Standardized Ileal Digestible Lysine Research Articles

146 Comparing feeding strategies during heat stress in finishing pigs using a stochastic swine model

Abstract Nutritionists may feed standard diets or increase dietary net energy (NE) and/or standardized ileal digestible lysine (SIDLys) to counter reduced average daily feed intake (ADFI) due to heat stress in the late finishing phase. The objective of this work was to develop a set of statistical tools to analyze different grow-finish feeding strategies using the simulations from a proprietary stochastic swine model (Watson) when heat stress occurs during the last 2 wk of the finishing phase. Financial considerations were excluded from the study. Nutrient recommendations for maximum feed efficiency were derived from Watson and used to formulate a grower diet for 25 to 60 kg body weight (BW), and four finisher diets for 60 to 135 kg BW: a) thermoneutral (10 MJ NE/kg, 7.9 g/kg SIDLys), b) high AA (10 NE/kg, 9.2 g/kg SIDLys), c) high NE (10.5 MJ/kg NE, 7.9 g/kg SIDLys), and d) high NE and high AA (10.5 MJ NE/kg, 8.3 g/kg SIDLys). The grow-finish period was simulated by feeding the grower diet followed by the finisher diets in 5 different scenarios: 1) thermoneutral, diet a; 2) heat stress, diet a; 3) heat stress, diet a, and b during last 2 wk; 4) heat stress, diet a, and c during last 2 wk; 5) heat stress, diet a, and d during last 2 wk. Performance results were obtained by running each scenario 100 times, generating a new population per simulation. Results from scenarios 1) and 2 showed that heat stress in the last 2 wk reduced (P < 0.05) ADFI and average daily gain of pigs fed diet a by 790 g/d and 310 g/d, respectively. This resulted in a decrease of 4.79 kg in final BW, an increase of 0.64% lean yield, and a decrease of 0.80 mm back-fat at slaughter (P < 0.05). An increased dietary SIDLys (3), NE (4), or both (5) during heat stress did not affect BW compared with scenario 2 (P > 0.05). An increased NE (4) or NE and SIDLys (5) did not affect lean yield and back fat compared with scenario 2 (P > 0.1). But increased SIDLys during heat stress (3), increased lean yield (P = 0.04) and a trend in less back fat (P = 0.07) compared with scenario 2. In conclusion, pig performance was reduced with heat stress in the late finishing period. With the developed statistical tools, we determined from the simulations that none of the proposed strategies significantly increased final BW compared with the baseline (2). But feeding greater SIDLys will likely result in significantly greater lean yield and less back fat. When formulating diets with greater nutrient density attention to ingredient cost and pig prices should be considered.

109 Evaluation of net energy, standardized ileal digestible lysine, and soybean meal content interaction in 13 to 25 kg pigs using a central composite design

Abstract Pigs [n = 4,683; 337 × 1050, PIC; initial body weight (BW) = 13.0 ± 0.01 kg] were used in a 21-d trial to investigate the interaction of net energy (NE), standardized ileal digestible lysine (SID Lys), and soybean meal (SBM) content used at five different levels on growth performance of nursey pigs. Pigs were housed in mixed sex pens with 35 pigs per pen and assigned in a randomized complete block design to 15 dietary treatments using a circumscribed central composite design (CCD). Factorial and axial points had 7 repetitions, and the central points had a total of 24. Eight diets were formulated to various levels of NE, SID Lys, and SBM and blended to create the 15 dietary treatments. The NE ranged from 2,334 to 2,762 kcal/kg, SID Lys from 1.08 to 1.52%, and SBM from 25.5 to 35.9%. Diets were corn-soybean meal based and soy hulls and soybean oil were added to reduce or increase NE content of the diet. Feed grade amino acids and SBM were used to adjust SBM and SID Lys content and to maintain SID Thr, Trp, Met, Val, and Ile ratios relative to SID Lys. For NE, a linear effect (P ≤ 0.052) was observed for average daily gain (ADG) and average daily feed intake (ADFI), and linear and quadratic effect was found (P ≤ 0.047) for gain to feed ratio (G:F) with a reduction in growth performance as NE increased due to reduction in SID Lys:calorie. When increasing SID Lys, ADG (P ≤ 0.044) and G:F (P ≤ 0.020) increased quadratically (Table). Increasing SBM content linearly improved ADG (P = 0.039) and G:F (P < 0.001), respectively. There was also a significant interaction between SID Lys and SBM for G:F (P = 0.082), where SID Lys positively impacted G:F as SBM increased in the diet. When including the significant terms, the resulting models can be used to predict the ADG (kg) response = [0.579392 + (-0.0063389 × NE) + (0.0260796 × Lys) + (0.0067428 × SBM%) + (-0.0065721 × Lys²) adjusted R2 = 0.36], and G:F (kg/kg) response = [0.7013215 + (0.0035198 × NE) + (0.0264389 × Lys) + (0.0060863 × SBM%) + (-0.0048012 × NE²) + (-0.0031838 × Lys²) + (-0.0034413 × Lys × SBM) adjusted R2 = 0.65]. In conclusion, using a CCD, increasing SID Lys resulted in a quadratic improvement in ADG and G:F, with this improvement being greater when SBM also increased. Overall, we observed few interactions between SID Lys, SBM, and NE.

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.

