Broken-line Linear Research Articles

27 Standardized ileal digestible lysine to metabolizable energy ratio equations for 12 to 127 kg boars, gilts, immunocastrated gilts and boars

Abstract We aimed to determine the standardized ileal digestible (SID) lysine (Lys) to metabolizable energy (ME) ratio equations for 12 to 127 kg boars, gilts, immunocastred gilts (IC gilts), and barrows (IC barrows). An average of 3,545 split-gender pigs (PIC 337×Camborough, initially 11.98 ± 1.26 kg) were used in a 21-d trial followed by a 21-d wash-out period in 2 replicates, totaling six feeding periods. In feeding phase 6, both genders were immunized against gonadotropin-releasing hormone (administrated with Vivax, Zoetis, São Paulo, SP, Brazil). Pens of pigs were weighed, blocked by body weight, and randomly allotted to 1 of 5 treatments consisting of 80, 90, 100, 110, and 120% of PIC SID Lys:Mcal of ME recommendations for mixed gender between boars, barrows, and gilts for each phase. The treatment diets were corn-soybean-meal-based and contained 3,300 Kcal of ME/kg. There were six split-gender pens•treatment-1•replicate-1 •phase-1 and 30 pigs/pen. Data were analyzed using generalized linear and nonlinear mixed models with a pen as the experimental unit. Competing models included linear, quadratic polynomial (QP), broken-line linear (BLL), and broken-line quadratic (BLQ) for average daily gain (ADG) and gain to feed ratio (G:F). There was no significant gender by quadratic coefficient interactions in all phases of this study (P > 0.05), then the mixed gender equation was determined, and the intact boars and gilts equation was estimated by the PIC overall difference in efficiency between genders. In the immunocastrated phase, after second dose, the mixed gender optimum level was determined and the equations for IC gilts and barrows was estimated by the differences in efficiency observed in the phase 6 of the two replicates. The SID Lys to calorie ratio recommended is based on the average for ADG and G:F (Table 1). Approximately 98.4% and 99.2% of maximum ADG and G:F were achieved at these levels, respectively, and these equations were similar compared with previous PIC biological requirements (Orlando et al., 2021).

130 Effects of Increasing Dietary Standardized Ileal Digestible Lysine Levels on Growth Performance of 102- to 127-kg Immunocastred Gilts and Boars

Abstract Our objective was to determine the effects of increasing dietary standardized ileal digestible (SID) lysine (Lys) on growth performance of immunocastrated gilts and boars. A total of 3,519 split gender pigs [PIC 337×Camborough, initial body weight (BW) = 101.7 ± 3.89 kg] were used in a 21-d trial in 2 replicates. Following the immunization against gonadotropin-releasing hormone (administrated with Vivax, Zoetis, São Paulo, SP, Brazil) in both genders, pens of pigs were weighed, blocked by BW, and randomly allotted to 1 of 5 treatments. Treatments consisted of 1.69, 1.90, 2.11, 2.32, and 2.53 g of SID Lys:Mcal of ME, which corresponded to 80, 90, 100, 110, and 120% of PIC SID Lys recommendations for mixed gender between barrow and gilts. This resulted in 0.56, 0.63, 0.70, 0.77, and 0.84% SID Lys given that the treatment diets were corn-soybean-meal-based and contained 3,300 Kcal of ME/kg. There were 6 split gender pens∙treatment-1∙replicate-1 and 29 pigs/pen. Data were analyzed using generalized linear and nonlinear mixed models with a pen as the experimental unit. Competing models included linear, quadratic polynomial (QP), broken-line linear (BLL), and broken-line quadratic (BLQ). There was no evidence of linear or quadratic SID Lys concentration by gender interaction (Table). Increasing SID Lys concentration improved average daily gain (ADG; quadratic, P < 0.01) and gain-to-feed ratio (G:F; quadratic, P < 0.01). The QP, BLL, and BLQ had a similar fit for the ADG and G:F. In the QP model, 95% and 100% of the ADG were achieved at 0.64 and 0.76% of SID Lys, respectively, and at 0.61 and 0.75% for G:F. The BLL and BLQ models estimated the breakpoint at 0.70% (95% CI: 0.65-0.74%) and 0.68% SID Lys (95% CI: 0.50-0.85%), for ADG, respectively. For G:F, the BLL, and BLQ models estimated the breakpoint at dietary SID Lys of 0.69% (95% CI: 0.52-0.86%) and 0.68% (95% CI: 0.58-0.78%), respectively. There was no evidence that increasing dietary SID Lys levels impacted the average daily feed intake or the removal and mortality rate. In the current trial the estimated optimum SID Lys:Mcal of ME ratio for 102- to 127-kg immunocastrated gilts and boars ranged from 2.06-2.30 (0.68-0.76% SID Lys based on a 3,300 kcal of ME/kg diet), depending on the statistical model.

