Standardized Ileal Digestible Trp Research Articles

31 Effects of dietary standardized ileal digestible (SID) lysine (Lys) levels and dietary SID tryptophan to Lys ratios on growth performance and behavior of late-nursery to finish maternal barrows

Abstract The objective was to determine the effects of dietary standardized ileal digestible (SID) lysine (Lys) levels and SID tryptophan (Trp) to Lys ratios on growth performance and behavior of late-nursery to finish maternal barrows. A total of 2,293 barrows (PIC Camborough, initially 11.9 ± 0.35 kg) were used in this trial with 96 mixed-sex pens and 23 to 25 pigs/pen. There was a total of 6 dietary phases: P1:11.9-29.5 kg; P2:29.5-49.6 kg; P3:49.6-62.6 kg; P4:62.6-80.3 kg; P5:80.3-103.3 kg; and P6:103.3-137.8 kg. Pens were blocked by body weight and randomly allotted to 1 of 6 treatments:T1: 100% Lys (dietary SID Lys levels meet PIC SID Lys recommendation) and 21.0% of SID Trp:Lys ratio; T2: 100% Lys and 18.5% of SID Trp:Lys ratio; T3: 100% Lys and 16.0% of SID Trp:Lys ratio; T4: 80% Lys (dietary SID Lys levels meet 80% of PIC SID Lys recommendation) and 21.0% of SID Trp:Lys ratio; T5: 80% Lys and 18.5% of SID Trp:Lys ratio; and T6: 80% Lys and 16.0% of SID Trp:Lys ratio for P1-P2 and then 100% Lys and 18.5% of SID Trp:Lys ratio for P3-P6. Ear lesion (EL) was monitored during P2-P5. Data were analyzed using a linear mixed model in R Studio (Version 3.5.2, R Core Team; Vienna, Austria). Pigs fed T1 and T2 showed improved average daily gain than T6 (P < 0.05), with other treatments intermediate (Table 1). Pigs fed T2 showed improved average daily feed intake as compared with T6 (P < 0.05), with other treatments intermediate. There was no evidence for significant difference on feed-to-gain ratio or mortality. Removal was significantly greater for pigs fed T6 compared with all other treatments (P < 0.05). Pigs fed T2 had significantly greater hot carcass weight than T4, with other treatments intermediate. There was no evidence for significant differences on carcass yield or lean percentage. Pig fed T6 had significantly greater incidence of EL in P2 than all other treatments (P < 0.05). Pigs fed T4 and T6 had greater incidence of EL in P3 than T1 (P < 0.05), with other treatments intermediate. Pigs fed T5 and T6 had significantly greater incidence of EL in P4 than T1, T2, and T3 (P < 0.05), with T4 intermediate. During P5, pigs fed T4 and T5 had the greatest incidence of EL (P < 0.05), while pigs fed T6 had significant greater incidence of EL than T3 (P < 0.05), with T1 and T2 intermediate. In conclusion, dietary SID Lys and SID Trp:Lys ratio less than PIC recommendation during late-nursery-to-grower phase resulted in compromised overall growth performance of maternal barrows, even with restored dietary SID Lys and SID Trp:Lys levels in finish phase. Dietary SID Lys level and/or SID Trp:Lys ratios lower than PIC recommendation may result in greater incidence of aggression behavior in maternal barrows.

214 Effects of Dietary Standardized Ileal Digestible (SID) Lysine (Lys) Levels and Dietary SID Tryptophan to Lys Ratios on Growth Performance of Late-Nursery Maternal Barrows

Abstract The objective was to determine the effects of dietary standardized ileal digestible (SID) lysine (Lys) levels and SID tryptophan (Trp) to Lys ratios on the growth performance of late-nursery maternal barrows. A total of 2,293 barrows (PIC Camborough, initially 11.9 ± 0.35 kg) were used in a 28-day trial with 96 mixed-sex pens in two rooms (48 pens/room), 16 pens/treatment, and 23 to 25 pigs/pen. Pens were blocked by body weight (BW) and randomly allotted to 1 of 6 treatments in a 2×3 factorial arrangement. Treatment factors were: 1) Dietary SID Lys levels: meet PIC SID Lys recommendation at 1.234% (PIC LYS) or below PIC SID Lys recommendation at 0.988% (BELOW LYS); 2) Dietary SID Trp to Lys ratios: 21.0, 18.5, and 16.0. Data were analyzed using a linear mixed model in R Studio (Version 3.5.2, R Core Team; Vienna, Austria). Dietary SID Lys levels, dietary SID Trp to Lys ratios, and their interaction were included as fixed effects, and room and weight block were included as random effects in the model. Pigs fed with PIC LYS diets showed significantly improved average daily gain (ADG; 672 vs. 594 g; P < 0.001), average daily feed intake (ADFI; 1227 vs. 1179 g; P < 0.001), gain-to-feed ratio (G:F; 550 vs. 508 g/kg; P = 0.002), and greater amount of SID Lys intake (22.5 vs. 19.5; P < 0.05) or Trp intake (4.2 vs. 3.6; P < 0.05) per kg of BW gain comparing to BELOW LYS diets. Significant interactive effects were observed between dietary SID Lys levels and dietary SID Trp and Lys ratios on final BW, ADG, ADFI, and G:F (P < 0.05; Table 1). For final BW and ADG, when feeding PIC LYS diets, decreasing dietary SID Trp to Lys ratios increased final BW and ADG (quadratic, P < 0.05); but when feeding BELOW LYS diets the decreasing ratios reduced final BW and ADG (quadratic, P < 0.05). For ADFI, when feeding PIC LYS diets, there was no evidence that decreasing dietary SID Trp to Lys ratios impacted ADFI (P > 0.05); but when feeding BELOW LYS diets the decreasing ratios reduced ADFI (quadratic, P < 0.05). When feeding PIC LYS diets, the decreasing dietary SID Trp to Lys ratios decreased and then increased G:F (quadratic, P < 0.05); but when feeding BELOW LYS diets, the decreasing ratios increased and then decreased G:F (quadratic, P < 0.05). In conclusion, late-nursery maternal barrows fed the PIC LYS diet had improved growth performance compared with those fed BELOW LYS diet; and decreasing dietary SID Trp to Lys ratios from 21.0 to 16.0 had deleterious impacts on growth performance when dietary SID Lys level was below PIC recommendation, but not when dietary SID Lys level met PIC recommendation.

