Evaluation of branched-chain amino acid interactions in 10 to 20 kg nursery pigs using a central composite design.

Two groups of 240 pigs (PIC 337 × 1050, PIC Genus, Hendersonville, TN) were used to investigate the interactions between leucine, isoleucine, and valine on the growth performance of approximately 10 to 20 kg nursery pigs. At weaning, pigs were placed into 40 pens with three barrows and three gilts per pen and fed a common diet for 3 wk. On day 21 postweaning, pens were randomly assigned to 1 of 15 dietary treatments in a central composite design. Diets were formulated to various levels of standardized ileal digestible (SID) Leu, Ile, and Val by supplementing L-Leu, L-Ile, and L-Val. Levels of the branched-chain amino acids, expressed as ratios to SID Lys, ranged from 98% to 180%, 46% to 64%, and 51% to 78% for Leu, Ile, and Val, respectively. Diets were formulated to be iso-Lys, isonitrogenous, and isocaloric. Pig weights and feed intake were measured for the 21-d experiment to calculate average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency (G:F). Growth performance data were analyzed using the lm() function in R version 4.2.2 (R Core Team, 2022). The second-order polynomial model included the linear and quadratic effects of Leu, Ile, and Val, their three two-way interactions, and initial body weight. Pen was the experimental unit, and parameters were considered significant at P ≤ 0.10. A linear and quadratic effect of Val was observed for ADG and G:F (P < 0.001). There was an interaction between Leu and Ile for ADG (P = 0.069) and G:F (P = 0.032), where increasing Leu and decreasing Ile, and the inverse, improved ADG and G:F. However, growth and efficiency were negatively impacted as Leu and Ile increased in the diet. There was an interaction between Leu and Val for ADFI (P = 0.060), where Leu negatively impacted feed intake at low levels of Val but had little impact as Val increased above NRC (2012) recommendations. In conclusion, Val linearly and quadratically impacted ADG and G:F, regardless of Leu and Ile levels in the diet, while ADG and G:F were reduced with high levels of Leu and Ile, which was resolved as either Leu or Ile was reduced. Furthermore, ADFI was negatively impacted by increased Leu when Val was below NRC (2012) recommendations but was not affected by Leu at higher Val levels. Together, the results of this experiment emphasize the complexity of amino acid metabolism in nursery pigs and the importance of considering potential interactions among amino acids when conducting requirement studies.

Leucine, isoleucine, and valine are known as the branched-chain amino acids (BCAA). Aside from being essential for protein synthesis, BCAA play signaling roles, stimulating pathways of muscle protein synthesis. The first two steps in the BCAA catabolic pathway are shared amongst the three amino acids; consequently, excess consumption of one BCAA may increase the catabolism of the other two, hindering growth performance. Therefore, the objective of this trial was to investigate the interactions of BCAA and their impact on the growth performance of approximately 10 to 20 kg nursery pigs. In the current trial, valine linearly and quadratically impacted average daily gain and feed efficiency, regardless of leucine and isoleucine levels in the diet, but high levels of both leucine and isoleucine negatively impacted growth and efficiency. Furthermore, increasing leucine in the diet reduced feed intake when accompanied by low levels of valine, which was resolved as valine increased. Using a central composite design allowed for the description of the complex interactions between BCAA in nursery pigs and demonstrated the utility and application of this design in swine nutrition research. Together, the results of this study highlight the importance of considering the balance of BCAA in the diet of nursery pigs.

Compensatory gain based on lysine level in finishing pigs after being fed lysine deficient 97% corn diets for 3 or 6 wk.

The objective of this experiment was to evaluate increasing the concentration of lysine on the compensatory gain of finishing pigs during their recovery period after being fed a 97% corn holding diet for 3 or 6 wk. One thousand six hundred and eighty pigs with a starting body weight of 73.5 ±â€…2.2 kg were blocked by starting body weight and assigned to a nested arrangement. Twenty replicates of seven treatments were comprised of two restriction lengths [3 weeks (3 wk) vs. 6 weeks (6 wk)], and three lysine concentrations during recovery (Lys:ME same as control:100; control + 10%: 110; control + 20%: 120) plus one control (CONT) that remained nutrient unrestricted. Pen weight and feed intake were recorded on days 0, 21, 41, and at marketing. Whole pens were marketed when the pen average met 130 kg and carcass measurements were collected. Data were analyzed by pen with the fixed effects of restriction length and lysine within restriction length. Nutrient restriction lowered (P < 0.01) average daily gain (ADG) compared to control, with 1.2, 0.4, and 0.5 kg for control, 3 wk, and 6 wk treatments, respectively. Restricted pigs showed decreased feed intake while restricted. After the respective restriction period, pigs were allowed a recovery diet until market. Previously restricted pigs had 16.7% and 27.3% greater (P < 0.01) ADG over control pigs for 3 and 6 wk treatments, respectively, in the first 3-wk of recovery. The lysine concentration in the recovery diet impacted (P < 0.01) the ADG with pigs allowed the highest lysine concentration having a 10% greater ADG than pigs fed the lower Lys:ME concentrations, for both restriction treatments. The increase in ADG was not paralleled by an increase in feed intake over control, thus, there was an improvement (P < 0.01) in gain to feed ratio in the recovery period. Control pigs reached market weight (131.5 kg) on experiment day 49 while pigs fed corn diets for 3 wk or 6 wk were slower to market (57 and 69 days, respectively; P < 0.01). Restricted pigs had greater backfat (CONT: 1.47, 3 wk: 1.55, 6 wk: 1.65 cm; P < 0.01), and decreased loin depth (CONT: 7.32, 3 wk: 7.03, 6 wk: 6.61 cm, P < 0.02) which was also impacted (P < 0.01) by lysine concentration. In conclusion, the use of restrictive diets reduced ADG and increased days to market. The use of recovery diets in which the Lys:ME ratio was greater than control pigs, resulted in increased compensatory growth.