106 Minimum Methionine Requirement in Adult Cats Using the Indicator Amino Acid Oxidation Technique

Abstract Despite the importance of Met for protein synthesis and a wide range of metabolic functions, little is known about its requirement in adult cats. Current recommendations for adult cats are based solely on studies using kittens and growth or nitrogen balance as the outcomes. Thus, this study aimed to determine the minimum Met requirement in mature cats using the indicator amino acid oxidation (IAAO) technique. Four adult neutered male cats (4.90 + 0.77 kg BW) were used in a Latin rectangle design. Cats were fed a semi-synthetic diet sufficient in Met for 2 weeks prior to being randomly allocated to one of the eight dietary Met treatments (0.12%, 0.17%, 0.21%, 0.28%, 0.35%, 0.42%, 0.50% and 0.57% dry-matter). Cys was provided in excess to spare the Met requirement and meet the Cys requirement. After 2d of adaptation, individual IAAO studies were performed. During each IAAO study day, cats were placed in indirect calorimetry chambers and fed 75% of their daily ration (12.38g/kg BW) split in 13 ½-hourly small meals. A priming dose of NaH13CO3 (0.44mg/kg) and L-[1-13C]-Phe (4.8mg/kg) were provided in the 4th and 5th meal, respectively, following by a constant dose (1.04mg/kg) of L-[1-13C]-Phe in the next meals. Breath samples were collected ½-hourly to measure 13CO2 enrichment to quantify 13CO2 and calculate F13CO2 during isotopic steady state (Phe oxidation). Competing models, broken-line linear (BLL) ascending model, and a broken-line quadratic (BLQ) ascending model, were fitted on F13CO2 to determine the minimum requirement of Met (breakpoint). The BLL yielded the best model with mean minimum Met requirement estimated at 0.305% (dry-matter), and the 95% confidence interval estimated at 0.521% (dry-matter) for adult cats. In conclusion, the estimated min Met requirement in this study is greater than those currently recommended by the NRC (2006; 0.17% dry-matter) and AAFCO (0.2% dry-matter).

145 Effects of Increasing Dietary Standardized Ileal Digestible Lysine Levels on Growth Performance of 12- to 23-Kg Boars and Gilts

Abstract Our objective was to determine the effects of increasing dietary standardized ileal digestible (SID) lysine (Lys) on growth performance of late nursery boars and gilts. A total of 1,920 pigs (PIC 337×Camborough, initially 12.1±1.34kg) were used in a 21-d trial. Pens of pigs were weighed, blocked by body weight, and randomly allotted to 1 of 5 treatments containing 1.10, 1.16, 1.29, 1.42, and 1.48% SID Lys (corresponding to 85, 90, 100, 110 and 115.0% of PIC SID Lys recommendations). Diets were corn-soybean-meal-based and contained 3,300 Kcal of ME/kg. There were 6 split gender pens/treatment and 32 pigs/pen. Data were analyzed using generalized linear and nonlinear mixed models with pen as the experimental unit. Competing models included linear, quadratic polynomial (QP), broken-line linear (BLL), and broken-line quadratic (BLQ). There was no evidence of linear or quadratic SID Lys concentration by gender interaction. Increasing SID Lys concentration improved average daily gain (ADG; quadratic, P < 0.05) and gain to feed ratio (G:F; quadratic, < 0.01). The QP, BLL, and BLQ had similar fit for the ADG and G:F. In the QP model, 95% and 100% of the ADG were at 1.18 and 1.36% of SID Lys, respectively, and 1.17 and 1.35% for G:F. The BLL and BLQ models estimated the breakpoint at 1.20% (95% CI: 1.06-1.35%) and 1.22% SID Lys (95% CI: 0.97-1.47%), for ADG, respectively. For G:F, the BLL and BLQ models estimated the breakpoint at dietary SID Lys of 1.20% (95% CI: 1.07-1.33%) and 1.20% (95% CI: 1.03-1.38%), respectively. There was no evidence that increasing dietary SID Lys levels impacted average daily feed intake or the removal and mortality rate. In the current trial with dietary ME level at 3,300 kcal/kg, the estimated optimum SID Lys concentration for 12- to 23-kg boars and gilts ranged from 1.20-1.36%, depending on the statistical model.

143 Effects of Increasing Dietary Standardized Ileal Digestible Lysine Levels on Growth Performance of 13- to 23-Kg Pigs Sired by PIC 800 Boars

Abstract An experiment was conducted to determine the effects of increasing dietary standardized ileal digestible (SID) Lys on growth performance of late nursery pigs. A total of 546 pigs (PIC 800 × Camborough, initially 12.6 ± 0.56 kg) were used in a 21-d trial. Pens of pigs were weighed, blocked by body weight, and randomly allotted to 1 of 6 treatments that contained 1.10, 1.16, 1.23, 1.29, 1.39, or 1.49% SID Lys (corresponding to 85.0, 90.0, 95.0, 100.0, 107.5, or 115.0% of PIC SID Lys recommendations). Diets were corn-soybean meal-based and contained 2,450 kcal/kg net energy (NE). There were 7 pens/treatment and 13 pigs/pen (6 or 7 gilts and 7 or 6 barrows, balanced among treatments). Data were analyzed using generalized linear and nonlinear mixed models with pen as the experimental unit. Competing models included linear, quadratic polynomial, broken-line linear (BLL), and broken-line quadratic (BLQ). Increasing SID Lys concentration increased average daily gain (ADG; quadratic, P = 0.05) and gain to feed ratio (G:F; linear, P < 0.05; Table 1). Although the best fitting model for G:F was linear, the greatest improvement in efficiency was observed as SID Lys increased from 1.10 to 1.23%. The best-fitting models for ADG were BLL and BLQ. The BLL and BLQ models estimated the breakpoint of SID Lys at 1.26% (95.4% of PIC SID Lys recommendation; 95% CI: 1.17 to 1.29%) and 1.23% (95.0% of PIC SID Lys recommendation; 95% CI: 1.18 to 1.28%), respectively. There was no evidence that increasing dietary SID Lys levels impacted average daily feed intake or the removal and mortality rate. In the current trial with dietary NE at 2,450 kcal/kg, the estimated optimum SID Lys concentration for 13 – 23 kg pigs sired by PIC 800 boars ranged from 1.23 to 1.26%, depending on the statistical model.

