Lys Requirement Research Articles

Short communication: Estimation of the dietary standardized ileal digestible valine to lysine ratio required for 40 to 130 kg pigs during the finisher periods

BackgroundThree experiments were conducted separately to determine the optimum standardized ileal digestible (SID) valine (Val) to lysine (Lys) ratio for early finishing (Experiment 1, 40 to 75 kg bodyweight), finishing (Experiment 2, 75 to 100 kg bodyweight), and late finishing (Experiment 3, 100 to 130 kg bodyweight) pigs. Dietary SID Val: Lys ratios were designed at 0.61, 0.65, 0.69, 0.73, and 0.77. The optimal SID Val: Lys ratio was estimated by different regression models, including a quadratic polynomial model, a two-slope quadratic broken-line model, a curvilinear-plateau model, and a one-slope straight broken-line model.ResultsIn Exp.1, a total of 550 early finishing pigs (initially 40.3 kg bodyweight) were used in a 38-day growth trial. Pigs consuming 0.61 dietary SID Val: Lys ratio had lower final bodyweight compared to those fed 0.69 in diets. Using regression models, the optimal dietary SID Val: Lys requirement for average daily gain (ADG) was between 0.63 and 0.68, and for feed to gain ratio (F: G) was between 0.62 and 0.68, respectively. In Exp.2, 525 finishing pigs (initially 76.4 kg) were used in a 26-day trial. Based on regression models, estimate of the required SID Val: Lys for ADG was between 0.65 and 0.71, and for F: G was between 0.64 and 0.70, respectively. In Exp.3, 640 late finishing pigs (102 kg bodyweight) were used in a 27-day trial. No significant improvement was found for performance parameters of pigs from 100 to 130 kg, while 0.73 SID Val: Lys ratio resulted in the highest ADG and the lowest F: G from a numerical point of view.ConclusionsThese findings indicated that the optimum SID Val: Lys requirement for pigs from 40 to 75 kg was between 0.62 and 0.68, and for pigs from 75 to 100 kg was estimated to be between 0.64 and 0.71, using different regression models.

Dietary supplementation with functional amino acids improves the capacity of growing pigs to cope with a health challenge

This study aimed to assess the effects of additional dietary supplementation with a blend of functional amino acids (FAA) with Thr, Trp, and Met as a preventive (prior to health challenge), curative strategy (during health challenge) or both targeting the performance, body composition, metabolic biomarkers of growing group-housed pigs raised under a health challenge. Additionally, the influence of these feeding strategies on pig response was investigated after the challenge (during the finishing phase). Sixty weaned piglets [6.3 ± 0.9kg body weight (BW)] were distributed based on BW in a nursery barn to one of two dietary treatments (n=30): control (CN) or supplemented with FAA blend (FAA+; 120% of the Thr:Lys, Trp:Lys, and Met+Cys:Lys requirements) for 7 weeks. After 7 weeks, the pigs (27.9 ± 4.2kg of BW) were distributed in a randomized complete block design to one of four treatments for the period of the health challenge period in the growing phase: pigs fed a CN diet during the nursery period were either maintained on a CN diet (control; n=14) or switched to an FAA+ diet (curative strategy; n=14), whereas the pigs fed an FAA+ diet during the nursery period were either fed a CN diet (preventive strategy; n=14) or continued receiving an FAA+ diet (continuous strategy; n=14). The health challenge consisted of subjecting growing pigs to batch mixing, poor housing conditions, and oral inoculation with Salmonella Typhimurium (ST). Poor housing conditions were maintained for 4 weeks (weeks 8 to 11). After this period, the pigs received the same standard diets for 9 weeks (weeks 12 to 20), and the facilities were cleaned daily. The health challenge increased the rectal temperature (P < 0.01) and serum concentrations of haptoglobin (P < 0.05), IgA (P < 0.05), IgG (P < 0.01), triglycerides (P < 0.01), creatinine (P < 0.01), and urea (P < 0.01), while reducing serum concentrations of lactate dehydrogenase (P < 0.01), albumin (P < 0.01), and glucose (P < 0.05). Pigs fed a continuous FAA+ diet trend towards lower fecal ST shedding (P < 0.10) than did the curative strategy pigs and had better fecal consistency scores (P < 0.01) than did the control pigs. During the challenge period, pigs fed FAA+ curatively or continuously demonstrated higher average daily gain and feed efficiency compared to control pigs (P < 0.01). Greater (P < 0.05) protein deposition (+30%) and improved (P < 0.05) nitrogen retention efficiency (+20% to curative and +30% to continuous strategies) were observed in the pigs fed the FAA+ diet during the health challenge compared with the control pigs. Curative-fed FAA+ pigs had greater BW at the end of the finishing phase than did the control and preventive group (P < 0.05). In conclusion, the use of FAA supplementation as a curative or continuous strategy is highly effective at improving the performance and body composition of growing pigs under a health challenge.