The effects of dietary essential fatty acid ratios and linoleic acid level in grow-finish pigs.

The objective of this study was to investigate the effects of dietary linoleic acid level and the ratio of linoleic acid:linolenic acid (LA:ALA) on the growth performance, expression of genes associated with lipid metabolism, and inflammatory status of grow-finish pigs. A total of 300 growing pigs (body weight [BW] = 41.1 ±â€…6.3 kg) were randomly assigned to either a high (30 g/kg; HLA) or low (15 g/kg; LLA) dietary linoleic acid level with a high (23:1; HR), moderate (13:1; MR) or low (4:1; LR) dietary LA:ALA in a 2 × 3 factorial design. Diets were fed across three 28-d phases and were balanced for dietary metabolizable energy. Pigs were housed five pigs per pen in single-sex pens. Blood samples were collected on days 0, 21, 42, and 84, and synovial fluid was collected from the hock joint on days 0 and 84 for inflammatory marker analysis. Data were analyzed as repeated measures using PROC MIXED (SAS 9.4) with initial BW as a covariate, pen as the experimental unit, and LA level, LA:ALA, sex, phases, and their interactions as fixed effects. Compared to HLA, LLA pigs tended to have increased BW at days 56 and 84 (P = 0.088). There was no effect of LA × LA:ALA for growth performance. For the overall days 0 to 84 growth period, pigs fed HR had increased ADG compared to MR, with pigs receiving LR performing intermediate of MR and HR. Gilts receiving HR diets had increased day 84 BW compared to gilts receiving the low and moderate LA:ALA (P = 0.006), which was a result of improved overall days 0 to 84 ADG compared to gilts receiving the MR diets (P = 0.023). Barrows fed LR had improved BW on day 56 compared to MR and HR and higher final BW compared to HR, with MR performing intermediately (P = 0.006). This was a result of greater days 0 to 84 ADG (P = 0.023). Overall, C-reactive protein (CRP), tumor necrosis factor-α (TNFα), and interleukin-6 were reduced in the plasma of pigs over time (P ≤ 0.037). Across all treatments, CRP and TNFα were reduced in the hock and carpus synovial fluid on day 84 vs. day 0 (P ≤ 0.049). In conclusion, LA:ALA ratios utilized in this study can be fed at varying linoleic acid levels without impacting growth or inflammation. Additionally, LA:ALA ratios can differentially impact the growth of gilts and barrows.

Previous research in lactating sows has reported that dietary inclusion of the essential fatty acids linoleic acid and linolenic acid is important for performance. Research in grow­finish pigs has shown an improvement in gilt growth performance when fed differing linoleic:linolenic acid ratios (LA:ALA); however, further research evaluating LA:ALA in diets with similar metabolizable energy is needed in growing pigs. In the present research, a 23:1 dietary essential fatty acid ratio increased the final body weight of gilts compared to a 13:1 or 4:1 LA:ALA, while barrows fed a 4:1 dietary essential fatty acid ratio had increased gain and final body weight compared to a 23:1 LA:ALA. Plasma and synovial fluid inflammatory markers were also reduced with time and were unaffected by dietary LA:ALA or linoleic acid inclusion. Dietary essential fatty acid ratio can differentially impact the growth of barrows and gilts, with no impact on systemic or joint inflammation.

The impact of essential fatty acid ratios and unsaturated to saturated fat ratio on growth performance of grow-finish pigs and estrus detection of gilts.