142 Effects of Increasing Dietary Standardized Ileal Digestible Lysine Levels on Growth Performance of 11- to 25-Kg Pigs Sired by PIC 337 High Index Boars

Abstract Our objective was to determine the effects of increasing dietary standardized ileal digestible (SID) lysine (Lys) on growth performance of late nursery pigs. A total of 1,116 pigs (PIC 337×Camborough, initially 11.1±0.11 kg) were used in a 21-d study. The pigs were sired by boars ranked in the top 15% of a selected PIC elite boar stud based on index. Pens of pigs were blocked by body weight and randomly allotted to 1 of 5 treatments that contained 1.13, 1.26, 1.32, 1.38, and 1.51% of dietary SID Lys (corresponding to 90, 100, 105, 110, and 120% of PIC SID Lys recommendations). Diets were corn-soybean meal-based and contained 2,385 Kcal of NE/kg. There were 9 mixed gender pens per treatment and 24 or 25 pigs per pen. Data were analyzed using generalized linear and nonlinear mixed models with pen as the experimental unit. Competing models included linear, quadratic polynomial (QP), broken-line linear (BLL), and broken-line quadratic (BLQ). Increasing SID Lys concentration improved average daily gain (ADG, linear, P = 0.001) and gain to feed ratio (G:F, quadratic, P = 0.011, Table 1). Although the best fitting model for ADG was the linear, the greatest improvement was observed as SID Lys level increased from 1.13 to 1.32%. The best-fitting models for G:F were BLL, BLQ, and QP. The BLL and BLQ models estimated the breakpoint at 1.31% (95% CI: 1.24 to 1.37%) and 1.30% (95% CI: 1.24 to 1.37%), respectively. The QP model estimated the maximum G:F at 1.44% (95% CI: 1.35 to >1.51%), with 98.7% of maximum G:F achieved at 1.30%. Increasing dietary SID Lys levels marginally reduced removal and mortality rate (linear, P = 0.061). In conclusion, the estimated optimum SID Lys concentration for 11- to 25-kg pigs sired by high index boars ranged from 1.30 to 1.44%, depending on the response criteria and statistical model.

144 Effects of Increasing Dietary Standardized Ileal Digestible Lysine Levels on Growth Performance of 15- to 23-Kg Maternal Barrows

Abstract Our objective was to determine the effects of increasing dietary standardized ileal digestible (SID) lysine (Lys) on growth performance of late nursery pigs. A total of 1,125 barrows (L02 ′ L03, initially 15.4 kg ± 0.003) were used in a 14-d study. Pens of pigs were weighed, blocked by location in the barn, and randomly allotted to 1 of 6 treatments that contained 1.05, 1.16, 1.23, 1.29, 1.39, and 1.52% of dietary SID Lys. Diets were corn-soybean meal-based and contained 3,300 Kcal of ME/kg, with treatments achieved by increasing the inclusion of synthetic lysine. There were 9 pens per treatment and 25 barrows per pen. Data were analyzed using generalized linear and nonlinear mixed models with pen as the experimental unit. Competing models included linear, quadratic polynomial (QP), broken-line linear (BLL), and broken-line quadratic (BLQ). Increasing SID Lys concentration improved average daily gain (ADG; linear, P < 0.05) and gain to feed ratio (G:F; quadratic, P < 0.05). Although no model provided better fit to the ADG data compared with the linear model, the greatest improvement in growth rate was observed as SID Lys increased from 1.05 to 1.41%. The best-fitting models for G:F were QP and BLL. The QP and BLL models estimated the plateau or breakpoint at dietary SID Lys of 1.45% (95% CI: 1.21 to >1.52%) and 1.41% (95% CI: 1.40 to 1.42%), respectively. There was no evidence that increasing dietary SID Lys levels impacted average daily feed intake or the removal and mortality rate (P > 0.10). Increasing SID Lys concentration increased (linear; P < 0.05) the grams of SID Lys intake per kg of gain. In the current trial, the estimated optimum SID Lys concentration for 15- to 23-kg maternal barrows ranged from 1.41 to 1.46%, depending on the statistical model.

157 Effects of Standardized Ileal Digestible Lysine Level on Growth Performance in 75 to 130 Kg DNA Finishing Pigs

Abstract Two studies were conducted to estimate the SID Lys requirement for growth and feed efficiency of 70-130-kg DNA finishing pigs. In Exp. 1, 616 pigs (600×241, DNA; initially 76.4±1.25 kg) were used from 70-100-kg and in Exp. 2, 679 pigs (600×241, DNA; initially 103.8±1.32 kg) were used from 100-130 kg. Pens of pigs were blocked by BW and randomly allotted to dietary treatments with 8-10 pigs/pen in a randomized complete block design. Diets were corn-soybean meal based and SID Lys increased by increasing soybean meal and feed-grade amino acids while maintaining minimum ratios for other amino acids. From 70-100 kg, ADG, G:F, Lys intake/d, and Lys intake/kg of gain all increased, (linear, P < 0.05) with increasing SID Lys. From 100-130 kg, ADG, Lys intake/d, and Lys intake/kg of gain increased (linear, P < 0.05) with increasing SID Lys, while G:F increased (quadratic, P = 0.032). At current ingredient and pig prices, there were no statistical differences in income over feed cost (IOFC) from 70-100 kg. From 100-130 kg, increasing SID Lys increased (quadratic, P = 0.001) IOFC. A broken-line linear (BLL) model predicted optimal ADG at 0.83% SID Lys, while a quadratic polynomial (QP) model predicted a requirement of 0.90% for G:F from 75-100 kg. A QP model predicted maximum IOFC at 0.78% SID Lys from 75-100 kg. From 100-130 kg, BLL models predicted optimal ADG and G:F at 0.64 and 0.59% SID Lys, respectively. A QP model predicted maximum IOFC at 0.64% SID Lys. In summary, these results suggest the optimal SID Lys level for 75-100 kg DNA finishing pigs for growth performance is between 0.83 and 0.90% SID Lys, and 0.78% SID Lys for maximum IOFC. The optimal SID Lys level in 100-130 kg DNA finishing pigs depends upon the response criteria, with growth performance and IOFC maximized between 0.59 and 0.64% SID Lys.