29 Effects of using different dietary standardized ileal digestible lysine plans on growth performance and carcass characteristics of PIC 337 or PIC 800 sired grow-finish pigs

Abstract The present study aimed to evaluate the impact of using different dietary standardized ileal digestible (SID) lysine (Lys) plans on growth performance of PIC 337 and PIC 800 sired grow-finish pigs. A total of 2,016 gilts and barrows were placed in 2 separate rooms with 48 single sex pens each (21 pigs/pen; 0.69 m2/pig). Pens were blocked by body weight (BW) and randomly allotted in a 2 × 2 × 2 factorial arrangement with genetic line (PIC 337 or 800), sex (barrows or gilts), and nutrition plan (current SID Lys curve recommendation for PIC 800 as % of PIC 337 SID Lys curve or alternative SID Lys curve) as factors. Pigs (27.4 ± 1.41 kg BW) were followed during the grower-finisher phase until slaughter. Pigs were fed either the current recommendation or an alternative SID Lys curve for PIC 800, in a 5 phase feeding program: phase 1 (23-40 kg; 97 vs 100%, respectively); phase 2 (40-60 kg; 97 vs 95%, respectively); phase 3 (60-80 kg; 97 vs 95%, respectively); phase 4 (80-105 kg; 97 vs 95%, respectively); and phase 5 (105-135 kg; 97 vs 90%, respectively). Pigs were fed isoenergetic diets. Performance and carcass traits, and removals and mortality were recorded. Data were analyzed using mixed models in R, and considering pen as the experimental unit for performance traits and individual carcasses for carcass traits. There was no evidence of interaction between genetic line and nutrition plan factors. Overall, PIC 337 vs 800 pigs did not differ on average daily gain (ADG; P > 0.05), but PIC 337 pigs consumed 150 g/d less and were 0.1 more feed efficient than PIC 800 pigs (P < 0.05; Table 1). Moreover, PIC 337 pigs had 1.9 kg less of hot carcass weight, but 2.1 mm more of loin depth compared with PIC 800 pigs (P < 0.05; Table 1). Regarding nutrition plan, no significant differences were observed for overall performance and carcass traits between pigs fed the current or alternative SID Lys curve (P > 0.05; Table 1). Additionally, no significant differences were observed for overall removals and mortality by genetic line or nutrition plan (P > 0.05; Table 1). In summary, different genetic sire line (PIC 337 and PIC 800) differed on performance and carcass traits. Further research is needed to continue studying the genetic evolution and nutrition plan for each genetic sire line in the grower-finisher period to understand their nutrient requirements.

30 Effects of using different dietary standardized ileal digestible lysine plans on growth performance and carcass characteristics of grow-finish pigs from high or low breeding value boars

Abstract The present study aimed to evaluate the impact of using different dietary standardized ileal digestible (SID) lysine (Lys) plans on growth performance and carcass characteristics of grow-finish pigs coming from high or low breeding value boars. A total of 2,080 pigs (PIC 800 × PIC Camborough) were housed in 20 mixed sex pens (26 pigs/pen), blocked by body weight (BW), and randomly allotted in a 2 × 2 factorial arrangement with boar breeding value (high or low) and nutrition Lys plan (current SID Lys curve recommendation for PIC 800 as % of PIC 337 SID Lys curve or alternative SID Lys curve). Pigs were weaned at 21 d of age (6.1 ± 0.05 kg BW) and followed during the wean-to-finish period until reach the market slaughter weight. Pigs were fed either the current recommendation or an alternative SID Lys curve for PIC 800, in a 6 phase feeding program: phase 1 (6-11 kg; 100 vs 100%, respectively); phase 2 (11-23 kg; 97 vs 100%, respectively); phase 3 (23-45 kg; 97 vs 100%, respectively); phase 4 (45-73 kg; 97 vs 95%, respectively); phase 5 (73-102 kg; 97 vs 95%, respectively); and phase 6 (102-132 kg; 97 vs 90%, respectively). Pigs were fed isoenergetic diets. Performance and carcass traits, and removals and mortality were recorded. Data were analyzed using mixed models in R, and considering pen as the experimental unit for performance traits and individual carcasses for carcass traits. There was no evidence of interaction between boar breeding value and nutrition plan factors. Overall, high breeding value pigs had greater average daily gain (ADG; 0.84 ± 0.005 g/d) compared with low breeding value pigs (0.82 ± 0.005 kg/d; P < 0.01), which was driven by increased average daily feed intake (ADFI; 1.92 ± 0.011 and 1.89 ± 0.011 kg/d, respectively; P < 0.05; Table 1). Moreover, high breeding value pigs had greater hot carcass weight (HCW; 97.8 ± 1.09 kg), carcass yield (74.1 ± 0.23%), backfat thickness (16.3 ± 0.29 mm) and lower lean meat % (57.0 ± 0.21%) compared with low breeding value pigs (96.0 ± 1.09 kg; 73.7 ± 0.23 %; 15.4 ± 0.28; 57.5 ± 0.21%, respectively; P < 0.05; Table 1). Regarding nutrition plan, no significant differences were observed for overall performance traits between pigs fed the current or alternative SID Lys curve (P > 0.05; Table 1). Nevertheless, pigs fed the alternative SID Lys curve had heavier HCW (97.3 ± 1.09 kg) compared with pigs fed the current SID Lys curve (96.6±1.09 kg; P < 0.05; Table 1). No significant differences were observed for overall removals and mortality by breeding value or nutrition Lys plan (P > 0.05). In summary, grow finish pigs from high breeding value boars have an improved productive performance. PIC 800 pigs may achieve the same productive performance with lower lysine levels at the end of the grow-finish period.