The objective of this study was to investigate the effects of dietary unsaturated and saturated fat ratio (U:S) and the ratio of linoleic and linolenic acid (LA:ALA) on the growth performance of grow-finish pigs and estrus detection of gilts. A total of 240 pigs with initial body weight (BW) 54.4 ± 5.5 kg were randomly assigned to a high (>1.8; HUS) or low (<1.0; LUS) U:S in combination with a high (20:1), moderate (12:1), or low (4:1) LA:ALA in a 3 × 2 factorial arrangement. Dietary ratios were achieved using blends of choice white grease, beef tallow, corn oil, flaxseed oil, or palm kernel oil. Diets were fed across three phases and balanced for energy and LA. Pigs were housed across 60 pens with either four gilts or four barrows per pen. On day 49, 1 gilt per pen was moved to individual housing at approximately 154 d of age for evaluation of reproductive characteristics. Data were analyzed as repeated measures using PROC MIXED (SAS 9.4; SAS Inst., Cary, NC) with pen as the experimental unit and U:S, LA:ALA, sex, and their interactions as fixed effects. Initial BW was fit as a covariate. Within each phase, there were no differences in BW, daily gain (ADG), feed intake (ADFI), or feed efficiency (G:F) for U:S, LA:ALA, or their interaction when averaged across sex (P ≥0.128). Gilt feed efficiency was improved during the second phase compared to barrows; however, feed efficiency was not different between barrows and gilts during the first and third phases; resulting in a similar feed efficiency between sexes for the overall period (P = 0.523). Compared to HUS, gilts receiving LUS had higher ADFI overall (P = 0.018), which translated into improved G:F for HUS gilts (P = 0.011). Overall, gilts receiving the 20:1 diet tended to have improved G:F compared to 12:1 (P = 0.086). ADG was improved in pigs fed diets formulated with unsaturated fat sources to a 20:1 LA:ALA, regardless of sex. Detection of first estrus by 235 d of age in gilts was not impacted by U:S or LA:ALA (P ≥ 0.356). In conclusion, feeding differing dietary U:S and LA:ALA ratios impacts growth of growing pigs, particularly improving feed efficiency of gilts fed diets with unsaturated fat sources or a 20:1 LA:ALA. Further investigation into the physiological mechanisms differentially affecting gilt growth when fed varying dietary LA:ALA is warranted to understand the impact on reproductive outcomes.

The impact of floor space allowance and dietary energy level on finishing pigs, from 65 to 120 kg, on growth performance.

The objective of this experiment was to evaluate the impact of lowering floor space allowance in finishing hogs from 65 to 120 kg when fed high- vs. low-energy diets on growth performance. Eighty-eight mixed-sex pens with 24 ±â€…1 pigs per pen were randomly assigned by weight in a complete block design to one of eight treatments in a 2 × 4 factorial arrangement with two energy levels: low (LE, 3267 ±â€…15 kcal/kg) vs. high (HE, 3389 ±â€…15 kcal/kg) accomplished through fat inclusion; and four floor space allowances: 0.6, 0.63, 0.65, and 0.67 m2/pig. Assigned floor space was accomplished by moveable gates in the rear of the pen which were adjusted at each pig removal until the marketing phase. Pen weight was measured at days 0, 29, and 48, with feed disappearance measured at days 29 and 48 to calculate average daily gain (ADG), average daily feed intake (ADFI), and gain-to-feed ratio (GF). Data were analyzed by pen (SAS 9.4, Cary, NC), as repeated measures, with the fixed effects of floor space allowance, dietary energy level, and the interaction between floor space allowance and energy level. For the overall experiment, decreased floor space had no effect (P > 0.1) on ADG, ADFI, or GF. Energy had a significant effect (P < 0.01) on ADFI (3.17 vs. 3.12 kg for LE and HE, respectively) and GF (0.35 and 0.36 for LE and HE, respectively), and tended to impact (P = 0.08) ADG (1.12 vs. 1.13 kg, for LE and HE, respectively). In conclusion, reducing space allowance from 0.67 m2 down to 0.6 m2 did not affect the growth performance of pigs from 65 to 120 kg. Pigs fed LE consumed more than the HE diets but had generally similar growth and no difference in body weight.

The effects of dietary essential fatty acid ratios and energy level on growth performance, lipid metabolism, and inflammation in grow-finish pigs.

The objective of this study was to investigate the effects of dietary metabolizable energy (ME) level and the ratio of linoleic acid:α-linolenic acid (LA:ALA) on the growth performance, lipid metabolism, circulatory and joint inflammatory status, and synovial fluid proteome of grow-finish pigs. A total of 224 pigs (BW = 41.5 ±â€…6.1 kg; PIC Genus 337 × 1050, Hendersonville, TN) were randomly assigned to either a high (3.55 Mcal/kg; HE) or low (3.29 Mcal/kg; LE) ME dietary treatment with a high (23:1) or low (12:1) LA:ALA in a 2 × 2 factorial arrangement. Diets were fed across three 28-d phases. Pigs were housed either four barrows or four gilts per pen. Blood samples were collected on days 0, 21, 42, and 84. Synovial fluid was collected from the hock and carpus joints on days 0 and 84. Liver and adipose tissue samples were collected on day 84. Data were analyzed as repeated measures using PROC MIXED (SAS 9.4) with pen as the experimental unit and energy level, essential fatty acid ratio, sex, phase, and their interactions as fixed effects. Compared to LE, HE increased days 28, 56, and 84 body weight (BW; P = 0.005). For the overall period, HE increased average daily gain (ADG) compared to LE (P < 0.001) and improved feed efficiency (P = 0.001), while LE increased feed intake compared to HE (P < 0.001). Gilts receiving diets with low LA:ALA had similar final BW to barrows receiving a low LA:ALA at days 28, 56, and 84 (P = 0.024), resulting from improved overall days 0-84 ADG compared to gilts receiving the high LA:ALA (P = 0.031). In the liver, HE decreased the mRNA abundance of acetyl CoA carboxylase (ACACA; P = 0.004), cluster of differentiation 36 (P = 0.034), and tended to decrease fatty acid synthase (FASN; P = 0.056). In adipose tissue, HE decreased ACACA (P = 0.001) and FASN (P = 0.017). Plasma inflammatory markers C-reactive protein (CRP) and tumor necrosis factor-α (TNFα) were reduced on day 84 compared to day 0 (P ≤ 0.014). In the hock and carpus synovial fluid, LE tended to reduce CRP and TNFα (P ≤ 0.096). Hock and carpus synovial fluid CRP were also reduced on day 84 compared to day 0 (P = 0.001). Age of the pig impacted serum and hock synovial fluid protein abundance, but not energy level, LA:ALA, or their interactions (P < 0.05). To conclude, the high and low LA:ALA ratios utilized in this study can be fed at varying energy levels without impacting growth. Additionally, LA:ALA ratios can differentially impact the growth of barrows and gilts.