Optimal Standardized Ileal Digestible Total Sulfur Amino Acids to Lysine REQUIREMENTS Are Increased in Nursery Pigs Raised under Antibiotic-Free Feeding Regime.

Simple SummaryTotal sulfur amino acids play a critical role in numerous biological functions, including antioxidative status and immunity, as well as protein synthesis. Weaning pigs commonly face multiple stressors which can impair their gut integrity and growth performance. Antibiotic removal from the diets in weaning pigs can stimulate immune response and divert nutrients from growth to optimize immune function. The objective of the current two studies was to determine the optimal ratio of the standardized ileal digestible (SID) total sulfur amino acid to lysine (TSAA:Lys) in nursery pigs under an antibiotics-free feeding regime. The results demonstrated that the optimal SID TSAA:Lys for nursery pigs raised without antibiotics during the first 21 d post-weaning was 62 to 72% in terms of growth performance, whereas the optimal SID TSAA:Lys was approximately 58% in terms of growth performance in the late nursery phase.This study aimed to investigate the effect of increasing the standardized ileal digestible (SID) total sulfur amino acid to lysine (TSAA:Lys) on the growth performance of nursery pigs raised with or without antibiotics (AGP) and to determine the optimal SID TSAA:Lys in nursery pigs raised without AGP. In Exp. 1, 924 nursery pigs (7.9 ± 1.3 kg), blocked by initial BW and sex, were randomly allotted to one of six treatments, with seven pens per treatment and twenty-two pigs per pen. The treatments were arranged in a 2 × 3 factorial design, with two AGP levels (0 or 50 mg/kg Carbodox) and three levels of SID TSAA:Lys (51.0, 58.5 or 66.0%). In Exp. 2, 990 weaned piglets (5.1 ± 0.9 kg), blocked by initial BW and sex, were randomly allotted to one of five dietary treatments (SID TSAA:Lys at 51, 58, 65, 72 or 79%) in the absence of AGP, with nine pens per treatment and twenty-two pigs per pen. Competing heteroskedastic models including broken-line linear (BLL), broken-line quadratic (BLQ), and quadratic polynomial (QP) were fitted for the growth performance data to estimate the optimal TSAA:Lys. In Exp. 1, AGP supplementation increased (p < 0.05) ADG and ADFI during the 21 d period. Increasing SID TSAA:Lys in the diets with AGP did not affect growth performance; however, increasing SID TSAA:Lys in the diets without AGP resulted in a linear increase (p < 0.05) in ADG and G:F. In Exp. 2, the best-fitting models for ADG and G:F from d 0 to 21 post-weaning were BLL, which yielded the optimal SID TSAA:Lys of 62% and 72%, respectively. The best-fitting models for ADG and G:F from d 21 to 42 post-weaning were BLL, which yielded the optimal SID TSAA:Lys of 59% and 58%, respectively. In conclusion, SID TSAA to Lys requirements under an antibiotic-free feeding regime during the first 21 d post-weaning were 62% and 72% in terms of ADG and G:F, respectively, whereas an SID TSAA:Lys of approximately 58% was required to maximize ADG and G:F for the late nursery phase.

168 Effects of Increasing Dietary Standardized Ileal Digestible Lysine Levels on Growth Performance of 12- to 26-kg Pigs Sired by High Index Boars

Abstract Our objective was to determine the effects of increasing dietary standardized ileal digestible (SID) lysine (Lys) on the growth performance of late nursery pigs. A total of 1,125 pigs (PIC 337×Camborough, initially 12.0±0.66 kg) were used in a 21-d study. The pigs used in the study were sired by boars ranked in the top 15% of a selected PIC elite boar stud based on index. Pens of pigs were blocked by body weight and randomly allotted to 1 of 5 treatments containing 0.95, 1.10, 1.20, 1.35, and 1.50% of SID Lys. Diets were corn-soybean meal-based and contained 2,480 Kcal of NE/kg. Treatments were achieved with increasing feed-grade amino acids. There were 9 mixed gender pens per treatment and 25 pigs per pen. Data were analyzed using generalized linear and nonlinear mixed models with pen as the experimental unit. Competing models included linear, quadratic polynomial (QP), broken-line linear (BLL), and broken-line quadratic (BLQ). Increasing SID Lys concentration improved average daily gain (ADG, linear, P &amp;lt; 0.001) and gain to feed ratio (G:F, quadratic, P = 0.011). The best-fitting models for ADG were QP and BLL. The QP model estimated the maximum ADG at 1.43% (95% CI: 1.12 to &amp;gt;1.50%), with 99% of maximum ADG achieved at 1.27%. The BLL plateau was estimated at 1.31% (95%CI: 1.06 to &amp;gt;1.50%). The best-fitting models for G:F were QP, BLL, and BLQ. The QP model estimated the maximum G:F at 1.48% (95%CI: 1.23 to &amp;gt;1.50%), with 99% of maximum G:F achieved at 1.24%. The BLL plateau was estimated at 1.30% (95% CI: 1.18 to 1.41%), whereas the BLQ plateau was estimated at 1.36% (95%CI: 1.14 to &amp;gt;1.50%). In conclusion, the estimated optimum SID Lys concentration for 12- to 26-kg pigs sired by high index boars ranged from 1.30 to 1.48%, depending on the response criteria and statistical model.

