Dietary Standardized Ileal Digestible Research Articles

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

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

Lysine requirement of weaned piglets

Lysine, often referred to as the ‘first limiting amino acid’ in pig nutrition, plays a pivotal role in growth performance. Variability in lysine requirements arises due to factors such as age, sex and environmental conditions. Optimising pig health and production efficiency and minimising nitrogen excretion require accurate knowledge of estimated lysine requirements accounting for factors such as genetics, feeding practices, scientific advancements, and environmental considerations. This study aimed to determine standardised ileal digestible (SID) lysine requirements of weaned piglets (5–30 kg) based on a literature review using meta-analytical approaches. The literature review yielded 344 studies that were screened for title and abstract. In total, 41 experiments met the inclusion criteria, resulting in a dataset of 206 treatment means. Linear, quadratic and linear-plateau models were used to gain insight into the effect of SID lysine addition on average daily gain and feed efficiency for the combined dataset and separately for the individual experiments. Regression analysis showed a predominant linear increase in average daily gain and feed efficiency as an overall response to increasing lysine levels across both the combined dataset and individual experiments. Breakpoint estimation from the linear-plateau models was inconclusive, indicating that the optimal SID lysine requirement to maximise piglet growth performance likely exceeded the upper lysine levels tested in most studies, thus surpassing 1.3 g SID lysine per MJ net energy. This review indicates high values for the lysine requirement to achieve maximum growth performance. Results may suggest that piglet feed formulation should focus on an optimal dietary SID lysine to CP ratio, rather than SID lysine per kg of diet or unit of net energy. However, more research is needed to investigate this suggestion.

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.

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.

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.

274 Socialization of piglets during suckling enhanced feed intake after weaning but did not alter their response to dietary amino acid concentration

Abstract The present study hypothesized that pre-weaning socialized piglets would reduce damaging behavior and when fed an increased dietary standardized ileal digestible (SID) Lys (and amino acids) to net energy (NE) ratio post-weaning would increase early post weaning feed intake (FI) and growth performance, and in nursery pigs. Socializing included two groups of five sows and their litters for which farrowing pen walls were removed allowing piglets to co-mingle for 10 d before weaning (S) whereas traditionally housed piglets pertained to housing a single sow with her litter (T; n = 15). At weaning, 120 mixed-gender piglets [7.2 ± 0.7 kg body weight (BW)] were allocated based on litter origin, sow parity, and piglet BW to 12 pens equipped with single-space electronic feeding stations with 10 pigs/pen for a 41-d study. In this 2 × 2 factorial arrangement, factors were litter background (socialized vs. traditional) and dietary SID Lys: NE (High 1.32 vs. Low 1.15 SID Lys:NE MJ/kg). Daily individual FI and BW and skin injuries at different timepoints after weaning were determined. Wheat-barley based diets were isoenergetic (10.6 MJ/kg) and offered in two phases (i.e., d 0-14 and d 14-41). The day after weaning, socializing reduced the proportion of piglets with more than five skin injuries from 45.7% to 3.0% compared with traditional housing (P < 0.05). Early post-weaning, daily FI was 50% greater for S-LowLys:NE pigs than S-HighLys:NE on d1, then, T-LowLys:NE was greatest (~25% above other treatments) during d 3-6 (all P < 0.05). The trend maintained during d 6-8 with T-LowLys:NE and S-HighLys:NE being similar each other (P > 0.05). The average number of visits per day during the first 10 d was greater (P < 0.01) for S-HighLys:NE and T-LowLys:NE (33 visits each) compared with T-HighLys:NE (24 visits). Overall, S-HighLys:NE pigs tended (P < 0.10) to have a greater end BW (23.8 vs. 22.1 kg) and a greater d 0-41 average daily gain (ADG) than T-HighLys:NE (530 vs. 472 g/d). For d22-29, the average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency (FE), were greater for S-HighLys:NE and T-LowLys:NE compared with S-LowLys:NE and T-HighLys:NE (P < 0.05). No other meaningful interactions were observed between socializing and Lys:NE on growth performance. However, looking at main factors, socializing increased ADG during d 29-41 by 9% (P = 0.01) coinciding with a 4% greater FE (P = 0.09). The data suggest that traditionally housed piglets fed a HighLys:NE diet post-weaning had lower daily FI and growth performance compared with T-LowLys:NE and socialized piglets irrespective of the Lys:NE contrast. In conclusion, the present study led to a better understanding of nutritional requirements and FI in situations with different pre-weaning housing schemes of piglets. In the present conditions, pre-weaning socialization of pigs may stimulate feed intake earlier post-weaning and allow a better transition independently from the Lys (and amino acid) to NE ratio.