In pig diets, it has been established that added fat can improve growth and feed efficiency; however, insufficient research has been reported evaluating specific essential fatty acids found in commonly available fat sources. Essential fatty acids are important in several biological functions in the body, including growth, inflammation, and immune function. Given shared metabolism between essential fatty acids linoleic acid and α-linolenic acid, it has been suggested that their dietary ratio is critical to balance inflammatory responses. In the present research, a 12:1 dietary linoleic:linolenic acid ratio improved gilt, but not barrow, daily gain and did not impact inflammation. Pro-inflammatory responses were reduced over time, both in the blood and joint fluid. High-fat diets also improved growth performance, suppressed genes involved in fatty acid synthesis, and tended to increase joint inflammation. There was no interaction between dietary fat level and essential fatty acid ratio for any variable. Overall, dietary essential fatty acid ratios impact the growth of gilts, regardless of dietary fat inclusion, with no apparent effects on inflammation.

The evaluation of the supplementation of vitamin A, beta-carotene, and oxidized beta-carotene in prepubertal gilts.

Finishing pigs (N = 224; 28.66 ± 1.90 kg bodyweight) were randomly assigned across 56 pens of either four barrows or gilts, and assigned to one of four diets: control (7,656 IU vitamin A/kg), control supplemented with vitamin A (4.36 ppm, Rovimix A 1000, DSM, Parsippany, NJ, USA), control supplemented with beta-carotene (163.28 ppm, Rovimix ß-Carotene 10%, DSM, Parsippany), or control supplemented with oxidized beta-carotene (40 ppm; 10% active ingredient, Avivagen, Ottawa, ON, Canada). Pigs and feeder weights were obtained at the start of the study (d 0), and end of each phase (d 21, 42, and 63). A subset of gilts had a blood sample taken via jugular venipuncture on d 0, a blood sample and vaccinations of Lawsonia intracellularis and porcine circovirus type 2 (PCV2) on d 18, a blood sample and booster vaccination of PCV2 on d 39, a blood sample on day 60, and a final blood sample on day 63. Gilts were euthanized at the end of the study to obtain a liver (entire right lobe) and a jejunum sample (15.24 cm at 10% of length). Additionally, the second and fourth right anterior mammary were collected to assess anterior mammary tissues. Data were analyzed in SAS 9.4 (Statistical Analysis System, Cary, NC) via GLIMMIX procedure. Oxidized beta-carotene supplementation increased (P = 0.02) ADG across phases over vitamin A supplementation, although there were no differences (P = 0.18) in the body weight of pigs. There was no effect (P > 0.05) of diet on plasma or hepatic retinol, IgG or IgM levels, or immune cell presence in developing mammary tissue. Supplemented vitamin A tended (P = 0.05) to increase the mRNA abundance of retinol binding protein in the jejunum, but other mRNA abundance for genes (alcohol dehydrogenase class 1, lecithin retinol acyltransferase phosphatidylcholine-retinol O-acyltransferase, and beta-carotene oxygenase 1) were not affected (P > 0.05) by dietary treatments. A diet by time interaction (P = 0.04) was noted for the circovirus S/P ratio, where vitamin A supplementation had the best ratio compared to other diets. Analyzed titer levels for the circovirus vaccine had an interaction (P < 0.01) for diet by time, where vitamin A supplementation had the highest titer at the end of the study. Thus, pigs supplemented with oxidized beta-carotene had an improved ADG over vitamin A supplemented pigs, but pigs supplemented with vitamin A seemed to have an improved immune status.

