Ileal Digestible Threonine Research Articles

Interaction effects of glycine equivalent and standardized ileal digestible threonine in low protein diets for broiler grower chickens.

This study aims to investigate the interactive effect of a glycine equivalent (Glyequi) and standardized ileal digestible threonine (SID Thr) levels in low crude protein diets on performance, blood biochemistry, pectoral muscular creatine content and oxidative stability of meat in broiler chickens from 21 to 42 days. A total of 1,500, twenty-one-day-old Cobb-Vantress male broiler chickens were distributed in a completely randomized 5×3 factorial arrangement of Glyequi×SID Thr with five replicates of 20 birds each. Fifteen dietary treatments of 16.5% CP were formulated to contain five levels of total Glyequi (1.16%, 1.26%, 1.36%, 1.46%, and 1.56%) and three levels of SID Thr (0.58%; 0.68% and 0.78%). Interaction effects (p<0.05) of Glyequi and SID Thr levels were observed for weight gain, carcass yield, pectoral muscular creatine content and serum uric acid. Higher levels of Glyequi increased (p = 0.040) weight gain in 0.58% and 0.68% SID Thr diets compare to the 0.78% SID Thr diet. The SID Thr level at 0.68% improved (p = 0.040) feed conversion compared to other SID Thr diets. Levels of Glyequi equal to or above 1.26% in diets with 0.78% SID Thr resulted in birds with higher (p = 0.033) pectoral muscular creatine content. The breast meat yield observed in the 0.68% SID Thr diet was higher (p = 0.05) compared to the 0.58% SID Thr diet. There was a quadratic effect of Glyequi levels for pectoral pectoral muscular creatine content (p = 0.008), breast meat yield (p = 0.030), and serum total protein concentrations (p = 0.040), and the optimal levels were estimated to be 1.47%, 1.35%, and 1.40% Glyequi, respectively. The lowest (p = 0.050) concentration of malondialdehyde in the breast meat was found in 0.68% SID Thr diets at 1.36% Glyequi. The minimum dietary level of Glyequi needed to improve performance in low crude protein diets is 1.26% with adequate SID Thr levels for broiler chickens.

Effects of Standardized Ileal Digestible Threonine to Lysine Ratio on Growth Performance of PIC Line 337 × 1050 Pigs

Effects of Standardized Ileal Digestible Threonine to Lysine Ratio on Growth Performance of PIC Line 337 × 1050 Pigs

Effect of glycine equivalent levels in low protein diet containing different SID threonine concentrations on performance, serum metabolites and muscle creatine of broiler chickens

This study was conducted to evaluate glycine equivalent (Glyequi) requirement in low crude protein (CP) diets with different levels of standardised ileal digestible (SID) threonine (Thr) on performance, serum metabolites, and muscle creatine of broiler chickens from 1 to 21 d age. A total of 1275 one-day-old male Cobb-Vantress chicks were distributed in a completely randomised 3 × 5 factorial arrangement for a total of 15 treatments with 5 replicates of 17 birds each. Diets were formulated to comprise three dietary SID of Thr concentrations 6.9, 8.1 and 9.3 g/kg and five dietary Glyequi levels (12.8, 14.3, 15.8, 17.3 and 18.8 g/kg). An interaction (p < 0.05) was observed between the Glyequi and SID Thr levels for feed:gain and serum uric acid (SUA). With increasing levels of Glyequi, feed:gain decreased linearly (p < 0.05) in 6.9 and 8.1 g/kg SID Thr diets while SUA decreased linearly (p < 0.05) in 6.9 g/kg SID Thr diet. In diet containing 9.3 g/kg SID Thr, increasing Glyequi level optimised feed:gain (p = 0.04) at an estimated minimum level of 15.5 g/kg. Glyequi levels resulted in a quadratic effect (P < 0.05) on BWG, feed:gain, muscle creatine with optimum point of 17.2, 16.7, 17.1 g/kg, respectively. Therefore, minimum requirement of Glyequi in low CP (174.0 g/kg) diet needed to optimised performance is 15.5 g/kg in 9.3 g/kg SID Thr diet, but could be or higher than 20.9 g/kg in 6.9 g/kg and 8.1 g/kg SID Thr diets for broilers. Highlights Feeding a low-protein diet of 174 g/kg with adequate Thr concentration at higher Glyequi levels could support performance in broilers of 1–21 d old. Provision of 15.5 g/kg Glyequi in low CP diet containing 9.3 g/kg SID Thr level is required to improve performance. Sufficient supply of dietary Thr concentration represents a sparing effect of Gly especially at marginal levels of dietary Glyequi in low-CP diets.