90 Evaluating water- and feed-based arginine supplementation on newly weaned pig growth and gastrointestinal health

Abstract The objective of this experiment was to assess the influence of arginine (Arg) supplementation in water and/or feed on the growth performance and gastrointestinal health of newly weaned pigs. Pigs (n = 240; PIC 337 Χ 1050, Genus, Henderson, TN) were randomly allocated into 80 mixed-sex test pens and subjected to a 2 Χ 4 factorial design, with two levels of Arg supplementation in water (0% or 8% stock, dosed through a 1:128 proportioner) for the first phase (d 0-7), and four dietary arginine levels (0.85, 0.95, 1.05, and 1.15 standardized ileal digestible (SID) Arg to Lysine (Lys) ratios for the first two phases (d 0-7 and 7-21). All treatments were provided a common diet (0.96 SID Arg:Lys) for the last phase d 21- 42. One pig per pen underwent a dual sugar absorption test of lactulose at 500 mg/kg and mannitol at 50 mg/kg of body weight (BW) via gastric tube on d 7 and 21, with blood plasma collected 4 h post-administration. The pig tested on d 7 was subsequently euthanized for intestinal tissue collection. Pen growth performance and feed disappearance were evaluated for 3 phases; d 0-7, 7-21, and 21-42. The statistical analysis utilized generalized linear mixed model methods (SAS 9.4, Cary, NC) with the main effects of SID Arg:Lys in the feed and Arg level within the water, and the interaction between the two. Pen was the experimental unit. Orthogonal contrasts were tested for the linear and quadratic effects of the diet. Growth performance during the 1st period exhibited variability, reflected by negative gain to feed ratio (G:F), caused by health challenges of Rotavirus A. Consequently, data were analyzed separately for each phase. Increasing dietary SID Arg:Lys caused a significant linear effect (improvement; P = 0.04) on final BW (18.47 and 21.90 kg, for 0.85 and 1.15 SID Arg:Lys, respectively). However, discernible differences between dietary treatments were not observed (P > 0.1). Similarly, a trend (P = 0.09) suggested a linear impact of dietary SID Arg:Lys on average daily gain during the third phase (d 21-42). In terms of intestinal absorption and morphology, Arg supplementation, whether through water or diet, had no effect on lactulose and mannitol absorption on both d 7 and d 21, nor did it impact villous height, crypt depth, or the villi:crypt ratio in ileum tissues collected on d 7 post-weaning. In conclusion, dietary supplementation with Arg increased final BW but had no clear impacts on intestinal health within the variables measured, potentially impacted by the rotavirus diagnosis in the first week post wean.

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.

Standardized ileal digestible methionine requirements for 22 to 29-d-old male broilers based on the growth performance and feather development.

The aim of the present experiment was to determine the standardized ileal digestible (SID) methionine (Met) requirement during the grower phase (22 to 29 days). A total of 192 Ross 308 male broilers (745 ± 50.5 g) were assigned to six dietary treatments in a randomized complete block design, with eight replicate cages per treatment. The experimental diets were formulated based on corn, soybean meal, and synthetic amino acids (AA), with different levels of dietary SID Met ranging from 0.40% to 0.65%, in increments of 0.05%. Individual body weight and feed intake per cage were measured at the beginning and end of the experimental period. Weight gain (g/bird), feed intake (g/bird), gain-to-feed ratio (g/kg), feather weight (g), and relative feather percentage (% of body weight) were analyzed for linear or quadratic responses using orthogonal polynomial contrasts. Final body weight, weight gain, and feed intake increased quadratically as dietary SID Met concentration increased (p < 0.05). However, the composition of AA in the feathers showed no quadratic or linear effect based on dietary SID Met concentrations, except for Ile (p = 0.05; quadratic). The SID Met requirements for optimum and maximum weight gain of 22 to 29-days-old male broilers were estimated using the broken-line and quadratic-line models to 0.45% and 0.55%, respectively.

The standardized ileal digestible lysine-to-net energy ratio in the diets of sows to optimize milk nitrogen retention is dynamic during lactation.