Vitamin A, beta-carotene, and oxidized beta-carotene were supplemented to finishing pigs to determine if feeding vitamin A, beta-carotene, or oxidized beta-carotene influences growth performance and the proliferation of immune cell populations in the developing mammary gland in prepubertal gilts. When evaluating overall growth parameters, there were no differences across the dietary treatments and no differences in the circulating immunoglobulin production. Supplementing vitamin A did increase the amount of retinol binding protein that was expressed in the small intestine. Pigs supplemented with oxidized beta-carotene did have an increase in average daily gain (ADG) during a health challenge over pigs supplemented with vitamin A. However, gilts that received vitamin A supplementation had an improved sample-to-positive ratio (S/P ratio) and titer response to porcine circovirus 2 vaccines, indicating that vitamin A supplemented gilts have an improved immune response to vaccinations.

Evaluation of oxidized beta-carotene on sow and piglet immune systems, sow reproductive performance, and piglet growth.

This study aimed to determine if supplementation of oxidized-beta carotene (OxC-Beta) improved sow reproductive performance, litter growth performance, vitamin A status, and ability to alter immune cells abundance in sows and piglets, subsequent litter performance, and nursery growth performance. On approximately day 60 of gestation and through the lactation period, 194 sows (blocked by parity) were assigned to a common gestation diet or the common diet supplemented with 80 ppm oxidized beta-carotene (OxC-Beta, Aviagen, Ottawa, ON, Canada). A subset of sows (N = 54 per treatment) were sampled for blood and body weight recorded at the beginning of the study, farrowing, and weaning. A blood sample was taken from a subset of piglets at birth and weaning, and all piglet weights were recorded. Blood was analyzed for vitamin A as retinol concentrations and immunoglobulin G (IgG) and immunoglobulin M (IgG) levels were assessed from the sow's blood. Twelve pigs (N = 6 per treatment) were euthanized at birth and weaning. The livers were collected and analyzed for the Kupffer cell phagocytic activity through flow cytometry. Whole blood was analyzed via flow cytometry for cluster of differentiation (CD335, CD8, and CD4). Colostrum during farrowing and milk at weaning were analyzed for IgG and IgA concentrations. Data were analyzed via SAS 9.4 using MIXED and frequency procedures where appropriate. No differences (P > 0.05) between dietary treatments were observed in sow reproductive performance, feed intake, wean to estrus interval, or piglet growth performance. No differences (P > 0.05) were observed in the plasma or liver for vitamin A. No differences (P > 0.05) were observed in the composition of the colostrum or milk. No immunological differences (P > 0.05) were observed in the piglets' liver and blood or sow antibodies in colostrum and milk. The supplementation of OxC-Beta did (P < 0.05) decrease IgM and tended (P < 0.10) to decrease IgG in sow plasma. No differences (P > 0.05) were observed in the reproductive performance of subsequent litter information from the sows. Gilt litter weaning weight and feed intake were reduced (P < 0.05) compared to sow performance. In conclusion, the supplementation of OxC-Beta at 80 ppm from day 60 of gestation through lactation does not affect the reproductive performance of sows, litter growth performance, vitamin A status, piglet immune status, and antibodies or composition in colostrum and milk.

Beta-carotene is a known antioxidant found in most red and orange-pigmented vegetables and has been documented to have health benefits. However, beta-carotene has been reported to gain oxygen molecules spontaneously, thus oxidizing it. Oxidized beta-carotene has been recognized to provide potential health benefits to animals, although its functions are independent of beta-carotene. Sows in this study were supplemented with an oxidized beta-carotene product to evaluate whether the product could improve reproductive performance, including the number of piglets born alive, piglet birth weight, weaning weight, sow milk quality, and immune function of both the sow and piglets. There were no significant findings between the reproductive performance or difference in colostrum and milk composition of the control sows and the sows supplemented with the product. There was also no difference in piglet growth between the two groups. The product did not affect the measured immune functions of the piglets. However, immunoglobulin G tended to decrease with the use of the product, and there was a decrease in immunoglobulin M. Overall, supplementing the oxidized beta-carotene product did not affect the reproductive performance of sows or the growth performance of piglets.

Effect of benzoic acid with or without a Bacillus-based direct-fed microbial on the performance and carcass merit of grow-finish pigs.

Two hundred and forty barrows and gilts (DNA 600 × 241, DNA Genetics, Columbus, NE) with an initial body weight (BW) of 35.5 ± 4.2 kg were sorted into split-sex pens, blocked by initial body weight, and randomly allocated to one of three dietary treatments with eight pigs per pen and ten pens per treatment. Dietary treatments included a standard diet (CON), CON plus 0.3% benzoic acid (BA; VevoVitall, DSM Nutritional Products, Parsippany, NJ), and CON plus 0.3% BA and 0.025% Bacillus-based direct-fed microbial (BA+DFM; PureGro, DSM Nutritional Products, Parsippany, NJ). The experimental diets were fed in four feeding phases. Pigs were weighed and feed intake measured at the beginning and end of each phase for the calculation of average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency (G:F). In addition, ultra-sound was utilized at the conclusion of the trial on day 81 for measurements of backfat and loin eye area. Data were analyzed as repeated measures in SAS 9.4 (SAS Institute, Cary, NC) with fixed effects of treatment, phase, sex, and block included in the model. Pen was the experimental unit, and results were considered significant if P ≤ 0.05 and a tendency if 0.05 < P ≤ 0.10. Overall, pigs fed BA had increased ADFI compared to pigs fed CON (2.88 vs. 2.75 kg, P = 0.015), while pigs fed BA + DFM had similar ADFI compared to pigs fed CON or BA (P ≥ 0.279). There was a tendency for an effect of dietary treatment on ADG (P = 0.063), where pigs fed BA tended to grow faster than pigs fed CON (1.11 vs. 1.08 kg, P = 0.051); however, there were no differences in feed efficiency between treatments (P = 0.450). Additionally, there was no evidence of an effect of dietary treatment on pig BF or LEA (P ≥ 0.334). In conclusion, supplementing 0.3% benzoic acid to grow-finish pigs stimulated feed intake, but did not affect efficiency, or carcass merit.

