Digestible lysine requirement for growing Japanese quails

A total of 1,000 one-day-old Japanese quails were distributed at random, with 5 digestible lysine levels, in 10 replicates and with 20 birds per experimental unit. The basal diet was formulated based on corn and soybean, with 200.6 g CP/kg, 2900.00 kcal/kg ME, and 8.8 g digestible lysine/kg. This basal diet was supplemented with L-lysine HCl (784 g/kg), replacing glutamic acid, and corresponding to digestible lysine levels of 8.8 g/kg, 9.8 g/kg, 10.8 g/kg, 11.8 g/kg, and 12.8 g/kg. The increase in the levels of digestible lysine produced a greater weight gain in birds with up to 12.2 and 12.1 g of lysine/kg at 40 d of age. Carcass weight increased as levels were increased to up to 11.85 g of lysine/kg, and, similarly, egg production per bird housed increased up to 12.03 g of lysine/kg. A linear increase took place in the growing phase for feathering, fat, and crude protein deposits in the carcass, feed intake, and lysine intake. Egg production and egg mass per bird per d increased linearly in the laying phase with the weight gain of birds decreasing linearly until 100 d of age, and, similarly, the feed conversion per egg mass linearly improved in function of the lysine levels. A level of 11.85 g of digestible lysine/kg in the diet, which corresponded to a lysine intake of 120.5 mg/bird/d, provided better carcass weight at the end of the growing phase and better performance at the beginning of the laying phase for the Japanese quails.     

生长肥育猪可消化色氨酸需求参数研究

色氨酸（Trp）往往是猪饲粮的第二或第三限制性氨基酸,Trp不足可影响5-羟色胺的代谢,降低猪的生产性能。国外饲养标准对猪Trp的推荐量差异很大,而且大部分没有可消化的需求参数。中国瘦肉型猪饲养标准（1987）未列出Trp需要量的数据,我国至今也未有对生长-肥育猪Trp需求参数的研究报道。本试验旨在研究饲粮色氨酸水平对生长-肥育猪生产性能和血清尿素氮浓度的影响,以探讨生长-肥育猪可消化Trp的需求参数。     

Escherichia coli phytase improves growth performance of starter, grower, and finisher pigs fed phosphorus-deficient diets

Corn-soybean meal-based diets, consisting of a high-P control (HPC) containing supplemental dicalcium phosphate (DCP), a basal diet containing no DCP, and the basal diet plus Escherichia coli phytase at 500 or 1,000 phytase units per kilogram (FTU/kg; as-fed basis) were fed to evaluate growth performance in starter, grower, and finisher pigs. Pigs were blocked by weight and gender, such that average weight across treatments was similar, with equal numbers of barrows and gilts receiving each treatment in each block. In Exp. 1, 48 pigs with an average initial BW of 11 kg, housed individually, with 12 pens per diet, were used to evaluate growth performance over 3 wk. Overall ADG and G:F were increased linearly (P < 0.05) by dietary phytase addition. Final BW and plasma P concentrations at 3 wk also increased linearly (P < 0.05). In Exp. 2, 128 pigs with an average initial BW of 23 kg, housed four pigs per pen, with eight pens per diet, were used to evaluate growth performance over 6 wk. A linear increase in response to phytase was noted for ADG and G:F in all three 2-wk periods, as well as overall (P < 0.05). Percentage of bone ash also showed a linear increase (P < 0.01). In Exp. 3, 160 pigs (53 kg), housed five pigs per pen, with eight pens per diet, were used to evaluate growth performance over 6 wk. A linear increase was detected for final BW, as well as ADG and G:F in the first and second 2-wk periods, and overall (P < 0.01). Twenty-four 15-kg individually housed pigs were used to evaluate total-tract nutrient digestibility in Exp. 4. Daily absorption of P linearly increased (P < 0.05) with phytase supplementation. Results of this research indicate that E. coli phytase is effective in liberating phytate P for uptake and utilization by starter, grower, and finisher pigs.     