165 Effects of Digestible Lysine Level on Growth Performance and Economics of Grow-finish Pigs

Abstract A total of 2,124 barrows and gilts (PIC 1050′DNA 600, initially 48.9 kg) were used in a 32-d study to determine the optimal dietary standardized ileal digestibility (SID) Lys level in a commercial setting. Pigs were randomly allotted to 1 of 5 dietary treatments with 24 to 27 pigs/pen and 16 replications/treatment. Similar number of barrows and gilts were placed in each pen. Diets were fed over 3 phases (48.9 to 58.6, 58.6 to 70.9, and 70.9 to 80.8 kg respectively). Dietary treatments were corn-soybean meal-based and contained 10 (phase 1 and 2) or 5% (phase 3) distillers dried grains with solubles. Diets were formulated to 85, 95, 103, 110, or 120% of the current Pig Improvement Company (PIC, Hendersonville, TN) SID Lys gilt recommendations with phase 1 SID Lys levels of 0.90, 1.01, 1.09, 1.17 and 1.27%, phase 2 levels of 0.79, 0.87, 0.94, 1.03, and 1.10%, and phase 3 levels of 0.71, 0.78, 0.85, 0.92, and 0.99%, respectively. Dose response curves were evaluated using linear (LM), quadratic polynomial (QP), broken-line linear (BLL), and broken-line quadratic (BLQ) models. For each response variable, the best-fitting model was selected using the Bayesian information criterion. Overall (d 0 to 32), increasing SID Lys increased (linear, P&amp;lt; 0.001) BW, ADG, G:F, Lys intake/d, and Lys intake/kg of gain. Modeling margin over feed cost (MOFC), BLL and QP estimated the requirement at 105.8% and 113.7% respectively. In summary, while growth increased linearly up to 120% of the PIC current feeding level, the optimal MOFC was 106% to 114% depending on the model used.

215 Effects of Increasing Dietary Standardized Ileal Digestible Lysine Levels on Growth Performance of 39- to 119-kg Pigs Sired by High Index Boars

Abstract Our objective was to determine the effects of increasing dietary standardized ileal digestible (SID) lysine (Lys) on the growth performance of grow-finish pigs. A total of 1,120 pigs (PIC 337×Camborough, initially 39.0±0.82 kg) were used in a 77-d study. Pigs used in the study were sired by boars ranked in the top 15% of a selected PIC elite boar stud based on index. Pens of pigs were blocked by body weight and randomly allotted to 1 of 5 treatments, which consisted of 85, 95, 105, 115, and 125% of the PIC2016 SID Lys recommendations within each phase. Diets were corn-soybean meal-based and formulated to be iso-caloric. Treatments were achieved with increasing feed-grade amino acids. There were 9 mixed-gender pens per treatment and 24 or 25 pigs per pen. Data were analyzed using generalized linear and nonlinear mixed models with pen as the experimental unit. Competing models included linear, quadratic polynomial (QP), broken-line linear (BLL), and broken-line quadratic (BLQ). Increasing dietary SID Lys from 85 to 125% marginally improved overall average daily gain (ADG, quadratic, P = 0.056), gain to feed ratio (G:F, quadratic, P = 0.062), and final body weight (linear, P = 0.075). There was no evidence for treatment effects on mortality and removals (P &amp;gt; 0.10). The best-fitting models for ADG were QP and BLL. The QP model estimated the maximum ADG at 110.6% (95% CI: 93 to &amp;gt;125%), with 99% of maximum ADG achieved at 97.4%. The BLL plateau was estimated at 105.0% (95% CI: 74 to 136%). The best-fitting model for G:F was QP, estimating the maximum G:F at 107.8% (95% CI: 92 to &amp;gt;125%). In conclusion, the estimated optimum overall SID Lys for 39- to 119-kg pigs sired by high index boars ranged from 105.0 to 110.6% of PIC2016 SID Lys recommendation within each phase, depending on the response criteria and statistical model.

PSVIII-13 Finishing non-castrated male and female pigs have different response to the lysine to energy ratio

Abstract The aim of the present study was to evaluate the differential effect of the lysine to energy ratio on boars and gilts in the finishing phase. The effect of the standardized ileal digestible Lysine (SID Lys) to net energy (NE) ratio was analyzed in a dose-response study with 780 crossbred finishing pigs (Pietrain x (Landrace x Large White)) with an initial weight of 69.6±8.7 kg. Pigs were distributed in pens of 13 pigs, used as the experimental unit. Each pen was randomly assigned by BW and block to one of the SID Lys:NE levels (2.64, 3.05, 3.46, 3.86 and 4.27 g SID Lys/Mcal NE), with 6 replicates per dietary treatment and sex. Diets were isoenergetic (2,460 kcal NE/kg) and fed for 41 days. Individual carcass composition was measured at the end of the experiment. Statistical analysis to determine the effect of SID Lys:NE consisted on linear and quadratic polynomial contrasts. In addition, broken-line linear (BLL) models were fit when possible. Increasing the SID Lys:NE ratio had a linear (p&amp;lt; 0.001) and quadratic (p=0.020) effect on boars ADG. However, it did not have neither a linear nor quadratic effect on gilts ADG. Regarding FCR, increasing the SID Lys:NE ratio linearly decreased (p&amp;lt; 0.001) and showed a quadratic tendency in boars (p=0.055). For gilts only a linear decrease was reported (p=0.001). In addition, carcass leanness increased linearly on boars (p&amp;lt; 0.001) but not in gilts (p=0.097). Based on BLL modelling, growth of boars was maximized at 3.13 g SID Lys/Mcal NE (95% CI: [2.84, 3.43]) and FCR minimized at 3.95 g SID Lys/Mcal NE (95% CI: [3.46, 4.44]). The results of this experiment confirmed a differential response of boars and gilts to the lysine to energy ratio.