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

Camborough PIC sows (n = 291) were fed 1 of 5 dietary treatments to evaluate the standardized ileal digestible (SID) Thr:Lys requirement during lactation. Sows were blocked by parity (1, 2, and 3+) and randomly allotted to 1 of 5 SID Thr:Lys ratios (52, 60, 68, 76, and 84). SID Lys was formulated to 1.03% and SID methionine and cystine (M + C):Lys was 55%. Sows were allowed 5.45 kg feed/day starting on the day of farrowing. All other nutrients met or exceeded the NRC (2012) requirements. Sows were allowed ad libitum access to water, and piglets were cross-fostered within treatment within 24 h of birth. Data collected during the study included sow prefarrow BW, sow weaning weight, starting litter weight, weaning litter weight, piglet mortality, weaning-to-estrus interval, and subsequent total born piglets. Data were analyzed as a randomized complete block design using PROC MIXED with sow as the experimental unit and treatment and parity as fixed effects. Requirement estimation models evaluated were quadratic polynomial, broken-line linear, and broken-line quadratic (BLQ) using PROC NLMIXED. Models that differed in their Bayesian information criterion (BIC) values by at least 2 points were considered to have meaningful differences in their data fit. The best-fit model was based on the best BIC value. As the SID Thr:Lys ratio increased, there was a quadratic response on ADFI (4.73, 4.57, 4.67, 4.55, and 4.60 kg/d; P = 0.001) and percent of sow BW loss (-6.4, -7.89, -7.35, -6.19, and -5.81; P = 0.004). In addition, there was a trend for weaning-to-estrus interval to be affected by the ratio (5.4, 4.4, 4.6, 4.5, and 4.8; P = 0.07). Daily litter gain was also quadratically improved as the SID Thr:Lys ratio increased (2.67, 2.67, 2.78, 2.77, and 2.68 kg/d; P-value = 0.001). For daily litter gain, the BLQ model was determined to be the best fit with an estimated SID Thr:Lys requirement of 65%. In conclusion, the optimal SID Thr:Lys ratio for litter growth was 65.

310 Effects of Standardized Ileal Digestible (SID) Threonine: Lysine Ratio on Nursery Pig Performance.

310 Effects of Standardized Ileal Digestible (SID) Threonine: Lysine Ratio on Nursery Pig Performance.

Effects of dietary fiber on the ideal standardized ileal digestible threonine:lysine ratio for twenty-five to fifty kilogram growing gilts.

Four experiments were conducted to determine effects of fiber on the ideal Thr:Lys ratio for 25- to 50-kg gilts. In Exp. 1, the objective was to determine the requirement for standardized ileal digestible Lys for gilts from 25 to 50 kg BW. Seventy gilts (24.54 ± 3.28 kg BW) were used in a growth assay with 2 pigs per pen, 5 diets, and 7 replicate pens per diet. The 5 diets were based on corn and soybean meal and contained between 0.80 and 1.32% SID Lys. Results indicated that 1.09% SID Lys was needed to optimize ADG and G:F. In Exp. 2, the objective was to determine the standardized ileal digestibility of AA in corn, soybean meal, field peas, fish meal, and soybean hulls. Six ileal-cannulated gilts (26.5 ± 0.74 kg BW) were allotted to a 6 × 6 Latin square design with 6 diets and 6 periods. Values for standardized ileal digestibility of AA were calculated for all ingredients. In Exp. 3, the objective was to determine the effect of fiber on the ideal SID Thr:Lys ratio for gilts from 25 to 50 kg BW. A total of 192 gilts (26.29 ± 4.64 kg BW) were used in a growth assay with 2 pigs per pen and 8 replicate pens per treatment. Six low-fiber diets and 6 high-fiber diets were formulated using the same batches of ingredients as in Exp. 2. Within each level of fiber, diets with SID Thr:Lys ratios ranging from 45:100 to 90:100 were formulated using the SID values calculated in Exp. 2. In both types of diets, ADG and G:F linearly and quadratically ( < 0.05) increased as the Thr:Lys ratio increased. Regression analysis estimated the ideal SID Thr:Lys ratio at 0.66 and 0.63 for ADG and G:F, respectively, for pigs fed low-fiber diets and at 0.71 and 0.63, respectively, for pigs fed high-fiber diets. In Exp. 4, the objective was to determine the N balance in pigs fed low-fiber or high-fiber diets that were formulated to have SID Thr:Lys ratios of 45:100 or 60:100. The 4 diets were formulated using the same batches of ingredients as in Exp. 2, and the SID values determined in Exp. 2 were used in diet formulations. Thirty-six gilts (29.0 ± 0.74 kg BW) were individually housed in metabolism crates with 9 replicate pigs per diet. Retention of N (% of intake) was greater (P < 0.05) for pigs fed the low-fiber diets compared with pigs fed the high-fiber diets regardless of the Thr:Lys ratio. Results of these experiments indicate that increased fiber levels in diets fed to growing gilts increase the requirement for Thr and that diets with higher fiber levels should be formulated to a greater SID Thr:Lys ratio.