PSII-13 Effects of Standardized Ileal Digestible Lysine, Fiber Level, and Amino Acid Ratios on Growth Performance of Nursery Pigs

Abstract An experiment was conducted to determine the interactive effects of standardized ileal digestible (SID) lysine, dietary fiber, and amino acid ratios on growth performance of nursery pigs. A total of 4,320 pigs (initial BW = 7.8 kg), placed in pens of 36 mixed sex pigs, were used in a 43-d trial. Treatments were arranged in a 2 × 2 × 2 factorial structure with two levels of SID Lys (1.15 or 1.38%), two levels of dietary fiber [control or high fiber (5% sugar beet pulp + 3.75% soy hulls)], and two amino acid ratio profiles [control (65% SID Thr:Lys, 58% SID Met+Cys:Lys, 67% SID Val:Lys, 55% SID Ile:Lys, and 18.5% SID Trp:Lys) or AA+ (5 percentage points greater than control ratios)] with 15 replicates per treatment. The experimental diets were fed from d 0 to 25 and a common corn-soybean meal-based diet was fed from d 25 to 43. Pigs were weighed on d 0, 25, and 43 to calculate ADG, ADFI, and G:F. Data were analyzed with the MIXED procedure in SAS. From d 0 to 25, there was a fiber × amino acid ratio interaction (P = 0.008) for ADFI, where pigs fed the high fiber diet had similar ADFI, regardless of AA ratios, but those fed control levels of fiber had reduced ADFI when fed AA+ ratios (Table 1). Similar interactions were also observed (P < 0.05) for overall (d 0 to 43) ADG, ADFI, and final BW. There were no other significant interactions (P > 0.05). As for main effects, pigs fed low Lys had reduced (P < 0.05) ADG, ADFI, and G:F. Feeding high fiber diets reduced (P < 0.05) G:F but did not impact (P > 0.05) ADG or ADFI. Pigs fed AA+ ratios had improved (P < 0.05) G:F but no evidence for differences (P > 0.05) for ADG or G:F was observed.

Standardized ileal digestible tryptophan and lysine affects the eating and sleeping behavior of 15-30 kg barrows.

The objective of this study was to evaluate the effect of standardized ileal digestible (SID) tryptophan (Trp) and lysine (Lys) levels on eating and sleeping behavior and the respective feed intake of barrows. Sixty-four pigs, averaging 15.00 ± 1.63 kg of initial body weight, were used and distributed in a randomized blocks design, in a 4 × 4 factorial scheme, consisting of four levels of SID Trp (0.155, 0.185, 0.215, 0.245%) and four levels of SID Lys (0.972, 1.112, 1.252, and 1.392%). Behavior evaluation was performed by an instantaneous sampling using 10-min intervals during 24 h, at each 7 days (days 7, 14, and 21), and each day was divided into four times of 6 h each one (08:30-14:20, 14:30-20:20, 20:30-02:20, and 02:30-08:20 h), during all the experimental period, yielding a total of 3 × 24 h behavior recordings (72 h) × 6 10-min intervals, totalizing 432 observations per animal. Data were analyzed by classifying behavior into eating or sleeping. All these behaviors were measured in order to obtain the estimated frequency of the eating and sleeping behaviors. Changes were observed (P<0.05) for all the behavioral parameters during the starting phase. SID Trp and SID Lys showed an interactive positive effect on the estimated frequency of eating behavior, and mainly SID Trp increased the estimated frequency of the sleeping behavior of starting pigs in the nocturnal time. Pig diets with increasing levels of SID Trp and SID Lys until 0.245 and 1.392%, respectively, increased the average daily feed intake, and the interaction of the amino acids increased the estimated frequency of eating behavior during all the starting phase, and mainly the increasing levels of SID Trp increased the estimated frequency of sleeping behavior of pigs from the middle to the end of the starting phase, from 2:30 to 8:20 h.

Performance response of increasing the standardized ileal digestible tryptophan:lysine ratio in diets containing 40% dried distiller grains with solubles.