Standardized ileal digestible lysine and valine-to-lysine requirements for optimal performance of 4 to 9-week-old Piétrain cross piglets

Reduction of crude protein (CP) content in swine diets must be associated with an adequate quantitative and qualitative provision of amino acids (AA). In piglet diets, the fifth limiting AA is Val, where deficiency has been proven to reduce feed intake. In addition, depending on the overall level of CP and AA, diets high or low in standardized ileal digestible (SID) Lys will have different branched chain amino acid (BCAA) balances, which may in turn affect the feed intake response. Therefore, two Lys dose response trials (Exp. 1 and 2) were performed to study the influence of different AA concentrations on feed intake and overall performance. CP levels differed between the two experiments (201–210 g/kg in Exp. 1 and 180 g/kg in Exp. 2). Next, one Val dose response (Exp. 3) was carried out to establish the optimal SID Val:Lys ratio for 4 to 9-week-old Piétrain piglets. In Exp. 1, raising dietary SID Lys from 8.50 to 13.50 g/kg resulted in a significant linear and quadratic increase of average daily gain (ADG) and gain to feed (G:F) (P < 0.001 and P < 0.01 respectively), while average daily feed intake (ADFI) showed a linear increase with increasing SID Lys levels (P < 0.001), with a tendency to a quadratic effect (P = 0.08). In Exp. 2, ADG and G:F responded linearly and quadratically to SID Lys levels from 8.50 to 13.50 g/kg (P < 0.001), and ADFI showed a quadratic (P < 0.001) but not linear (P = 0.144) response to increased dietary SID Lys. For Exp. 1, the break points were above the tested SID range. For Exp. 2, quadratic polynomial (QP) and broken line quadratic (BLQ) model for ADG gave an optimal SID Lys of 12.05 and 11.39 g/kg, respectively, the QP ADFI reached an optimum of 11.33 g/kg of SID Lys. For G:F an optimal SID Lys level of 13.23, 11.72, and 13.28 g/kg SID Lys were estimated with a QP, broken line linear (BLL), and BLQ respectively. In Exp. 3, increasing the dietary SID Val:Lys level resulted in a linear and quadratic increase of ADG and ADFI (P < 0.001), but not G:F (P = 0.626 and P = 0.114). For ADG and ADFI it was possible to fit a QP and a BLQ model, with an optimal SID Val:Lys of 0.74 for the QP and 0.68 for the BLQ model, respectively, for the two response variables. In conclusion, SID Lys requirements of 4 to 9-week-old piglets are estimated to be equal or greater than 11.4 g/kg (1.14%), and SID Val:Lys requirements were found to be between 68 and 74% for optimal growth and feed intake.

Interrelationships between sex and dietary lysine on growth performance and carcass composition of finishing boars and gilts.

The main goals of this study were to determine whether boars and gilts respond differently to the standardized ileal digestible lysine to net energy ratio (SID Lys:NE) and model the response to optimize growth performance. A total of 780 finishing pigs, 390 boars and 390 gilts [Pietrain NN × (Landrace × Large White)], with an initial individual body weight of 70.4 ± 9.2 for boars and 68.7 ± 8.0 kg for gilts, were used in a 41-d dose–response experiment. Pens (13 pigs per pen) were randomly allocated to a dietary treatment (2.64, 3.05, 3.46, 3.86, 4.27 g SID Lys/Mcal NE) by block and sex, with six replicates per treatment and sex. Two isoenergetic diets (2,460 kcal NE/kg), representing the extreme SID Lys:NE, were formulated and then mixed. Pigs were individually weighed at days 0, 22, and 41, when the experiment finished. The differential effect of SID Lys:NE on growth performance and carcass composition between sexes was analyzed with orthogonal polynomial contrasts to compare the linear and quadratic trends in each sex. In addition, broken-line linear (BLL) models to optimize average daily gain (ADG), including average daily feed intake (ADFI) as a covariate, were fitted when possible. As expected, boars had a greater ADG and feed efficiency (G:F; P < 0.001) than gilts, but there was no evidence of differences in ADFI (P = 0.470). Increasing SID Lys:NE had a greater linear impact on boars ADG (P = 0.087), G:F (P = 0.003), and carcass leanness (P = 0.032). In contrast, gilts showed a greater linear increase in SID Lys intake per kg gain (P < 0.001) and feed cost per kg gain (P = 0.005). The best fitting BLL models showed that boars maximized ADG at 3.63 g SID Lys/Mcal NE [95% confidence interval (CI): (3.32 to 3.94)], although another model with a similar fit, compared with the Bayesian information criterion, reported the optimum at 4.01 g SID Lys/Mcal NE [95% CI: (3.60, 4.42)]. The optimum to maximize ADG for gilts was estimated at 3.10 g SID Lys/Mcal NE [95% CI: (2.74, 3.47)]. Thus, the present study confirmed that boars and gilts have a different linear response to SID Lys:NE, explained by the greater protein deposition potential of boars. Likewise, BLL models indicated that boars require a higher SID Lys:NE to maximize ADG from 70 to 89 kg. These results suggest that split feeding of finishing boars and gilts could be beneficial in terms of both performance and cost return.

Effects of standardized total tract digestible phosphorus on growth performance of 11- to 23-kg pigs fed diets with or without phytase1,2.