Commercial validation of the true ileal digestible lysine requirement for eleven- to twenty-seven-kilogram pigs

Five experiments utilizing 3,628 pigs were conducted to determine the true ileal digestible (TID) Lys requirement for 11- to 27-kg pigs fed corn-soybean meal diets. In Exp. 1, 216 barrows (initial BW = 11.5 kg) were used, with dietary TID Lys levels from 1.05 to 1.40% TID Lys (0.07% increments). All diets were isocaloric (3.42 Mcal of ME) and contained the same inclusion of soybean meal (33.1%). Dietary Lys content was increased by adding graded levels of L-Lys.HCl (0.0 to 0.445%), with other crystalline AA supplied to meet minimum AA-to-Lys ratios. For the 21-d period, ADG and G:F increased linearly (P < 0.001) with increasing Lys levels. Experiments 2 through 5 were each conducted in different commercial research facilities. In Exp. 2, a 5-point titration (1.05 to 1.41% TID Lys; 0.09% increments) was used containing the same level of soybean meal (34.3%), with graded levels of L-Lys.HCl addition as in Exp. 1 for a 16-d period. Exp. 3 used similar diets, but was a 28-d period from 11.8 to 28 kg. There were linear increases in ADG (P < 0.01) and G:F (P < 0.01) with increasing dietary Lys in both experiments. On the basis of these results, 2 additional 28-d experiments were conducted with similar diets, except for 1 additional level at 1.50% TID Lys. In Exp. 4, linear increases (P < 0.01) in ADG and G:F were observed from d 0 to 14. From d 14 to 28, there were quadratic increases (P < 0.04) in ADG and G:F, which resulted in quadratic increases (P < 0.01) in ADG and G:F with increasing dietary Lys for the entire 28-d period. Similarly, in Exp. 5, there were linear increases (P < 0.01) in growth performance from d 0 to 14, but there were quadratic increases in G:F (P < 0.001) with increasing dietary Lys for the overall period. Data from all 5 experiments yielded a single-slope, broken-line response, with requirement estimates for TID Lys of 1.33 and 1.35% for 11- to 19-kg pigs. The 5 experiments gave requirement estimates of 1.30% TID Lys (3.80 g of TID Lys/Mcal of ME) for 11- to 27-kg pigs, equivalent to 19 g of TID Lys/kg of gain.     

Digestible valine-to-digestible lysine ratios in brown commercial layer diets

Considering that Val may potentially be a limiting amino acid for laying hens, an experiment was carried out to determine the ideal digestible Val-to-Lys ratio in the diets of 42- to 54-wk-old brown layers. Literature reports are divergent, with ratios varying between 86 and 102%, which suggests that further research is needed. Five different digestible Val-to-Lys ratios were evaluated: 84 (0.555% digestible Val), 88, 92, 96, and 100%. Feed intake (g/hen per day), egg production (%), egg weight (g), egg mass (g), FCR (kg/dozen and g/g), egg quality (yolk, eggshell, and albumen %), and egg weight (g) were evaluated. Egg weight, egg internal quality, and weight gain were not influenced by the different dietary digestible Val-to-Lys ratios. The evaluated ratios linearly affected feed intake and had a quadratic effect on egg production, egg mass, and FCR (kg/dozen and g/g). Based on the evaluated parameters, the ideal digestible Val-to-Lys ratio is 92%, corresponding to 0.607% digestible Val or 567 mg/hen per day of digestible Val.     

Serum urea concentration as a predictor of dietary lysine requirement in selected lines of pigs