A total of 1,170 pigs (PIC 800 × PIC, initially 38.6 kg) were used in a 98-d grow-finish study to determine the performance response of pigs fed increasing levels standardized ileal digestible (SID) Trp:Lys ratio in diets containing 40% dried distillers grains with solubles (DDGS). Five dietary treatments were fed and consisted of a corn-soybean meal (SBM) diet or diets containing 40% DDGS with SID Trp:Lys ratios of 15%, 18%, 21%, or 24%. Each treatment was replicated 9 times and pens contained 26 pigs with the equal number of gilts and barrows. Data was analyzed as a randomized complete block design with previous nursery treatment as a random blocking factor. Pair-wise comparisons were used to evaluate the impact of diets on performance and carcass traits; specifically to compare the corn-SBM dietary treatment against other dietary treatments. Single degree of freedom orthogonal polynomials were used to evaluate the dose-response of increasing the SID Trp:Lys ratio in 40% DDGS diets. Increasing the SID Trp:Lys ratio in diets containing 40% DDGS increased (linear, P ≤ 0.02) average daily gain (ADG), average daily feed intake (ADFI), final body weight (BW), hot carcass weight (HCW), carcass gain, and daily carcass gain. Increasing the SID Trp:Lys ratio in 40% DDGS diets did not impact (P ≥ 0.65) gain to feed (G:F) for the cumulative period. Pigs fed the corn-SBM diet had greater (P ≤ 0.01) ADG and a heavier (P ≤ 0.01) final BW compared to pigs fed 40% DDGS diets, regardless of the SID Trp:Lys ratio. Diets that contained 40% DDGS with a SID Trp:Lys ratio of 24% had no difference (P|t| = 0.25) in ADFI compared to the corn-SBM dietary treatment. The cumulative G:F of pigs did not differ (P = 0.32) between pigs fed corn-SBM diets and diets containing 40% DDGS regardless of the SID Trp:Lys ratio. However, pigs receiving the corn-SBM diets had heavier HCW, greater carcass yields, total carcass gain, and daily carcass gain (P < 0.01) compared to pigs fed the 40% DDGS diets regardless of SID Trp:Lys ratio. In conclusion, increasing the SID Trp:Lys ratio in 40% DDGS diets improved ADG and ADFI for the overall grow-finish period. However, when compared to a corn-SBM diet, increasing the SID Trp:Lys ratio in 40% DDGS diets did not correct the growth performance or carcass characteristics of pigs.

Effects of reducing the standardized ileal digestible lysine and tryptophan to lysine ratio to slow growth of finishing pigs.

The COVID-19 global pandemic greatly affected pork processing plants in the United States. These pork processing plants were forced to either temporarily close or operate at reduced capacity due to the increased number of health-related employee absences. Because finishing pigs could not be timely marketed, methods to reduce growth performance were required to keep pigs from becoming too heavy at slaughter weight. Therefore, our objective was to determine the extent that reducing dietary standardized ileal digestible (SID) Lys and tryptophan-to-lysine ratio (Trp:Lys) ratio would slow finishing pig average daily gain (ADG) in a commercial setting. A total of 1,080 finishing pigs (327 × 1050, PIC; initially 32.3 kg) were used in a 119-d growth trial. Pigs were allotted by initial body weight (BW) and randomly assigned to 1 of 4 dietary treatments in a completely randomized block design with 27 pigs per pen and 10 pens per treatment. Three dietary regimes were formulated to contain either 100%, 90%, or 80% of the estimated SID Lys requirement for pigs in this facility, with a SID Trp:Lys ratio of 19%, with the exception of the last dietary phase formulated to 17% SID Trp:Lys. Seven different dietary phases were fed. The SID Lys concentrations in the 100% diets were: 1.10%, 1.01%, 0.91%, 0.83%, 0.79%, 0.71%, or 0.67% SID Lys from 32 to 40, 40 to 51, 51 to 72, 72 to 85, 85 to 98, 98 to 112, and 112 to 130 kg, respectively. A fourth regime was formulated to 80% SID Lys with a SID Trp:Lys ratio of 16% (80-16% SID Trp:Lys) throughout all phases. Overall from d 0 to 119, ADG (linear, P < 0.001), final BW (linear, P < 0.001), and gain-to-feed (G:F) decreased (linear, P = 0.087) as SID Lys decreased from 100% to 80% of the estimated requirement. Pigs fed the 80-16% SID Trp:Lys diets had an additional decrease in ADG (P < 0.05) and G:F (P < 0.10) compared with pigs fed 80% of the SID Lys requirement with the normal Trp:Lys ratio. The reduction in SID Lys (from 100% to 80%) and reduction in SID Lys and Trp:Lys ratio resulted in an 8.6 and 11.7 kg, respectively, decrease in final BW compared with pigs fed Lys and Trp at the requirement (100%). This study provides alternatives for pork producers to reduce growth rate of finishing pigs.

166 Optimal tryptophan:lysine Ratio for 25–40 Kg Growing Pigs Fed Diets Containing 35 % Distillers Dried Grains with Solubles

Abstract Distillers dried grains with solubles (DDGS) has a high concentration of Leu, and the Trp requirement for growing pigs may be increased if diets contain excess Leu. Therefore, the objective of this experiment was to determine the optimum standardized ileal digestible (SID) Trp:Lys ratio in growing pigs fed diets with excess Leu from DDGS. A diet based on corn, soybean-meal, and 35% DDGS was formulated to be deficient in Trp and Lys, according to NRC requirements (0.13% SID Trp; 0.88% SID Lys; 15% SID Trp:Lys ratio). Four diets were prepared by adding L-Trp to the basal diet, which resulted in analyzed SID Trp:Lys ratios of 18, 20, 23, and 24% in these diets. One-hundred and twenty growing pigs (26.3 ± 2.0 kg) were allotted to one of the 5 dietary treatments with 3 pigs per pen and 8 pen replicates in a completely randomized design. Diets were fed for 21d and blood samples were collected on d-21. Data were analyzed by linear and quadratic contrasts in SAS. The optimal SID Trp:Lys ratio was estimated using linear broken-line (LBL) and quadratic broken-line (QBL) regressions for ADG and G:F, using NLIN procedure in SAS. Results indicated that average daily feed intake, ADG, G:F, and final body weight increased (linear and quadratic, P &amp;lt; 0.01) and plasma-urea-nitrogen decreased (linear and quadratic, P &amp;lt; 0.05) as dietary SID Trp:Lys increased (Table 1). The SID Trp:Lys ratio to optimize ADG was 20.9 and 23.4% by LBL and QBL, respectively. The G:F was optimized at 18.7 and 20.2% by LBL and QBL, respectively. The average SID Trp:Lys ratio for the 4 measurements was 20.8% which is greater than the current NRC requirement (SID 17.3%). In conclusion, diets formulated with 35% DDGS may need more dietary Trp than current NRC values.