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).

26 Effects of increasing net energy or standardized ileal digestible lysine in soybean meal-based diets on early and late finishing pig performance

Abstract A total of 2,265 finishing pigs [337×1050, PIC; initial body weight (BW) = 50.2 kg) were used in two 28-d trials to determine the effect of increasing net energy (NE) or standardized ileal digestible Lys in soybean meal (SBM) based diets on early and late finishing pig performance. There were 27 pigs/pen and 21 pens/treatment. Soybean meal NE value used in diet formulation was either 78% (2,087 kcal/kg) or 100% (2,672 kcal/kg) of corn NE. Four treatment diets were assigned to pens in a completely randomized design and consisted of: 1) high level of SBM estimated at 100% NE of corn (High SBM); 2) low level of SBM estimated at 100% NE of corn with added feed-grade AA (Low SBM); 3) low level of SBM estimated at 78% NE of corn with added fat (Low SBM w/fat) to equal the NE in diets 1 and 2; and 4) low level of SBM estimated at 100% NE of corn with increased feed-grade AA and increased Lys:NE (Low SBM w/AA). Following the early finishing 28-d growth trial (initial BW = 50.2 kg), pigs were fed a common diet for 30-d and pens were randomly reallotted to 1 of the same 4 treatments for the late finishing trial (initial BW 114.1 kg). In early finishing, there were no differences (P > 0.10) in average daily gain (ADG), but pigs fed Low SBM w/AA had increased (P < 0.05) average daily feed intake (ADFI) compared with pigs fed High SBM (Table). The increased ADFI without increased ADG resulted in decreased (P < 0.05) gain to feed ratio (G:F) in pigs fed Low SBM w/AA compared with pigs fed Low SBM w/fat. Pigs fed Low SBM w/fat had improved (P < 0.05) caloric efficiency (CE) compared with pigs fed Low SBM w/AA. In late finishing, there was a tendency (P = 0.099) for a treatment effect on G:F where pigs fed High SBM had the greatest G:F, but there was not a significant difference (P > 0.05) between any two treatments when using a Tukey multiple comparison adjustment. There was no evidence (P > 0.10) for a difference between treatments on ADG, ADFI, or CE. Based on the performance of pigs fed the Low SBM w/AA diet, the decreased growth performance of low SBM diets is not due to a low Lys:Calorie ratio that results when NE is underestimated. Using caloric efficiency, an estimate of the NE of SBM was calculated by adjusting NE of SBM used in formulation until CE for the High SBM and Low SBM treatments were equal. These results showed SBM was estimated to contain 94% the NE of corn in the early finishing period and 125% the NE of corn in the late finishing period.

14 Effects of increasing daily dietary standardized ileal digestible lysine intake of gilts and sows during d 35 to 112 of gestation on reproductive performance

Abstract Our objective was to determine the effects of increasing daily dietary standardized ileal digestible (SID) lysine (Lys) intake during d 35 to 112 of gestation on sow and litter performance. A total of 704 gilts and sows (PIC Camborough) were used. Females were group-housed after d 35 of gestation and individually fed with electronic sow feeders (ESF). At d 35 of gestation, females were balanced for body weight (BW) and caliper scores within parity categories, and randomly allotted to 1 of 4 treatments. Treatments consisted of increasing daily dietary SID Lys intake (11.1, 13.5, 16.1, and 18.5 g/d). Both gilts and sows received 2.37 kg/d of a gestation diet containing 3.17 Mcal of ME/kg, which was estimated to avoid feeding females below their maintenance requirements throughout the entire gestation. Treatments were achieved by different blend of low (0.47% SID Lys) and high (0.78% SID Lys) Lys diets via ESF based on the set feed allowance for females. Sow was the experimental unit and data were analyzed using generalized linear mixed models with the lmer and glmerfunctions of R, considering treatment, parity, and their interaction as fixed effects. There was no evidence (P > 0.10) of treatment and parity interaction for any response criteria. Body weight at d 112 of gestation and BW change from d 35 to 112 of gestation increased (linear; P < 0.05) with increasing daily dietary SID Lys intake (Table 1). No evidence for SID Lys treatment differences were observed for BW at weaning or BW change during lactation (P > 0.10). There was no evidence (P > 0.10) for treatment differences on caliper score (CS) at d 35 of gestation, d 112 of gestation, at weaning, or CS changes during gestation and lactation. There was no evidence for treatment difference on total born, percentage stillbirth and percentage of mummified fetuses (P > 0.10). However, there was a marginal reduction in percentage born alive piglets (quadratic, P = 0.056), with the least proportion of piglets born alive observed in females receiving 16.1g of daily SID Lys intake from d35 to d112 of gestation. Increasing daily dietary SID Lys intake during d 35 to 112 of gestation did not affect piglet birth weight, piglet average daily gain during lactation, proportion of removed pigs, and proportion of dead pigs during lactation. In summary, increasing daily dietary SID Lys intake during d35-to-112 of gestation increased female BW; however, no evidence of benefits was observed for female reproductive performance and litter performance during lactation.

