Effect of standardized ileal digestible arginine:lysine on growth performance of 6- to 13-kg nursery pigs.

A total of 480 newly weaned pigs (PIC 337 × 1050; Genus, Hendersonville, TN) with an initial body weight (BW) of 6.20 ±â€…0.61 kg were used in a dose-response study to investigate the impact of increasing standardized ileal digestible (SID) Arg:Lys on nursery pig growth performance. At weaning, pigs were placed into 48 pens with 5 barrows and 5 gilts per pen. Pens were randomly assigned to 1 of 6 dietary treatments. The experimental diets were formulated with increasing SID Arg:Lys, achieved by substituting corn starch, glycine, and l-alanine with l-arginine, resulting in SID Arg:Lys ranging from 45% to 145%. Diets were sublimiting in SID Lys and exceeded all other essential amino acid requirements. The experimental diets were fed across two feeding phases from days 0 to 10 and 10 to 27, with adjustments made to account for the Lys requirement of the pigs. All pens were placed on a common diet for the remaining 14 d of the study to evaluate carryover effects. Pigs and feeders were weighed at the start and end of each phase to calculate average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency (G:F). Data were analyzed according to a linear regression model, which included the linear and quadratic effects of SID Arg:Lys and initial BW. Pen was the experimental unit, and results were considered significant at P ≤ 0.05 and a tendency at 0.50 < P ≤ 0.10. From days 0 to 27, Arg:Lys tended to have a quadratic effect on ADFI (P = 0.058), where 97.00 ±â€…7.631% SID Arg:Lys maximized feed intake. Similarly, Arg:Lys had a quadratic impact on ADG (P = 0.046), where ADG was maximized at a SID Arg:Lys of 95.65 ±â€…7.165. Correspondingly, Arg:Lys had a quadratic effect on pig BW on day 27 (P = 0.014). These effects were carried through the end of the study, where Arg:Lys quadratically impacted days 0 to 41 ADFI (P = 0.006), ADG (P = 0.077), and day 41 BW (P = 0.028). There was no evidence of an effect of SID Arg:Lys on G:F throughout the study (P ≥ 0.315). In conclusion, SID Arg:Lys quadratically impacted ADFI and ADG in 6- to 13-kg nursery pigs, where ADFI was maximized at a SID Arg:Lys of 97.00% (95% CI [81.6%, 112.4%]), and ADG was maximized at a SID Arg:Lys of 95.65% (95% CI [81.2%, 110.1%]). Together, these data suggest that the SID Arg:Lys requirement of nursery pigs is at least 81%, based on the lower bounds of the 95% CI for maximum ADG and ADFI, and excessive Arg supplementation may negatively affect growth performance.

Arginine is considered a conditionally essential amino acid (EAA) in swine, meaning that under certain circumstances, the rate of Arg utilization is greater than endogenous synthesis, resulting in a dietary Arg requirement to meet the pig's needs for growth and other biological functions. Our group and others have shown benefits to feeding Arg levels above the NRC (2012) estimated requirement; however, there has been a lack of research to determine the SID Arg requirement relative to lysine in young pigs. Therefore, the objective of this study was to determine the optimal dietary SID Arg:Lys to maximize growth performance in 6- to 13-kg nursery pigs. In the current trial, average daily gain (ADG) and average daily feed intake (ADFI) responded quadratically to increasing SID Arg:Lys from 45% to 145%, where ADFI was maximized at a SID Arg:Lys of 97.00% (95% CI [81.6%, 112.4%]) and ADG was maximized at 95.65% (95% CI [81.2%, 110.1%]). Together, the results of this study suggest the SID Arg:Lys requirement of 6- to 13-kg nursery pigs is at least 81%, based on the lower bounds of the 95% confidence intervals for maximum ADG and ADFI, but excess supplementation may reduce performance.

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.

Effects of increasing dietary arginine supply during the three first weeks after weaning on pig growth performance, plasma amino acid concentrations, and health status.