172 Effects of Dietary Valine, Isoleucine, and Tryptophan Supplementations to Diets Containing Excess Leucine from Corn Protein on Growth Performance of Growing Pigs

Abstract An experiment was conducted to test the hypothesis that addition of Val, Ile, or Trp alone or in combination will reduce the negative effects of excess Leu in diets for growing pigs. A total of 288 growing pigs (28.6 ± 2.5 kg) were randomly assigned to 1 of 9 dietary treatments in a randomized complete block design. There were 2 barrows and 2 gilts in each pen and 8 replicate pens per treatment. A control diet based on corn and soybean meal and 8 diets based on corn and a high-protein corn product (48% crude protein) with 2 levels of crystalline L-Val (0 or 0.10%), L-Ile (0 or 0.10%), and L-Trp (0 or 0.05%) were formulated. The crystalline L-Val, L-Ile, and L-Trp increased standardized ileal digestible (SID) Val:Lys from 70 to 80%, SID Ile:Lys from 53 to 63%, and SID Trp:Lys from 18 to 23%, respectively. All diets were formulated to contain 1.00% SID Lys and the 8 diets containing corn protein contained 171% SID Leu:Lys. Individual pig weights were recorded at the beginning and at the conclusion of the 28-d experiment. Data were analyzed using the PROC MIXED of SAS with a pen as the experimental unit. Diet was the fixed effect and block and replicate within block were random effects. Results indicated that final body weight and average daily gain were not different between pigs fed the control diet and pigs fed the diet with Val and Trp addition, but greater (P &amp;lt; 0.001) than for pigs fed the diet with Val addition, Ile addition, Trp addition, Val and Ile addition, Ile and Trp addition, or Val, Ile, and Trp addition (Table 1). In conclusion, addition of Val and Trp to diets with excess Leu may prevent negative effects of excess Leu in diets for growing pigs.

Standardized ileal digestible tryptophan to lysine ratios affect performance and regulate intestinal mRNA expression of amino acid transporters in weaning pigs fed a low crude protein diet

The objective of this study was to estimate the effect of standardized ileal digestible (SID) tryptophan (Trp) to lysine (Lys) ratios on growth performance and jejunal expression of amino acid transporters in weaning pigs. A total of 240 hybrid [(Duroc, male) x (Large White x Landrace, female)] piglets (6.52 ± 0.42 kg) were used in a 28-day growth trial and randomly allotted to one of four diets providing SID Trp to Lys ratios of 0.15, 0.18, 0.21, or 0.24 and were allocated in 6 pens per treatment with 10 pigs per pen. The average daily gain (ADG), average daily feed intake (ADFI), and serum levels of Trp, serine, isoleucine and leucine in pigs significantly increased when the SID Trp to Lys ratios increased from 0.15 to 0.18, 0.21, or 0.24 (P < 0.05). The pigs fed the diet with the 0.24 ratio had a reduced serum urea nitrogen (SUN) concentration compared with the pigs fed the 0.15 ratio diet (P < 0.05). The villus heights of the duodenum and jejunum in pigs fed the diet with a 0.21 ratio were greater than those of pigs fed the 0.15 ratio diet (P < 0.05). The increase in the SID Trp to Lys ratio from 0.15 to 0.18 decreased the intestinal ASCT2 mRNA level in weaning pigs (P < 0.05). The increase in the SID Trp to Lys ratio from 0.15 to 0.21 or 0.24 increased the mRNA abundance of intestinal B°AT1 (P < 0.05). The increase in the SID Trp to Lys ratio from 0.15 to 0.18 increased the mRNA abundances of intestinal CAT-1 and rBAT (P < 0.05). The intestinal b0,+AT mRNA level in the pigs fed the 0.21 ratio diet was higher than that in pigs in other three treatments (P < 0.05). The mRNA abundances of y+LAT1 and 4F2hc in the pigs fed the 0.15 ratio diet were lower than those in pigs in other three treatments (P < 0.05). The intestinal PepT-1 mRNA level in the pigs fed the 0.15 or 0.24 ratio diet was lower than that of the pigs fed the 0.21 ratio diet (P < 0.05). In conclusion, the optimal SID Trp to Lys ratio was determined to be 0.18 for weaning pigs that were fed a low crude protein diet using ADG and jejunal amino acid transporter mRNA expression as the response criteria.