Fifty-two multiparous sows (average parity 3.1 ± 0.9 and initial BW 245.6 ± 32.5kg) were used to evaluate the effects of dietary standardized ileal digestible (SID) Lys-to-net energy (NE) ratios on nitrogen (N) utilization throughout a 24-d lactation period. Sows were randomly assigned to one of five isoenergetic feeding programs that provided equally spaced and increasing SID Lys-to-NE ratios between 2.79 and 5.50g SID Lys/Mcal NE. The feeding programs were generated by blending the two extreme diets in varying proportions and were provided to sows immediately after farrowing (day 1) and until weaning at day 24 ± 1. Nitrogen balances were conducted between days 4 and 7, 12 and 15, and 20 and 23 ± 1 of lactation to represent weeks 1, 2, and 3, respectively, using total urine collection and fecal grab sampling. Contrast statements were used to determine the linear and quadratic effects of increasing Lys-to-NE ratios. Linear and quadratic broken-line and polynomial quadratic (QPM) models were used to determine the optimum dietary Lys-to-NE ratios for N retention in milk. The Bayesian information criterion was used to assess the best fit. Feeding program did not influence sow average daily feed intake (5.8 ± 0.1kg), BW change (-8.2 ± 3.1kg), or change in back fat thickness (-2.6 ± 0.7mm) over the 24-d lactation period, but piglet average daily gain increased with dietary SID Lys-to-NE ratio (linear; P < 0.05). Sow N intake increased with increasing dietary Lys-to-NE ratio in weeks 2 and 3 (linear; P < 0.001). Whole-body N retention (N intake-N output in urine and feces) increased with increasing dietary Lys-to-NE ratio in all weeks (linear; P < 0.05). The N retention in milk tended to increase then decrease with increasing dietary Lys-to-NE ratio in weeks 1 and 2 (quadratic; P = 0.051 and P = 0.081) and the QPM showed optimal milk N retention at 4.28, 4.42, and 4.67g Lys/Mcal NE for weeks 1, 2, and 3, respectively. Maternal N retention (N intake-N output in urine, feces, and milk) decreased and then increased in week 1 (quadratic; P < 0.01) and increased in weeks 2 and 3 (linear; P < 0.01) with increasing dietary Lys-to-NE ratio. Therefore, the SID Lys-to-NE ratio necessary to optimize milk N output is dynamic throughout lactation. A two-diet feeding program could be created to match optimal weekly or daily SID Lys-to-NE ratios, which could lead to improved piglet ADG and body weights at weaning.

Impact of increasing dietary standardized ileal digestible arginine to lysine ratio from 0.85 to 1.15 and water-based arginine supplementation on growth performance and gut integrity of weaned pigs.

The objective of this experiment was to assess the influence of arginine (Arg) supplementation in water and/or feed on the growth performance and gastrointestinal health of newly weaned pigs. Two hundred and forty pigs (5.06kg; PIC, Hendersonville, TN) were randomly allocated into 80 mixed-sex pens (3 pigs/pen) and subjected to a 2 × 4 factorial design. Two levels of Arg were supplemented in water (0% or 8% stock, dosed through a 1:128 proportioner) for the first phase (days 0 to 7), and four dietary arginine levels (0.85, 0.95, 1.05, and 1.15) standardized ileal digestible (SID) Arg to Lysine (Lys) ratios for the first two phases (days 0 to 7 and 7 to 21). All treatments were provided a common diet (0.96 SID Arg:Lys) for the last phase days 21 to 42. One pig per pen underwent a dual sugar absorption test of lactulose at 500mg/kg and mannitol at 50mg/kg of body weight (BW) via gastric tube on days 7 and 21 postweaning, with blood plasma collected 4h later. The pig tested on day 7 was subsequently euthanized for intestinal tissue collection. Pen growth performance and feed disappearance were evaluated for 3 phases: days 0 to 7, 7 to 21, and 21 to 42 postweaning. The statistical analysis used linear models to examine the effects of SID Arg:Lys in the feed, Arg level in water, and their interactions, with pen as the experimental unit. Orthogonal contrasts were used to test the linear and quadratic effects of increasing SID Arg:Lys in the diet. Growth performance during the first period exhibited variability, reflected by negative gain-to-feed (G:F) ratios, caused by the enteric health challenge. Consequently, data were analyzed separately for each phase. Increasing dietary SID Arg:Lys caused a linear improvement (P = 0.04) in final BW (18.47 and 21.90kg, for 0.85 and 1.15 SID Arg:Lys, respectively). A trend (P = 0.09) suggested a linear impact of dietary SID Arg:Lys on average daily gain during days 21 to 42. Arg supplementation, whether administered through water or diet, did not affect lactulose and mannitol absorption on both days 7 and 21, nor did it alter histological measurements in the collected ileum tissues on day 7 postweaning. In conclusion, increasing dietary SID Arg:Lys increased final BW but had no clear impacts on intestinal health within the parameters measured, potentially impacted by the rotavirus diagnosis in the first week post-wean.