Two experiments were conducted to determine the standardized total tract digestible phosphorus (STTD P) requirement for 11- to 23-kg nursery pigs fed diets with or without phytase. A total of 1,080 and 2,140 pigs (PIC 359 × Camborough, Hendersonville, TN; initially 11.4 ± 0.29 and 11.1 ± 0.24 kg) were used in Exp. 1 and Exp. 2, respectively. There were 23 to 27 pigs per pen with 6 and 12 replicate pens per treatment in Exp. 1 and Exp. 2, respectively. After weaning, pigs were fed a common pelleted diet with 0.45% STTD P for 7 d, and a common phase 2 meal diet with 0.40% STTD P for 14 d in Exp. 1 and 18 d in Exp. 2. Pens of pigs were then allotted to dietary treatments in a randomized complete block design with body weight (BW) as the blocking factor. In Exp. 1, dietary treatments consisted of 0.26%, 0.30%, 0.33%, 0.38%, 0.43%, 0.48%, and 0.53% STTD P. Treatments were achieved with the inclusion of monocalcium phosphate at the expense of corn. In Exp. 2, diets contained 1,000 phytase units (FYT; Ronozyme Hiphos 2500, DSM Nutritional Products, Inc., Parsippany, NJ) with assumed release value 0.132% STTD P, and treatments consisted of 0.30%, 0.33%, 0.38%, 0.43%, 0.48%, 0.53%, and 0.58% STTD P. These STTD P concentrations included the expected phytase release of 0.132% STTD P. In both experiments, a similar 1.17:1 Ca:P ratio was maintained across treatments. Statistical models included linear model (LM), quadratic polynomial (QP), broken-line linear (BLL), and broken-line quadratic (BLQ). In Exp. 1, increasing STTD P increased (linear, P < 0.001) ADG, ADFI, G:F, final BW, and grams of STTD P intake per day and per kilogram of gain. There was also a marginal quadratic response for G:F (P < 0.066). In Exp. 2, ADG and G:F increased quadratically (P < 0.05), whereas ADFI increased linearly (P = 0.060) with increasing STTD P. The BLL and QP model provided similar fit to G:F in Exp. 1, estimating the requirement for maximum G:F at 0.34% and 0.42%, respectively. The BLL was the best fitting model for ADG and G:F in Exp. 2, estimating the breakpoint at 0.40% and 0.37% STTD P, respectively. The BLL and BLQ models estimated the breakpoint for ADG as a function of STTD P intake in grams per day at 2.92 and 3.02 g/d, respectively. These data provide empirical evidence that for 11- to 23-kg pigs, the NRC (2012) accurately estimates the STTD P requirement on a g/d basis. As a percentage of the diet, the STTD P requirement for diets without or with 1,000 FYT added phytase ranged from 0.34% to 0.42%.

171 Standardized total tract digestible phosphorus requirement of 6- to 13-kg pigs fed diets with or without phytase

Abstract A total of 1,080 pigs (initially 5.9 kg) were used to determine the standardized-total-tract-digestible (STTD) P requirements in diets without and with 2,000 units of phytase. Pens (10 pigs/pen, 9 pens/treatment) were balanced for weights and allotted to 12 treatments in two 6-level dose-titrations.The STTD P levels were expressed as percentage of the NRC (2012) requirement (0.45 and 0.40% for phases 1 [d 0–11] and 2 [d 11–25], respectively) and were: 80, 90, 100, 110, 125, and 140% of NRC in diets without phytase and 100, 110, 125, 140, 155, and 170% of NRC in diets with 2,000 units of phytase (assuming 0.158% STTD P released). On d 25, radius samples from 1 gilt/pen were collected for bone ash analysis. Linear and quadratic responses to increasing STTD P were tested using GLIMMIX procedure of SAS and modeled separately for each dose-titration. Increasing STTD P increased ADG (quadratic, P &lt; 0.05), G:F (linear, P &lt; 0.01), and percentage bone ash (linear, P &lt; 0.01) regardless of phytase addition (Table 1). Estimated STTD P requirement in diets without phytase was 117 and 91% of NRC for maximum ADG according to quadratic polynomial (QP) and broken-line linear (BLL) models, respectively, and ranged from 102 to &gt; 140% of NRC for G:F using BLL, broken-line quadratic, and linear models. Estimated P requirement in diets containing phytase was 138% for ADG (QP) and was 147% (QP) and 116% (BLL) of NRC for G:F. Comparing diets containing the same STTD P levels, phytase increased (P &lt; 0.01) ADG and G:F. In conclusion, estimated P requirements varied depending on the response criteria and statistical models. Phytase promoted pig growth and improved the P dose responses for ADG and G:F.

PSIII-2 Optimal ratio of standardized ileal digestible total sulfur amino acid to lysine for 5 to 22 kg pigs under antibiotic-free regime

Abstract The present study aimed to determine the optimal ratio of standardized ileal digestible (SID) total sulfur amino acid (TSAA) to Lys for growth performance in 5 to 22 kg pigs under antibiotic-free regime. Experimental diets were formulated to ensure that lysine was the second limiting AA throughout the experiments. A total of 990 weaning piglets (PIC 337 × 1050, Hendersonville, TN; 5.08 ± 0.86 kg), blocked by initial BW and gender, were randomly allotted to 1 of 5 dietary treatments, with 9 pens per treatment and 22 piglets per pen. Dietary treatments consisted of SID TSAA to Lys ratios of 51%, 58%, 65%, 72% and 79%, with 1.31%, 1.28% and 1.20% SID Lys in phases 1, 2 and 3, respectively. The source of TSAA used in this study was the dry calcium salt of D, L-2-hydroxy-4-(methylthio)butanoic acid (84% Met, MHA®, Novus International, Inc., St. Charles, MO). Data was analyzed using general linear mixed models accounting for heterogeneous residual variances. Competing heteroskedastic models included broken-line linear (BLL), broken-line quadratic (BLQ), and quadratic polynomial (QP). For each response, the best-fitting model was selected using Bayesian information criterion. Results showed that increasing ratios of SID TSAA to Lys linearly (P = 0.01) increased ADG during the entire nursery period. Increasing SID TSAA to Lys ratios tended to increase (P = 0.09) overall ADFI in a quadratic manner. The best-fitting model for overall ADG is BLL in which the maximum ADG was estimated at 60% SID TSAA to Lys ratio, with 95% confidence interval (CI) between 55% and 65%. In conclusion, the optimal ratio of SID TSAA to Lys was 60% for maximum ADG. These results indicate that the NRC (2012) recommendation may underestimate the SID TSAA to Lys requirement for nursery pigs raised under antibiotic-free regime.