A total of 425 weaned pigs (Exp. 1: 225 pigs [5.8 ±â€…0.9 kg]; Exp. 2: 200 pigs [6.1 ±â€…1.2 kg]) were used to determine the optimal dietary standardized ileal digestible (SID) arginine (Arg) level in early nursery diets based on growth and health responses. The basal diet in Exp.1 was formulated to meet SID Arg recommendation (0.66%; NRC, 2012) and in Exp. 2, SID Arg was set to simulate current industry practices for feeding nursery pigs (1.15 %). Basal diets were supplemented with 0.3%, 0.6%, 0.9%, and 1.2% of l-arginine to provide five levels of dietary SID Arg. Experimental diets were fed during phases I (days 0 to 7) and II (days 8 to 21) with common diets until market. Feed disappearance and body weight (BW) were measured on days 7, 14, 21, and 43. Final BW was recorded at first removal of pigs for market. Pen fecal score was assigned daily from days 0 to 21. Plasma immunoglobulin A (IgA) was determined on days 0, 7, and 14 and amino acids (AAs) concentration and plasma urea nitrogen (PUN) on days 0 and 14. Orthogonal polynomial contrasts were used to determine the linear and quadratic effects of dietary Arg. Optimal SID Arg was determined by fitting the data with piecewise regression, using growth performance as the primary response variable. In Exp. 1, dietary Arg linearly increased (P < 0.1) BW, average daily gain (ADG), and gain to feed ratio (G:F) ratio on day 21, as well as reduced (χ2 = 0.004) the percentage of pigs that lost weight (PLW) in week 1 by 29%. Dietary Arg resulted in linear improvement (P = 0.082) of ADG for the overall nursery period and quadratic improvement (P < 0.1) of final BW at marketing. In Exp. 2, dietary Arg linearly increased (P < 0.05) ADG and average daily feed intake (ADFI) in week 1, BW and ADFI (P < 0.1) on day 14, as well as reduced (χ2 ≤ 0.001) PLW in week 1. From days 0 to 21, G:F was improved quadratically (P < 0.1). Dietary Arg linearly increased (P < 0.1) ADG and BW on day 43. Dietary Arg supplementation decreased the incidence (χ2 < 0.05) of soft and watery feces during the first weeks after weaning and lower concentration of plasma IgA on days 7 and 14. Dietary Arg linearly and/or quadratically influenced plasma AA concentrations (P < 0.05), including an increase in Arg, Leu, Phe, Val, citrulline, ornithine, and PUN concentrations. Overall, weaned pigs exhibit optimal nursery growth performance and health when provided with dietary SID Arg ranging from 1.5% to 1.9%. This dietary range contributes to a reduction in the occurrence of fall-back pigs and improvements in final BW at marketing.

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.

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.

Improving performance of finishing pigs with added valine, isoleucine, and tryptophan: validating a meta-analysis model.