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

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

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

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

272 The Effect of Increasing Standardized Ileal Digestible Methionine Intake on Whole-Body Nitrogen Retention and Plasma Amino Acids, Homocysteine, and Glutathione of Gilts in Late Gestation

Abstract Gestating gilts (n = 70; 166 ± 13 kg initial body weight at d 31 of gestation) were used to determine the dietary standardized ileal digestible (SID) Methionine (Met) content required to optimize whole-body nitrogen (N) retention versus the appearance of biomolecules derived via Met metabolism. On d 102 of gestation, gilts were randomly assigned to one of seven dietary treatments that provided between 50 and 150% of estimated SID Met requirements for late gestation gilts (0.10 to 0.30% SID Met). All other indispensable amino acids were supplied at least 20% above estimated requirements (NRC, 2012). A N balance (total urine collection and fecal grab sampling) was conducted for each gilt between days 109 and 112 of gestation, blood samples were collected on day 109 after a 24-h fasting period for analyses of plasma amino acids, homocysteine (Hcys), and reduced glutathione (GSH). Contrast statements were used to determine linear and quadratic effects of dietary SID Met levels. Linear and quadratic broken-line and polynomial quadratic models were used to determine the optimum level of SID Met for whole-body N retention and plasma concentrations of Hcys and GSH. Whole-body N retention increased with increasing dietary Met (linear and quadratic; P &amp;lt; 0.001; Table 1). Plasma concentrations of Hcys increased with increasing dietary Met (linear; P &amp;lt; 0.05). Glutathione tended to decrease and then increase at dietary SID Met greater than 0.20% (quadratic; P = 0.061; Table 2). Plasma glutamine increased with increasing dietary SID Met (linear; P &amp;lt; 0.01). Histidine increased then decreased at dietary SID Met greater than 0.20% (quadratic; P &amp;lt; 0.05), other amino acids were not influenced by dietary treatment. Linear and quadratic broken-line models described a lower breaking point for whole-body N retention, plasma Hcys, and plasma GSH compared with the quadratic polynomial model (0.154% and 0.155% vs. 0.226%, 0.185% and 0.188% vs. 0.328%, and 0.114% and 0.124% vs. 0.224% SID Met, respectively). The Bayesian information criterion (BIC) indicated that the quadratic polynomial model best fit the data versus the linear and quadratic broken-line models for plasma GSH (BIC 317.9 vs. 320.3 and 322.6, respectively; Graphic 1). However, the fits were similar among models for whole-body N retention (BIC 385.2 vs. 384.6 and 386.9, respectively; Graphic 2) and Hcys (BIC 465.5 vs. 465.6 and 467.9, respectively; Graphic 3). Based on the best fit (quadratic polynomial) model 0.226% SID Met is required to optimize whole-body N retention for late gestation gilts which is greater than that recommended by the NRC (2012; 0.20% SID Met). It appears that gilts have further capacity for Met transmethylation since the plasma Hcys breakpoint occurred at a greater dietary SID Met level than for whole-body N retention, though the impact on transsulfuration and remethylation pathways cannot be discounted. Therefore, greater feeding levels of SID Met might be required to maximize both protein and non-protein utilization of Met.

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 &amp;lt; 0.01) and gain-to-feed ratio (G:F; quadratic, P &amp;lt; 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.