Gut morphology of young pigs fed diets differing in standardized ileal digestible threonine and wheat gluten used as a source of non-essential amino acids

Gut morphology of young pigs fed diets differing in standardized ileal digestible threonine and wheat gluten used as a source of non-essential amino acids

Utilization of threonine in young pigs fed diets differing in standardized ileal digestible threonine and wheat gluten used as a source of non-essential amino acids

1. Gut morphology of young pigs fed diets differing in standardized ileal digestible threonine and wheat gluten used as a source of non-essential amino acids E. Święch, M. Barszcz, A. Tuśnio, M. Taciak Journal of Animal and Feed Sciences CrossRef

Effects of dietary threonine:lysine ratioes and sanitary conditions on performance, plasma urea nitrogen, plasma-free threonine and lysine of weaned pigs.

Two 21 d-experiments were conducted to determine the optimum standardized ileal digestible (SID) threonine:lysine ratio (Thr:Lys) for weaned piglets reared under clean (Exp. 1) or unclean (Exp. 2) sanitary conditions and fed antibiotic-free diets. In each experiment, 90 mixed-sex pigs (Duroc × [Yorkshire × Landrace]; initial BW 7.2 ± 0.3 kg) were randomly assigned to 5 dietary treatments each with 6 replicates (3 pigs per pen). The dietary treatments were 5 graded levels of SID Thr:Lys (55, 59, 63, 67 and 71%). Diets were corn-wheat-soybean meal-based with a constant SID Lys of 1.18% that was set to be second limiting amino acid. In Exp. 1 and Exp. 2, plasma-free Thr increased (P = 0.05) with increasing dietary SID Thr:Lys. In Exp. 1, the SID Thr:Lys for gain-to-feed ratio (G:F) was optimized at 65%. In Exp. 2, the estimated optimal SID Thr:Lys for overall G:F was 66.5%. In conclusion, an average optimal SID Thr:Lys of 65 and 66.5% could be used to optimize feed efficiency for weaned pigs under clean and unclean sanitary conditions, respectively.

The effects of red grape pomace inclusion in grower diet on amino acid digestibility, intestinal microflora, and sera and liver antioxidant activity in broilers

The objective of this study was to evaluate the effect of dietary red grape pomace (RGP) on amino acid digestibility (AIAAD), intestinal microflora, and antioxidant activity in the sera and liver. Sixty-six broilers were housed in battery cages. They were allocated to six cages corresponding to two dietary treatments with three replicates of each treatment. The treatments were administered from 10 to 36 days and included a control diet and a diet containing 1.5% RGP dry powder with the other components remaining unchanged, compared to the control. The RGP had a significant (P < 0.05) positive effect on the apparent metabolizable energy. The majority of coefficients of AIAAD were higher in the RGP. The ileal digestibility of threonine, serine, proline, and glycine was significantly (P < 0.05) higher in RGP. RGP had a positive effect (P < 0.05) on the content of Lactobacillus in the lower part of the ileum. The blood sera of broilers fed RGP had significantly (P < 0.05) lower 2,2-diphenyl-1-picrylhydrazyl (DPPH) and uric acid content. The RGP at a concentration of 15 g/kg in the grower diet did not affect the growth of broilers, and RGP is suitable for broiler diets to improve gastrointestinal tract functionality.

