Amino acid composition of fetus, placenta, and uterus in gilts throughout gestation.

An accurate understanding of the AA composition of the products of conception is needed to accurately model dietary AA needs of pregnant swine. To determine AA composition in fetal pigs, the placenta, and the uterus at various stages of gestation, samples from a total of 65 gilts slaughtered at assigned days of gestation (d 43, 58, 73, 91, 101, and 108) were used. The AA concentrations (g/kg each wet tissue) in the fetus, placenta, or uterus increased as gestation progressed, with major increases occurring from d 73 to 108 of gestation ( < 0.05). For fetus, AA content on a DM basis (%) and AA contribution to total fetal AA (g/100 g total AA of fetal tissue) generally decreased as gestation progressed ( < 0.05) except for Arg and Ala, which increased from d 73 of gestation, and for Gly and Pro, which increased progressively ( < 0.05) from d 43. Placental AA content on a DM basis increased up to d 91 or 101 of gestation ( < 0.05) and then slightly decreased on d 108 of gestation except for His, Cys, and Met + Cys. Amino acid contribution to total placental AA decreased for all AA as gestation progressed ( < 0.05), except for Arg, Ala, Gly, and Pro, which increased from d 58 of gestation. Essential AA content in the uterus on a DM basis had no major changes during gestation, whereas nonessential AA content decreased ( < 0.05) as gestation progressed, except for Asp. For AA contribution to total uterine AA, some essential AA (Ile, Leu, Lys, Met, Trp, and Val; < 0.06) and Asp ( < 0.01) contributions increased with increasing gestational ages, whereas Arg ( = 0.08), Cys, Gly, and Pro ( < 0.05) contributions decreased as gestation progressed. Differences in AA contribution to total AA within each tissue varied among the fetus, placenta, and uterus by type of AA. These results demonstrate that AA compositions of fetal pigs, placenta, and uterus are changed differentially as gestation progresses; in particular, Arg, Ala, Gly, and Pro compositions in fetus and placenta increased progressively. These compositional data for each reproductive tissue and fetus will help to model AA requirements in gestation.

Effects of reducing dietary crude protein levels and replacement with crystalline amino acids on growth performance, carcass composition, and fresh pork quality of finishing pigs fed ractopamine hydrochloride.

Progeny of GPK-35 females mated to PIC 380 boars were blocked by initial BW, and within the 9 blocks, pens of pigs (3 gilts and 3 barrows/pen) were randomly assigned to dietary treatments where CP of finisher-I, -II, and -III diets was 1) 16.04, 14.55, and 16.23%, respectively (Ctrl); 2) 14.76, 13.48, and 15.27%, respectively (ILE); 3) 14.26, 12.78, and 14.28%, respectively (VAL); or 4) 12.65, 12.38, and 13.32%, respectively (NoSBM). All finisher-III diets included 10 mg/kg of ractopamine hydrochloride (RAC) and a Lys:ME ratio of 2.79 g/Mcal. At slaughter, HCW and Fat-O-Meat'er data were recorded before carcasses were subjected to a rapid chilling process. A subsample of whole hams (2/pen) and whole loins (2/pen) were transported under refrigeration to the University of Arkansas. Hams were dissected with a knife into lean, fat, and bone, and 2.5-cm-thick chops from the semimembranosus (SM) and the LM were used to measure fresh pork quality characteristics. Both ADG and G:F decreased (linear, = 0.05) as CP decreased in finisher-I diets, whereas ADFI was reduced (linear, = 0.01) in response to decreasing CP in finisher-II diets. When RAC was included in the finisher-III diets, ADFI and BW decreased (linear, ≤ 0.03) with decreasing CP, and pigs fed the ILE diet had greater (cubic, < 0.01) G:F than pigs fed the Ctrl and VAL diets. Across the entire finishing period, ADG and ADFI decreased (linear, = 0.01) in response to reductions in dietary CP. Conversely, reducing CP in finisher diets did not ( ≥ 0.13) affect carcass yield, fat depth, LM depth, or calculated fat-free lean yield, and dietary CP content did not ( ≥ 0.09) alter the lean, fat, or bone composition of fresh hams. Moreover, there was no effect of dietary CP on the visual and instrumental color or firmness of the LM ( ≥ 0.06) or SM ( ≥ 0.12). However, there were linear increases in LM marbling scores ( = 0.02) and intramuscular fat content ( = 0.03) as CP was reduced in the finisher diets. Although reducing dietary CP decreased overall ADG and ADFI by approximately 6.1 and 4.9%, respectively, carcass composition was not impacted by dietary CP level. More importantly, reducing dietary CP, although meeting the standard ileal digestible requirements for Lys, Thr, Trp, Met, Ile, and Val with crystalline AA, did not impact pork color or water-holding capacity and actually increased the intramuscular fat content of the LM.

Antibiotic inclusion in the diet did not alter the standardized ileal digestible tryptophan to lysine ratio for growing pigs.