11 The effect of increased standardized ileal digestible lysine through increased soybean meal during late gestation on lactating sow and litter performance

Abstract A total of 87 sows (Line 241, DNA) and their offspring were used to evaluate the effect of increasing standardized ileal digestible (SID) lysine through increasing soybean meal (SBM) concentration in late gestation diets on lactating sow and litter performance. Sows were blocked by parity and body weight (BW) on approximately d 90 of gestation and allotted to 1 of 3 treatments with 29 replications per treatment. Diets included increasing SID lysine (0.60, 0.80, or 1.00%) through increased SBM (14, 21, or 29% of the diet). Sows received approximately 2.04 kg/d of their treatment diet for an average SID Lys intake of 11.9, 15.8, or 19.9 g/d, respectively. Diets were fed from d 90 of gestation until farrowing. After farrowing, all females were fed a common lactation diet containing 1.10% SID Lys until weaning (19 d post-farrow). Sow BW, caliper score, and backfat and loin depth were collected on d 90, upon entry into the farrowing house (d 110), and at weaning. Urine samples were collected on d 90 and 110 of gestation to ascertain urinary creatinine concentrations. Litters were cross-fostered within sow treatment by 48 h after farrowing to equalize litter size. Parity was included in the statistical model as a fixed effect with females being classified as either a primiparous (n = 35) or multiparous (n = 52) sow. Body weight gain from d 90 to 110 of gestation increased as SID Lys increased (linear, P < 0.001; Table). There were no differences in starting litter size or piglet birth weight with increasing SID Lys in late gestation (linear, P > 0.10). Change in urinary creatinine level from d 90 to 110 of gestation tended to decrease as SID Lys increased in the diet (linear, P = 0.063) suggesting that less muscle catabolism occurred with increasing SID Lys. Piglet average daily gain (ADG) from d 2 to 10 of lactation linearly increased as SID Lys increased (P = 0.017), but not from d 2 to weaning. From d 2 until weaning, litters from sows fed the 0.80% SID Lys gestation diet had the greatest litter gain (quadratic, P = 0.044). Pre-weaning mortality from birth until d 2 of lactation was greatest for sows fed 0.80% SID Lys (quadratic, P = 0.025). There was a parity × gestation diet interaction for pre-weaning mortality from d 2 to weaning (P = 0.049) where mortality increased as SID Lys increased in primiparous sows but decreased in multiparous sows. In conclusion, increased SID Lys through increased SBM linearly increased late gestation sow BW gain and piglet ADG during the first portion of lactation. However, litters from sows on the 0.80% SID Lys treatment exhibited the highest litter ADG during late lactation and overall.

25 Effects of dietary standardized ileal digestible lysine on growth performance, carcass characteristics, and economics of pigs from 100 to 130 kg

Abstract A total of 1,570 finishing pigs (337 × 1050, PIC; initially 103.4 ± 0.85 kg) were used in a 28-d trial to determine the effects of feeding increasing standardized ileal digestible (SID) Lys to pigs between 100 to 130 kg on growth performance, carcass characteristics, and economics. Before the beginning of the study, the 3 heaviest pigs per pen were removed and marketed with all remaining pigs marketed 28-d later at the end of the study. Pigs were housed in mixed sex pens, with 20 pigs per pen and 20 pens per treatment. The experiment was a randomized complete block design with four dietary treatments: 0.63, 0.68, 0.75, and 0.82% SID Lys. Diets were corn-soybean meal-based and fed in meal form. Dietary treatments were similar in NE and increasing SID Lys was achieved by increasing soybean meal and feed grade amino acids. For the first 14 d from 100 to approximately 118 kg, there was a linear tendency for increased (P = 0.074) average daily gain (ADG), a linear improvement (P < 0.05) in gain to feed ratio (G:F), and increase (P < 0.001) in SID lysine intake per kg of gain as SID Lys increased (Table). For the second 14 d from 118 to 128 kg, SID Lys intake per kg of gain increased (P < 0.001) as SID Lys increased, however; there was no evidence for difference (P > 0.10) for any growth performance traits. Overall, there was a linear increase (P = 0.018) in G:F and increase (P < 0.001) in SID lysine intake per kg of gain as SID Lys increased. Increasing SID Lys also linearly increased (P < 0.05) percentage lean and decreased (P < 0.05) backfat depth with no evidence for differences (P > 0.10) in other carcass criteria. For economics, feed cost and feed cost per kg of gain linearly increased (P < 0.05) as SID Lys increased in both low and high-price scenarios. Income over feed cost linearly decreased (P < 0.05) as dietary SID Lys increased in a low-price scenario, but there was no difference between treatments in a high-price scenario (P > 0.10). In conclusion, increasing dietary SID lysine in the last 28-d of the finisher period linearly increased G:F and SID Lys intake per kg of gain without significantly influencing other growth performance traits. Feed cost per kg of gain was linearly increased for both low and high-price scenarios with a detriment for IOFC with increasing SID Lys in the low-price scenario.