Serum urea concentrations were measured in Large White pigs from lines divergently selected for components of efficient lean growth rate and performance tested over three 14-d test periods starting at 30, 50, and 75 kg. Two methods of performance testing were used. Phase-fed pigs were fed to appetite isoenergetic diets differing in total lysine:energy ratio (0.58, 0.69, 0.81, 0.91, 1.01, 1.12, and 1.23 g/MJ of digestible energy), whereas diet-choice pigs were offered a choice of the 0.69 and 1.12 lysine:energy diets. Between test periods, all animals were fed one diet: 0.91 g of lysine/MJ of digestible energy. The study consisted of 230 boars and gilts with 150 pigs performance tested on phase-feeding and 80 pigs on diet-choice. The line selected for high lean food conversion had lower urea concentrations on each diet than the line selected for high lean growth rate, despite similar predicted lysine balances. Efficiency of lean growth rather than the rate of lean growth may be a better selection strategy in the context of nitrogen excretion. Urea concentrations at the end of each test period were correlated with lysine intake (0.33, 0.48 and 0.65; standard error, 0.08) and predicted lysine balance (0.39,0.44, and 0.64), but were uncorrelated with predicted lysine for protein deposition (0.01, 0.08, and 0.08) and maintenance. Urea concentration at the end of a test period was not a useful predictor of protein deposition, even after accounting for pretest variation in urea concentration and food intake during test. The expected response pattern of serum urea concentration to diets differing in total lysine:energy would be nonlinear, with the point of inflection occurring at the required dietary total lysine:energy for each genotype. However, there was no evidence of such an inflection point such that the prediction of lysine requirement from urea concentration was not possible for the selection lines in the study.     

基于协方差分析对20～40 kg生长猪真可消化赖氨酸需要量研究

试验选用35头体重为20kg左右的杜×(长×大)三元杂交阉公猪,采用完全随机单因子试验设计,随机分为5个处理,单栏饲喂,自由采食,试验期为35d。分别饲喂真可消化赖氨酸水平(TLys)为1.15%、1.05%、0.95%、0.85%和0.75%的等能(14.23MJ/kg)、等氨基酸模式的玉米-豆粕型日粮。基于协方差分析校正生长猪始重差异,通过测定不同TLys水平对生产性能的影响,确定真可消化赖氨酸需要量。结果表明,当TLys为0.95%时,平均日增重最高(P<0.01),料重比最低(P<0.05);经回归分析,TLys含量为0.95%时,平均日增重达到最大值,而料重比最低。上述结果提示,20～40kg生长猪的TLys需求量为0.95%。     

Hematologic and biochemical reference intervals for Norwegian crossbreed grower pigs

Background: Hematologic and biochemical reference intervals depend on many factors, including environment and age. Reference intervals for Norwegian grower pigs are lacking, and previously published reference intervals for similar pigs from other countries are now outdated due to significant changes in management and breeding on the pig farms. Objectives: The aim of this study was to determine updated reference intervals for hematologic and biochemical analytes in healthy crossbred grower pigs, and to compare the results among 3 different farms. Methods: Blood samples were collected from 104 clinically healthy pigs of the most common Norwegian crossbreed (Landrace Yorkshire sow × Landrace Duroc boar). The pigs were 12–16 weeks old, weighed 30–50 kg, of both sexes, and lived on 3 farms in eastern Norway. Automated hematologic and biochemical analysis were performed using ADVIA 2120 and ADVIA 1650 analyzers. Results: Five samples were excluded because of hemolysis (1) or outliers (4). Reference intervals were calculated using parametric or nonparametric methods, depending on data distribution. Mean, median, minimum, and maximum values were tabulated. Conclusions: The reference intervals calculated in this study will be useful for the diagnosis and monitoring of disease in this widespread crossbreed pig. Compared with previously published reference values, reference intervals for total WBC count, creatine kinase and alanine aminotransferase activities, and albumin, bilirubin, and urea concentrations in this study differed notably.     

Digestible and metabolizable energy of crude glycerol for growing pigs

The apparent DE and ME values of crude glycerol for growing pigs were determined in 5 experiments using crude glycerol (86.95% glycerol) from a biodiesel production facility, which used soybean oil as the initial feedstock. Dietary treatments were 0, 5, or 10% glycerol addition to basal diets in Exp. 1; 0, 5, 10, or 20% glycerol addition to basal diets in Exp. 2; and 0 and 10% crude glycerol addition to the basal diets in Exp. 3, 4, and 5. Each diet was fed twice daily to pigs in individual metabolism crates. After a 10-d adjustment period, a 5-d balance trial was conducted. During the collection period, feces and urine were collected separately after each meal and stored at 0 degrees C until analyses. The GE of each dietary treatment and samples of urine and feces from each pig were determined by isoperibol bomb calorimetry. Digestible energy of the diet was calculated by subtracting fecal energy from the GE in the feed, whereas ME was calculated by subtracting the urinary energy from DE. The DE and ME values of crude glycerol were estimated as the slope of the linear relationship between either DE or ME intake from the experimental diet and feed intake. Among all experiments, the crude glycerol (86.95% glycerol) examined in this study was shown to have a DE of 3,344 +/- 8 kcal/kg and an ME of 3,207 +/- 10 kcal/kg, thereby providing a highly available energy source for growing pigs.     