237 Increasing the threonine-to-lysine ratio improves the growth performance of slow-growing pigs when fed with precision feeding techniques

Abstract Individual precision feeding (IPF) is a suitable tool to account for the nutritional requirement variability among pigs. It was previously reported that, within IPF, pigs require greater Thr:Lys than conventional group-phase feeding (GPF) pigs. It remains unknown if these differences in Thr:Lys requirements occur due to different growth rates (Gr). This study evaluated whether the Thr:Lys requirements of pigs fed with IPF systems are affected by Gr. Sixty pigs (30 barrows and 30 gilts) with 38.1 ± 3.8 kg of body weight were distributed in a completely randomized 3 × 5 factorial arrangement. Pigs were classified into fast (FGr), medium (MGr) and slow (SGr) Gr based on their average daily gain (ADG) during 6 wk previous to the trial. After classification, pens with 2 barrows and 2 gilts from the same Gr group were randomly assigned to one of five treatments (12 repetitions per treatment). Treatments consisted of a conventional GPF (GPF100) receiving 100% of the optimal 0.65 Thr:Lys and 4 IPF treatments providing 140% (IPF140), 120% (IPF120), 100% (IPF100) and 80% (IPF80) of the optimal ratio. GPF100 pigs were fed a single diet with 0.97% standardized ileal digestible Lys. IPF diets of the pigs were adjusted every 2 d to meet the Lys requirements of the most demanding pig in the pen. Body weight was recorded twice a week, and individual feed intake (ADFI) daily over 21 d. At d 1 and 21, pigs were scanned with dual X-ray to estimate their body composition. Body weight, body protein and lipid masses were analyzed as repeated measures over time. The Dunnett test was used to compare the IPF treatments to GPF100 and the Tukey test to compare Gr groups. The pig was considered the experimental unit. FGr maintained greater (treatment × Gr, P &amp;lt; 0.05) ADFI and ADG and greater (P &amp;lt; 0.05) lipid deposition over the trial when compared with MGr and SGr. However, increasing Thr:Lys enhanced (P &amp;lt; 0.05) ADG and ADFI of SGr pigs within IPF, resulting in similar (P &amp;gt; 0.05) values between Gr groups in IPF120 and IPF140. Although FGr tended (P = 0.05) to have greater final body protein mass, SGr presented leaner gain (P &amp;lt; 0.05), independently of the Thr:Lys. Threonine supplementation supports metabolic processes like glycine and serine synthesis, impacting gut health, protein synthesis, energy production, and oxidative stress, potentially explaining lower lipid deposition in SGr pigs when the same level of energy in the diet. SGr pigs might need a different AA profile where a higher Thr:Lys ratio likely enhances the metabolic capacity to support fast growth in SGr pigs within IPF. Consequently, increasing the Thr:Lys ratio within IPF led to improved growth performance in SGr pigs.

162 The role of functional amino acids in optimizing nutrition and health

Abstract The ability of a diet or an individual protein-containing ingredient to satisfy the indispensable amino acid (IAA) requirements of an individual is a reflection of protein quality. In human nutrition, the concept of PQ is well recognized and widely applied to facilitate guidance on the extensive range of food items we consume. In the pet food industry, the concept of PQ is gaining recognition as a way in which to identify ideal candidate ingredients for diet formulation and our laboratory has recently completed a large data base of PQ estimates of typical ingredients used in the pet food industry to compliment the emerging PQ ingredient data. Our laboratory has also used more advanced methodologies, specifically the IAAO technique, to measure the dietary Phe, Trp, Met, Thr, and Lys requirements for adult dogs of small, medium and large breed dogs. The role of AA beyond support of protein turnover (adults) or protein deposition (growth) is being explored, such as the role of certain AA in behavior, immune function and inflammation. For example, the ratio of tryptophan to the large neutral amino acids of 0.75:1.0 in contrast to 0.46:1.0 resulted in better indices of gut health and may reduce agonistic behaviors both of which are underpinned by improved serotonergic status. The role of the sulfur AA in the development of dilated cardiomyopathy further highlights the role of IAA as sources for secondary metabolites, such as taurine and glutathione in supporting animal health. Indeed, many AA are becoming referred to as functional AA and the requirement of these AA may differ in healthy and challenged animals and deserve attention in dog and cat nutrition as well. Overall, the pattern of AA that defines the requirement of healthy dogs and cats, may not be the pattern that would support the animal under challenging conditions. Research into supporting different physiological challenges and how these may affect amino acid requirements is warranted.

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 ± 0.61kg 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 ± 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 ± 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.

PSV-16 Effect of precision feeding and functional amino acids on immune response and protein metabolism of growing pigs raised in poor sanitary conditions

