Impact of increasing dietary standardized ileal digestible arginine to lysine ratio from 0.85 to 1.15 and water-based arginine supplementation on growth performance and gut integrity of weaned pigs.

The objective of this experiment was to assess the influence of arginine (Arg) supplementation in water and/or feed on the growth performance and gastrointestinal health of newly weaned pigs. Two hundred and forty pigs (5.06 kg; PIC, Hendersonville, TN) were randomly allocated into 80 mixed-sex pens (3 pigs/pen) and subjected to a 2 × 4 factorial design. Two levels of Arg were supplemented in water (0% or 8% stock, dosed through a 1:128 proportioner) for the first phase (days 0 to 7), and four dietary arginine levels (0.85, 0.95, 1.05, and 1.15) standardized ileal digestible (SID) Arg to Lysine (Lys) ratios for the first two phases (days 0 to 7 and 7 to 21). All treatments were provided a common diet (0.96 SID Arg:Lys) for the last phase days 21 to 42. One pig per pen underwent a dual sugar absorption test of lactulose at 500 mg/kg and mannitol at 50 mg/kg of body weight (BW) via gastric tube on days 7 and 21 postweaning, with blood plasma collected 4 h later. The pig tested on day 7 was subsequently euthanized for intestinal tissue collection. Pen growth performance and feed disappearance were evaluated for 3 phases: days 0 to 7, 7 to 21, and 21 to 42 postweaning. The statistical analysis used linear models to examine the effects of SID Arg:Lys in the feed, Arg level in water, and their interactions, with pen as the experimental unit. Orthogonal contrasts were used to test the linear and quadratic effects of increasing SID Arg:Lys in the diet. Growth performance during the first period exhibited variability, reflected by negative gain-to-feed (G:F) ratios, caused by the enteric health challenge. Consequently, data were analyzed separately for each phase. Increasing dietary SID Arg:Lys caused a linear improvement (P = 0.04) in final BW (18.47 and 21.90 kg, for 0.85 and 1.15 SID Arg:Lys, respectively). A trend (P = 0.09) suggested a linear impact of dietary SID Arg:Lys on average daily gain during days 21 to 42. Arg supplementation, whether administered through water or diet, did not affect lactulose and mannitol absorption on both days 7 and 21, nor did it alter histological measurements in the collected ileum tissues on day 7 postweaning. In conclusion, increasing dietary SID Arg:Lys increased final BW but had no clear impacts on intestinal health within the parameters measured, potentially impacted by the rotavirus diagnosis in the first week post-wean.

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.

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.

Water- and feed-based arginine impacts on gut integrity in weanling pigs.

Two hundred and forty newly weaned pigs (PIC, Hendersonville, TN) were used to determine if supplementing additional arginine (Arg) either in the water or in the feed, and the combinations thereof, improved intestinal integrity and growth performance in nursery pigs. Each of the 80 pens contained three pigs (21 ± 2 d of age) which were randomly allotted to treatments in 4 × 3 factorial arrangement consisting of four water treatments (0%, 4%, 8%, and 12% Arg stock delivered through a 1:128 medication delivery system) in combination with three dietary Arg treatments (1.35%, 1.55%, and 1.75% standardized ileal digestible Arg; SID). Pigs and feeders were weighed at the d0, d6 (water and diet change), d20 (diet change), and d41 for the calculation of average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency (G:F). Eighty pigs, 1 pig/pen, were euthanized at d6 for ileum evaluation of villus height and crypt depth. The remaining pigs were taken off the Arg-water treatment and fed phase-2 diets formulated to contain 1.35%, 1.55%, and 1.75% SID Arg. All pigs received a common diet from d20 to d41. Data were analyzed by pen as repeated measures (SAS 9.4). No interaction between water- and dietary-Arg was detected on nursery pig growth performance. There was a significant quadratic effect of SID Arg in the feed on pig final body weight (BW), ADG, ADFI, and G:F (P ≤ 0.037), where feeding 1.55% dietary Arg tended to improve growth performance compared to the 1.35% level for the 41 d of the trial (P ≤ 0.088). The use of the stock 8% Arg in the water resulted in a reduction in crypt depth (0:132.5, 4:140.7, 8:117.3, 12:132.0; P ≤ 0.01) and an improvement in intestinal permeability. The 4% oral Arg significantly reduced villous height:crypt depth ratio (0:2.50, 4:2.09, 8:2.56, 12:2.43; P ≤ 0.02). In conclusion, the feeding of 1.55% Arg resulted in an improvement in nursery pig ADG, ADFI, G:F, and final BW but did not alter intestinal villi morphology; however, the use of Arg in the water resulted in an improvement in intestinal villi, but no phenotypical change in piglet growth in the nursery.

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.

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.

Evaluation of a novel threonine source for nursery pig diets.

Four hundred and eighty (PIC 337 X 1050, PIC Genus, Hendersonville, TN) pigs were used to evaluate a novel threonine source (ThrPro, CJ America Bio, Fort Dodge, IA) for nursery pigs from approximately 7 to 20 kg body weight (BW). After weaning, pigs were sorted by sex and fed a common diet for 1 wk. Upon completion of the first week, pigs were sorted into randomized complete blocks, equalized by weight, within 16 replications. Pigs were allocated to one of three dietary treatments: positive control (POS)-standard ileal digestible threonine-to-lysine ratio (SID; Thr:Lys) 0.60, negative control (NEG)-SID Thr:Lys ≤0.46, and alternative Thr source (TEST)-SID Thr:Lys 0.60. The alternative Thr source included fermentative biomass and was assumed to contain 75% Thr and a digestibility coefficient of 100% based on the manufacturer's specifications. All other nutrients met or exceeded the NRC recommendations. Growth and intake data were analyzed as repeated measures with a compound symmetry covariance structure using the MIXED procedure in SAS 9.4 (SAS Institute Inc., Cary, NC) with pen as the experimental unit. Treatment, phase, the interaction between treatment and phase, and block were included as fixed effects in the model. Differences in total removals were tested using Fisher's Exact Test of PROC FREQ. Results were considered significant at P ≤ 0.05 and considered a trend at P > 0.05 and P ≤ 0.10. During the first 14 d, pigs fed TEST had decreased gain-to-feed ratio (G:F; 0.77 vs. 0.80, P = 0.022) compared to POS and increased G:F (0.77 vs. 0.73, P < 0.001) compared to NEG. Over days 14-28, pigs fed TEST had similar G:F (0.71 vs. 0.70, P = 0.112) compared to POS and increased G:F (0.71 vs. 0.63, P < 0.001) compared to NEG. Overall (days 0-28), pigs fed TEST had similar average daily gain (ADG; 0.47 vs. 0.47 kg/d, P = 0.982) and G:F (0.76 vs. 0.74, P = 0.395) compared to POS and increased ADG (0.47 vs. 0.43 kg/d, P < 0.001) and G:F (0.76 vs. 0.67, P < 0.001) compared to NEG. The average daily feed intake was not significantly different across treatments for the entirety of the study. In conclusion, the replacement of crystalline L-Thr with a novel Thr source resulted in similar growth performance in nursery pigs from approximately 7 to 20 kg.