209 Effects of high standardized ileal digestible tryptophan:lysine ratios with ractopamine HCL on growth and carcass performance of pigs from 110 to 135 kg

Abstract Recent research has reported that increasing standardized ileal digestible (SID) Trp:Lys ratio above 20% in finishing pigs fed Ractopamine HCL (RAC) resulted in improved growth and carcass performance, however this response has been inconsistent. Therefore, the objective of this study was to evaluate the effects of feeding high SID Trp:Lys ratios with RAC on growth and carcass performance. A total of 1,791 finishing pigs (PIC 1050×337; initially 110 kg BW) were used in a 27-d study. Pens of 25 or 26 pigs were allotted by initial BW and randomly assigned to 1 of 5 dietary treatments in a RCBD with 14 replications per treatment. The dietary treatments consisted of 5 SID Trp:Lys ratios (20, 22, 24, 26, and 28%). Corn-soybean meal-based diets were formulated to 0.90% SID Lys and contained 10 ppm ractopamine. At d 27, pigs were transported to a packing plant for processing and carcass data collection. Growth data were analyzed (GLIMMIX procedure of SAS) as a RCBD with pen as the experimental unit and initial BW as a covariate. Carcass data were analyzed with pen as the experimental unit and block × treatment as the random effect. Hot carcass weight served as a covariate for analysis of backfat, loin depth, and lean percentage. For overall growth performance, increasing SID Trp:Lys increased (linear, P&amp;lt; 0.0001) SID Trp g/kg of gain and SID Trp intake (Table 1); however, there were no evidence of treatment differences (P &amp;gt;0.10) for ADG or G:F. For carcass characteristics, increasing SID Trp:Lys decreased (linear; P=0.002) carcass yield and tended to decrease (P=0.078) lean percentage. There was no evidence of treatment differences (P &amp;gt;0.10) for HCW, loin depth, carcass ADG, or carcass feed efficiency. In summary, increasing SID Trp:Lys ratios above 20% in pigs fed RAC did not improve growth or carcass performance.

132 Performance response of the grow-finish pig (38 to 142 kg) fed different levels of tryptophan:lysine in diets containing 40% dry distiller grains with solubles

Abstract Dried distiller grains with solubles (DDGS) is a popular protein source in grow-finish swine diets to replace soybean meal. An experiment was conducted at the South Dakota State University commercial swine research facility to determine the effect of standardized ileal digestible (SID) Trp:Lys ratio in grow-finish swine diets containing 40% DDGS compared to a standard corn-soybean meal diet. A total of 1,170 pigs (38.6 ± 0.2 kg initial BW) were utilized in a 98-d trial (9 pens per treatment). Pens of pigs were randomly allotted to 1 of 4 DDGS dietary treatments providing SID Trp at 15, 18, 21, and 24% of Lys or a corn-soybean meal diet (18%). Diets were isocaloric, with lysine at 100% of the requirement. From d 0 to 82, increasing Trp:Lys ratio in DDGS diets improved (P &amp;lt; 0.01) BW, ADG, and ADFI with no effect on F:G. Pigs fed the corn-soybean meal diet had greater (P &amp;lt; 0.01) BW, ADG, ADFI, and F:G compared to the DDGS diets with the exception of the ADFI of the 24% Trp:Lys treatment. From d 82 to 98, increasing SID Trp:Lys in DDGS diets had no effect on performance. Overall (d 0 to 98), increasing SID Trp:Lys in DDGS diets increased (P &amp;lt; 0.02) final BW and ADG, but pigs failed to perform to the same degree as the corn-soybean meal diet. Increasing SID Trp:Lys in DDGS diets resulted in an increase in hot carcass weight (P &amp;lt; 0.01); however, diets containing DDGS had decreased (P &amp;lt; 0.02) hot carcass weight, dressing percentage, percent lean, and loin depth compared to pigs fed the corn-soybean meal diet. These results indicate that increasing the SID Trp:Lys in diets containing 40% DDGS improved performance in early grow-finish phases with no effect in late finishing, but performance was inferior to standard corn-soybean meal diets.

Optimum standardized ileal digestible tryptophan intake for broiler chickens

Six feeding trials were conducted to determine the optimum intake of standardized ileal digestible (SID) tryptophan of male and female broiler chickens in the starter (0 to 14 d), grower (14 to 28 d), and finisher (28 to 42 d) phases. In each trial, 640 broiler chickens were randomly assigned to 1 of 8 treatments, with 4 replicates of 20 broiler chickens. Diets were formulated by mixing a high and a low protein diet in different proportions, and dietary concentrations of SID Trp ranged 0.56 to 2.94, 0.54 to 2.75, and 0.52 to 2.60 g/kg in the starter, grower, and finisher phases, respectively. Tryptophan intake was regressed against average daily gain (ADG) and feed conversion ratio (FCR) using polynomial regression and broken-line regression model and the model that better fitted data was chosen according to Bayesian information criterion. Broiler chickens responded quadratically to increasing dietary Trp concentration and ADG was maximized at 86, 264, and 441 mg SID Trp/d for male broiler chickens (R2 = 0.96; P < 0.01) and at 76.5, 237, and 278 mg SID Trp/d for females (R2 = 0.97; P < 0.01) in the starter, grower and finisher phases, respectively. Feed conversion ratio was optimized at 69.9, 247, and 338 mg SID Trp/d for males (R2 = 0.91; P < 0.01) and 67.8, 223, and 280 mg SID Trp/d for females (R2 = 0.93; P < 0.01) in the starter, grower, and finisher phases, respectively. The optimum SID Trp intake for each sex and phase was determined based on ADG.