Increased levels of standardized ileal digestible threonine attenuate intestinal damage and immune responses in Escherichia coli K88+ challenged weaned piglets

This study was conducted to investigate the effects of graded levels of standardized ideal digestible threonine (SIDT) on the small intestinal morphology and immune responses of Escherichia coli K88+ challenged weaned piglets. Thirty-six crossbred (Large White×Landrace) barrows, with an initial BW of 7.34±0.55kg and weaned at 21d, were assigned to 1 of 6 treatments according to a 3 (3.7, 7.5 or 11.1g/kg dietary SIDT content)×2 (non-challenged or challenged) factorial arrangement. On d 16, half of the piglets in each SIDT treatment were orally challenged with 10mL E. coli K88+ culture (1×109CFU/mL), while the other half were orally inoculated with the same amount of phosphate buffer (PBS). On d 18 (on 2d after E. coli challenged), the pigs were killed and blood and intestinal samples were collected. The average daily gain (ADG) and feed conversion ratio (FCR) of piglets receiving the 7.5 and 11.1g/kg SIDT diets were significantly improved (P<0.01) during pre-challenge (0–16d), post-challenge (16–18d) and over the entire experiment (0–18d) compared with pigs fed the 3.7g/kg SIDT diet. E. coli K88+ challenge markedly decreased (P<0.05) ADG and FCR of piglets compared with PBS. Increasing dietary SIDT increased the relative thymus body weight of non-challenged piglets while the relative body weight of challenged piglets was not affected by SIDT. Increasing of dietary SIDT significantly increased (P<0.05) lymphocyte proliferation under challenge. Compared with pigs fed the 3.7g/kg SIDT diet, the interleukin-1β concentration significantly (P<0.05) decreased, and the interleukin-6 concentration significantly (P<0.05) increased in the jejunum of piglets fed the 7.5 and 11.1g/kg SIDT diets. It was observed that an interaction between dietary SIDT and E. coli challenge on the levels of mucosal IgA and interleukin-1β (P<0.05). Increasing SIDT increased the duodenal villus width in non-challenged piglets and there was no difference among challenged piglets. Duodenal villi height decreased (P=0.05) after E. coli challenge. Piglets receiving either the 7.5 or 11.1g/kg SIDT diets had increased villi heights and villi height to crypt depth ratio (P<0.05), and decreased crypt depth (P<0.05) in jejunum compared with the 3.7g/kg SIDT diet. Once challenged with E. coli K88+, villus height and villus height to crypt depth ratio of jejunal decreased (P<0.05). The interaction between challenge and dietary SIDT was observed in jejunal crypt depth and villus height to crypt depth ratio. Increasing dietary SIDT decreased the jejunal crypt depth and increased villus height to crypt depth ratio in non-challenged piglets. Moreover, the ileal crypt depth increased (P<0.05) and ileal villus height to crypt depth ratio decreased (P<0.05) after E. coli challenge. Collectively, these results indicate that appropriate dietary SIDT improved mucosal immune function and intestinal morphology of non-challenged pigs and also had beneficial effects in maintaining jejunal integrity and repairing villous damage caused by E. coli challenge. Our findings indicate that appropriate dietary SIDT levels need to be considered when formulating diets for weaned piglets in different physical status.

Effect of Actigen and threonine interaction on the development of gut immunity of nursery pigs (816.3)