Glycemic index of starch affects nitrogen retention in grower pigs

Three studies were performed to examine the effect of starch and protein digestion rates on N retention in grower pigs. In Exp. 1, the glycemic index (GI) of corn, a malting barley, and a slow-rumen-degradable barley (SRD-barley) were measured using 6 barrows (BW = 18.0 ± 0.5 kg). The GI of malting barley was greater (P < 0.05) than that of SRD-barley (71.1 vs. 49.4), and the GI of both barley cultivars was less (P < 0.05) than that of corn (104.8). In Exp. 2, the standardized ileal digestibility of AA and DE content of the 3 ingredients were determined using 5 ileal-cannulated barrows (BW = 20.7 ± 2.3). The apparent total-tract energy digestibility values of corn (86.1%) and malting barley (85.7%) were greater (P < 0.05) than that of SRD-barley (82.3%). The standardized ileal digestibility of Lys was 94.0, 92.6, and 92.4% for corn, malting barley, and SRD-barley, respectively, and did not differ among grains. In Exp. 3, 6 diets were formulated to equal DE (3.40 Mcal/kg), standardized ileal digestibility of Lys (8.6 g/kg), starch (424.9 g/kg), and digestible CP (180.0 g/kg) using the values obtained in Exp. 2. Three GI [high (corn), medium (malting barley), and low (SRD-barley)] and 2 rates of protein digestion [rapid (soy protein hydrolysate) and slow (soy protein isolate)] were tested in a 3 × 2 factorial arrangement with 36 barrows (BW = 32.2 ± 2.5 kg). Pigs were fed 3.0 times the maintenance energy requirement daily in 2 meals for 2 wk and were housed in metabolic crates to collect feces and urine separately. At the end of the study, intestinal contents were collected from 4 equal-length segments of the small intestine. The percentage of unabsorbed CP in segment 1 relative to dietary CP was greater (P < 0.05) for the soy protein isolate diet than for the soy protein hydrolysate diet (170.3 vs. 116.5%). The percentages of unabsorbed starch in segments 1 and 2 were greater (P < 0.05) for the SRD-barley diet than for the malting barley or corn diet. Nitrogen intake and fecal N excretion were greater (P < 0.05) for pigs fed the malting barley and SRD-barley diets than for pigs fed the corn diet. Urinary N excretion was greater (P < 0.05) for pigs fed the SRD-barley diet than for pigs fed the corn or malting barley diet. Pigs fed slowly digestible starch (SRD-barley; 46.6%) had less (P < 0.05) net N retention than pigs fed corn or malting barley (54.7 and 54.1%, respectively). In conclusion, slowly digestible starch sources such as SRD-barley may not be suitable to support maximum protein deposition in restricted-fed grower pigs.     

Performance dependent lysine requirement of fattening pigs. 3. Effect of amino acid and energy intake on fat, protein and lysine deposition of swine

The gain in structural matter had a linear course with a corresponding feeding intensity and depending on the period of fattening. However, the animals given high-energy diets deposited 130 g protein per day during the first fattening period, this deposition being compensated in the course of further growth by a considerably lower deposition in the sense of aequifinality. Up to a live weight of 70 kg, animals subjected first to restricted feeding and then to fully balanced feeding revealed the highest protein deposition during the last period of fattening, this fact emphasizing the leanmeat character of the animal material used. The daily fat deposition was found clearly determined by energy intake and independent of amino acid supply. Lysine conversion was influenced by the intake of lysine and energy. Under feeding to norm it reached some 40 and 30% during the first and second periods of fattening, respectively.     