Two 21-d experiments were conducted to determine the optimum standardized ileal digestible (SID) Trp:Lys ratio for growing pigs; 1 experiment fed diets supplemented with or without an antibiotic. The primary response variables in both experiments were ADG, ADFI, G:F, and plasma urea N (PUN) concentrations with the optimum SID Trp:Lys ratio detected using broken-line analysis. Experiment 1 evaluated the optimum SID Trp:Lys ratio in growing pigs fed diets supplemented with an antibiotic. This experiment used 120 crossbred pigs that were blocked by sex and initial BW (24.13 ± 2.72 kg) and allotted to 6 SID Trp:Lys ratios in 4 replicates. Dietary treatments were formulated by the addition of crystalline Trp to create 6 SID Trp:Lys ratios (13.08%, 14.06%, 15.04%, 17.00%, 18.95%, and 20.91%) with a constant SID Lys level of 0.655%. As SID Trp:Lys ratios increased, ADG, ADFI, and G:F increased, and PUN concentrations decreased linearly ( < 0.05) and quadratically ( < 0.05). Linear broken-line analysis yielded optimum SID Trp:Lys ratios of 17.93% ( < 0.001) and 16.17% ( = 0.009) for ADG and PUN, respectively, resulting in a mean optimum SID Trp:Lys ratio of 17.05%. Experiment 2 evaluated the optimum SID Trp:Lys ratio in growing pigs fed diets supplemented with or without an antibiotic. It used a total of 324 crossbred pigs (initial BW: 30.81 ± 3.56 kg) that were allotted to 6 SID Trp:Lys ratios in 6 replicates. Dietary treatments were formulated by the addition of crystalline Trp to create 6 SID Trp:Lys ratios (12.52%, 14.86%, 17.20%, 19.54%, 21.88%, and 24.22%) with a constant SID Lys level of 0.67%. As SID Trp:Lys ratios increased, ADG, ADFI, and G:F increased, and PUN concentrations decreased linearly ( < 0.001) and quadratically ( < 0.001) regardless of antibiotic inclusion. There were no differences by the antibiotic treatment in ADG, ADFI, G:F, or PUN concentrations ( > 0.49) and no interactions between antibiotics and Trp:Lys ratios ( > 0.29). When the data for all pigs were pooled for the various Trp:Lys ratios, the optimum SID Trp:Lys ratios for ADG and PUN based on linear broken-line analysis were 14.58% ( < 0.001) and 14.54% ( < 0.001), respectively, resulting in an optimum SID Trp:Lys ratio of 14.56% as the mean of the determined optima for ADG and PUN responses. These results demonstrate that the optimum SID Trp:Lys ratio for 30- to 50-kg growing pigs is not impacted by the dietary inclusion of an antibiotic as long as the diets are formulated on an SID AA basis.

Standardized Ileal Amino Acid Digestibility of Corn, Corn Distillers' Dried Grains with Solubles, Wheat Middlings, and Bakery By-Products in Broilers and Laying Hens.

Standardized ileal amino acid digestibility (SIAAD) of 5 samples of corn distillers dried grain with solubles (DDGS), 5 samples of bakery by-products (BBP), 3 samples of corn, and 1 sample of wheat middlings (WM) were evaluated in broilers and laying hens. Diets containing each of the 14 feed ingredients were evaluated in 21 day-old broiler chickens. The DDGS and BBP containing diets were fed to 30-week-old laying hens, while corn and wheat middling were evaluated in 50-week-old laying hens. All the diets were semi-purified with each feed ingredient being the only source of amino acid (AA). To obtain SIAAD values, apparent ileal AA digestibility was corrected for basal ileal endogenous AA losses using values generated from broilers and laying hens fed a nitrogen-free diet. Ileal crude protein digestibility for the 5 DDGS samples was higher (P < 0.05) in broilers than in laying hens. Broilers had higher SIAAD for DDGS 2, 3, 4, and 5 while there was no difference for DDGS 1 except for 4 AA where broilers had higher (P < 0.05) SIAAD values. Standardized ileal AA digestibility values for broilers were higher (P < 0.05) for BBP 1 and 4. Ileal CP digestibility for corn 1 was higher (P < 0.05) for broilers compared to laying hens, and SIAAD values for the 16 AA (9 indispensable and 7 dispensable) evaluated in this study were higher (P < 0.05) in broilers. Broilers had higher (P < 0.05) SIAAD values for 4 (histidine, leucine, phenylalanine, and valine) and 6 (histidine, leucine, methionine, phenylalanine, threonine, and valine) indispensable and 3 (cysteine, glutamic acid, and proline) and 4 (cysteine, glutamic acid, proline, and serine) dispensable AA for corn 2 and corn 3, respectively. No difference in SIAAD between broilers and laying hens was observed for WM. Results from this study confirm that high variability in digestibility exists between different samples of DDGS. Differences in SIAAD between broilers and laying hens were observed in some samples of DDGS and BBP.

Standardized ileal amino acid digestibility of meat and bone meal and soybean meal in laying hens and broilers.

The objective of this study was to determine the standardized ileal amino acid digestibility (SIAAD) of 7 meat and bone meal (MBM) and 3 soybean meal (SBM) samples in broilers (Ross 708) and laying hens (Hy-line W36). All 10 feed ingredients were evaluated in 21-d-old broiler chickens and 30- or 50-wk-old laying hens. Standardization was accomplished by correcting for basal ileal endogenous amino acid losses using a nitrogen-free diet. Broilers were reared in cages from d 0 to 16 on a standard broiler starter diet adequate in all nutrients and energy; thereafter, they were allotted to treatments using a randomized complete design with 6 replicate cages of 8 birds each. For the laying hens, 6 replicate cages of 6 birds each (542 cm(2)/bird) were used. Each treatment diet, which was fed for 5 d, was semipurified, with MBM or SBM being the sole source of amino acids in each diet. Ileal endogenous amino acid losses were not different between broilers and the 2 groups of laying hens. Meat and bone meal from different locations varied widely in digestibility. Broilers had higher (P < 0.05) SIAAD in 4 of the 7 MBM samples. In 2 of the 3 SBM samples, broilers had higher (P < 0.05) SIAAD for most of the nonessential amino acids. Generally, hens had 6.4 and 7.7% units less Met and Lys digestibility of all MBM samples after standardization. Dry matter digestibility values of the SBM samples were higher (P < 0.05) in broilers. Likewise, broilers had 4.1 and 1.5% units more Met and Lys digestibility of all the SBM samples evaluated compared with those from laying hens. The results of these experiments suggest that differences exist in the digestive capabilities of laying hens and broilers, which indicates that species-specific nutrient digestibility values or adjustments may be needed.

