease attributed to Streptococcus suis was observed within the trial between days 0 and 14, and water-soluble antimicrobial therapy was administered to all treatment groups for 7 d. From days 0 to 35, pigs fed OH-SeMet tended to have decreased average daily gain (P < 0.10) and increased (P < 0.05) serum and tissue selenium concentration compared to other treatments. There was marginally significant evidence of a source × day interaction (P = 0.027) for total antioxidant capacity where the numerical increase over time was less for the OH-SeMet than sodium selenite or selenium yeast treatments. There was no difference (P > 0.05) in antioxidant status as measured by serum glutathione peroxidase or thiobarbituric acid reactive substances assay between treatments. In summary, compared to sodium selenite and selenium yeast, OH-SeMet may have a 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.

Effect of different sow lactation feeder types and drip cooling on sow bodyweight, litter performance, and feeder cleaning criteria.

A total of 600 sows (line 3; PIC, Hendersonville, TN) were used to evaluate the effect of different lactation feeder types and drip cooling on sow farrowing performance and litter growth performance during the summer. For the feeder evaluation, the trial was conducted in two sequential groups with 300 sows per group. Five 60-farrowing-stall rooms with tunnel ventilation were used for each group. On approximately days 110 to 112 of gestation, sows were blocked by body condition score (BCS), parity, and offspring sire (lines 2 or 3 sires; PIC), then randomly allotted to one of three feeder types: 1) PVC tube feeder, 2) Rotecna feeder (Rotecna), or 3) SowMax feeder (Hog Slat). The three feeder types were placed in one of three stalls with the same sequence from the front to the end of all rooms to balance for environmental effects. For drip cooling evaluation, the trial was conducted during the 2nd group of 300 sows. Drippers were blocked in three of every six farrowing stalls to balance feeder type and environmental effects. After farrowing, sows had ad libitum access to feed. For litter performance data, only pigs from sows bred to line 2 sires were recorded. Line 3 sire pigs were not included in litter performance data, but sows of these pigs were included in sow body weight (BW) and feed disappearance data. After weaning, feeder cleaning time was recorded on a subsample of 67 feeders (19, 23, and 25 for PVC tube, Rotecna, and SowMax, respectively). There was no evidence of difference (P > 0.05) in sow entry BW, exit BW, BW change, and litter performance among the different feeder types. However, sows using the SowMax feeders had decreased (P < 0.05) total feed disappearance, average daily feed disappearance, and total feed cost compared to those fed with the PVC tube feeders. There was a marginal difference (P < 0.10) between feeder types in cleaning time, with PVC tube feeders requiring less time than the Rotecna feeders; however, cleaning time varied greatly between the personnel doing the cleaning. Sows with drip cooling had greater (P < 0.05) feed disappearance, litter growth performance, and subsequent total born, and reduced (P < 0.05) BW change. In conclusion, using a SowMax feeder reduced feed disappearance with no effects on sow and litter performance compared to a PVC tube feeder, and drip cooling improved sow and litter performance during summer.

Effect of early vs. late maturing sire lines and creep feeding on the cortisol response, intestinal permeability, and growth performance of nursery and finishing pigs.

A total of 21 litters (11 early and 10 late maturing Duroc × DNA 241) resulting in 241 pigs were used in 170 d trial to determine the effect of sire lines selected for either early or late maturing growth rates and creep feeding on the cortisol concentration, intestinal permeability, and growth performance of nursery and finishing pigs. Treatments were arranged in a 2 × 2 factorial with main effect of Duroc sire line (early or late maturing) and creep feeding (with or without). Creep feed was provided for 14 d prior to weaning. After weaning (approximately 21 d of age; initially 6.4 kg), no interactions were observed for blood cortisol. However, blood cortisol levels were increased (P = 0.011) in late maturing pigs compared to early maturing pigs. A lower percentage (P < 0.001) of early maturing pigs lost weight 3 d post-weaning compared to late maturing pigs. Likewise, early maturing pigs had improved (P < 0.001) average daily gain (ADG) and average daily feed intake (ADFI) during the first 3 d in the nursery and also had increased ADFI (P < 0.001) from days 2 to 14 in the nursery. Creep feeding had no effect on initial nursery performance. On day 7, after a 2-h fast, a subsample of pigs was administered an oral gavage of lactulose and mannitol dissolved in distilled water. No differences by sire line, creep feeding, or their interactions were observed in lactulose:mannitol ratio. For overall nursery growth performance, an interaction was observed for ADG (P = 0.007) and ADFI (P < 0.001), with creep feed providing a benefit in late maturing pigs, but not in early maturing pigs. Early maturing pigs had poorer gain-to-feed ratio (G:F) (P < 0.001) than late maturing pigs. For overall finishing performance, an interaction was observed for ADG (P = 0.037) and ADFI (P = 0.007), with creep feed providing a benefit in late maturing pigs, but not in early maturing pigs. This resulted in an interaction for final body weight (P = 0.005), with late maturing pigs that did not receive creep feed having decreased market weights (P ≤ 0.003) compared to the other treatments. In summary, early maturing pigs had decreased cortisol concentration at weaning and improved ADG and ADFI until approximately 100 kg, at which point late maturing pigs began to exhibit greater ADG. Late maturing pigs had improved G:F from 46 d of age until market. Interestingly, creep feeding late maturing pigs resulted in increased day 170 weight compared with providing no creep feed, whereas creep feed did not impact early maturing pigs (sire line × creep feed interaction, P < 0.005).