Xylanase supplementation improves energy digestibility of wheat by-products in grower pigs

Value-added processing of cereals produces high-value fractions for food and bio-processing application and by-products that are used in animal nutrition to reduce feed costs. Wheat by-products contain arabinoxylans that might limit nutrient digestibility. Effects of xylanase supplementation (0 or 4375 U/kg feed) on energy digestibility were studied in a wheat control and by-product diets (30% millrun, middlings, shorts, screenings, and bran) in a 2 × 6 factorial arrangement. The wheat control diet was formulated to contain 3.34 Mcal digestible energy (DE)/kg and 2.8 g apparent digestible lysine/Mcal DE, and included 0.4% chromic oxide as a marker for digestibility. Twelve ileal-cannulated pigs (32.5 ± 2.5 kg) were each fed seven of 12 diets. Faeces and then digesta were each collected for 2 d, and diet digestibility values are reported. Wheat had higher ileal and total-tract energy digestibility than by-products (P < 0.01). Xylanase improved energy digestibilities for by-products (P < 0.001) but not for wheat. Among by-products, ileal energy digestibility was lowest for middlings (62%), then bran < screenings < millrun, and highest for shorts (66%). Xylanase improved (P < 0.05) ileal energy digestibility of millrun by 19% to 76%. Total-tract energy digestibility of millrun improved from 72 to 79% (similar to wheat) with xylanase (P < 0.05). In summary, xylanase improved energy digestibility in the selected wheat by-product diets, indicating that arabinoxylans in wheat by-products limit nutrient digestibility.     

Estimate of the variability of the lysine requirement of growing pigs using the indicator amino acid oxidation technique

Although AA requirements for the mean in a population of growing pigs are well established, there are no direct estimates of their variability within the population. The indicator AA oxidation method allows repeated measurements in a short period of time so that the AA requirement can be determined for individual pigs. The objective was to determine the Lys requirement in individual pigs to derive a first estimate of the population mean requirement and its variability. Nine individually housed barrows (15 to 18 kg) were surgically implanted with venous catheters for isotope infusion. Pigs were offered, in random order, isonitrogenous and isoenergetic diets with one of seven Lys concentrations (4.8 to 15.5 g of Lys/kg diet, as-fed basis). The pigs were fed twice daily, except for study days when they received one-half of the daily allowance in eight equal hourly meals. After a validated minimum adaptation period, indicator (Phe) oxidation was determined for each dietary Lys level during a 4-h primed, constant infusion of L-[1-(14C)]Phe at a rate of 464 kBq/h. The Lys requirement was calculated using a two-phase linear regression crossover analysis within individual pigs. For each pig, Phe oxidation decreased linearly (P < 0.02) as the dietary Lys concentration increased until the requirement was reached; thereafter, Phe oxidation was not different. The true ileal digestible Lys requirement ranged from 7.5 to 10.6 g/kg of diet (as-fed basis) for the nine animals. The mean requirement for all pigs was 9.1 g/d (CV, 11.6%) or 93.9% (CV, 9.8%) of the predicted (NRC, 1998) requirement based on each pig's mean BW and energy intake. The measured and predicted requirements did not differ. The indicator AA oxidation method gave values for Lys requirement similar to conventional methods. The short (< 3 wk) experimental period allows, for the first time, the estimate of population variability, which provides for more accurate calculation of the effect of altering Lys intake on herd performance and production economics. This method is suitable to use with all dietary indispensable AA.     

Digestible tryptophan requirements of starting, growing, and finishing pigs.