Weaned piglets were allocated to six treatment groups (n = 6/treatment) in a 2 x 3 factorial design experiment: Actigen (0 or 400 g/T), true ileal digestible (TID) threonine (Thr):lysine (Lys) ratio (57 [low], 67[recommended], and 77 [high]). After 6 wk of feeding, duodenum, jejunum and ileum tissues were sampled for qPCR analysis. Expression of cytokines was reported relative to the control (no Actigen + 67 TID Thr:Lys). In jejunum, interleukin 6 (IL6) was down‐regulated (P &lt; 0.05) with Actigen + 57 or 77 TID Thr:Lys, (‐5.89 and ‐4.14‐fold, respectively). In ileum, interleukin 1 beta (IL1B) was down‐regulated (P &lt; 0.05) with Actigen + 57 and 77 TID Thr:Lys (‐1.35 and ‐1.75‐fold, respectively). In duodenum, IL1B was up‐regulated (P &lt; 0.05) (1.89‐fold) with Actigen +57 TID Thr:Lys. In duodenum and jejunum, tumor necrosis factor (TNF) was up‐regulated (P &lt; 0.05) with Actigen + 67 TID Thr:Lys (1.21‐fold and 1.33‐fold, respectively). In duodenum, IL6 (‐1.51‐fold) and TNF (1.32‐fold) differed (P &lt; 0.05) in response to no Actigen +57 and 77 TID Thr:Lys, respectively. Relative to the control, Actigen and Thr, in combination, were associated with decreased mRNA levels of the inflammatory cytokines IL6, IL1B in the intestine of weaned pigs.

Effects of dietary threonine supplementation on immune challenge induced by swine Pseudorabies live vaccine in weaned pigs

The present study was conducted to determine whether dietary threonine supplementation can improve immunity of weaned pigs challenged by swine Pseudorabies live vaccine (SPLV). Thirty crossbred piglets weaned at 21 days of age were randomly assigned to three groups receiving diets containing true ileal digestible threonine (TIDT) at 0.74, 0.89 and 1.11% for 14 days. On day 8, all pigs were injected intramuscularly with SPLV or sterile 0.9% NaCl solution. SPLV injection enhanced serum IgA, IgM, IgG, IFN-γ, IL-1β, TNF-α and IL-10 concentrations (p < 0.05) and stimulated the relative mRNA abundance of Toll-like receptors (TLR3, TLR7 or TLR9) in different tissues (p < 0.05). Under no challenge, increasing dietary TIDT levels enhanced serum IgG (p < 0.05), IgM (p = 0.07) and IFN-γ (p < 0.05) concentration, tended to decrease serum IL-1β, TNF-α and IL-10 concentration, and regulated relative mRNA abundance of TLR3, TLR7 or TLR9 in different tissues (p < 0.05). However, there was a synergistic role for increasing the serum IL-10 concentration between dietary TIDT levels and SPLV injection (p < 0.05). Under SPLV challenge, increasing dietary TIDT levels attenuated the increase of the serum IFN-γ concentration, and the increase of the relative mRNA abundance of TLR3, TLR7 and TLR9 in the different tissues (p < 0.05). These results suggest that an appropriate dietary threonine supplementation could improve the immune status of weaned pigs injected with SPLV by down-regulating the expression of TLR3, TLR7 and TLR9 in tissues, and thus regulating T-helper cytokine secretion.

Estimation of the optimal ratio of standardized ileal digestible threonine to lysine for finishing barrows fed low crude protein diets.

Two experiments were conducted to determine the standardized ileal digestible (SID) lysine (Lys) requirement and the ideal SID threonine (Thr) to Lys ratio for finishing barrows. In Exp. 1, 120 barrows with an average body weight of 72.8±3.6 kg were allotted to one of six dietary treatments in a randomized complete block design conducted for 35 d. Each diet was fed to five pens of pigs containing four barrows. A normal crude protein (CP) diet providing 15.3% CP and 0.71% SID Lys and five low CP diets providing 12% CP with SID Lys concentrations of 0.51, 0.61, 0.71, 0.81 and 0.91% were formulated. Increasing the SID Lys content of the diet resulted in an increase in weight gain (linear effect p = 0.04 and quadratic effect p = 0.08) and an improvement in feed conversion ratio (FCR) (linear effect p = 0.02 and quadratic effect p = 0.02). For weight gain and FCR, the estimated SID Lys requirement of finishing barrows were 0.71 and 0.71% (linear broken-line analysis), 0.79 and 0.78% (quadratic analysis), respectively. Exp. 2 was a 26 d dose-response study using SID Thr to Lys ratios of 0.56, 0.61, 0.67, 0.72 and 0.77. A total of 138 barrows weighing 72.5±4.4 kg were randomly allotted to receive one of the five diets. All diets were formulated to contain 0.61% SID Lys (10.5% CP), which is slightly lower than the pig’s requirement. Weight gain was quadratically (p = 0.03) affected by SID Thr to Lys ratio while FCR was linearly improved (p = 0.02). The SID Thr to Lys ratios for maximal weight gain and minimal FCR and serum urea nitrogen (SUN) were 0.67, 0.71 and 0.64 using a linear broken-line model and 0.68, 0.78 and 0.70 using a quadratic model, respectively. Based on the estimates obtained from the broken-line and quadratic analysis, we concluded that the dietary SID Lys requirement for both maximum weight gain and minimum FCR was 0.75%, and an optimum SID Thr to Lys ratio was 0.68 to maximize weight gain, 0.75 to optimize FCR and 0.67 to minimize SUN for finishing barrows.