Amino acid and phosphorus digestibility and concentration of digestible and metabolizable energy in hydrolyzed feather meal fed to growing pigs.

Two experiments were conducted to determine the standardized ileal digestibility (SID) of AA (Exp. 1), the standardized total tract digestibility (STTD) of P, and the concentration of DE and ME (Exp. 2) in hydrolyzed feather meal (FM) fed to growing pigs. Eight samples of FM were obtained from 4 different processing plants (FM1, FM2, FM3, and FM4). Each plant provided samples of FM without and with added blood. In Exp. 1, 10 barrows (initial BW: 24.0 ± 0.8 kg) were prepared with a T-cannula in the distal ileum and allotted to a 10 × 10 Latin square design with 10 diets and ten 7-d periods. A N-free diet, a diet based on soybean meal (SBM), and 8 diets based on a combination of SBM and each of the 8 sources of FM were formulated. Values for the SID of CP and AA in each source of FM were calculated using the difference procedure. The SID of CP and all AA was different (P < 0.001) among sources of FM. Among the indispensable AA, the overall effect of addition of blood was statistically significant (P < 0.05) for the SID of Ile, Leu, Lys, Phe, and Val, but for some sources, the SID of these AA was increased by addition of blood, whereas for other sources, the SID was reduced or not changed (interaction, P < 0.05). As an example, the SID of Lys in FM3 and FM4 with added blood were greater (P < 0.05) than in FM3 and FM4 without blood, but no difference in the SID of Lys was observed for FM1 and FM2 without and with blood (interaction, P < 0.01). In Exp. 2, 72 growing barrows (initial BW: 13.3 ± 1.5 kg) were used with 9 diets and 8 replicate pigs per diet. A corn-diet consisting of 98.4% corn was formulated and 8 additional diets were formulated by mixing corn with 25% FM. The STTD of P and the DE and ME of each source of FM were calculated using the difference procedure. The STTD of P tended (P = 0.09) to be different among FM sources and the STTD of P in FM with added blood was less than in FM without blood. On a DM basis, DE and ME values were affected (P < 0.05) by both source of FM and addition of blood. However, an interaction (P < 0.05) between source of FM and addition of blood for ME was observed because addition of blood to FM3 and FM4 reduced (P < 0.05) the ME, whereas addition of blood to FM1 and FM2 had no impact on ME. In summary, the SID of AA, STTD of P, and the energy concentration vary among sources of FM and the effects of adding blood to FM is not consistent among sources.

Dietary guanidino acetic acid is an efficacious replacement for arginine for young chicks.

Guanidino acetic acid (GAA) is synthesized in the liver and kidney from Arg and Gly and subsequently methylated by S-adenosylmethionine to form creatine. Four bioassays were carried out to determine the capacity of GAA to serve as a dietary replacement for Arg for growing chicks. Broiler chicks were fed Arg-deficient dextrose-casein (0.88% Arg) or corn-corn coproduct-soybean meal (1.0% Arg) basal diets during 9-d battery feeding trials involving 5 pens of 4 chicks per treatment. The dextrose-casein diet was shown to be markedly deficient in Arg as both weight gain and G:F increased (P < 0.01) due to addition of Arg, GAA, or creatine. The optimal level of added GAA was 0.12% of the diet, but this level of GAA or 1.0% creatine-H(2)O did not improve growth performance when added to an Arg-adequate diet. A second assay confirmed this level of optimal Arg in a 2 × 2 factorial arrangement of l-Arg and GAA supplementation. Using a practical-type diet based on corn, corn gluten meal, distillers dried grains with solubles, and soybean meal, similar improvements (P < 0.05) in G:F resulted from addition of 0.25% Arg, 0.12% GAA, or 0.15% creatine·H(2)O. These results demonstrate that 0.12% supplemental GAA, like creatine, produces consistent growth responses in young chicks fed Arg-deficient diets. To provide further evidence of the capacity for GAA to serve as a dietary Arg replacement, the dextrose-casein diet was supplemented with 7 graded doses of Arg in the absence or presence of 0.12% GAA (14 total diets). Quadratic (P < 0.01) responses in weight gain and G:F responses to supplemental Arg were observed. Similar supplemental Arg requirements were estimated in the absence and presence of 0.12% GAA, but GAA elicited a greater improvement (P < 0.05) in G:F when added to Arg-deficient, compared with Arg-adequate, diets. Collectively, these data indicate that GAA can be used as an efficacious replacement for dietary Arg for young chicks.

Ileal digestibility of amino acids in pea protein isolates, wheat-corn distillers dried grains with solubles, and short-season corn fed to broiler chicks.