19 Evaluation of precision feeding standardized ileal digestible lysine to meet the requirements of lactating sows

Abstract Two experiments evaluated the effects of precision feeding lactating sows. In both experiments, sows were blocked by parity and allotted to treatment on d 2 of lactation. The first experiment included a total of 95 mixed parity sows and litters. Treatments included a control, NRC (2012), or INRA (2009) treatment curve. Sows on the NRC or INRA treatment curves received a blend of a low (0.25% SID Lys) and high (1.10% SID Lys) Lys diet using the Gestal Quattro Opti Feeder (Jyga Technologies, St-Lambert-de-Lauzon, Quebec, Canada) to target specific SID Lys intake/d based on parity and litter size according to NRC and INRA models. Control sows received only the high Lys diet. Blend of the high and low Lys diets were adjusted every 2 d based on actual Lys intake to more closely meet target Lys intake (NRC and INRA curves). Control sows had greater (P < 0.05) average Lys intake (76.7 g/d) compared with sows fed either NRC (53.1 g/d) or INRA (42.8 g/d) curves (Table). Pigs from sows fed the high Lys diet had greater (P < 0.05) body weight at weaning and average daily gain (ADG) compared with pigs from sows fed INRA treatment, with NRC curve fed sows intermediate. Nitrogen excretion, estimated from NRC equations, was greatest (P < 0.05) in sows fed the high Lys diet, followed by sows fed the NRC curve, and INRA curve sows the least. In Exp. 2, 56 mixed parity sows and litters were used. Treatments included a control where sows were provided a high Lys (1.10% SID Lys) diet and two treatments where sows were fed either a static or dynamic blend of a low (0.40 % SID Lys) and high Lys diet to target a specific SID Lys intake/d based on parity and litter size. The dynamic curve blend was adjusted based on actual Lys intake every 2 d to reach target Lys intake while the static curve was not adjusted. Lysine intake curves were based on the NRC (2012), but targets were increased by 20% to reach an average Lys intake of 60 g/d across parities. Control sows had greater Lys intake (P < 0.05; 77.7 g/d) compared with sows fed the blend curves, with no differences between the two blend curves (P > 0.05; 60.1 vs. 59.7 g/d). There were no differences (P > 0.05) observed in litter size, piglet or litter weight at weaning, or ADG. Estimated nitrogen excretion was greater (P < 0.05) for sows on the control diet compared with both blend curves. These data would suggest that 60 g/d of SID Lys is sufficient to maximize litter weight gain for litter sizes of 13.5 weaned piglets. Overall, feed blending can be used to decrease N excretion while achieving similar performance compared with feeding a standard high Lys diet.

23 The effects of dietary net energy level on grow-finish performance and carcass characteristics of intact male market pigs managed with Improvest

Abstract Improvest is a gonadotropin releasing factor (GnRF) analogue-diphtheria toxoid conjugate product approved for temporary suppression of testicular function and reduction of boar taint in intact male pigs (Zoetis Canada Inc.). Objectives for this study were to determine the effects of dietary net energy (NE) level during the grow-finish period on live performance and carcass characteristics of intact male pigs managed with Improvest/immunological castration (IC) when compared with physically castrated (PC) male pigs. The 101-d study began when 1,008 pigs (504 intact male pigs and 504 PC male pigs; 10 wk old) were allocated by body weight to 48 pens with 21 intact males or 21 PC males per pen. Three dietary NE treatments were fed to pigs using five dietary phases to provide an average of 2,212 kcal/kg (Low NE), 2,337 kcal/kg (Medium NE), or 2,462 kcal/kg (High NE). Dietary programs were formulated according to standardized ileal digestible lysine requirements of IC males or PC males. The experiment was designed and analyzed as a 2 × 3 factorial with main effects of Improvest management and NE. For the overall study period, there were no significant interactions between Improvest management and NE (P ≥ 0.19) for average daily feed intake (ADFI), average daily gain (ADG), or gain to feed ratio (G:F; Table). There were also no significant interactions between Improvest management and NE (P ≥ 0.06) for carcass characteristics. Immunologically castrated male pigs consumed less feed (5.3% less ADFI; P < 0.01), grew faster (5.1% greater ADG; P < 0.01), and were more efficient (11.2% greater G:F; P < 0.01) compared with PC male pigs. Hot carcass weight (HCW) did not differ (P = 0.16) between IC males and PC males (attributed to 1.6 percentage unit less dressing percentage for IC males; P < 0.01); however, IC males were leaner (0.9 mm less backfat and 0.65% greater predicted lean yield; P < 0.01) compared with PC males. For the overall study period, pigs fed Low NE and Medium NE diets consumed more feed than pigs fed High NE diets, and pigs fed Low NE diets grew slower than pigs fed Medium NE and High NE diets. This resulted in pigs fed Low NE diets having 4.4% less G:F than pigs fed Medium NE and 8.6% less G:F than pigs fed High NE diets (P < 0.01). Pigs fed Low NE had 3.0 kg lighter (P < 0.01) HCW compared with Medium NE, while High NE had intermediate HCW that did not differ from the other two treatments. Overall, typical Improvest response levels were sustained for each of the NE treatments in this study; however, consideration should be provided to the known production impacts of low NE diets when male market pigs are managed with Improvest.