The effects of Actigen™ and dietary threonine on nursery pig gut morphology

Adequate dietary threonine (Thr) is necessary for proper gut health in nursery pigs. Supplementing with a mannan oligosaccharide product, such as Actigen™ (ACT, Alltech Inc.), can aid in preventing bacterial colonization in the gut. This study was designed to determine whether supplementation with Thr and ACT had beneficial effects on intestinal morphology. Weaned pigs (17 d old) were randomly assigned to one of six factorial treatments: three ratios of true ileal digestible threonine:lysine (Thr:Lys TID): 57% (low), 67% (requirement), or 77% (high) and with or without 400g/T ACT. On d 42 of treatment, pigs (n=6) were euthanized and jejunal sections were fixed and embedded in paraffin wax for histological analysis. Sections (5 μm) were stained with Alcian blue‐periodic acid Schiff stain. Image analysis revealed that piglets fed 77% Thr:Lys with or without ACT supplementation had increased villi height (P&lt;0.01), villus height‐to‐crypt depth ratio (P&lt;0.05), and goblet cell density (cells/μm2; P&lt;0.04) compared to 57% or 67% Thr:Lys. Total goblet cell area (μm2) and goblet cell density were increased (P&lt;0.05) in treatments containing ACT. There were no significant interactions, indicating that adequate Thr levels and ACT supplementation positively influenced gut morphology characteristics independently to increase absorptive capacity and efficiency. The study was funded by Alltech Inc. (Nicholasville, KY).

Estimation of the ideal ratio of standardized ileal digestible threonine to lysine for growing pigs (22–50 kg) fed low crude protein diets supplemented with crystalline amino acids

Two experiments were conducted to investigate the effects of various standardized ileal digestible (SID) threonine (Thr) to lysine (Lys) ratios on the performance and serum parameters of growing pigs fed low crude protein (CP) diets supplemented with crystalline amino acids (CAA). In Exp. 1, 144 growing pigs (22–50kg) were randomly allotted to one of three dietary treatments. The treatments included a high CP (186g/kg) diet with 10.2g/kg SID Lys or one of two low CP diets (dietary CP reduced by 40g/kg but supplemented with crystalline Lys, Thr, methionine, tryptophan, isoleucine and valine) providing 9 or 10.2g/kg SID Lys. Six pens of pigs (three with gilts and three with barrows) were fed each treatment and each pen housed eight pigs. The average daily gain (ADG) of pigs receiving the low CP diet containing 9g/kg SID Lys was lower (P<0.05) than that of pigs fed diets containing 10.2g/kg SID Lys with either a high or low CP level confirming that the dietary Lys concentration in this diet was deficient and therefore this SID Lys level was used in all diets fed in Exp. 2. In Exp. 2, 300 growing pigs (22–50kg) were utilized in a dose–response study. Pigs were randomly allotted to one of five dietary treatments containing 9g/kg SID Lys. Graded levels of crystalline Thr (0.6, 1.0, 1.5, 1.9 or 2.4g/kg) were added to the basal diet to produce diets providing SID Thr to Lys ratios of 0.55, 0.60, 0.65, 0.70 or 0.75. Each diet was fed to six pens of pigs (three with barrows and three with gilts) with ten pigs per pen. Serum Thr (linear and quadratic, P<0.05) and glycine were increased (linear, P<0.05) as the dietary SID Thr to Lys ratio increased. Serum urea nitrogen (SUN; linear and quadratic, P<0.05), Lys, methionine and cystine decreased (linear, P<0.05) as the dietary SID Thr to Lys ratio increased. The optimum SID Thr to Lys ratios to maximize ADG and feed conversion ratio (FCR) as well as to minimize SUN levels were 0.68, 0.67 and 0.62 using a linear-breakpoint model and 0.73, 0.70 and 0.65 using a curvilinear-plateau model. Taking an average of these values, we conclude that the optimum SID Thr to Lys ratio for 22–50kg pigs fed low CP protein diets supplemented with CAA is 0.70 to maximize ADG, 0.68 to optimize FCR and 0.63 to minimize SUN.