The apparent ileal digestibility (AID) of amino acids (AA) in 4 pea protein isolates [PPI; experiment (Exp.) 1], 5 wheat- and corn-derived distillers grains with solubles (wcDDGS; Exp. 2), and 5 short-season corn (Exp. 3) samples for broiler chickens were determined. In addition, a reference wheat sample was included in each experiment to measure the repeatability of the ileal digestibility assay used. Birds (n = 180 for Exp. 1 and n = 216 for Exp. 2 or 3) were fed test diets from d 15 to 21 of age. Reference wheat and PPI were included in test diets at 91.7 and 25%, respectively, as the sole source of AA, whereas wcDDGS and corn were combined with wheat in test diets at 47.7% test ingredient (wcDDGS or corn) and 51% wheat as the sources of AA. Chromic oxide at 0.3% was added in all diets as the indigestible marker. Each test diet was randomly assigned to 6 cages of 6 male birds each. On d 21, birds were killed and ileal digesta were collected to determine the AID of AA. The mean AID values for indispensable AA ranged from 86.0% (Thr) to 94.7% (Arg) for PPI, 50.7% (Lys) to 79.8% (Leu) for wcDDGS, and 73.9% (Thr) to 95.3% (Arg) for corn. Overall, the CV range for AID of AA was widest for wcDDGS (8.1% for Met to 29.4% for Lys) followed by corn (3.0% for Met to 10.7% for Thr) and then PPI (2.7% for Lys to 6.1% for Thr). For wcDDGS and corn, the within-sample variation (assay condition) was more than between-sample variation (feed differences), whereas the reverse was true for PPI. No differences were detected in the AID of CP and AA for reference wheat among experiments.

Valine and isoleucine requirement of 20- to 45-kilogram pigs.

Three experiments were conducted to determine the Val and Ile requirements in low-CP, corn-soybean meal (C-SBM) AA-supplemented diets for 20- to 45-kg pigs. All experiments were conducted for 26 to 27 d with purebred or crossbred barrows and gilts, which were blocked by initial BW. Treatments were replicated with 5 or 6 pens of 3 or 4 pigs per pen. At the beginning of Exp. 1 and the end of all experiments, blood samples were obtained from all pigs to determine plasma urea N (PUN) concentrations. All diets were C-SBM with 0.335% supplemental Lys to achieve 0.83% standardized ileal digestible (SID) Lys, which is the Lys requirement of these pigs. In Exp. 1, 0, 0.02, 0.04, 0.06, 0.08, or 0.10% L-Val was supplemented to achieve 0.51, 0.53, 0.55, 0.57, 0.59, or 0.61% dietary SID Val, and Thr, Trp, Met, and Ile were supplemented to maintain Thr:Lys, Trp:Lys, TSAA:Lys, and Ile:Lys ratios of 0.71, 0.20, 0.62, and 0.60, respectively. Also, supplemental Gly and Glu were added to all diets to achieve 1.66% Gly + Ser and 3.28% Glu, which is equal to the Gly + Ser and Glu content of a previously validated positive control diet that contained no supplemental AA. Treatment differences were considered significant at P < 0.10. Valine addition increased ADG, ADFI, and G:F in pigs fed 0.51 to 0.59% SID Val (linear, P < 0.08), but ADG and ADFI were decreased at 0.61% SID Val (quadratic, P ≤ 0.10). On the basis of ADG and G:F, the SID Val requirement is between 0.56 and 0.58% in a C-SBM diet supplemented with AA. In Exp. 2 and 3, 0, 0.02, 0.04, 0.06, or 0.08% L-Ile was supplemented to achieve 0.43, 0.45, 0.47, 0.49, or 0.51% dietary SID Ile, and Thr, Trp, Met, and Ile were supplemented to maintain Thr:Lys, Trp:Lys, TSAA:Lys, and Val:Lys ratios of 0.71, 0.20, 0.62, and 0.74, respectively. Also, supplemental Gly and Glu were added to achieve 1.66% Gly + Ser and 3.28% Glu as in Exp. 1. Data from Exp. 2 and 3 were combined and analyzed as 1 data set. Daily BW gain, ADFI, and G:F were not affected by Ile additions to the diet; however, ADFI was decreased among pigs fed the diet with 0.45% SID Ile (P < 0.10) compared with pigs fed the 0.43% SID Ile diet. Broken-line analysis requirements could not be estimated for the combined data from Exp. 2 or 3. The results of this research indicate that the SID Val requirement is between 0.56 to 0.58% (0.67 to 0.70 SID Val:Lys), and the Ile requirement is adequate at 0.43% SID Ile (0.52 SID Ile:Lys) for 20- to 45-kg pigs.

Standardized ileal digestible tryptophan-to-lysine ratios in growing pigs fed corn-based and non-corn-based diets.