Abstract The activation of the immune system reduces the nutrient availability for growth and increases the variability among pigs. Functional amino acids (AA) supplementation can reduce the negative effects of immune activation. Additionally, providing daily tailored diets using individual precision feeding (IPF) was shown to account for individual variability. Therefore, we hypothesized that the association of IPF and functional AA supplementation could reduce the negative effect of immune-challenged pigs fed with daily tailored diets. The aim of this study was to assess performance and blood parameters variation of growing pigs under poor sanitary conditions while being fed functional AA 120% above the estimated INRA AA ratios within IPF, compared with a conventional group-phase (GP) feeding system. The sanitary condition was characterized by oral inoculation of 2 × 109 cfu of Salmonella typhimurium and manure spreading on the pen floor on d 0. Sixty gilts (23 ± 2.8 kg body weight; BW) were distributed in a complete randomized block design in a 2 x 2 factorial arrangement composed of 2 diets: CN with 100% INRA AA ratio or AA+ with 120% of the ratio for Met, Thr and Trp; and 2 feeding systems: GP or IPF. GP pigs received a single diet matching the SID Lys requirement of the 80th-percentile pig at the beginning of the trial whereas IPF pigs received a diet tailored daily to each pig requirement. All pigs were group-housed and fed ad libitum for 28 d by automatic feeders. Body weight was measured at d 0 and 28 and feed intake was recorded daily. Blood samples were collected at d 0, 7 and 28. Data were analyzed with diet and feeding systems and their interactions as fixed effects and BW blocks as random effect. Blood parameters were analyzed as repeated measurements over time. The pig was considered the experimental unit. No diet effect or interactions were observed for any variable (P &amp;gt; 0.05), suggesting that only supplementing Met, Trp, and Thr is not enough to support growth during a sanitary challenge (Table 1). Haptoglobin and IgG increased linearly whereas IgA, urea, and creatinine had a quadratic increase over time (P &amp;lt; 0.05; Table 2). The IPF decreased growth performance and increased serum IgA and creatinine (P &amp;lt; 0.05), mostly due to the fact that IPF reduces AA provision compared with GP system. The IPF model, as most mathematical models, does not account for the AA and energy costs related to the immune challenge. Therefore, IPF might have underestimated the requirements of the pigs, and limited the amount of nutrients provided. In conclusion, the combined effect of IPF and functional AA supplementation was not able to reduce the negative effect of the sanitary challenge.

140 Response of 6 to 13 kg nursery pigs to increasing SID Arg:Lys

Abstract Newly weaned pigs (n = 480; PIC 337 × 1050; Genus, Hendersonville, TN) with an initial body weight (BW) of 6.20 ± 0.61 kg were used in a dose-response study to evaluate the effects of increasing standardized ileal digestible (SID) Arg:Lys in nursery pigs. At weaning, pigs were placed into 48 pens with five barrows and five gilts per pen and randomly assigned to one of six dietary treatments. The experimental diets were formulated with increasing levels of SID Arg by replacing corn starch, glycine, and L-alanine with L-arginine. Levels of SID Arg:Lys ranged from 45 to 145%. Diets were sub-limiting in SID Lys and exceeded all other essential amino acid requirements. Furthermore, diets were formulated to be isocaloric, isonitrogenous, and met or exceeded NRC (2012) vitamin and mineral recommendations. The experimental diets were fed in two feeding phases from d 0 to 10 and d 10 to 27, with adjustments made to account for the decreasing Lys requirement of the pigs. Pigs were subsequently fed a common diet for the remaining 14 d of the nursery period to determine carryover effects. Pigs and feeders were weighed at the beginning and end of each dietary phase for the calculation of average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency (gain to feed ratio; G:F). The data were fit using linear regression with R version 4.3.1 (R Core Team, 2023). The model included 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 0.05 &amp;lt; P ≤ 0.10. There was a significant linear and quadratic effect of SID Arg:Lys on BW on d 27 (P ≤ 0.024), where BW was maximized at a SID Arg:Lys 97.09%. From d 0 to 27 there was a linear and quadratic tendency of SID Arg:Lys on ADFI (P = 0.069), where feed intake was maximized at a SID Arg:Lys of 97.00%. Furthermore, there tended to be a linear and quadratic effect of SID Arg:Lys on ADG from d0 to 27 (P ≤ 0.081), where ADG was maximized at a SID Arg:Lys of 95.65%. There was no evidence for an effect of SID Arg:Lys on G:F at any timepoint throughout the trial (P ≥ 0.298). In conclusion, SID Arg:Lys linearly and quadratically impacted ADFI and ADG in 6 to 13 kg nursery pigs, where ADG was maximized at a SID Arg:Lys of 95.65%, but ADFI was maximized at a SID Arg:Lys of 97.00%. Together, these data suggest that the SID Arg:Lys requirement of nursery pigs is greater than NRC (2012) recommendations, and excessive Arg supplementation may have negative consequences on growth performance.

252 Evaluation of phase feeding and complete diet blending at different standardized ileal digestible lysine levels on finishing pig growth performance, carcass characteristics and diet costs