Finishing pig growth potential varies across different genotypes; however, limited research is available on performance of nursery pigs sired from boars selected for different finishing growth patterns. With selection of terminal sires focused on improved lean gain in late finishing, anecdotal or field observations suggest that starting weanling pigs on feed has become more challenging. Hence, our hypothesis that improving post-weaning feed intake by creep feeding may be of greater importance today than in the past due to sire line selection criteria. Therefore, our objective was to determine the possible interaction of Duroc sires selected for early vs. late maturing growth rates and creep feeding on the growth performance of pigs from birth to market. Early maturing pigs had increased feed intake from days 2 to 14 post-weaning compared to late maturing pigs. Likewise, a lower percentage of early maturing pigs lost weight from weaning to 3 d post-weaning. Early maturing pigs had improved average daily gain (ADG) and average daily feed intake until approximately 100 kg, at which point late maturing pigs began to exhibit greater ADG. Overall, offering creep feed to late maturing pigs resulted in improved growth performance compared to no creep feed, whereas creep feed did not impact early maturing pigs.

Impact of dietary analyzed calcium to phosphorus ratios and standardized total tract digestible phosphorus to net energy ratios on growth performance, bone, and carcass characteristics of pigs.

A total of 2,184 pigs (337 × 1,050, PIC; initially 12.4 ± 0.17 kg) were used in a 143-d study to evaluate the effects of feeding varying analyzed calcium to phosphorus ratios (Ca:P) at two standardized total tract digestible (STTD) phosphorus to net energy ratios (STTD P:NE). Pens of pigs (26 pigs per pen) were assigned to 1 of the 6 dietary treatments in a 2 × 3 factorial with main effects of STTD P:NE and Ca:P ratio. Diets consisted of two levels of STTD P:NE; High (1.80, 1.62, 1.43, 1.25, 1.10, and 0.99 g STTD P/Mcal NE from 11 to 22, 22 to 40, 40 to 58, 58 to 81, 81 to 104, and 104 to 129 kg, respectively); or Low (75% of the High levels), and three analyzed Ca:P ratios (0.90:1, 1.30:1, and 1.75:1). There were 14 pens per treatment. Diets were corn-soybean meal-based and contained a constant phytase concentration within each dietary phase with levels decreasing throughout the trial (phases 1 through 3, 500 FTU/kg, assumed release of 0.13% STTD P; phase 4, 400 FTU/kg, assumed release of 0.11% STTD P; phase 5, 290 FTU/kg, assumed release of 0.09% STTD P; and phase 6, 210 FTU/kg, assumed release of 0.07% STTD P). Overall, there was a Ca:P × STTD P:NE interaction (P < 0.05) observed for average daily gain (ADG), feed efficiency (G:F), final body weight (BW), hot carcass weight (HCW), bone mineral density, bone mineral content, and bone-breaking strength. When feeding Low STTD P:NE levels, increasing the analyzed Ca:P ratio decreased (linear, P < 0.001) ADG final BW, HCW, and tended to worsen G:F, bone mineral density, and bone mineral content (linear, P < 0.10). However, when feeding High STTD P:NE levels, increasing the analyzed Ca:P ratio significantly improved bone mineral content and bone mineral density (linear, P < 0.05), and tended to improve ADG and final BW (linear, P < 0.10) and G:F (quadratic P < 0.10). Additionally, increasing the analyzed Ca:P ratio worsened ADG, G:F, and bone mineralization with Low STTD P:NE but had marginal impacts when adequate STTD P:NE was fed.

Calcium (Ca) and phosphorus (P) are the most abundant minerals in the pig and are involved in lean tissue deposition and synthesis and maintenance of the skeletal structure. Swine diets are typically formulated with low margins of safety for P and excess P in the diet can lead to increased P excretion, which can result in negative environmental effects. To have an adequate utilization of both Ca and P, it is important to consider the Ca:P ratio when formulating pig diets. Research has shown that a wide Ca:P is detrimental to pig growth performance and bone mineralization when diets are low in STTD P. Therefore, the objective of this study was to evaluate the impact of varying Ca:P ratios fed at two levels of STTD P:NE on growth performance, bone, and carcass characteristics of pigs from 12 to 129 kg. When P levels were below requirement estimates, widening the Ca:P ratio from 0.90:1 to 1.75:1 reduced growth performance and bone mineralization; however, widening the Ca:P ratio improved performance and bone mineralization when P levels of the diet were above requirement estimates.