Two 21-d experiments were conducted to determine the optimum standardized ileal digestible (SID) Trp:Lys in growing pigs fed corn-based diets compared with non-corn-based diets. The primary response variables in both experiments were ADG and plasma urea N (PUN) concentrations with the optimum SID Trp:Lys determined using broken-line analysis. Experiment 1 evaluated the optimum SID Trp:Lys in growing pigs fed corn-based diets consisting primarily of corn with minor inclusion of Canadian field peas and corn gluten meal to keep the SID Trp:Lys low. This experiment used 120 crossbred pigs (initial BW: 25.73 ± 2.46 kg) that were blocked by sex and initial BW and allotted to 5 SID Trp:Lys with 5 pens each for the first 4 treatments and 4 pens for the last treatment and 5 pigs/pen. Diets were formulated by the addition of supplemental Trp to create various SID Trp:Lys (12.77, 14.07, 15.50, 16.91, and 17.94%) with a constant SID Lys of 0.66%, which was determined to be 83% of the Lys requirement for pigs at this location. As the SID Trp:Lys increased from 12.77 to 17.94%, ADG increased (0.562, 0.648, 0.788, 0.787, and 0.815 kg/d) linearly (P < 0.001) and quadratically (P = 0.009), resulting in an optimum SID Trp:Lys of 15.73% (P < 0.001). Plasma urea N decreased (10.43, 9.30, 8.21, 8.55, and 9.25 mg/dL) linearly (P = 0.069) and quadratically (P = 0.015), resulting in an optimum SID Trp:Lys of 15.83% (P = 0.007). Experiment 2 evaluated the optimum SID Trp:Lys in growing pigs fed non-corn-based diets consisting primarily of barley and Canadian field peas, with smaller proportions of corn and wheat. Experiment 2 used 120 crossbred pigs (initial BW: 28.49 ± 2.92 kg) that were allotted to 5 increasing SID Trp:Lys (13.05, 14.32, 15.59, 16.85, and 18.11%; 0.66% SID Lys) in the same manner as Exp. 1. As SID Trp:Lys increased in Exp. 2, ADG increased linearly (P = 0.007) with the optimum SID Trp:Lys of 15.99% (P = 0.048). Plasma urea N concentrations decreased linearly (P = 0.056) and quadratically (P = 0.067) as SID Trp:Lys increased, resulting in an optimum SID Trp:Lys of 15.29% (P = 0.009). Averaging the break point values for ADG and PUN obtained from broken-line analysis for Exp. 1 and 2 produced optimum SID Trp:Lys of 15.78 and 15.64%, respectively. Based on the results from these 2 experiments, it seems that the optimum SID Trp:Lys is virtually unaffected by the dietary feedstuffs used as long as the diets are formulated on an SID AA basis.

Technical note: Effect of determining baseline plasma urea nitrogen concentrations on subsequent posttreatment plasma urea nitrogen concentrations in 20- to 50-kilogram pigs.

Plasma urea N (PUN) has been used as an indicator of AA requirements and efficiency of AA utilization in swine. However, PUN concentrations vary among a population of pigs, even a population with a close range of BW and fed the same diet. Thus, pretreatment or baseline PUN concentrations are used as a covariate to reduce variation of posttreatment PUN. However, this procedure increases experimental costs and stress to the pigs. Data from 14 experiments (26 to 28 d in duration) conducted using PUN as a response variable were compiled into 1 data set. Each experiment had 4 to 6 treatments. The purpose of this technical report was to summarize the effect of determining pretreatment baseline PUN concentrations on subsequent posttreatment PUN concentrations in 20- to 50-kg pigs. In all experiments, pigs were fed corn- and soybean meal-based diets and low-CP diets with various AA additions; pigs were assigned to dietary treatments in a randomized complete block design with a minimum of 4 replicates of 3 to 5 pigs each. Before the start of each experiment, all pigs were fed a common diet for a minimum of 3 d. Blood samples were collected from each pig before allotment to dietary treatments (d 0) and at the end of each experiment. The baseline (d 0) PUN was analyzed as a covariate for posttreatment PUN. Data from each experiment were analyzed without and with baseline PUN in the statistical model. In all experiments combined, there were 768 possible treatment comparisons. The covariate baseline PUN was statistically significant (P < 0.10) in 9 of 14 experiments. However, only 8 treatment differences changed statistical significance as a result of analyzing the data with baseline PUN as a covariate. These 8 treatment differences were in 3 experiments. These results indicate that it is not always necessary to determine baseline PUN concentrations when feeding diets with large differences in AA content.

Growth performance of 20- to 50-kilogram pigs fed low-crude-protein diets supplemented with histidine, cystine, glycine, glutamic acid, or arginine.

The purpose of this investigation was to compare the growth performance of grower pigs fed low-CP, corn-soybean meal (C-SBM) AA-supplemented diets with that of pigs fed a positive control (PC) C-SBM diet with no supplemental Lys. Five experiments were conducted with Yorkshire crossbred pigs, blocked by BW (average initial and final BW were 21 and 41 kg, respectively) and assigned within block to treatment. Each treatment was replicated 4 to 6 times with 4 or 5 pigs per replicate pen. Each experiment lasted 28 d and plasma urea N was determined at the start and end of each experiment. All diets were formulated to contain 0.83% standardized ileal digestible Lys. All the experiments contained PC and negative control (NC) diets. The PC diet contained 18% CP and was supplemented with only DL-Met. The NC diet contained 13% CP and was supplemented with L-Lys, DL-Met, L-Thr, and L-Trp. The NC + Ile + Val diet was supplemented with 0.10% Val + 0.06% Ile. The NC + Ile + Val diet was supplemented with either His (Exp. 1), Cys (Exp. 2), Gly (Exp. 2, 3, and 4), Glu (Exp. 3), Arg (Exp. 4), or combinations of Gly + Arg (Exp. 4 and 5) or Gly + Glu (Exp. 5). Treatment differences were considered significant at P < 0.10. In 3 of the 4 experiments that had PC and NC diets, pigs fed the NC diet had decreased ADG and G:F compared with pigs fed the PC diet. The supplementation of Ile + Val to the NC diet restored ADG in 4 out of 5 experiments. However, G:F was less than in pigs fed the PC diet in 1 experiment and was intermediate between the NC and PC diets in 3 experiments. Pigs fed supplemental Ile + Val + His had decreased G:F compared with pigs fed the PC. Pigs fed supplemental Cys to achieve 50:50 Met:Cys had decreased G:F compared with pigs fed the PC. Pigs fed Ile + Val + 0.224% supplemental Gly had similar ADG, greater ADFI, and decreased G:F compared with pigs fed the PC. Pigs fed Ile + Val + 0.52% supplemental Gly had ADG and G:F similar to that of pigs fed the PC. Pigs fed supplemental Glu had decreased G:F compared with pigs fed the PC. Pigs fed Ile + Val + 0.48% supplemental Arg had decreased G:F compared with pigs fed the PC. Pigs fed the diet supplemented with Gly + Arg had ADG and G:F similar to pigs fed the PC. Pigs fed the low-CP diets had reduced plasma urea N compared with pigs fed PC. The results of these experiments indicate that supplementing Gly or Gly + Arg to a low-CP C-SBM diet with 0.34% Lys, Met, Thr, Trp, Ile, and Val restores growth performance to be similar to that of pigs fed a PC diet with no Lys supplementation.