49 The Effect of Increasing Standardized Ileal Digestible Methionine Intake During Lactation on Whole-Body Nitrogen Utilization of Primiparous Sows

Abstract Seventy-five primiparous Yorkshire × Landrace and Yorkshire sows were used to determine the effect of increasing dietary standardized ileal digestible (SID) methionine (Met) intake on whole-body nitrogen (N) utilization during lactation. Upon farrowing (190.2 ± 18.0kg initial body weight), sows were assigned to 1 of 7 dietary SID Met levels (n = ~10), ranging from 70% to 130% of estimated SID Met requirements (0.182 to 0.338% SID Met) via the addition of DL-Met. All other indispensable amino acids were supplied above estimated requirements (1.19% SID lysine, 19.74% crude protein) and additional cysteine was supplied to minimize Met utilization for transsulfuration. Litters were standardized to 13 ± 2 piglets within 48 hours of birth and feed was offered according to a standard feeding curve (NRC, 2012). The N balance periods were between days 5 to 9 (early; N1) and 17 to 21 (Peak; N2) of lactation where total urine was collected via urinary catheters and feces was grab-sampled; titanium dioxide was used as an indigestible marker for determining apparent total tract N digestibility. In N1 and N2, 5.22 and 6.87 kg/d of experimental diet was offered in three equal meals at 0830, 1200, and 1530 h to each sow. Milk N output (g/d) was calculated using estimated milk yield based on litter growth rate and size and analyzed milk N concentration. Contrast statements were used to assess linear and quadratic effects of dietary SID Met level. During N1, N intake increased and then decreased when dietary SID Met content surpassed 0.286% (quadratic; P &amp;lt; 0.05). Similar relationships were observed for total N excretion (urine + fecal N; P &amp;lt; 0.05) resulting in no SID Met effect on N retention (77.1 ± 6.6, -12.5 ± 10.4, and 89.5 ± 8.9 g/d for total, maternal, and true milk protein N retention, respectively) or apparent N utilization efficiency (N retention/N intake×100; 53.2 ± 3.4%). During N2, as SID Met increased, N intake tended to increase (205.5 to 210.2 ± 5.7g/d; linear; P = 0.078), total N excretion tended to decrease (87.3 to 78.7 ± 6.2 g/d; linear; P = 0.087), and total N retention increased (117.9 to 131.4 ± 8.0g/d; linear; P &amp;lt; 0.05). True milk protein N output increased with SID Met (100.3 to 112.5 ± 8.1 g/d; linear; P &amp;lt; 0.05) and maternal N retention decreased and then increased when dietary SID Met content surpassed 0.260% (quadratic; P &amp;lt; 0.05). Apparent N utilization efficiency increased with increasing dietary SID Met (57.5 to 62.5 ± 1.2%; linear; P&amp;lt; 0.05). Therefore, in early lactation, SID Met intake had minimal effects on N utilization, indicating that the requirement for lactating primiparous sows may be equal to or less than 0.182% SID Met. During peak lactation, the supply of SID Met needed to maximize true milk protein N and apparent N utilization efficiency may be greater than 0.338%, which does not take into consideration the non-protein partitioning of dietary Met.

132 The Effects of Increasing Dietary Standardized Ileal Digestible Lysine Levels on Growth Performance and Carcass Characteristics of 11- to 133-kg Late-Nursery-to-Finish Pigs Sired by PIC 800 Boars

Abstract Our objective was to determine the effects of increasing standardized ileal digestible (SID) lysine (Lys) levels on growth performance and carcass characteristics of late-nursery-to-finish pigs sired by PIC 800 boars. Barrows and gilts [n = 1,00; PIC800×Camborough, initial body weight (BW) = 10.9 ± 0.39 kg] were used in a 142-d growth trial with 40 mixed sex pens, 10 pens per treatment, and 25 pigs per pen. At the beginning of the trial, pens were blocked by BW and randomly allotted to one of four treatments (overall dietary SID Lys level as 87, 95, 102, or 110% of PIC SID Lys recommendations) in a randomized complete block design. Diets were corn-soybean meal (SBM)-based, and treatments were achieved through the inclusion of SBM with adjustments of corn and choice white grease. Diets were fed in 7 phases (11-17, 17-34, 34-44, 44-57, 57-77, 77-95, and 95-133 kg) and formulated to be iso-caloric across treatments for each phase. Within each phase, only the diets of the least and greatest SID Lys levels were manufactured, and the diets of intermediate SID Lys levels were blended by the automatic feeding system in the research facility. Growth performance data were analyzed using the GLIMMIX procedure in SAS (Version 9.4, SAS Institute, Inc., Cary, NC) and considered pen as the experimental unit. The statistical model considered fixed effects of SID Lys levels and random effects of the block. Mortality and removals were also analyzed using the GLIMMIX procedure and specified a binomial distribution. All data are reported as least square means and considered statistically significant at P &amp;lt; 0.05 and marginally significant at P &amp;lt; 0.10. Increasing overall dietary SID Lys levels reduced overall average daily feed intake (linear, P = 0.045) and increased overall gain-to-feed ratio (linear, P = 0.002), but there was no evidence for a difference across treatments for overall average daily gain (P &amp;gt; 0.10) or overall removal and mortality rate (Table 1; P &amp;gt;0.10). Pigs fed overall SID Lys level as 102% of PIC recommendation had significantly greater carcass yield compared with those fed 95 or 110% (P &amp;lt; 0.05), with the pigs fed 87% being intermediate. Increasing overall dietary SID Lys levels reduced backfat depth (linear, P&amp;lt; 0.001) and increased lean yield (linear, P = 0.012), but there was no evidence for a difference among treatments for loin depth (P &amp;gt; 0.10). In conclusion, increasing overall dietary SID Lys level beyond PIC recommendations through increasing SBM levels resulted in improved feed efficiency, backfat depth, and lean yield of 11 to 133 kg pigs sired by PIC 800 boars.