Abstract A total of 2,160 mixed-gender pigs [PIC 337 × 1050; initial body weight (BW) = 24.9 ± 0.97 kg) were used in the 120-d study to compare feeding strategies (phase feeding vs complete diet blending) at different SID Lys levels (90 vs 100% of suggested requirement estimates) on finishing pig growth performance, carcass characteristics, and economics. Pens of 27 pigs were assigned to 1 of 4 treatments in a completely randomized block design with barn and initial BW as blocking factors resulting in 20 pens/treatment. The treatments included two feeding programs: a 5-phase feeding strategy at either 90% (Phase-90) or 100% of SID Lys requirement estimates (Phase-100) or blending of complete diets with pre-defined mixing proportions of a low and high SID Lys diet to meet 90 (Blend-90) or 100% (Blend-100) of the SID Lys curve requirement estimates for 23 to 127 kg pigs. Lysine levels were based on PIC 2021 requirement estimates. The 90% SID Lys diets were formulated to contain 4.38, 3.73, 3.06, 2.66 and 2.44 g SID Lys per Mcal NE for phases 1 to 5, respectively. The 100% SID Lys diets were formulated to contain 4.86, 4.15, 3.40, 2.96 and 2.71 g SID Lys per Mcal NE for phases 1 to 5, respectively. Pigs in phase-feeding strategies were fed on a feed budget with 21, 65, 67, 63 and 62 kg per pig for phases 1 to 5, respectively. Final BW and overall average daily gain (ADG; d 0 to 120) were not affected by the feeding strategy nor by diet SID Lys levels. In contrast, overall average daily feed intake (ADFI0 of pigs fed by diet blending was less than those fed by phase feeding (P = 0.002) resulting in increased gain to feed ratio (G:F; P &amp;lt; 0.001) for pigs fed by diet blending (table). The SID Lys levels did not influence overall ADFI or G:F. Hot carcass weight, carcass yield, percentage lean, fat depth and loin depth were not affected by the feeding program. Despite the decreased overall ADFI and increased G:F of pigs fed by diet blending, feeding strategy resulted in no significant differences in economic criteria except for reduced feed cost per kg gain at high price scenario (P = 0.049) for diet blending. With low diet cost, the 90% SID Lys level resulted in decreased feed cost per pig and feed cost per kg gain than 100% SID Lys (P &amp;lt; 0.001), but differences were not detected in income over feed cost (IOFC). In conclusion, diet blending at either 90 or 100% of the SID Lys requirement estimate reduced ADFI and increased G:F without impacting average daily gain (ADG) or carcass characteristics. At ingredient prices used in this study, feeding strategies at either 90 or 100% SID Lys did not significantly affect IOFC, but feeding 90% of SID Lys recommendation reduced feed cost.

Effect of dietary nitrogen content and ammonium phosphate inclusion on lysine requirement for nitrogen retention in growing pigs

Inclusion of a source of non-protein nitrogen (NPN) may improve essential amino acid (EAA) and nitrogen (N) utilization in N-limiting diets. Growing barrows (20.4 ± 0.5 kg) were randomly assigned to 1 of 10 dietary treatments ( n = 9 pigs/treatment) in nine blocks. Diets contained no ammonium phosphate (NAP) or 1.7% ammonium phosphate (AP) to have an EAA-N:total N ratio of 0.36 and 0.33, respectively, with graded levels of dietary lysine (Lys; 0.8%, 0.9%, 1.0%, 1.1%, and 1.2% standardized ileal digestible (SID)). Following a 7-day dietary adaptation, a 4-day N-balance collection period was conducted. Blood samples were obtained on day 2 of the collection period. Nitrogen retention (NR) increased and urinary N output decreased with inclusion of NPN and increasing Lys ( P &lt; 0.01). Plasma urea N decreased with increasing Lys ( P &lt; 0.05). Total plasma EAA content was reduced with NPN supplementation ( P &lt; 0.05), while content of Arg, Asp, Gln, and Glu was increased ( P &lt; 0.01). The linear breakpoint model indicated that NR was maximized at 1.00% SID Lys in NAP-fed pigs and at 1.09% SID Lys in AP-fed pigs. These results indicate that diets deficient in dietary N reduce NR and Lys requirement, which were in turn increased with NPN supplementation.

221 Increasing Functional Amino Acid Ratios Does Not Improve Growth Performance in Pigs Raised Under Poor Sanitary Conditions When Fed with Individual Precision Feeding Or Conventional Feeding Systems

Abstract Immune system activation redirects dietary nutrients to defense mechanisms, thereby impairing growth performance of pigs. Supplementing pigs with functional amino acids (AA) such as Met, Thr and Trp was shown to support the immune system and reduce the negative effects on growth. However, pigs respond differently to immune stressors which increase herd variability. In this context, individual precision feeding (IPF) might be an alternative approach to reduce herd variability and increase nutrient efficiency in immune challenged pigs. This study aimed to evaluate growth performance, body composition, nitrogen (N) efficiency and haptoglobin and triglycerides serum concentration in growing pigs raised in poor sanitary conditions (PoorSC). The PoorSC was characterized by oral inoculation with 2 × 109 cfu of Salmonella typhimurium and manure spreading on the pen floor. Sixty gilts (23 ± 2.8 kg BW) were distributed in BW blocks according to a 2 dietary (D) × 2 feeding system (FS) factorial arrangement composed of to 2 diets [control (CN): INRA ideal AA ratio or supplemented (AA+) 120% of the ideal ratio for Met, Thr and Trp] and 2 feeding systems [conventional (GP) or IPF]. GP pigs were fed with a unique diet that matched the SID Lys requirement of the 80th-percentile pig at the beginning of the trial whereas the IPF pigs received a diet tailored daily to each pig requirement. All pigs were housed in the same pen and fed ad libitum during 28 experimental days with automatic feeding stations able to provide to each pig the assigned diet. Body composition was obtained by dual X-ray absorptiometry at days 0 and 28 and blood samples were collected at d 28. Data were analyzed with D and FS and their interaction as main fixed factors and body weight (BW) blocks as a random effect (Table 1). Haptoglobin serum concentration increased from d 0 to 28 regardless of FS and D (P &amp;lt; 0.10). IPF pigs fed with CN diet had the lightest BW at the end of the trial (P ≤ 0.10; FS × D), whereas BW was similar for the other treatments. However, across diets, IPF pigs had final BW, and protein, ADG, G:F, protein and lipid deposition, N intake and excretion and circulating triglycerides that were less than GP pigs. N utilization efficiency was similar across treatments. Additionally, increasing the provision of the studied functional AA did not improve pig performance. Thus, showing no benefits in increasing AA ratios for growth and immune response. The increased triglycerides concentration and low protein and lipid deposition suggests that IPF pigs prioritized the immune system to the expense of protein and lipid accretion. In conclusion, AA supplementation and IPF do not improve growth performance and N efficiency of pigs raised in poor sanitary conditions.