Maximizing the use of supplemental amino acids in corn-soybean meal diets for 20- to 45-kilogram pigs.

Four experiments were conducted to determine the Lys requirement, the maximum amount of supplemental Lys that does not decrease growth performance, and to determine the order of limiting AA beyond Lys, Thr, Trp, and Met in a corn-soybean meal diet for 20- to 45-kg pigs. All experiments were conducted for 27 to 28 d with purebred or crossbred barrows and gilts, which were blocked by initial BW. Treatments were replicated with 4 to 6 pens of 4 to 6 pigs per pen. In all experiments, pigs and feeders were weighed on d 0, 14, and 27 or 28. At the beginning and end of all experiments, blood samples were obtained from all pigs to determine plasma urea N (PUN) concentrations. In Exp. 1, 0.830, 0.872, 0.913, and 0.955% standardized ileal digestible (SID) Lys was fed, whereas 0.747, 0.788, 0.830, 0.872, and 0.913% SID Lys was fed in Exp. 2. Broken-line analysis requirement estimates could not be estimated from any response variable in Exp. 1, but in Exp. 2, using ADG and PUN, the estimated SID Lys requirement was 0.83%. In Exp. 3, 0, 0.118, 0.191, 0.264, and 0.335% supplemental Lys was added to achieve 0.83% SID Lys in all diets, and Thr, Trp, and Met were supplemented to maintain Thr:Lys, Trp:Lys, and TSAA:Lys of 0.65, 0.18, and 0.60, respectively. Based on ADG, ADFI, and G:F, up to 0.23% supplemental Lys can be added along with supplemental Thr, Trp, and Met without negatively affecting growth performance; PUN was linearly decreased (P < 0.001) by supplemental Lys. In Exp. 4, treatments were 1) positive control (PC) without supplemental AA, 2) negative control (NC) with 0.335% supplemental Lys + 0.140% l-Thr + 0.035% l-Trp + 0.117% dl-Met, 3) NC + 0.044% l-Val, 4) NC + 0.021% l-Ile, and 5) NC + 0.044% l-Val + 0.021% l-Ile. Individual addition of Val and Ile did not improve (P > 0.10) ADG or G:F compared with the NC. The combined addition of Val + Ile resulted in ADG that was intermediate between the PC and NC diets but not different from either diet (P > 0.10); G:F was not improved (P > 0.10) to that observed in pigs fed the PC diet. The PUN was not different (P > 0.10) among pigs fed diets with supplemental AA but less (P < 0.10) than pigs fed the PC. The results of this research indicate that the Lys requirement for 20- to 45-kg pigs is 0.83% SID Lys, up to 0.23% supplemental Lys (0.29% l-Lys·HCl or 0.45% l-Lys·SO(4)) can be added along with supplemental Thr, Trp, and Met without negatively affecting growth performance, and another AA besides Val and Ile may be limiting growth performance in a corn-soybean meal diet with 0.335% supplemental Lys.

Evaluation of corn distillers dried grains with solubles as an alternative ingredient for broilers.

The effects of graded levels of corn distillers dried grains with solubles (DDGS) were investigated as a partial replacement for sources of protein, energy, and other nutrients for broilers when the digestible amino acid balance was maintained. Zero, 8, 16, and 24% DDGS were incorporated into isonutritive diets at the expense of corn, soybean meal, and dl-Met. Poultry oil, l-Lys, and l-Thr additions increased with increasing levels of DDGS. Diets were each fed to 36 Cobb 500 straight-run broilers in 6 floor pens in 2 experiments. In experiment 1, broilers fed ≥8% DDGS showed increased BW gain compared with those fed the control diet during the 0- to 18-d starter period (P = 0.0164) but were almost identical in BW at 42 d (P = 0.9395). The only difference at 42 d was in the carcass fat composition of female broilers: percentage of fat pad decreased with increasing DDGS level (P = 0.0133). Corn DDGS reduced the pellet durability index. However, the pellet durability index was not related to growth or feed utilization. In experiment 2 at 42 d, broilers fed all levels of DDGS showed increased BW gain compared with those fed the control diet. Broilers may perform well when fed properly balanced feeds containing up to 24% DDGS despite reduced pellet quality.