133 The Effects of Increasing Dietary Standardized Ileal Digestible Lysine Levels on Growth Performance and Carcass Characteristics of 24- to 130-kg Grow-Finish Pigs Sired by PIC 800 Boars

Abstract Our objective was to determine the effects of increasing overall standardized ileal digestible (SID) lysine (Lys) levels on growth performance and carcass characteristics of grow-finish pigs sired by PIC 800 boars. A total of 1,715 barrows and gilts (PIC800×Camborough, initially 23.7±0.58 kg) were used in a 117-d growth trial with 70 mixed sex pens in two rooms (35 pens per room), 14 pens per treatment, and 23 to 25 pigs per pen. At the beginning of the trial, pens within each room were blocked by body weight and randomly allotted to one of five treatments (overall dietary SID Lys level as 80, 88, 94, 100, or 110% of PIC SID Lys recommendations) in a randomized complete block design. Diets were corn-soybean meal (SBM)-based, and treatments were achieved through the inclusion of SBM with adjustments of corn and choice white grease inclusion rates. Diets were fed in 6 phases (24-47, 47-63, 63-75, 75-95, 95-113, and 113-130 kg) and formulated to be iso-caloric across treatment for each phase. Within each phase, only the diets of the lowest and highest SID Lys levels were manufactured, and the diets of intermediate SID Lys levels were blended by the automatic feeding system in the research facility. Growth performance data were analyzed using the GLIMMIX procedure in SAS (Version 9.4, SAS Institute, Inc., Cary, NC) and considered pen as the experimental unit. The statistical model considered fixed effects of SID Lys levels and random effects of the block. Mortality and removals were also analyzed using the GLIMMIX procedure and specified a binomial distribution. All data are reported as least square means and considered statistically significant at P &amp;lt; 0.05 and marginally significant at P &amp;lt; 0.10. Increasing overall dietary SID Lys levels marginally reduced average daily feed intake (linear, P = 0.108) and increased gain-to-feed ratio (linear, P &amp;lt; 0.001), but there was no evidence for difference among treatments for average daily gain (P &amp;gt;0.10) or removal and mortality rate (Table 1; P &amp;gt; 0.10). There was no evidence for increasing overall dietary SID Lys levels affect hot carcass weight, carcass yield, backfat depth, loin depth, or lean yield. In conclusion, increasing overall dietary SID Lys level over PIC recommendations through increasing SBM levels resulted in improved feed efficiency of 24 to 130 kg pigs sired with PIC 800 boars, but there was no evidence for difference in the carcass characteristics.