The effect of benzoic acid with or without a direct-fed microbial on the nutrient metabolism and gas emissions of growing pigs.

Twenty-four gilts (PIC 337 × 1050, PIC Genus, Hendersonville, TN) with an initial body weight (BW) of 33.09 ± 1.33 kg were used to investigate the effects of benzoic acid (BA) and a Bacillus-based direct-fed microbial (DFM) on the nutrient metabolism and manure gas emissions of growing pigs. Pigs were blocked by BW, placed into metabolism stalls, and randomly assigned to one of four dietary treatments: basal control (PC), low nitrogen (NC), PC plus 0.3% BA (PC+BA; VevoVitall, DSM Nutritional Products), and PC plus 0.3% BA and 0.025% DFM (PC+BA+DFM; PureGro, DSM Nutritional Products). Pigs were fed a common diet from day 0 to 14, and the experimental diets were fed in two phases (day 14 to 28 and day 28 to 53). The experiment consisted of four collection periods, with each period subdivided into two subperiods to collect samples for gas emissions and nutrient balance. Firstly, manure samples were collected for 72 h. Twice daily, urine and feces were weighed, and urine pH was measured. After each period, manure was subsampled and taken to the lab to measure gas emissions. Secondly, urine and feces were quantitatively collected for 96 h to allow for measurement of nutrient digestibility (ATTD) and retention. Data were analyzed as repeated measures in SAS 9.4 (SAS Inst., Cary, NC) with fixed effects of treatment, collection period, and block. Pig was the experimental unit, and results were considered significant at P ≤ 0.05 and a tendency at 0.05 < P ≤ 0.10. Pigs fed PC+BA had the greatest ADG compared to pigs fed NC (P = 0.016), with intermediate ADG for pigs fed PC or PC+BA+DFM (P ≥ 0.148). The ATTD of dry matter, gross energy, P, and N did not differ between treatments (P ≥ 0.093). However, the ATTD of Ca was reduced in pigs fed PC+BA+DFM compared to pigs fed PC+BA (P = 0.012). Pigs fed PC+BA or NC excreted less urinary N compared to PC and PC+BA+DFM (P ≤ 0.034), which contributed to greater nitrogen retention in PC+BA compared to PC (P = 0.016). Furthermore, decreased manure pH from pigs fed PC+BA or NC resulted in lower ammonia (NH3) emissions compared to pigs fed PC+BA+DFM or PC. There was no effect of dietary treatment on manure hydrogen sulfide, methane, or carbon dioxide emissions. In conclusion, supplementing 0.3% BA improved N retention and reduced manure pH and NH3 emissions, similar to feeding pigs low N, but improved the ADG of pigs when compared to feeding a low N diet.

Diet formulation as a strategy to improve economic and nutritional efficiency may be combined with nonnutritive feed additives, such as organic acids, specifically benzoic acid, and direct-fed microbials, to further improve nutrient utilization in pigs. Therefore, the objective of this trial was to investigate the effect of supplementing benzoic acid with or without a direct-fed microbial on the nutrient metabolism and emissions of ammonia, hydrogen sulfide, carbon dioxide, and methane from the manure of growing pigs. Feeding a diet containing 0.3% benzoic acid did not affect nutrient digestibility but reduced urinary nitrogen excretion, which resulted in improved nitrogen retention compared to the basal diet. Furthermore, benzoic acid reduced urine and manure pH, contributing to reduced manure ammonia emissions. However, supplementing the direct-fed microbial alongside benzoic acid attenuated these effects.

The validation of the existence of the entero-mammary pathway and the assessment of the differences of the pathway between first and third parity sows.