Standardized total tract digestible phosphorus requirement of 6 to 13 kg pigs fed diets without or with phytase

Dietary phosphorus concentration greatly affects pig’s growth performance, environmental impact and diet cost. A total of 1080 pigs (initially 5.9 ± 1.08 kg) from three commercial research rooms were used to determine the effects of increasing standardized total tract digestible (STTD) P concentrations in diets without and with phytase on growth performance and percentage bone ash. Pens (10 pigs/pen, 9 pens/treatment) were balanced for equal weights and randomly allotted to 12 treatments. Treatments were arranged in two dose titrations (without or with 2000 units of phytase) with six levels of STTD P each. The STTD P levels were expressed as a percentage of NRC (2012) requirement estimates (% of NRC; 0.45 and 0.40% for phases 1 and 2, respectively) and were: 80%, 90%, 100%, 110%, 125% and 140% of NRC in diets without phytase and 100%, 110%, 125%, 140%, 155% and 170% of NRC in diets with phytase. Diets were provided in three phases, with experimental diets fed during phases 1 (days 0 to 11) and 2 (days 11 to 25), followed by a common diet from days 25 to 46. On day 25, radius samples from one median-weight gilt per pen were collected for analysis of bone ash. During the treatment period, increasing STTD P from 80% to 140% of NRC in diets without phytase improved average daily gain (ADG; quadratic, P < 0.01), average daily feed intake (ADFI; quadratic, P < 0.05) and gain–feed ratio (G : F; linear, P < 0.01). Estimated STTD P requirement in diets without phytase was 117% and 91% of NRC for maximum ADG according to quadratic polynomial (QP) and broken-line linear (BLL) models, respectively, and was 102%, 119% and >140% of NRC for maximum G : F using BLL, broken-line quadratic and linear models, respectively. When diets contained phytase, increasing STTD P from 100% to 170% of NRC improved ADG (quadratic, P < 0.05) and G : F (linear, P < 0.01). Estimated STTD P requirement in diets containing phytase was 138% for maximum ADG (QP), and 147% (QP) and 116% (BLL) of NRC for maximum G : F. Increasing STTD P increased (linear, P < 0.01) the percentage bone ash regardless of phytase addition. When comparing diets containing the same STTD P levels, phytase increased (P < 0.01) ADG, ADFI and G : F. In summary, estimated STTD P requirements varied depending on the response criteria and statistical models and ranged from 91% to >140% of NRC (0.41% to >0.63% of phase 1 diet and 0.36% to >0.56% of phase 2 diet) in diets without phytase, and from 116% to >170% of NRC (0.52% to >0.77% of phase 1 diet and 0.46% to >0.68% of phase 2 diet) for diets containing phytase. Phytase exerted an extra-phosphoric effect on promoting pig’s growth and improved the P dose-responses for ADG and G : F.

Effects of standardized ileal digestible histidine to lysine ratio on growth performance of 7- to 11-kg nursery pigs.

Histidine may be the sixth limiting amino acid (AA) in practical nursery diets supplemented with high amounts of feed-grade AA. Therefore, 2 experiments were conducted to determine the standardized ileal digestible (SID) His:Lys ratio requirement estimate for growth performance of 7- to 11-kg nursery pigs. A total of 360 and 350 pigs (DNA 241 × 600, Columbus, NE; initially 7.1 ± 0.31 and 6.6 ± 0.36 kg) were used in Exp. 1 and 2, respectively. There were 5 pigs per pen with 12 replicates per treatment in Exp. 1 and 10 replicates per treatment in Exp. 2. After weaning, pigs were fed a common pelleted diet for 10 d in Exp. 1 and 7 d in Exp. 2. Then, pens were assigned to treatments in a randomized complete block design with body weight (BW) as the blocking factor. Dietary treatments consisted of SID His:Lys ratios of 24%, 28%, 32%, 36%, 40%, and 44% in Exp. 1 and 24%, 28%, 30%, 32%, 34%, 36%, and 42% in Exp. 2. Experimental diets were fed in pellet form for 10 or 14 d in Exp. 1 and 2, followed by a common mash diet for 15 or 14 d, respectively. Data were analyzed using the GLIMMIX and NLMIXED procedures of SAS, fitting data with heterogeneous variance when needed. The competing statistical models utilized were quadratic polynomial, broken-line linear (BLL), and broken-line quadratic. In Exp. 1, increasing SID His:Lys ratio increased (quadratic, P = 0.001) ADG, ADFI, G:F, and day 10 BW. In Exp. 2, ADG, G:F, and day 14 BW increased (quadratic, P = 0.001), and ADFI increased linearly (P = 0.001) with increasing SID His:Lys ratio. The best-fitting model for all response variables analyzed was the BLL. In Exp. 1, requirement estimates were 29.7%, 29.1%, and 29.8% SID His:Lys ratio for ADG, ADFI, and G:F, respectively. In Exp. 2, the SID His:Lys ratio requirement estimates were 31.0% for ADG and 28.6% for G:F. These results suggest that the SID His requirement estimate for growth performance is no more than 31% of Lys and that the NRC (2012) SID His requirement of 34% of Lys may be overestimated for 7- to 11-kg pigs.