28 Investigation of protein deposition pattern of PIC337×Camborough commercial pigs

Abstract The objective of the trial was to investigate the protein deposition pattern of PIC337×Camborough commercial pigs. A total of 1,064 barrows and gilts [PIC337×Camborough, initial body weight (BW) = 6.0 ± 0.1 kg] were used in the trial with 38 mixed sex pens, 28 pigs per pen. At the beginning of the trial, the lightest 10% of the barrows and gilts were selected and placed in four pens (equal numbers of barrows and gilts within a pen), and the remaining pigs were randomly placed into the other pens (equal numbers of barrows and gilts within a pen). A common 6-phase corn-soybean based wean-to-finish diets were fed throughout the trial. Dietary net energy and standardized ileal digestible lysine levels were (6-10 kg BW: 2,600 Kcal/kg and 1.35%; 10-20 kg BW: 2,520 Kcal/kg and 1.30%; 20-38 kg BW: 2,470 Kcal/kg and 1.20%; 38-72 kg BW: 2,450 Kcal/kg and 0.98%; 72-127 kg BW: 2,450 Kcal/kg and 0.87%; and 127-149 kg BW: 2,450 Kcal/kg and 0.77%). On d 97 after placement, 5 barrows and 5 gilts with BW close to pen average were selected for individual BW by a portable scale and 10th rib backfat and loin depth measurements (ExaGo portable ultrasound scanner, Imv imaging, UK). Then on d 111, 117, 136, 142, and 167 after placement, the same 5 barrows and 5 gilts were measured for individual BW, 10th rib backfat and loin depth. The fat-free lean mass is estimated by the equation 6.783-0.6198×(10th rib backfat depth, mm)+0.1578×(10th rib loin depth, mm)+1.0362×(warm carcass weight, kg). A constant carcass yield of 75% was used to estimate warm carcass weight. Data were analyzed using a linear mixed model in R Studio (Version 3.5.2, R Core Team; Vienna, Austria). The average BW of pigs at the 6 measurements were: 77.2, 92.4, 99.2, 122.5, 128.0, and 153.6 kg, respectively. The average daily gain (ADG) was 1,139, 1,155, 1,145, 1,126, and 977 g/d for 77.2 to 92.4 kg BW, 92.4 to 99.2 kg BW, 99.2 to 122.5 kg BW, 122.5 to 128.0 kg BW, and 128.0 to 153.6 kg BW, respectively. The average daily 10th rib backfat depth gain was 0.05, 0.08, 0.15, 0.17, and 0.20 mm/d. The average daily 10th rib loin depth gain was 0.42, 0.43, 0.41, 0.39, and 0.23 mm/d. The average daily fat-free lean mass gain (ADFFLG) was 547, 551, 528, 515, and 422 g/d. The fitted quadratic model for ADG is 83.57782 + 19.90632 × (BW, kg)-0.09176×(BW, kg)2, and the calculated maximum ADG was 1,163 g/d when BW was 108.5 kg. The fitted quadratic model for ADFFLG is 85.90926 + 9.23773 × (BW, kg) - 0.04591 × (BW, kg)2, and the calculated maximum ADFFLG is 550.6 g/d when BW was 100.6 kg. Under the conditions of the current trial, PIC337×Camborough pigs reaches the maximum rate of protein deposition at BW between 100.6 and 108.5 kg.

18 Effect of precision feeding standardized ileal digestible lysine to lactating sows compared with conventional feeding strategies in a commercial farm

Abstract A total of 728 sows and litters were used in a 19-d lactation study to evaluate effects of precision feeding SID Lys and other amino acids on sow and litter performance and feed cost in a commercial farm. Sows were blocked by parity and allotted to 1 of 2 treatments at entry into farrowing. Treatments consisted of a control diet or a feed blending curve. Two diets were used to create treatment curves, a low Lys diet (0.60% SID Lys) or a high Lys diet (1.07% SID Lys). Sows on the control treatment were fed only the high Lys diet and sows on the blend curve were fed a blend of the low and high Lys diets using the Gestal Quattro Opti Feeder (Jyga Technologies, St-Lambert-de-Lauzon, Quebec, Canada) to target a specific Lys intake/d. Lysine intake targets were based on the NRC (2012) model requirements, except targets were increased by 20% to reach average Lys intake of approximately 63 g/d. The blend of the low and high Lys diet was adjusted on d 7 and 14 for sows fed the blend curve in an attempt to reach target Lys intake. Average Lys intake was 87% of target Lys intake because feed intake was lower than predicted. Sows fed the control diet had greater (P < 0.001; 72.0 vs 54.8 g/d) Lys intake compared with sows on blend curves because they were fed only the high Lys diet (Table). No differences (P > 0.05) in body weight (BW), backfat, loin depth, caliper score, or average daily feed intake (ADFI) were observed. There were no differences (P > 0.05) in litter size at d 2 after equalization or weaning; however, piglets and litters from sows fed the control treatment tended to have greater weaning weights (P = 0.090) and average daily gain (ADG; P = 0.071) compared with piglets and litters from sows fed the blend curve, likely due to insufficient Lys intake for sows on the blend curve to maximize litter growth performance. Feed cost per sow was less (P < 0.05) for sows fed the blend curve in both a low and high ingredient price scenario. No differences (P > 0.05) in feed cost per kg of litter weight gain were observed; however, feed cost per weaned pig was less (P < 0.05) for sows on the blend treatment. Serum urea nitrogen was greater (P < 0.05) at weaning compared with d 10 for control fed sows and was greater (P < 0.05) than blend-fed sows at both time points. Sows fed the control diet had greater milk crude protein (P = 0.05) compared with sows fed the blend curve. While precision feeding sows using diet blending during lactation can be used to reduce feed cost, future research should focus on using technology to automatically adjust diet blend for low or high-feed intake sows to avoid the over or under-feeding of nutrients.