Functional interactions of manno-oligosaccharides with dietary threonine in chicken gastrointestinal tract. II. Mucosal development, mucin dynamics and nutrient utilisation

1. A 3 × 2 factorial experimental design was used to investigate the interaction between threonine concentration (0·7, 1·0 and 1·3 of National Research Council (NRC), 1994, recommendations) and manno-oligosaccharides (MOS) supplemented at 0 and 2 g/kg on growth performance in relation to intestinal flow of crude mucins, mucosal development and nutrient utilisation. 2. There was no interaction between MOS and dietary threonine in any performance variable analysed, except for body weight gain during the period to 14 d of age, where body weight gain was significantly lower in birds fed excess threonine in the absence of MOS. Dietary MOS was also observed to significantly increase the body weight gain at deficient and adequate concentrations of threonine. 3. Dietary treatments had no significant effect on either the ileal external muscularis thickness or crypt depth. However, there was a MOS and threonine interaction in the ileal villus to crypt ratio and ileal crude mucin output with both being increased only at the adequate threonine concentration. 4. Dietary MOS tended to interact with threonine to increase the ileal uptake of D-glucose and L-threonine, but the effect was only apparent in birds fed on the deficient or excess threonine diet. There was no significant interaction between MOS and threonine on ileal digestibility of amino acids. Supplementation of MOS or increased dietary threonine significantly increased the apparent and standardised ileal digestibility of threonine. 5. Results from the current study indicate the possible link between the modulating effects of these supplements on intestinal mucosal development and mucin dynamics. This, in turn, may suggest a relatively higher proportion of mature enterocytes and absorptive area, which would be expected to improve the capacity for digestion and mucosal nutrient absorption.

Optimal Dietary True Ileal Digestible Threonine for Supporting the Mucosal Barrier in Small Intestine of Weanling Pigs1–3

Threonine is of great importance for the maintenance of intestinal health. However, little is known about the optimal level of dietary threonine for neonates or the underlying mechanisms of its beneficial action. Our objective in this study was to determine the effects of graded levels of true ileal digestible (TID) threonine on the intestinal mucosal barrier in weanling pigs. Four groups of piglets (n = 8/group) were fed for 14 d diets containing 0.37, 0.74, 0.89, or 1.11% TID threonine. The duodenal mucosa of piglets fed the 0.37 and 1.11% TID threonine diets exhibited distorted villus architecture. Compared with pigs fed the 0.74 and 0.89% TID threonine diets, apoptosis was higher (P < 0.05) in pigs fed the 1.11% TID threonine diet. Feeding 0.37 and 1.11% TID threonine reduced (P < 0.05) concentrations of ileal acidomucins and duodenal sulfomucins, respectively, compared with the 0.74% TID threonine group. Compared with piglets fed the 0.89% TID threonine diet, the total amounts of mucins in duodenum, as well as expression of MUC2 mRNA in duodenum and jejunum, were reduced (P < 0.05) in piglets fed the 0.37 and 1.11% TID threonine diets. Collectively, these findings indicate that a deficiency or excess of dietary threonine affects the intestinal mucosal barrier and that the optimal level of dietary TID threonine for supporting gut barrier function is 0.89% for weanling pigs. These new findings have important implications for both the maintenance of normal physiological functions and the prevention of gut-related diseases in neonates.