PSII-11 Supplementation of Non-Protein Nitrogen to a Nitrogen-Deficient Diet Increases Lysine Requirement for Nitrogen-Retention

Abstract Low protein (LP) diets have improved nutrient utilization while maintaining animal performance. Regardless, these diets may be limiting in nitrogen (N) content to meet non-essential amino acid (NEAA) requirements, potentially altering essential amino acid (EAA) utilization and requirements. Inclusion of a non-protein nitrogen (NPN) may be beneficial for improving utilization of EAA in LP diets. The objective of this study was to determine the impact of NPN in an N-deficient diet, as indicated by EAA-N:total N ratio (EAA-N:TN) on the Lys requirement for nitrogen retention (NR). A total of 90 growing barrows (initial BW of 20.4 ± 0.46 kg) were randomly assigned to 1 of 10 dietary treatments (n = 9 pigs/treatment) in 9 blocks in a 2 × 5 factorial design. Diets contained no ammonium phosphate (NAP; EAA-N:TN of 0.56) or were supplemented with 1.7% ammonium phosphate (AP; EAA-N:TN of 0.50) with graded levels of dietary lysine [Lys; 0.8%, 0.9%, 1.0%, 1.1% and 1.2% standardized ileal digestible (SID)]. Diets were corn and soybean meal-based and formulated to meet or exceed nutrient requirements according to NRC (2012). Diets were fed at 2.8 × maintenance metabolizable energy requirements in two equal meals per day. A 4-d nitrogen balance collection period was conducted following a 7-d dietary adaptation period. Urine was collected quantitatively, and fresh fecal samples were obtained daily. Nitrogen retention was determined as the difference between N intake and output (fecal and urinary). Linear breakpoint modeling with PROC NLIN was used to estimate Lys requirement. Nitrogen retention was optimized at 1.00% SID Lys (15.6 g/d NR; R2 = 0.68) in pigs fed NAP diets and 1.09% SID Lys (16.4 g/d NR; R2 = 0.61) in pigs fed AP diets. Overall, deficient dietary N reduced NR and Lys requirement, which were increased with NPN supplementation.

245 Effects of Standardized Ileal Digestible Tryptophan to Lysine Ratio on Growth Performance of PIC Line 337-Sired Grow-Finish Pigs

Abstract This study was conducted to estimate the SID Trp:Lys requirement for growth and feed efficiency of PIC 337 × 1050 pigs from approximately 46- to 73-kg. A total of 840 pigs [initial body weight (BW) = 45.9 ± 0.95 kg] were used in a 28-d growth performance study. Pens of pigs were blocked by BW and randomly allotted to dietary treatments with 22 to 27 pigs per pen and 7 replications per treatment in a randomized complete block design. Pens were provided 1 of 5 dietary treatments with increasing SID Trp:Lys ratios at 15, 17.5, 19, 21, and 23%. Two corn-soybean meal-based diets with 30% DDGS containing 15 and 23% Trp:Lys ratios were blended to achieve dietary targets for SID Trp:Lys. Average daily gain, ADFI, G:F, Trp Intake/kg of gain, and final BW increased (quadratic, P ≤ 0.008) with increasing Trp:Lys ratio, while Trp intake/d increased linearly (P &amp;lt; 0.001; Table). Additionally, Lys intake/d increased (quadratic, P = 0.009) while Lys intake/kg of gain decreased (quadratic, P = 0.008). A broken-line linear model predicted no further improvement to ADG beyond 19.5% SID Trp:Lys for 46- to 73-kg pigs. Meanwhile, a broken-line linear model suggested no further improvement to G:F beyond 19.3% SID Trp:Lys, while a similar fitting quadratic polynomial model suggested that maximum G:F was achieved at 21.3% SID Trp:Lys. In summary, these results suggest that the optimal SID Trp:Lys level for 46- to 73-kg pigs is 19.5% for ADG and 19.3 to 21.3% for feed efficiency.

PSII-12 Growth Performance of Pigs Fed Diets Containing Supplemental Lysine and a Low or High Essential Amino Acid-Nitrogen to Total Nitrogen Ratio