279 Effect of multiple feed additives on sow inflammatory status and reproductive performance during lactation

Abstract Low grade inflammation and insulin resistance were associated with increased gut permeability in lactating sows during the farrowing transition period. The objective of the present study is to investigate the effect of 4 feed additives including monolaurin, essential oil (Cinergy FIT 3S), phytogenic prototype 1 (PT1) and 2 (PT2) on sow inflammatory status and reproductive performance. It was hypothesized that the active components in these additives will reduce sow inflammation during lactation and lead to better sow reproductive performance. A randomized block design with 5 treatments was used in the study. A total of 550 gestating sows were enrolled with entry body weight of 240.1 ± 14.6 kg and allotted to one of the following five diets: Control; monolaurin; Cinergy; PT1 and PT2. Corn-soy based lactation diet was formulated with CP of 18%. All diets were formulated to be at similar net energy and standardized ileal digestible Lysine level. Experimental diets were fed beginning approximately 4 d before farrowing and throughout the entire lactation phase (21 d). Blood was collected from 16 sows per treatment before farrowing and within 5 d post farrowing to measure inflammatory cytokine concentrations. Performance data were analyzed using a general linear model in R (version 4.0.0). Count data were analyzed using a generalized linear model with a binomial distribution. Dietary treatments did not impact average daily feed intake. Dietary treatment did not affect probability of still born or number of weaned pigs, but diet supplemented with PT1 resulted in greater (P < 0.05) probability of born alive compared with the control (Table 1). There was a tendency (P < 0.10) in treatment effect on pre-weaning mortality, with sows received PT2 supplemented diet having lowest value numerically. The concentration of cytokines IL-1α (P < 0.05), IL-1β (P < 0.01), IL-4 (P < 0.01), IL-6 (P < 0.10) and IL-10 (P < 0.10) were reduced between pre and post farrowing to a greater extent in sows fed Cinergy supplemented diet compared with the control. In conclusion, Cinergy worked best in reducing multiple inflammatory cytokine concentrations post-farrowing. Sows received PT1 supplemented diet had greater born alive and those received PT2 supplemented diet had numerically least pre-weaning mortality.

141 Determination of the optimum standardized ileal digestible lysine for nursery pigs fed high levels of dietary fiber

Abstract An experiment was conducted to determine the optimum standardized ileal digestible (SID) Lys for nursery swine-fed high levels of dietary fiber. A total of 2,525 pigs [PIC 337 × 1050, initial body weight (BW) = 6.5 kg], placed in pens of 36 mixed-sex pigs, were used in a 42-d trial. Pigs were allotted to 1 of 5 dietary treatments with 14 replicates per treatment. Increasing dietary SID Lys concentrations of 1.14, 1.22, 1.30, 1.38, and 1.45% were obtained by blending the 1.14% and the 1.45% SID Lys diets via Big Dutchman DryExact Pro feeding system (Big Dutchman, Holland, MI). The different SID Lys levels were obtained by changing the inclusion rate of soybean meal, which ranged from 15 to 28%. The experimental diets contained sugar beet pulp and soy hulls, resulting in an NDF level of 10.5%. Experimental diets were fed for 17 d and followed by a common corn, soybean meal, and 10% DDGS diet with 1.30% SID Lys from d 17 to 42. Pigs were weighed on d 0, 17, and 42 to calculate average daily gain (ADG), average daily feed intake (ADFI) and gain to feed ratio (G:F). From d 0 to 17, a quadratic (P < 0.05) improvement in ADG and ADFI was observed for pigs fed increasing SID Lys up to 1.38%, plateauing thereafter. Pigs fed increasing SID Lys had linearly (P = 0.001) improved G:F (Table 1). From d 17 to 42, there was no evidence (P > 0.10) for differences in ADG, yet ADFI increased linearly (P = 0.004) while G:F decreased linearly (P = 0.001) for pigs previously fed increasing concentrations of SID Lys. Overall (d 0 to 42) for pigs fed increasing SID Lys, ADG and ADFI increased quadratically (P < 0.05) up to 1.38% SID Lys, whereas G:F increased linearly (P = 0.001) up to 1.45% SID Lys. Mortality and removal rate was quadratically influenced (P < 0.05) by feeding increasing SID Lys. Our findings suggest feeding weaned pigs from d 0 to 17 a diet containing 1.38% SID Lys is optimal for growth performance while minimizing mortality and removal rate.

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 < 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 < 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.

17 Effect of branched-chain amino acids on lactating sow and piglet performance

Abstract Sows (n = 360 PIC 1050 and Genesus) were used to investigate the effect of various branched-chain amino acid (BCAA) levels on sow lactation and litter growth performance. Upon entering the farrowing room, sows were blocked by parity group (P0, P2, P3+) and randomly assigned to one of six dietary treatments containing various levels of BCAA. Experimental diets were formulated to various standardized ileal digestible (SID) leucine, isoleucine, and valine levels by replacing cornstarch with L-leucine, L-isoleucine, and L-valine. Levels of the BCAA were expressed as ratios to SID lysine and were formulated at 114 or 180 for Leu, 56 or 64 for Ile, and 64 or 120 for Val. Diets were formulated to be isocaloric (3.23 Mcal ME/kg) and met or exceeded all other NRC (2012) essential amino acid and vitamin and mineral recommendations. Sow body weight (BW), backfat, and body condition score were recorded at the time of entry into the farrowing room and at the time of weaning. Piglet litter weights were recorded after cross-fostering and at weaning to determine litter growth rate. Data were analyzed using generalized linear mixed models with fixed effects of dietary treatment and parity group and a random effect of lactation group. The models were fit using R version 4.3.1 (R Core Team, 2023). The sow and her litter were the experimental unit, and results were considered significant if P ≤ 0.05 and a tendency if 0.05 < P ≤ 0.10. Sows nursed piglets for 21.3 d (P = 0.998). The mean parity by treatment ranged from 3.8 to 3.9 (P = 0.999). After farrowing, the mean estimated sow BW was 219 kg, with a range between treatments of 216 to 221 kg (P = 0.651). On average, sows gained 2.82% of their BW (P = 0.696) with an average daily feed intake (ADFI) of 8.75 kg/d (P = 0.932). However, as expected, sow Leu, Ile, Val, and total BCAA intakes were different across treatments (P ≤ 0.001). Sows entered the farrowing house with an average of 11.50 mm of backfat (P = 0.919) and lost 6.04% backfat through lactation (P = 0.667). Sows started the trial with an average of 14.1 piglets/sow (P = 0.967) and weaned 12.6 piglets per sow (P = 0.981) with a piglet average daily gain of 0.22 kg/d (P = 0.193) and a daily litter growth rate of 2.89 kg/d (P = 0.291). In conclusion, there was no evidence of an effect of the various leucine, isoleucine, and valine levels evaluated in this study on lactating sow and piglet performance.