Standardized ileal amino acid digestibility in dry-extruded expelled soybean meal, extruded canola seed-pea, feather meal, and poultry by-product meal for broiler chickens.

Ileal digestibility of amino acids (AA) in dry-extruded expelled soybean meal (DESBM), co-extruded canola seed-pea blend (ECSP, 50:50 wt/wt basis), poultry by-product meal (PBPM), and feather meal (FM) were determined in broiler chicks. For each ingredient, 5 samples each collected on different occasions were evaluated. Birds (n = 180 for each sample) were fed a commercial starter diet from d 1 to 15 of age followed by the test diets from d 15 to 21. Dry-extruded expelled soybean meal, ECSP, PBPM, and FM were included in the test diets at 95.3, 95.3, 38.4, and 28.4%, respectively, as the sole source of AA and balanced for minerals and vitamins. Chromic oxide (0.3%) was included in all diets as a digestibility marker. Each diet (5 per ingredient) was randomly assigned to 6 replicate cages, each with 6 birds. On d 21, birds were killed to collect ileal digesta for determining the apparent ileal AA digestibility on cage basis. The standardized ileal digestibility (SID) values were calculated using ileal endogenous AA losses previously determined in our laboratory. The apparent ileal digestibility of AA ranged from 78 to 91%, 68 to 83%, 51 to 81%, and 39 to 74% for DESBM, ECSP, PBPM, and FM, respectively. The respective ranges for SID values were 83 to 96%, 72 to 85%, 58 to 86%, and 42 to 78%. Among the indispensable AA, the lowest SID was observed for Thr in all test ingredients, whereas the highest SID was observed for Phe except in ECSP in which Arg had the highest SID. The SID of Lys (CV) were 91% (2.8%), 79% (2.0%), 78% (7.4%), and 60% (10%) for DESBM, ECSP, PBPM, and FM, respectively, whereas the SID of TSAA (CV) were 88% (4.5%), 77% (2.4%), 74% (9.0%), and 55% (18%), respectively. These SID AA data will help nutritionists to formulate broiler diets that more closely match the birds' requirements and minimize nutrient excess.

Effect of incremental levels of L-lysine and determination of the limiting amino acids in low crude protein corn-soybean meal diets for broilers.

Research was conducted to determine the level of l-Lys that can be included in corn-soybean meal (C-SBM) diets for broilers before an amino acid (AA) beyond Met, Lys, Thr, or Gly becoming limiting and to determine the order of limiting AA in low CP C-SBM diets. All experiments were conducted with Ross 708 broilers (0 to 18 d of age) in brooder batteries. Treatments contained 7 or 8 replicates with 6 birds per replicate. In all experiments, a control C-SBM diet containing no l-Lys.HCl and a similar diet [positive control (PC) + Gly] with supplemental Gly to provide 2.32% total dietary Gly + Ser were fed. All diets were formulated to contain 1.26% total Lys. All diets with added l-Lys.HCl contained supplemental Gly to provide 2.32% total dietary Gly + Ser. In experiment 1, l-Lys.HCl was added to the diets at 0.02% increments from 0.15 to 0.27%. Compared with the PC + Gly diet, there were no negative effects (P > 0.10) of supplemental Lys on ADG, ADFI, or G:F. In experiment 2, l-Lys.HCl was added to the diets at 0.05% increments from 0.25 to 0.60%. Compared with the PC + Gly diet, ADG and G:F were decreased (P < 0.03) in broilers fed diets containing greater than 0.30% l-Lys.HCl but not (P > 0.10) in the 0.25% l-Lys.HCl diet. In experiment 3, l-Lys.HCl was added to the diets at 0.05% increments from 0.20 to 0.30%. Daily gain was decreased (P < 0.03) in broilers fed 0.30% l-Lys.HCl but not in those fed 0.20 or 0.25% l-Lys.HCl. In experiment 4, the order of limiting AA was determined in a C-SBM diet containing 0.45% L-Lys.HCl. In addition to the PC and PC + Gly diets, diets consisted of a negative control (NC) diet with 0.45% l-Lys.HCl, NC + 0.247% Ile, NC + 0.484% l-Arg.HCl, NC + 0.249% Val, and all possible 2- and l-way combinations of all 3 AA. Compared with the NC diet, addition of Arg and the combination of Arg and the other AA increased ADG and ADFI, indicating that Arg was the limiting AA in this diet. Experiment 5 was conducted in an identical manner to experiment 4 except the diets with the added AA contained the same ratio of corn to soybean meal that is present in a diet with 0.25% l-Lys.HCl. The results of experiment 5 suggest that Arg and Val are equaling limiting in a diet with 0.25% l-Lys.HCl. In summary, 0.25% l-Lys.HCl can be added to C-SBM diets supplemented with Met, Thr, and Gly with no negative effects on growth performance, and Arg and Val are equaling limiting (after Met, Thr, Lys, and Gly) in diets containing 0.25% l-Lys.HCl.

Effect of dietary protein level on growth performance, indicators of enteric health, and gastrointestinal microbial ecology of weaned pigs induced with postweaning colibacillosis.