238 Impact of Increasing Standardized Ileal Digestible Tryptophan to Lysine Ratio in Diets Containing 20% Corn Distillers Dried Grains with Solubles fed to Growing-Finishing Pigs

Abstract A study was conducted to investigate the optimal standardized ileal digestible (SID) Trp to Lys ratio in diets containing a moderately high level (20%) of corn distillers dried grains with solubles (DDGS) fed to growing-finishing pigs. A total of 2,232 pigs [initial body weight (BW) = 31.41 kg ± 0.53 kg] were allotted to a randomized complete block design with 4 dietary treatments (18 pens/treatment; 31 pigs/pen, mixed gender) and fed experimental diets for 15 wk in a 6-phase feeding program. The level of SID Trp/Lys in each treatment was formulated to 0.15, 0.18, 0.21, and 0.24, respectively, and was manipulated by crystalline Trp inclusion. Within each phase, diets were formulated to be isocaloric and contained equal provisions of SID Lys, sulfur containing amino acids, Thr, and Ile. Diets met or exceeded NRC (2012) estimated nutrient requirements. The levels of SID Thr/Lys (0.65 – 0.70 from grower to finisher) and SID Ile/Lys (0.60 – 0.62 from grower to finisher) were adjusted to a greater level to accommodate the potential negative effects of greater levels of fiber and Leu, respectively, from the inclusion of DDGS. Results were analyzed using the lme4 package of R 4.1.2, and the statistical models included the fixed effect of SID Trp/Lys and the random effect of body weight block. Orthogonal contrasts were used to test linear and quadratic effects of increasing dietary SID Trp/Lys (Table 1). Results indicated that increasing SID Trp/Lys in diets containing 20% corn DDGS improved final body weight (FBW) in a quadratic pattern (128.67, 130.61, 130.83, and 130.37 kg, for diets formulated to SID Trp/Lys at 0.15, 0.18, 0.21, and 0.24, respectively, P &amp;lt; 0.05). Average daily feed intake (ADFI) was quadratically increased with increasing SID Trp/Lys (2.51, 2.57, 2.60, and 2.57 kg/d, respectively, P &amp;lt; 0.05). A linear tendency was observed on average daily gain (ADG) with increasing SID Trp/Lys (0.96, 0.98, 0.98, and 0.98 kg/d, respectively, P &amp;lt; 0.10). In summary, increasing SID Trp/Lys in diets with moderately high levels of corn DDGS improved FBW and ADFI in a quadratic pattern and tended to increase ADG linearly.

208 Effect of SID LYS Level with Constant Non-Essential Amino Acids

Abstract Many investigations on the effect of low protein diets reduce crude protein (CP) and have a constant standardized ileal digestible (SID) LYS resulting in reductions in ADG, ADFI, and gain:feed is some cases. This experiment was conducted to determine the impact of maintaining constant non-essential amino acids and changing SID LYS and other essential amino acids. For the experiment, 288 pigs (~22 d of age, 6.61 ± 0.95 kg, 8 replicates/treatment, 6 pigs/pen) were stratified by body (BW) and randomly allotted to one of 6 treatments in a randomized complete block design. Non-essential amino acids were fixed in all diets and synthetic amino acids were added to increase SID LYS from 1.15% to 1.4% while maintaining constant ratios of MET+CYS, THR, TRP, VAL, and ILE to LYS. Diets were corn, wheat, barley, and soy based with 1.1% corn starch in the least SID LYS diet. Synthetic amino acids were added to the diet at the expense of corn starch to maintain non-essential amino acid levels. The CP ranged from 17.8% when SID LYS was 1.15% and 18.6% when SID LYS was 1.4%. Experimental diets were fed for 21 d. Body weight, feed disappearance, visual fecal scores, and visual piglet scores were measured. Visual fecal scores (1 = normal to 4 = watery) and visual pig appearance scores (1 = pale and hairy to 4 = normal color and well-rounded muscle) were assessed on ordered likert scales to determine the probabilities of observing a more normal stool quality and a worse visual appearance, respectively. Performance data were analyzed as a general linear model. Stool quality and visual appearance were analyzed as a generalized linear mixed model. Contrasts were used to test linear and quadratic effects of dietary SID LYS. Results of the experiment are presented in Table 1. Increasing SID LYS with constant non-essential amino acids did not affect ADG or BW. The ADFI was linearly decreased (P &amp;lt; 0.1) and gain:feed was linearly increased (P &amp;lt; 0.0001) with increasing SID LYS (Table 1). Stool quality was not affected. Visual appearance of the pigs was quadratically affected (P &amp;lt; 0.05) by changing SID LYS. Pigs that had consumed diets with the lowest or highest SID LYS had the best visual appearance (lowest probability). The results of the current experiment differ suggest SID LYS may regulate feed intake and nutrient efficiency, but BW gain is not affected when non-essential amino acids are held constant. This differs from cases where CP is reduced, which results are decreased growth in many cases.