Forty sows (PIC Camborough 1050) from a single farm were randomly selected at 112 days of gestation to evaluate if gut bacteria transverse the blood system of the sow to deposit gut microbiota into the colostrum for piglet gut inoculation via the entero-mammary pathway. Fourteen first-parity gilts and 20 third-parity sows were used for the study. At the time of farrowing, colostrum, fecal samples, and blood samples were collected to evaluate the presence of bacteria in each sample. Colostrum and blood samples were processed via centrifugation to separate the immune cell fraction. Total DNA was extracted from fecal, colostrum, and white blood cell fractions. 16S ribosomal RNA gene amplicon sequencing was conducted at the Iowa State University DNA Facility (Ames, IA) to further characterize the bacterial and archaeal taxa present within each sample. Data were analyzed using Mothur and using R v4.0.3 (R Core Team, 2020). The experimental unit was the sow. Tables were generated to demonstrate the relative abundances of bacteria and archaea present in each type of sample and also identify organisms differentially abundant between sample types. Firmicutes were the most abundant phylum in colostrum and fecal samples and Tenericutes had the greatest abundance in blood comparative to other phyla. Further evaluation of the classification of bacteria present demonstrated that a few genera of bacteria are present in all three samples. Clostridum_sensu_stricto 1 was present in high relative abundance in colostrum and moderate abundance in the feces while also being present within the blood. Other genera present in all three sample types include Ruminococcus and Mycoplasma. In conclusion, the data suggest that there are bacteria present in all three locations of the sow at the time of farrowing and that first parity sows have different microbial populations than third parity sows.

Nutritional approaches to slow late finishing pig growth: implications on carcass composition and pork quality.

Although pork producers typically aim to optimize growth rates, occasionally it is necessary to slow growth, such as when harvest facility capacity is limited. In finishing pigs, numerous dietary strategies can be used to slow growth so pigs are at optimal slaughter body weights when harvest facility capacity and/or access is restored. However, the impact of these diets on pork carcass quality is largely unknown. Thus, this study aimed to evaluate the efficacy of dietary strategies to slow growth in late finishing pigs and evaluate their effects on carcass composition and pork quality. Mixed-sex pigs (n = 897; 125 ± 2 kg BW) were randomly allotted across 48 pens and assigned to 1 of 6 dietary treatments (n = 8 pens/treatment): (1) Control diet representative of a typical finisher diet (CON); (2) diet containing 3% calcium chloride (CaCl2); (3) diet containing 97% corn and no soybean meal (Corn); (4) diet deficient in isoleucine (LowIle); (5) diet containing 15% neutral detergent fiber (NDF) from soybean hulls (15% NDF); and (6) diet containing 20% NDF from soybean hulls (20% NDF). Over 42 d, pen body weights and feed disappearance were collected. Pigs were harvested in 3 groups (14, 28, and 42 d on feed) and carcass data collected. From the harvest group, 1 loin was collected from 120 randomly selected carcasses (20 loins/treatment) to evaluate pork quality traits. Overall, ADG was reduced in CaCl2, Corn, and 20% NDF pigs compared with CON pigs (P < 0.001). However, ADFI was only reduced in CaCl2 and 20% NDF pigs compared with CON (P < 0.001). Feed efficiency was reduced in CaCl2 and Corn pigs compared with CON (P < 0.001). Hot carcass weights were reduced in CaCl2 pigs at all harvest dates (P < 0.001) and were reduced in Corn and 20% NDF pigs at days 28 and 42 compared with CON pigs (P < 0.001). In general, CaCl2 and 20% NDF diets resulted in leaner carcasses, whereas the Corn diet increased backfat by 42 d on test (P < 0.05). Loin pH was reduced and star probe increased in CaCl2 pigs compared with CON pigs (P < 0.05); no treatments differed from CON pigs regarding drip loss, cook loss, color, firmness, or marbling (P ≥ 0.117). Overall, these data indicate that several dietary strategies can slow finishing pig growth without evidence of behavioral vices. However, changes to carcass composition and quality were also observed, indicating quality should be taken into consideration when choosing diets to slow growth.

Innovative strategies for managing swine welfare during the COVID-19 pandemic in Iowa.

Coronavirus Disease 2019 (COVID-19) was declared a global pandemic on March 11, 2020 by the World Health Organization and its impact on animal agriculture in the United States was undeniable. By April, COVID-19 resulted in the simultaneous closure or reduced operations of many meat processing plants in the upper Midwest, leading to supply chain disruptions. In Iowa, the leading pork production and processing state, these disruptions caused producer uncertainty, confusion, and stress, including time-sensitive challenges for maintaining animal care. The Iowa Resource Coordination Center (IRCC) was quickly created and launched by the Iowa Department of Agriculture and Land Stewardship (IDALS). The IRCC included public representation from the Iowa Pork Producers Association (IPPA), Iowa Pork Industry Center (IPIC), and Iowa State University Extension and Outreach, and private partners including producers, veterinarians, and technical specialists. Supporting swine welfare, the IRCC provided information on management strategies, dietary alterations to slow pig growth, alternative markets, on-farm euthanasia, and mass depopulation under veterinary oversight. In a crisis, Iowa created a model that reacted to producers' pragmatic, mental and emotional needs. This model could be quickly replicated with an introduction of foreign animal disease.

Pilot-Scale Assessment of a Novel Farrowing Creep Area Supplementary Heat Source.