Abstract With the provision of low protein (LP) diets, it is possible that N, or non-essential amino acids (NEAA), become limiting. We have previously shown that the lysine (Lys) requirement for N retention is greater when pigs are fed a diet with sufficient N, as indicated by a low EAA-N:total N ratio (EAA-N:TN). The objective of this study was to investigate the effect of EAA-N:TN and Lys content on growth performance of growing pigs. A total of 240 growing pigs (20.6 ± 2.03 kg initial body weight) were randomly placed into groups of 5 pigs/pen (either 2 barrows and 3 gilts, or 3 barrows and 2 gilts) and randomly assigned to 1 of 4 dietary treatments (n = 12 pens/treatment) in 3 blocks in a 2 × 2 factorial design. Factors consisted of dietary EAA-N:TN [optimal ratio (LR) of 0.48 or high ratio (HR) of 0.55] and dietary Lys level of 1.03% SID or 1.22% SID, representing the NRC (2012) requirement and the requirement as determined previously, respectively. Diets were corn and soybean meal based and formulated to meet or exceed nutrient requirements according to NRC (2012). Pigs were individually weighed and feed intake determined weekly to determine average daily gain (ADG), average daily feed intake (ADFI), and gain:feed (G:F). Fecal samples were collected on d 14 for determination of N output. Data were analyzed using a mixed model with fixed effects of ratio, lysine, and their interaction and block as a random effect. Increasing dietary Lys resulted in increased overall ADG and ADFI, regardless of EAA-N:TN ratio (P &amp;lt; 0.01). Pigs fed the HR diets had improved ADG in week 4 (P &amp;lt; 0.05), whereas pigs fed the LR diets had improved ADG and G:F in week 1 (P &amp;lt; 0.01). There was an interactive effect of ratio and Lys on N output (P &amp;lt; 0.01), where N output decreased in the HR diets with 1.22% Lys. Overall, current Lys requirements may not be sufficient to maximize growth in 20-50 kg pigs, and greater Lys may be beneficial for reducing N output in LP diets.

134 Meta-Analysis to Determine the Standardized Ileal Digestible Lysine Requirements of Growing-Finishing Pigs from 11- to 150-kg Utilizing the Ingredients Database of Inra

Abstract A meta-analysis was conducted to determine the standardized ileal digestible (SID) lysine (Lys) recommendations for 11–150 kg PIC pigs housed under commercial conditions utilizing the INRA feed ingredients database. Data from 29 trials dating from 2013 to 2020 utilizing 48,338 pigs were recorded in a database. Number of pens/treatment and pigs/pen ranged from 9 to 16 and 12 to 25, respectively. Sire lines were PIC 337 in 25 trials, PIC 327 in 3 trials, and PIC TR4 and 327 in 1 trial. Dam lines were PIC Camborough in 18 trials and PIC Camborough 29 in 9 trials. The SID Lys levels reported in each trial were used, and the SID Lys to calorie ratio curves were built for both metabolizable energy (ME) and net energy (NE) systems using the feed ingredient composition in INRA for energy levels. The response variables, average daily gain (ADG) and feed efficiency (G:F), were analyzed within 7 phases using generalized linear and non-linear mixed models with heterogeneous variance (Gonçalves et al., 2016). Phases consisted of the following body weight ranges: 11-23, 23-41, 41-59, 59-77, 77-104, 104-127, and 127-150 kg . Each treatment mean within a trial (n = 288) was considered the experimental unit and each trial was used as a random effect. There was no evidence for an interaction between sire lines or dam lines and treatment (P &amp;gt; 0.10). The SID Lys to calorie recommendations are based on the average of the requirement estimates for ADG and G:F. At these levels, approximately 100% of maximum ADG and 99.7% of maximum G:F are achieved. After determining the requirement estimates within each of the 7 weight breaks, a quadratic equation of Lys to calorie ratio was fit for each energy system. The equations are described as: g of SID Lys:Mcal of ME = 0.0001381709 × (weight, kg)2 - 0.0366272129 × (weight, kg) + 4.6073086522; and g of SID Lys:Mcal of NE = 0.0000400092 × (weight, kg)2 - 0.0235648387 × (weight, kg) + 6.2762350341. These data provide the estimated SID Lys requirements for maximal growth performance for PIC pigs from 11- to 150-kg based on the ingredients database of INRA.

PSII-10 Ammonium Phosphate is an Appropriate Nitrogen Source in Nitrogen-Limiting Diets for Growing Pigs

Abstract The use of low protein (LP) diets is common in swine production, but there is potential for reduced dietary N for the endogenous synthesis of non-essential amino acids (NEAA), impacting overall animal growth. It has been previously demonstrated that inclusion of non-protein nitrogen (NPN) in a diet with an increased essential amino acid-nitrogen:total nitrogen (EAA-N:TN) ratio (i.e. limiting in total N) reduced the Lys requirement and maximum NR in growing pigs. The objective of this study was to determine the impact of NPN inclusion and Lys content on growth performance of growing pigs. A total of 240 growing pigs (120 gilts and 120 barrows) with an initial body weight (BW) of 20.2 ± 2.18 kg were housed in groups of 5 pigs/pen. Pens were randomly assigned to 1 of 6 dietary treatments over 3 blocks (n = 8 pens/treatment) in a 2 × 3 factorial design, with factors of NPN inclusion (no ammonium phosphate [NAP] or ammonium phosphate inclusion at 1.7% [AP]) and dietary lysine (Lys; 1.03%, 1.15% or 1.27% standardized ileal digestible). The AP and NAP diets were formulated to have an EAA-N:TN ratio of 0.48 and 0.54, respectively. All diets were corn and soybean meal-based and formulated to meet or exceed NRC (2012) nutrient requirements. The experimental period was 28 d, with individual BW and per pen feed intake determined weekly. On d 28, backfat and lean depth were measured on 2 pigs per pen, one male and one female. Data were analyzed using a mixed model with fixed effects of N content, Lys, and their interactions, and block as a random effect. Backfat and lean depth analysis included sex as a fixed effect. Inclusion of NPN reduced feed intake and increased gain:feed compared with pigs fed NAP diets (P &amp;lt; 0.05). Overall ADG and d 28 BW increased with increasing Lys, but were not impacted by dietary NPN content (P &amp;gt; 0.05). Pigs fed AP diets had increased lean depth (P &amp;lt; 0.05) and reduced backfat. Overall, NPN, as ammonium phosphate, can improve feed efficiency and increase lean depth while maintaining similar ADG and final BW.