Effects of Standardized Ileal Digestible Tryptophan:Lysine Ratio on Growth and Carcass Performance of Finishing Pigs Fed Ractopamine HCl

Recent research has reported that increasing standardized ileal digestible (SID) Trp:Lys ratio above 20% in finishing pigs fed ractopamine HCl (RAC) resulted in improved growth and carcass performance, however, this response has been inconsistent. Therefore, the objective of this study was to evaluate the effects of feeding high SID Trp:Lys ratios with RAC on growth and carcass performance. A total of 1,791 finishing pigs (PIC 1050 × 337, initially 245.1 lb BW) were used in a 27-d study to evaluate the effects of feeding high SID Trp:Lys ratios on growth and carcass performance of pigs fed ractopamine HCl (RAC, Paylean, Elanco Animal Health, Greenfield, IN). Pens of 25 or 26 pigs were allotted by initial body weight (BW) and randomly assigned to 1 of 5 dietary treatments with 14 replications per treatment. The dietary treatments included 5 SID Trp:Lys ratios (20, 22, 24, 26, and 28% of Lys). All diets were formulated to 0.90% SID Lys and contained 10 ppm ractopamine. At d 27, pigs were transported to a commercial packing plant (JBS Swift and Company, Worthington, MN) for processing and carcass data collection. For overall growth performance, increasing SID Trp:Lys ratio increased (linear; P = <0.0001) SID Trp intake and Trp g/kg of gain; however, there was no evidence of a treatment difference (P > 0.10) for average daily gain (ADG) or feed efficiency (F/G). For carcass characteristics, increasing SID Trp:Lys decreased (linear; P = 0.002) carcass yield and tended to decrease (P = 0.078) lean percentage. There was no evidence of treatment differences (P > 0.10) for hot carcass weight, loin depth, carcass ADG, or carcass feed efficiency. The results from this study showed that grams per day of SID Trp intake ranged from 5.5 to 7.5. Greater feed intakes observed in this study resulted in increased Trp g/d of intake and could potentially be a reason why no evidence for treatment differences was observed. In summary, increasing SID Trp:Lys ratios above 20% (approximately 5.4 g SID Trp intake per day) in pigs fed RAC did not improve growth or carcass performance.

Effect of different levels of tryptophan on productive performance, egg quality, blood biochemistry, and caecal microbiota of hens housed in enriched colony cages under commercial stocking density

A study was conducted to determine the tryptophan (Trp) requirement of brown hens housed in enriched colony cages. A corn and wheat-based diets with 8 levels of standardized ileal digestible (SID) Trp (0.10, 0.13, 0.16, 0.19, 0.22, 0.25, 0.28, and 0.31% of the diet) were manufactured. The diet containing SID Trp 0.10% had no supplemental Trp and was treated as control. A total of 1,344 hens were randomly allocated to 8 treatments, each having 8 replicate cages with 21 hens per cage. Body weight gain (BWG), egg production (EP), feed conversion ratio (FCR), egg quality, blood biochemistry, caecal microbial profile, and concentration of indoles were determined over a period of 16 wk. The EP was linearly improved by supplementing diet with Trp and was highest in 0.25% SID-Trp group compared to control. Trp supplementation improved (P < 0.05) FCR, overall BWG, egg shell characteristics compared to control. The microbial shift in the caecum in response to Trp supplementation was significant in response to higher than current recommendations (0.22% of SID Trp) and indicated a microbial shift towards beneficial bacteria. Indole and skatole concentrations were only significantly different (P < 0.05) when hens in control group were compared with those containing highest levels of SID-Trp. This study demonstrates that when hens are at its peak production and are reared in enriched colony cages their Trp requirement is higher than current National Research Council (1994) recommendations and 0.22% of the SID-Trp in diet can be considered as an optimal level based on regression analysis.

The response of performance in grower and finisher pigs to diets formulated to different tryptophan to lysine ratios

Three experiments were conducted to determine the optimal dietary standardized ileal digestible (SID) Trp to Lys ratio (Trp:Lys) for grower-finisher pigs with body weight of 20–50 (Experiment (Exp.) 1), 50–80 (Exp. 2), and 80–110 kg (Exp. 3). A total of 4032 Duroc × Yorkshire × Landrace barrows and gilts were used in the experiments with a randomized complete blocked design. For each experiment, 1344 pigs were randomly assigned into 6 dietary treatments (SID Trp:Lys levels: 0.150, 0.165, 0.180, 0.195, 0.210, and 0.225) with 8 replicate pens per treatment (14 barrows and 14 gilts per pen). Synthetic Trp was used to adjust the dietary SID Trp:Lys, while the Lys content in all 6 diets remained fixed in each experiment. In Exp. 1, the average daily gain (ADG), average daily feed intake (ADFI), gain to feed ratio (G:F), and serum urea N (SUN) were increased quadratically (P < 0.01) as the SID Trp:Lys increased from 0.150 to 0.225. The optimal SID Trp:Lys for ADG estimated using broken-line and curvilinear-plateau models were 0.171 and 0.188, respectively. For G:F, the break-points were 0.192 and 0.207 for the linear and quadratic models, respectively. In Exp. 2, a quadratic increase was observed in ADG, ADFI, G:F, and SUN as the SID Trp:Lys increased from 0.150 to 0.225 (P < 0.05). The optimal SID Trp:Lys for ADG estimated using the broken-line and curvilinear-plateau models were 0.183 and 0.200, respectively. The break-points for G:F estimated using broken-line and curvilinear-plateau models were 0.195 and 0.213, respectively. In Exp. 3, the ADG, G:F, and SUN increased quadratically with increasing SID Trp:Lys, while ADFI increased linearly (P < 0.05). The optimal SID Trp:Lys for ADG estimated using the broken-line and curvilinear-plateau models were 0.184 and 0.201, respectively. Likewise for G:F, the best ratios were 0.174 and 0.198 for the linear and curvilinear models, respectively. In summary, the optimal Trp:Lys for ADG estimated using the broken-line model in pigs weighing 20 to 50, 50 to 80, and 80 to 110 kg were 0.171, 0.183, and 0.184, respectively. The optimal Trp:Lys for G:F estimated using the broken-line model in pigs weighing 20 to 50, 50 to 80, and 80 to 110 kg were 0.192, 0.195, and 0.174, respectively.