Use of a precision feeding program during gestation improves the performance of high-producing sows

Current gestating sow feeding strategies are based on using a single diet regardless of parity or gestation stage. Precision feeding (PF) of the individual sows allows dynamic changes in amino acid and energy requirements throughout gestation. The hypothesis of the study was that meeting the daily predicted amino acid and energy demands of gestating sows using a mathematical model and automatic precision feeder to establish the nutrition programs, would improve reproductive and productive performance compared to conventional feeding programs. Seventy-five mixed-parity sows were distributed among 3 treatments. A treatment managed as flat curve (FLAT: 2.1 kg/d, 1 – 110 d), a high-low-high curve (HLH: 2.2 kg/d, 1 – 49 d; 2.0 kg/d, 50 – 84 d; 2.6 kg/d, 85 – 110 d), where sows received the same diet with 3.2 Mcal/kg of metabolizable energy (ME) and 0.7 g/kg of standardized ileal digestible (SID) lysine. For the PF treatment, feeding level and blend of 2 basal diets (3.0 Mcal/kg of ME; 8.0 and 2.0 g/kg of SID lysine for high and low lysine, respectively) was adjusted daily for each sow to accurately meet estimated amino acid and energy requirements based on live weight, gestation stage and parity. Sows fed PF were heavier on d 110 of gestation (P = 0.011) and tended to increase total number of born (P = 0.092) and born alive (P = 0.077). Sows fed PF showed a higher litter weight (P = 0.003) at birth, lower lactation feed intake (P = 0.010), higher milk yield (P = 0.043) and a larger litter size (P = 0.050). Precision feeding sows also presented an improved maternal transformation index (P = 0.013) when compared to HLH and FLAT. In conclusion, our results demonstrate that the application of PF strategies based on daily nutrient adjustments is highly beneficial for high-producing sows to support the dynamic needs for nutrient availability for the sow´s body growth, mammary gland and fetal development.

Effects of dietary protein level on intestinal function and inflammation in nursery pigs.

High crude protein (CP; 21% to 26%) diets fed during the first 21 to 28 d postweaning are viewed negatively because of a perceived increase in the incidence rates of diarrhea due to increased intestinal protein fermentation and/or augmented enteric pathogen burden. This is thought to antagonize nursery pig health and growth performance. Therefore, our objective was to evaluate the impact of low vs. high dietary CP on 21-day postweaned pig intestinal function. Analyzed parameters included ex vivo intestinal barrier integrity (ileum and colon), ileal nutrient transport, tissue inflammation, and fecal DM. One hundred and twenty gilts and barrows (average body weight) were randomly assigned to one of two diets postweaning. Diets were fed for 21 d, in two phases. Phase 1 diets: low CP (17%) with a 1.4% standardized ileal digestible (SID) Lys (LCP), or high CP (24%) with a 1.4% SID Lysine (HCP). Phase 2: LCP (17%) and a 1.35% SID lysine, or HCP (24%) formulated to a 1.35% SID lysine. Pig growth rates, feed intakes, and fecal consistency did not differ (P > 0.05) due to dietary treatment. Six animals per treatment were euthanized for additional analyses. There were no differences in colonic epithelial barrier function as measured by transepithelial electrical resistance (TER) and fluorescein isothiocyanate (FITC)-dextran transport between treatments (P > 0.05). Interleukins (IL)-1α, IL-1β, IL-1ra, IL-2 IL-4, IL-6, and IL-12 were not different between treatments (P > 0.05). However, IL-8 and IL-18 were higher in HCP- vs. LCP-fed pigs (P < 0.05). There were no differences in fecal dry matter (DM; P > 0.05) between treatments. In the ileum, there was a tendency (P = 0.06) for TER to be higher in HCP-fed pigs, suggesting a more robust barrier. Interestingly, glucose and glutamine transport were decreased in HCP- vs. LCP-fed pigs (P < 0.05). FITC-dextran transport was not different between treatments (P > 0.05). There were also no differences in ileal cytokine concentrations between diets (P > 0.05). Taken together, the data show that low CP does not negatively impact colonic barrier function, fecal DM, or inflammation. In contrast, ileal barrier function and nutrient transport were altered, suggesting a regional effect of diet on overall intestinal function.