Standardized ileal digestible lysine requirement of pregnant sows under commercial conditions.

The present experiment aimed to determine standardized ileal digestible (SID) lysine (Lys) requirements for pregnant sows individually housed under commercial farm conditions. Two hundred multiparous sows (parity = 5.1±2.0) on day 42 of gestation were randomly allocated to five dietary treatments with a balanced parity. Experimental diets were formulated to contain 0.22%, 0.32%, 0.42%, 0.52%, and 0.62% of SID Lys for the mid-gestation period (days 42 to 76) and 0.36%, 0.46%, 0.56%, 0.66%, and 0.76% of SID Lys for the late gestation period (days 77 to 103). All indispensable amino acids except Lys were provided at 110% of their requirement estimates. Daily feed allowance per sow was determined based on the back-fat thickness and body condition score at the second pregnancy check and on day 90 of gestation. Three different statistical models were used to estimate the SID Lys requirement. Total born piglets alive per litter increased linearly and quadratically (p<0.001) as dietary SID Lys increased. For total born piglets alive per litter, the SID Lys requirement estimates ranged from 9.69 to 12.4 g/d for the mid-gestation period (1.19 to 1.52 g/Mcal metabolizable energy; 0.39% to 0.49%) and 14.6 to 17.4 g/d for the late gestation period (1.62 to 1.93 g/Mcal metabolizable energy; 0.52% to 0.62%). The mean values of the SID Lys requirement for the mid-gestation period and the late gestation period are 11.1 and 16.1 g/d (1.36 and 1.79 g/Mcal metabolizable energy; 0.44% and 0.58%), respectively, for maximal total born piglets alive per litter.

Bioavailability of a novel rumen protected methionine supplement and its effect on milk production and body composition in dairy cows

Our objective was to evaluate the bioavailability of a rumen-protected Met product (EMT 3.4) using milk selenium (Se) marker method and its impact on milk production and body composition in dairy cows. Twelve multiparous Holstein cows (82 ± 27 days in milk, 38.7 ± 3.4 kg/d of milk; mean ± SD) were used in a replicated 3 × 3 Latin-square design with 21 d periods. Prior to the study, cows were fed Se-yeast for 2 wk to reach stable milk Se concentration. Treatments were 1; a negative control diet (NCT) providing 100% of the metabolizable protein (MP) requirement and 90% of the metabolizable Lys and Met requirements, 2; a positive control diet (PCT) providing 101% of the MP, and 110% of the Met and Lys requirements (Met supplied by Smartamine M, Adisseo), and 3; an experimental Met treatment (EMT; Met supplied by EMT 3.4, Ajinomoto Inc.) that was formulated to provide 101% of the MP, and 110% of the metabolizable Met and Lys requirements (AMTS.Cattle.Professional utilizing CNCPS 6.5.5 models). The NCT cows were not supplemented with additional Met or Lys, whereas supplemental Lys for both the EMT and PCT diets was supplied by Aji-Pro L (Ajinomoto). The PCT and EMT treatments decreased milk Se-to-N ratio (i.e. bioavailability; Se:N), by 11% and 9.5% respectively compared with NCT (P < 0.05). The PCT increased DMI and tended to increase milk yield compared to NCT and EMT. The PCT treatment increased yields of milk protein, solids, lactose, and milk lactose concentration compared to NCT and EMT treatments. The EMT treatment increased milk urea nitrogen (MUN) concentration compared with NCT and PCT. However, the potential for milk Se to be inconsistently diluted due to differences in MUN and DMI poses challenges with interpretation. The lack of measurable production responses when supplementing EMT compared to NCT, may indicate less bioavailable Met than the bioavailability calculation assumes.

Standardized ileal digestible lysine requirements based on growth performance and histochemical characteristics of male broilers from 10 to 21d of age.

The growth performance and histochemical characteristics of breast muscle fibers were used to estimate the standardized ileal digestible (SID) Lys requirements for 10- to 21-d-old male broilers. Three hundred and sixty 10-d-old Ross 308 broilers (290±16.6g) were allocated to 6 diets in a randomized complete block design with 6 replicate cages per treatment and 10 birds per cage. The 6 experimental diets were formulated to contain equally spaced increasing levels of SID Lys from 0.86% to 1.36%. The data were analyzed using the MIXED procedure of SAS. The Lys requirements were estimated by the NLIN procedure of SAS. An increase in dietary SID Lys from 0.86% to 1.36% resulted in a quadratic increase (P<0.05) in body weight gain (BWG), gain to feed ratio (G:F), breast weight, muscle cross-sectional area (MCSA), and fiber area. The SID Lys requirements based on the one-slope broken-line, quadratic line, the first intercept between the plateau of the one-slope broken-line and quadratic-line models and 95% of the upper asymptote of the quadratic-line model were estimated to be 1.01%, 1.19%, 1.08%, and 1.13% for BWG, 1.06%, 1.22%, 1.11%, and 1.16% for G:F, 1.10%, 1.29%, 1.19%, and 1.22% for breast weight, 1.06%, 1.22%, 1.12%, and 1.16% for MCSA, and 1.14%, 1.22%, 1.16%, and 1.16% for breast muscle fiber area, respectively. It was concluded that the SID Lys requirements for broilers at the age of 10 to 21d depended on the response variables used for estimation, and that histochemical characteristics of breast muscle fibers could be good indicators for estimating SID Lys requirements.