Effects of vitamin B6 and tryptophan on pork quality and amount of lean meat in gilts of 70–100 kg bodyweight

Supplementary tryptophan in pig diets has shown improvement in carcass traits and pork quality by reducing the animals' response to stress at slaughter. Vitamin B6 could enhance this response since it acts as an enzymatic cofactor of many tryptophan pathways. The present experiment was designed to evaluate dietary vitamin B6 supplementation and tryptophan levels on carcass traits, organ weights, abdominal fat, and pork quality of 70–100 kg gilts. Sixty-four crossbred gilts (initial bodyweight (BW) 70.52 ± 2.95 kg) were distributed in a 2 x 4 factorial scheme, consisting of two supplementary vitamin B6 levels (1 and 5 mg kg -1 ) and four dietary standardized ileal digestible (SID) tryptophan (Trp) levels (0.140%, 0.167%, 0.194%, and 0.221%). No significant interactions between the dietary SID Trp levels and B6 supplementation were observed on these variables. Vitamin B6 supplementation (5 mg kg -1 ) showed a minor reduction in meat pH measured 24 hours after slaughter and resulted in a ham yield higher than B6 basal level (1 mg kg -1 ). The lean meat yield increased linearly as the SID Trp levels increased in the diet. These findings suggested that vitamin B6 supplementation enhanced the pork quality and the increasing levels of SID tryptophan enhanced the lean meat yield of 70–100 kg gilts. Keywords : Carcass yield, meat colour, organ weight

Dose–response evaluation of the standardized ileal digestible tryptophan : lysine ratio to maximize growth performance of growing-finishing gilts under commercial conditions

Environmental regulations as well as economic incentives have resulted in greater use of synthetic amino acids in swine diets. Tryptophan is typically the second limiting amino acid in corn-soybean meal-based diets. However, using corn-based co-products emphasizes the need to evaluate the pig’s response to increasing Trp concentrations. Therefore, the objective of these studies was to evaluate the dose–response to increasing standardized ileal digestible (SID) Trp : Lys on growth performance of growing-finishing gilts housed under large-scale commercial conditions. Dietary treatments consisted of SID Trp : Lys of 14.5%, 16.5%, 18.0%, 19.5%, 21.0%, 22.5% and 24.5%. The study was conducted in four experiments of 21 days of duration each, and used corn-soybean meal-based diets with 30% distillers dried grains with solubles. A total of 1166, 1099, 1132 and 975 gilts (PIC 337×1050, initially 29.9±2.0 kg, 55.5±4.8 kg, 71.2±3.4 kg and 106.2±3.1 kg BW, mean±SD) were used. Within each experiment, pens of gilts were blocked by BW and assigned to one of the seven dietary treatments and six pens per treatment with 20 to 28 gilts/pen. First, generalized linear mixed models were fit to data from each experiment to characterize performance. Next, data were modeled across experiments and fit competing dose–response linear and non-linear models and estimate SID Trp : Lys break points or maximums for performance. Competing models included broken-line linear (BLL), broken-line quadratic and quadratic polynomial (QP). For average daily gain (ADG), increasing the SID Trp : Lys increased growth rate in a quadratic manner (P<0.02) in all experiments except for Exp 2, for which the increase was linear (P<0.001). Increasing SID Trp : Lys increased (P<0.05) feed efficiency (G : F) quadratically in Exp 1, 3 and 4. For, ADG the QP was the best fitting dose–response model and the estimated maximum mean ADG was obtained at a 23.5% (95% confidence interval (CI): [22.7, 24.3%]) SID Trp : Lys. For maximum G : F, the BLL dose–response models had the best fit and estimated the SID Trp : Lys minimum to maximize G : F at 16.9 (95% CI: [16.0, 17.8%]). Thus, the estimated SID Trp : Lys for 30 to 125 kg gilts ranged from a minimum of 16.9% for maximum G : F to 23.5% for maximum ADG.

Antibiotic inclusion in the diet did not alter the standardized ileal digestible tryptophan to lysine ratio for growing pigs.

Two 21-d experiments were conducted to determine the optimum standardized ileal digestible (SID) Trp:Lys ratio for growing pigs; 1 experiment fed diets supplemented with or without an antibiotic. The primary response variables in both experiments were ADG, ADFI, G:F, and plasma urea N (PUN) concentrations with the optimum SID Trp:Lys ratio detected using broken-line analysis. Experiment 1 evaluated the optimum SID Trp:Lys ratio in growing pigs fed diets supplemented with an antibiotic. This experiment used 120 crossbred pigs that were blocked by sex and initial BW (24.13 ± 2.72 kg) and allotted to 6 SID Trp:Lys ratios in 4 replicates. Dietary treatments were formulated by the addition of crystalline Trp to create 6 SID Trp:Lys ratios (13.08%, 14.06%, 15.04%, 17.00%, 18.95%, and 20.91%) with a constant SID Lys level of 0.655%. As SID Trp:Lys ratios increased, ADG, ADFI, and G:F increased, and PUN concentrations decreased linearly ( < 0.05) and quadratically ( < 0.05). Linear broken-line analysis yielded optimum SID Trp:Lys ratios of 17.93% ( < 0.001) and 16.17% ( = 0.009) for ADG and PUN, respectively, resulting in a mean optimum SID Trp:Lys ratio of 17.05%. Experiment 2 evaluated the optimum SID Trp:Lys ratio in growing pigs fed diets supplemented with or without an antibiotic. It used a total of 324 crossbred pigs (initial BW: 30.81 ± 3.56 kg) that were allotted to 6 SID Trp:Lys ratios in 6 replicates. Dietary treatments were formulated by the addition of crystalline Trp to create 6 SID Trp:Lys ratios (12.52%, 14.86%, 17.20%, 19.54%, 21.88%, and 24.22%) with a constant SID Lys level of 0.67%. As SID Trp:Lys ratios increased, ADG, ADFI, and G:F increased, and PUN concentrations decreased linearly ( < 0.001) and quadratically ( < 0.001) regardless of antibiotic inclusion. There were no differences by the antibiotic treatment in ADG, ADFI, G:F, or PUN concentrations ( > 0.49) and no interactions between antibiotics and Trp:Lys ratios ( > 0.29). When the data for all pigs were pooled for the various Trp:Lys ratios, the optimum SID Trp:Lys ratios for ADG and PUN based on linear broken-line analysis were 14.58% ( < 0.001) and 14.54% ( < 0.001), respectively, resulting in an optimum SID Trp:Lys ratio of 14.56% as the mean of the determined optima for ADG and PUN responses. These results demonstrate that the optimum SID Trp:Lys ratio for 30- to 50-kg growing pigs is not impacted by the dietary inclusion of an antibiotic as long as the diets are formulated on an SID AA basis.