Effect of Phytase on Ileal Amino Acid Digestibility, Nitrogen Retention and AMEn for Broilers Fed Diets Containing Low and High Phytate Phosphorus

A 42 d broiler experiment was conducted to determine the effect of added Escherichia coli phytase (Phyzyme-XP 5000G) to low and high phytate P (PP) diets on performance and nutrient digestibility. The experiment consisted of 12 treatments with 2 levels of PP: 0.24% low-phytate (LP) group and 0.32% highphytate (HP) group. Both LP and HP groups had respective positive controls (PCS) with 0.39% in the starter and 0.29% NPP in the grower, respectively, and 5 basal diets with graded levels (0, 250, 500, 750 and 1000 FTU’s/kg diet) of added phytase. The PP level in the HP diets was increased by substituting part of the corn and soybean meal with canola and rice bran. Ileal GE digestibility and GE retention were significantly higher in the PCLP group compared to the PC-HP fed group. Ileal GE digestibility at d 42 was lower in the HP groups and increased with the addition of phytase. A PP x phytase interaction was detected for ileal GE retention at d 21, due to a significant phytase response in the LP groups, but no response in the HP groups. In contrast, at d 42 a significant PP x phytase interaction was detected for ileal GE retention due to a significant response to phytase addition in the HP groups, but not in the LP groups. The % ileal digestibility of threonine, tryptophan, and serine were affected by PP levels and phytase, with a significant interaction of PP and phytase for 21 d broilers, and cystine for 42 d broilers. In general, interactions of phytase and PP for ileal digestibility of specific amino acids were due to a lack of positive response to phytase when added to the HP diet for 21 d broilers, compared to improvements in ileal digestibility of all amino acids (P=0.1284) in either the HP or LP fed broilers at d 42. The slight improvement of ileal digestible amino acids seemed to correlate with a 6.2 percentage point improvement in ileal N digestibility for 42 d broilers fed either the LP or HP diets. Broilers fed the LP PC diet had a higher % ileal nitrogen and energy digestion than broilers fed the HP PC diet at 21 d but there was no difference in 42 d broilers fed different PP levels. In summary adding phytase to broiler diets improved energy utilization by 2.1-4.9% for both LP and HP fed broilers and an improved ileal total AA (TAA) digestibility by 1.9-6.1% for LP fed broilers.

A Deficiency or Excess of Dietary Threonine Reduces Protein Synthesis in Jejunum and Skeletal Muscle of Young Pigs

Dietary threonine imbalance is known to reduce the growth of the small intestine, liver, and skeletal muscle in young animals, but the underlying mechanism is largely unknown. Using the pig model, this study was conducted to test the hypothesis that either a deficiency or an excess of dietary threonine impairs protein synthesis in these tissues. Young pigs (25 d of age) were fed diets containing 0.37, 0.74 (current NRC requirement) or 1.11% true ileal digestible threonine (TIDT) (n = 6/diet). Pigs receiving the 0.74 and 1.11% TIDT diets were pair-fed with the same amount of feed as pigs receiving the 0.37% TIDT diet. After a 14-d dietary treatment, the fractional synthesis rate (FSR) of protein in tissues was measured using a flooding dose of l-phenylalanine plus l-[ring-2H5]phenylalanine. The results indicated that the FSR of protein in liver was reduced (P < 0.05) in pigs fed the 0.37% TIDT diet compared with pigs fed the 0.74 or 1.11% TIDT diet, and did not differ between pigs fed the 0.74 and 1.11% TIDT diets. The FSR of protein in longissimus muscle, jejunal mucosa, and mucins was reduced (P < 0.05) in pigs fed the 0.37 or 1.11% TIDT diet compared with pigs fed the 0.74% TIDT diet. The absolute synthesis rate of protein in the jejunal mucosa and muscle was also reduced (P < 0.01) in pigs fed the 0.37 and 1.11% TIDT diets compared with the controls. The absolute synthesis rate of hepatic protein was lower (P < 0.01) in pigs fed the 0.37% TIDT diets when compared with pigs fed the 0.74% TIDT diet. Protein synthesis in skeletal muscle as well as jejunal mucosa and mucins was reduced to a greater extent than that in liver in response to an imbalance of dietary threonine. Collectively, these results indicate that either an excess or a deficiency of dietary threonine decreases protein synthesis in rapidly growing tissues of young pigs. The findings provide a mechanism for the low growth performance of animals fed a threonine-imbalanced diet.