Effect of the essential amino acid-nitrogen to total nitrogen ratio on lysine requirement for nitrogen retention in growing pigs.

Low protein diets supplemented with essential amino acids (EAA) fed to pigs reduce the excess supply of EAA and nitrogen (N). However, low protein diets may become limiting in non-essential amino acids (NEAA) and N, thus affecting the utilization of EAA for N retention. It has been suggested that the EAA-N:total N (E:T) ratio can give an indication of dietary N sufficiency. An N-balance study was conducted to determine the effect of E:T ratio on the Lys requirement for maximum N retention. A total of 80 growing barrows (19.3 ± 0.21 kg initial body weight) were randomly assigned to 1 of 10 diets (n = 8) in 8 blocks in a 2 × 5 factorial arrangement. Diets consisted of a low ratio (LR; E:T of 0.33) or a high ratio (HR; E:T of 0.36) with graded Lys content (0.82%, 0.92%, 1.02%, 1.12%, and 1.22% standardized ileal digestible [SID]). After a 7-d adaptation, a 4-d N-balance collection was conducted. Blood samples were obtained on d 2 of the collection period 2 h after the morning meal for plasma urea N (PUN) analysis. Data were analyzed using the MIXED model procedure with fixed effects of ratio (n = 2), Lys (n = 5), and their interactions. The experimental block (room) was included as a random effect (n = 8). The SID Lys requirement was estimated using PROC NLIN linear broken-line breakpoint model. There was a significant interaction between E:T ratio and Lys (P < 0.01), where LR diets had a higher N retention than HR diets, while increasing Lys linearly increased N retention (P = 0.01) in both HR and LR diets. The marginal efficiency of utilizing SID Lys (P < 0.01) reduced with increasing Lys content, while the efficiency of utilizing N (P < 0.05) increased as Lys increased. The SID Lys required to maximize N retention of pigs fed HR diets was estimated at 1.08% (R2 = 0.61) and LR diets at 1.21% (R2 = 0.80). The current results indicate that N may be limiting in diets with a high E:T ratio, limiting N retention. Supplying additional dietary N, as intact protein, can increase N retention, resulting in a greater Lys requirement.

Optimal dietary standardized ileal digestible lysine level for pigs during the grower, early and late finisher periods

BackgroundLysine (Lys) is the first limiting amino acid for pigs fed corn-soybean meal diets. Three experiments were conducted to estimate the optimal standardized ileal digestible (SID) Lys requirement for growing (Exp. 1), early finishing (Exp. 2), and late finishing (Exp. 3) pigs under commercial conditions.Results and conclusionsIn Exp. 1, a total of 650 growing pigs (32.21 ± 0.33 kg bodyweight), were allocated to 5 dietary treatments supplemented with 0.75, 0.85, 0.94, 1.03, and 1.13% SID Lys. Each treatment had 5 replicate pens with 26 pigs per pen. The lowest feed to gain ratio (F:G) was obtained by pigs fed the 1.03% Lys diet and F:G showed both a linear and a quadratic response with increasing Lys (P < 0.05). Based on broken-line and quadratic analysis models, dietary SID Lys levels for the minimum F:G were 0.94%. In Exp. 2, 650 finishing pigs (57.24 ± 2.00 kg bodyweight) were allotted to 5 dietary treatments providing SID Lys of 0.63, 0.71, 0.79, 0.87, and 0.95%. Each treatment had 5 replicates, 26 pigs per replication. The highest final bodyweight was achieved by 0.79% Lys while the highest average daily gain (ADG) and average daily feed intake (ADFI) was achieved by pigs consuming the 0.87% Lys diet (P < 0.05). Additionally, the lowest F:G was obtained by pigs fed the 0.79 and 0.87% Lys diet (P < 0.05). Based on broken-line and quadratic analysis models, the optimum Lys was 0.81 and 0.82% for ADG and F:G, respectively. In Exp. 3, 600 late finishing pigs (92.22 ± 2.41 kg bodyweight), were divided into 5 treatments providing Lys levels of 0.53, 0.60, 0.66, 0.73, and 0.79%. Each treatment had 5 replicates, 24 pigs per replication. Results showed that final bodyweight, ADG, ADFI, and F:G was not affected by increasing dietary Lys level, suggesting that the lowest SID Lys (0.53%) was sufficient for this group of pigs. Taken together, the SID Lys requirement for pigs from 30 to 60 kg, 60 to 90 kg, 90 to 120 kg was 0.94%, 0.81 to 0.82, and 0.53%, respectively, depending on the response criteria with performance maximized.