Evaluation of the optimal standardized ileal digestible tryptophan:lysine ratio in lactating sow diets.

Three hundred and fifteen primiparous and multiparous sows were evaluated in a study to determine the effect of standardized ileal digestible (SID) Trp:Lys ratio in lactating sow diets. Camborough sows (PIC USA, Hendersonville, TN) ranging from first parity to eighth parity were blocked by parity and randomly allotted to 1 of 4 experimental diets containing different levels of added L-Trp (0.006, 0.026, 0.045, and 0.064%, respectively) while soybean meal, 30% corn dried distiller's grain with solubles (DDGS), and L-Lys levels were held constant. The SID Lys level for the rations was 0.95% so that the SID Trp:Lys ratios were formulated to be 14, 16, 18, and 20%, respectively. All diets were formulated to have 3.2 Mcal ME/kg and to contain vitamins and minerals that exceeded NRC (1998) recommendations. Sows were fed twice a day with a Howema computerized feed system and were allowed a maximum intake (5.9 kg/d). Average daily feed intake had a tendency to be quadratically improved when the SID ratio was increased (5.11, 5.28, 5.24, 5.21 kg/d, P = 0.09). In addition, sow wean to estrus (6.71, 5.53, 5.58, 6.33, P < 0.02) was quadratically improved as SID Trp:Lys ratio increased. Percent of sows bred by 10 d (84.39, 90.82, 90.28, 90.61) was not linearly (P = 0.25) or quadratically (P = 0.40) improved. There was no difference in litter gain (2.44, 2.52, 2.60, 2.57 kg/d, P = 0.16). Based on a broken-line quadratic model, when sows are fed 30% DDGS, the SID Trp:Lys ratio of 17.6 is required for optimal sow average daily feed intake and 17.2 for wean to estrus interval.

Effects of dietary standardized ileal digestible tryptophan:lysine ratio on performance, plasma urea nitrogen, ileal histomorphology and immune responses in weaned pigs challenged with Escherichia coli K88

A study was conducted to determine the optimal standardized ileal digestible (SID) tryptophan:lysine (Trp:Lys) ratio in piglets challenged with Escherichia coli K88 (E.coli K88) and fed antibiotic-free diets. Thirty individually housed mixed-sex pigs (Duroc × [Yorkshire × Landrace]) with an initial body weight (BW) of 6.4 ± 0.18kg and weaned at 21 ± 1day (d) were randomly assigned to 5 dietary treatments each with 6 pig replicates. Dietary treatments consisted of increasing levels of SID Trp:Lys ratios (16.1%, 18.6%, 20.3%, 22.9%, and 24.6%). Diets were corn-wheat-soybean meal-based with a constant SID Lys of 1.18% that was set to be the second limiting amino acid (AA) but adequate in other AA. Pigs had ad libitum access to feed and water for 13 d. After feeding the experimental diets for 6 d, pigs were orally challenged with 6mL of E. coli K88 (2 × 1011 colony forming unit/mL) on d 7. Body weights and pen feed disappearance were recorded weekly to determine ADG, ADFI and G:F. On d 13, all pigs were euthanized and ileal tissue samples were collected to measure mRNA expression of tumour necrosis factor-α (TNF- α), interleukin-10 (IL-10) and interferon-γ (IFN-γ) using qRT-PCR. During the pre-challenge period (d 0–6), increasing dietary SID Trp:Lys ratio increased (linear, P < 0.05) ADG (157, 162, 173, 179 and 201g/d) and G:F (0.71, 0.73, 0.74, 0.81 and 0.84). During the post-challenge period, increasing SID Trp:Lys ratios tended (linear, P = 0.08) to increase ADG (177, 180, 208, 210 and 213g/d), whereas there was no effect on G:F (0.58, 0.63, 0.67, 0.66, 0.65) (P > 0.10). The optimal SID Trp:Lys ratio determined using the broken-line regression analysis for ADG and G:F in piglets subjected to E.coli K88 challenge was 21.7% and 20.1%, respectively. Expression of IL-10 mRNA, increased (linear and quadratic, P < 0.01) with increasing SID Trp:Lys ratio, however, expression of TNF- α and IFN- γ mRNAs were not affected. In conclusion, in antibiotic-free starter diets, an average optimal SID Trp:Lys ratio of 21% optimized performance of piglets under an E. coli K88 challenge.