Seven hundred eight crossbred pigs were used in growth and digestion trials to determine the digestible tryptophan (Trp) requirement of starting (6 to 16 kg), growing (22 to 50 kg), and finishing (55 to 97 kg) pigs. Each growth trial evaluated a corn-fish meal-corn gluten meal basal diet, the basal diet with five incremental additions of L-Trp, and a control corn-soybean meal diet. The tryptophan content of the six incremental diets ranged from .13 to .255% for starting pigs, .08 to .18% for growing pigs, and .063 to .163% for finishing pigs. Lysine contents of basal diets were 1.38, .90, and .72% for starting, growing, and finishing diets, respectively. In all trials, ADG, ADFI, and gain/feed increased (P less than .001) linearly and quadratically as dietary Trp increased. Broken-line regression analyses determined the total dietary Trp requirements needed to optimize performance to be .19, .13, and .09% (as-fed basis) for starting, growing, and finishing pigs, respectively. These concentrations equated to Trp intakes of .96, 2.18, and 2.88 g/d. A digestion trial using growing pigs (29 kg initially) determined the apparent ileal digestibility of Trp in the basal starting and growing diets to be 72 and 70%, respectively; a similar trial with finishing pigs (55 kg initially) found 59% Trp digestibility for the basal finishing diet. Mean digestibility of L-Trp was 97%. Based on these values and the total Trp requirements given above, the digestible Trp requirements are .15, .10, and .06% for starting, growing, and finishing pigs, respectively.     

The effect of dietary lysine restriction during the grower phase and subsequent dietary lysine concentration during the realimentation phase on the performance, carcass characteristics and nitrogen balance of growing–finishing pigs

Two experiments (exp.) were conducted to determine the effect of dietary lysine restriction during the grower phase and subsequent dietary lysine concentration during realimentation on the performance, carcass characteristics and nitrogen (N) balance of growing–finishing pigs. Seventy-two pairs of crossbred [meatline sires × (Large White × Landrace) dams] pigs (36 pairs entire male, 36 pairs female) were used in a 2 × 4 factorial performance study (exp. 1, 35 to 96 kg). The two factors were Diet1 (two lysine levels: LO or HI, day (d) 0 to 35) and Diet2 (four lysine levels: LO, M1, M2 and HI, d36 to slaughter). A further 30 boars were used in a 2 × 3 factorial N-balance study (exp. 2, 31 to 42 kg; Diet1: LO or HI; Diet2: LO, M3 and HI). The crude protein (CP) and lysine contents of the five isoenergetic (14.0 MJ DE/kg) diets were: LO (139 g/kg CP, 8.1 g lysine/kg), M1 (162 g/kg CP, 9.7 g lysine/kg), M2 (190 g/kg CP, 11.4 g lysine/kg), M3 (180 g/kg CP, 10.7 g lysine/kg) and HI (217 g/kg CP, 13.1 g lysine/kg). Diets were based on barley, wheat and soyabean meal with added vitamins, minerals and amino acids. Ratios of amino acids relative to lysine were similar for all diets. From d0 to 35 in exp. 1, pigs fed LO had lower daily gains (ADG: 785 vs. 939 g/day; P < 0.001), daily lysine intakes (DLYIN: 14.4 vs. 22.6 g/day; P < 0.001) and poorer feed conversion ratios (FCR: 2.28 vs. 1.84 kg/kg; P < 0.001) than pigs fed HI. From d36 to slaughter, pigs initially fed LO had higher ADG than those initially fed HI (948 vs. 879 g/day; P < 0.01). However, from d0 to slaughter, pigs initially fed LO had lower ADG (868 g/day; P < 0.01) and DLYIN (19.1 g/day; P < 0.001) than those fed HI (913 g/day and 23.3 g/day respectively). There was a Diet1 × Diet2 interaction for FCR from d36 to slaughter and d0 to slaughter (P < 0.05). FCR of pigs previously fed LO improved with each increase in dietary lysine concentration up to 13.1 g/kg (HI), but improvement was only evident for lysine concentrations up to 11.4 g/kg (M2) for pigs previously fed HI. In exp. 2, Diet1 was fed for an initial 5-day collection period (after adjustment to crate; C1). Diet2 was then fed and immediately there were 2 successive 5-day collection periods (C2 and C3). A Diet1 × Time interaction (P < 0.001) indicated that although N retention (NRET) during C1 was lower for pigs fed LO, there was no difference during C2 and C3 in NRET of pigs initially fed either LO or HI (14.5 vs. 25.0 g/day; 23.2 vs. 23.0 g/day; 26.0 vs. 26.6 g/day, for C1, C2 and C3, respectively). However, a similar interaction indicates that although N excretion (NEX) was 23% lower for LO compared with HI pigs during C1, there was no residual reduction in NEX of pigs initially fed LO (P < 0.01: 8.9 vs. 11.6 g/day; 12.3 vs. 12.7 g/day; 13.8 vs. 14.0 g/day, for C1, C2 and C3, respectively). Exp. 1 indicated improved performance and an ability to respond positively to higher lysine concentrations during realimentation for previously restricted compared with unrestricted pigs, however, overall performance was reduced. However, exp. 2 indicated that although NRET of initially restricted pigs increased during realimentation, it did not surpass that of unrestricted pigs. This apparent discrepancy may have been due to the time period of the N balance study.     