Pre-weaning morality (PWM) is attributed to a poor creep area microclimate and causes major economic and productivity losses for the US swine industry. Piglets need supplementary heat to overcome a high surface area to body weight ratio and minimal thermoregulation. A pilot-scale study was conducted to evaluate a semi-enclosed heated microclimate (SEHM) as a supplementary heat source for farrowing creep areas over six farrowing cycles (from January to July 2019) in two rooms with 24 farrowing stalls in each room. Six SEHMs (each SEHM covers two stalls) were randomly distributed to each room and compared to heat lamps (HLs) for productivity and electricity usage. Data from 113 (SEHM) and 101 litters (HL) showed no significant difference between treatments in average daily gain (p = 0.26), 252.4 ± 8.0 g hd-1 d-1 (SEHM) and 260.3 ± 8.1 g hd-1 d-1 (HL) and PWM (p = 0.08), 9.67% ± 0.82% (SEHM) and 12.04% ± 0.87% (HL). However, a significant difference (p = 0.02) was noted in the PWM attributed to over-lay mortalities, 4.05% ± 0.76% (SEHM) compared to 6.04% ± 0.78% (HL). The SEHM electricity averaged 3.25 kWh d-1 (2.91, 3.59 kWh d-1; 95% CI), which was significantly different (p < 0.01) from the HL equivalent (125 W bulb; 6 kWh d-1).

Effects of feeding melatonin during proestrus and early gestation to gilts and parity 1 sows to minimize effects of seasonal infertility1.

This study tested whether supplemental melatonin given to mimic the extended nighttime melatonin pattern observed in the higher fertility winter season could minimize infertility during summer and fall in swine. Exogenous melatonin was fed during periods coinciding with follicle selection, corpus luteum formation, pregnancy recognition, and early embryo survival. Experiments were conducted at a commercial farm in 12 sequential replicates. In Exp. 1a, mature gilts (n = 420) that had expressed a second estrus were assigned by weight to receive once daily oral Melatonin (MEL, 3 mg) or Control (CON, placebo) at 1400 h for 3 wk starting before insemination at third estrus. In Exp. 1b, parity 1 sows (n = 470) were randomly assigned by lactation length to receive MEL or CON for 3 wk, starting 2 d before weaning. Follicles, estrus, pregnancy, and farrowing data were analyzed for the main effects of treatment, season (4-wk periods), and their interaction. Environmental measures were also analyzed for reproductive responses. In Exp. 1a, there was no effect (P > 0.10) of MEL on age at third estrus (203 d), follicle size after 7 d of treatment (5.0 mm), estrous cycle length (22.6 d), return to service (9.2%), farrowing rate (FR, 80.0%), or total born pigs (TB, 13.6). However, there was an effect of season (P = 0.03) on number of follicles and on gilts expressing estrus within 23 d of the previous estrus (P < 0.005). In Exp. 1b, there was no effect of MEL (P > 0.10) on follicle measures, wean to estrous interval, FR (84.0%), or TB (13.0). But MEL (73.5%) reduced (P = 0.03) estrous expression within 7 d of weaning compared with CON (82.0%) and season (P = 0.001) decreased FR by ~14.0% during mid summer. Also, gilts and parity 1 sows exposed to low light intensity (<45 lx) during breeding had reduced conception (-8%) and farrowing (-15%) rates, compared with higher light intensity. Similarly, high temperatures (>25 °C) during breeding also reduced gilt conception rates by 7%. Although there was clear evidence of seasonal fertility failures in gilts and sows, MEL treatment did not improve fertility in gilts and reduced estrus in parity 1 sows. It is possible that differences in lighting and thermal environments before breeding could explain the differential response to MEL in sows and gilts.

Characterization of anti-porcine epidemic diarrhea virus neutralizing activity in mammary secretions.

Porcine epidemic diarrhea virus (PEDV) causes a severe clinical enteric disease in suckling neonates with up to 100% mortality, resulting in devastating economic losses to the pork industry in recent years. Maternal immunity via colostrum and milk is a vital source to neonates of passive protection against diarrhea, dehydration and death caused by PEDV. Comprehensive information on neutralizing activity (NA) against PEDV in mammary secretions is critically important for assessing the protective capacity of sows. Therefore, the objectives of this study were to characterize anti-PEDV neutralizing activity in mammary secretions. Anti-PEDV NA was present in colostrum, milk and serum from PEDV-infected sows as determined both by immunofluorescence and ELISA-based neutralizing assays, with neutralization levels higher in colostrum and milk than in serum. The highest NA was observed in colostrum on day 1, and decreased rapidly in milk at day 3, then gradually declined from day 3 to day 19 post-farrowing. Notably, the NA in mammary secretions showed various patterns of decline over time of lactation that may contribute to variation in sow protective capacities. The kinetics of NA decline were associated with total IgA and IgG antibody levels. Neutralizing activity significantly correlated with specific IgA primarily to spike domain 1 (S1) and domain 2 (S2) proteins of PEDV rather than to specific IgG in colostrum. Subsequently, the NA in milk was mainly related to specific IgA to S1 and S2 during lactation.