Based on results of a recent meta-analysis, we hypothesized that increased dietary Val, Ile, or Trp could correct possible amino acid interactions because of excess Leu in diets containing high levels of corn protein, namely dried distiller's grains with solubles (DDGS). A total of 1,200 pigs (PIC TR4 × (Fast LW × PIC L02); initially 33.6 ± 0.6 kg) were used in a 103-d study. The 6 dietary treatments were corn-soybean meal (SBM)-DDGS-based as follows: (1) high SBM and low level of l-Lys HCl (HSBM), (2) high l-Lys HCl and moderate Ile, Val, Trp (AA above NRC 2012 estimates; NC), (3) moderate l-Lys HCl and high Ile, Val, and Trp (PC), and PC with either increased (4) L-Val (PC+Val), (5) L-Ile (PC+Ile), or (6) L-Trp (PC+Trp). Pigs fed the NC diet were predicted to have the poorest average daily gain (ADG), the PC diet to be intermediate, and pigs fed the HSBM, PC+Val, PC+Ile, and PC+Trp have the same and highest predicted ADG. In the grower period (34 to 90 kg), ADG was greater (Ρ < 0.05) for the pigs fed HSBM and PC+Val diets than the NC with pigs fed other diets intermediate. Pigs fed HSBM were more (Ρ < 0.05) efficient (G:F) than the NC and PC with pigs fed other diets intermediate. In the finisher period (90 to 136 kg), ADG was greater (Ρ < 0.05) for pigs fed PC+Ile than that of the NC with pigs fed other diets intermediate. Pigs fed PC+Val had greater (Ρ < 0.05) average daily feed intake (ADFI) than the NC with pigs fed other diets intermediate. However, PC+Ile pigs were more (Ρ < 0.05) efficient than PC+Val with pigs fed other diets intermediate. Overall, ADG was greater (Ρ < 0.05) for pigs fed HSBM, PC+Val, and PC+Ile diets than the NC with pigs fed other diets intermediate. Pigs fed the PC+Val diet had greater (Ρ < 0.05) ADFI than the NC with pigs fed other diets intermediate. No differences were detected between treatments for overall G:F or other carcass characteristics. In conclusion, increasing Val or Ile in high l-Lys-HCl-DDGS-based diets improved growth performance compared with pigs fed diets containing high levels of l-Lys HCl without added Val and Ile. These results present evidence that the recently developed meta-analysis can predict the relative differences in overall ADG for pigs fed the NC, PC, PC+Val, and PC+Ile diets; however, the predicted G:F was less accurate. The data demonstrate that the negative effects of high Leu concentrations in corn-DDGS-based diets can be reversed by increasing the ratios of Val and Ile relative to Lys.

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.

Effects of amino acid biomass or feed-grade amino acids on growth performance of growing swine and poultry.

Three experiments were conducted to determine the effect of three fermented amino acids (AA) with their respective biomass compared to crystalline AA on the growth performance of swine and poultry. In experiment 1, 315 barrows (DNA 200 × 400, initially 11.3 ± 0.69 kg) were allotted to 1 of 4 dietary treatments with 5 pigs per pen and 15 or 16 pens per treatment. Dietary treatments included a negative control (16% standardized ileal digestible [SID] Tryptophan:lysine [Trp:Lys] ratio), positive control (21% SID Trp:Lys ratio from crystalline Trp), or diets containing Trp with biomass to provide 21 or 23.5% SID Trp:Lys ratios, respectively. Pigs fed the positive control or low Trp with biomass diet had increased (P < 0.05) ADG compared to pigs fed the negative control diet, with pigs fed the high Trp with biomass diet intermediate. Pigs fed the low Trp with biomass diet had increased (P < 0.05) G:F compared to the negative control diet, with others intermediate. In experiment 2, 1,320 1-d-old male broilers (Cobb 500, initially 45.2 g) were allotted to one of four dietary treatments with 33 birds per pen and 10 pens per treatment. Dietary treatments included a negative control (58/58% Threonine:lysine [Thr:Lys] ratio), positive control (65/66% Thr:Lys ratio from crystalline Thr), or diets containing Thr with biomass to provide 65/66 or 69/70% Thr:Lys ratios in starter and grower diets, respectively. Broilers fed the positive control or Thr with biomass diets had increased (P < 0.05) ADG compared to broilers fed the negative control diet. Broilers fed the positive control or the low Thr with biomass diet had increased (P < 0.05) G:F compared to the negative control and high Thr with biomass treatments. In experiment 3, 2,100 one-day-old male broilers (Cobb 500, initially 39.4 g) were allotted to one of four dietary treatments with 35 birds per pen and 15 pens per treatment. Dietary treatments included a negative control (59/63% Valine:lysine [Val:Lys] ratio), positive control (75/76% Val:Lys ratio from crystalline Val), or diets containing Val with biomass to provide 75/76 or 84/83% Val:Lys ratios in starter and grower diets, respectively. Broilers fed the positive control or Val with biomass diets had increased (P < 0.05) ADG, ADFI, and G:F compared to those fed the negative control diet. In conclusion, Trp, Thr, or Val with their respective biomass appear to be equally bioavailable and a suitable alternative to crystalline AA in swine and poultry diets.