Valine requirement of nursery pigs

Six experiments were conducted to determine the true digestible valine requirement of 5- to 20-kg pigs. In Exp. 1, a valine-deficient diet for 5- to 10-kg pigs was developed and validated in terms of growth performance in response to supplemental L-valine. A different basal diet was validated for 10- to 20-kg pigs in Exp. 2. Both diets were demonstrated to be deficient in valine and to support performance equivalent to typical nursery diets when fortified with L-valine. In Exp. 3, true ileal digestibility of valine in the two basal diets was determined in eight pigs fitted with a simple T-cannula at the terminal ileum. Another four pigs received an enzymatically hydrolyzed casein-based diet to determine endogenous contributions to collected ileal digesta. The two diets were found to have true valine digestibilities of 82% (5- to 10-kg pigs) and 86% (10- to 20-kg pigs). In Exp. 4, 80 weaned pigs (5.8 kg) were offered the basal diet fortified with five incremental doses (0.08%) of L-valine. Weight gain increased quadratically (P < 0.05) with increasing levels of valine. Broken-line analysis revealed a true digestible valine requirement of 0.86 +/- 0.03%. In Exp. 5, the true digestible valine requirement of 10- to 20-kg pigs was estimated with 120 pigs (10.9 kg) using the second basal diet fortified with six incremental doses (0.05%) of L-valine. The data suggested a digestible valine requirement level of about 0.775%, which was reevaluated in Exp. 6, wherein pigs did not respond to levels of digestible valine higher than 0.775%. In conclusion, requirement estimates were 2.50 and 2.22 g of true digestible valine per megacalorie of ME for 5- to 10- and 10- to 20-kg pigs, respectively. These empirical estimates are in close agreement with recent estimates of the National Research Council Subcommittee on Swine Nutrition of 2.48 and 2.11 g of true digestible valine per megacalorie of ME, respectively.     

Estimation of the standardized ileal digestible lysine requirement and optimal sulphur amino acids to lysine ratio for 30–50 kg pigs

Two experiments were conducted to determine the standardized ileal digestible (SID) lysine (Lys) requirement and the ideal SID sulphur amino acids (SAA) to Lys ratio for 30–50 kg crossbred pigs. In experiment 1, a total of 72 crossbred pigs with an average initial body weight (BW) of 28.9 kg were allotted to one of six dietary treatments in a randomized complete block design. Each diet was assigned to six pens containing two pigs each. Six diets were obtained by supplementing graded levels of L‐Lysine?HCl to create six dietary levels of SID Lys (0.70%, 0.80%, 0.90%, 1.00%, 1.10% and 1.20%). Responses of weight gain (ADG) and gain:feed (G:F) to increasing the SID Lys content of the diet fitted well with the curvilinear‐plateau model; whereas, for plasma urea nitrogen (PUN) two‐slope linear broken‐line model was well fitted. The optimal SID Lys requirement for the pigs of this period was 1.10%. Experiment 2 was a dose–response study using SID Met+Cys to Lys ratios of 50%, 55%, 60%, 65%, 70% and 64%. A total of 72 crossbred pigs with initial BW of 32.9 kg were randomly allotted to receive one of the six diets. Diets 1–5 were formulated to contain 1.0% SID Lys to be second limiting in Lys and diet 6 contained 1.11% SID Lys to be adequate in Lys. The average optimal SID SAA:Lys ratio for maximal ADG and G:F and minimal PUN was 65.2% using curvilinear‐plateau and linear broken‐line models.