The effect of dietary CP level on performance, enteric health, and gastrointestinal microbial ecology of weaned pigs challenged with enterotoxigenic Escherichia coli (ETEC) K88 was investigated in a 14-d study. Forty weaned pigs (BW = 5.32 +/- 0.24 kg, mean +/- SD), housed 4 per pen, were randomly assigned to 2 diets (5 pens/diet): 1) 22.5% CP or 2) 17.6% CP supplemented with AA. Diets contained the same amount of ME and standardized ileal digestible Lys, Met + Cys, Thr, and Trp based on the ideal protein ratio. Isoleucine and Val were added to the 17.6% CP diet up to the level in the 22.5% CP diet. On d 8 postweaning, pigs were challenged with 6 mL of ETEC suspension (10(10) cfu/mL) by gavage. Feed disappearance and BW were measured on d 7, 9, 10, 12, and 14 for determination of ADG, ADFI, and G:F. One pig from each pen was serially slaughtered on -1, 3, and 7 d postchallenge (10 pigs/d of slaughter) to evaluate gut morphology, and gut microbial ecology and metabolites. Pigs fed the 22.5% CP diet had greater (P < 0.05) ADG and G:F than those fed the 17.6% CP diet before infection, but performance was similar between the 2 diets after ETEC challenge and overall. On d 3 after challenge, ETEC was not detected in the ileal digesta of pigs fed the 17.6% CP diet but was detected in the ileal digesta of 80% of pigs fed the 22.5% CP diet (5.22 +/- 1.07 cfu/g, mean +/- SD). Pigs fed the 17.6% CP diet had a greater (P < 0.01) prevalence of order Clostridiales (73 vs. 50%), family Lachnospiraceae (43 vs. 18%), and genus Roseburia (13 vs. 3%) in the colon digesta 7 d after challenge compared with those fed the 22.5% CP diet. The richness and diversity of bacteria in the colon digesta were less (P < 0.05) in pigs fed the 17.6% CP diet than in those fed the 22.5% CP diet at -1, 3, and 7 d postchallenge. Pigs fed the 22.5% CP diet had greater (P < 0.05) ammonia N concentration in the colon digesta on -1 and 7 d after challenge compared with those fed the 17.6% CP diet. Pigs fed the 22.5% CP diet had deeper (P < 0.05) crypts 1 d before challenge, shorter villi 3 d after challenge, and reduced villus height:crypt depth 1 d before and 3 d after challenge compared with those fed the 17.6% CP diet. In conclusion, a reduction in the dietary CP level of weaned pigs from 22.5 to 17.6% with AA supplementation impaired growth performance before, but not after, the ETEC challenge and increased the relative composition of butyrate producing bacteria in the colon digesta after ETEC challenge.

Amino acid supplementation of hydrolyzed feather meal diets for finisher pigs.

The objective of this study was to determine the possibility of replacing soybean meal (SBM) in finisher pig diets completely with hydrolyzed feather meal (FM). Forty-five gilts and 45 castrated males (57.8+/-0.8 kg of BW; 3 gilts or 3 castrated males/pen) were randomly assigned to 5 finisher-1 diets with 6 pens per diet. At an average pen BW of 81.0+/-1.4 kg, pigs were offered finisher-2 diets. Corn-SBM, finisher-1 and finisher-2 positive control (PC) diets were formulated to contain 6.1 and 4.7 g of apparent ileal digestible (AID) Lys/kg, respectively. Corn-FM negative control (NC) diets were formulated to be iso-N to the PC diets. The NC diets were supplemented with Lys and Trp (NRC; NC + Lys and Trp) to alleviate apparent deficiencies based on AID AA in FM reported by the 1998 NRC. In addition, the NC diets were supplemented further with the third limiting AA, Thr (40+3AA; NC + Lys, Trp, and Thr), and fourth and fifth limiting AA, His and Ile (40+5AA; NC + Lys, Trp, Thr, His, and Ile), based on the assumption that the apparent ileal digestibility of all indispensable AA in FM is 40%. Pigs had ad libitum access to feed and water. At the end of the study (112.1+/-1.8 kg), blood samples were collected from all pigs before slaughter. As expected, overall ADFI, AID Lys (representing indispensable AA) intake (LysI), ADG, and G:F were greater and BW gain:LysI (G:LysI) was less in pigs fed the PC diet than those fed the NC diet (P<0.001). Pigs fed the NRC diet grew slower than those fed the PC diet (P=0.004), and their G:LysI tended to be less than those fed the PC (P=0.083) or the 40+3AA and 40+5AA diets (P=0.094). Greater fat-free lean percentage (P=0.005), fat-free lean gain (LG; P<0.001), and LG:F (P<0.001) were observed in pigs fed the PC diet compared with those fed the NC diet, but their LG:F or LG:LysI was similar to those fed the NRC diet. However, LG:F (P=0.030) and LG:LysI (P=0.028) were greater in pigs fed the 40+3AA and the 40+5AA diets than those fed the NRC diet. Pigs fed the 40+5AA diet tended to utilize AID Lys more efficiently for LG than those fed the 40+3AA diet (P=0.068). Subjective meat color (P<0.001), firmness (P=0.004), and marbling (P<0.001) scores were greater in pigs fed the 40+5AA diet than those fed the 40+3AA diet. Diets seemed to have no clear effect on the weight of liver, kidney, and heart or serum urea N and triacylglycerides. Pigs fed the PC diet had more serum albumin and total protein (P<0.001), but less glucose (P=0.031) and cholesterol (P<0.001) than those fed the NC diet. Serum total protein was greater (P=0.031) in pigs fed the 40+5AA diet than those fed the 40+3AA diet. The results indicated that the corn-FM diets were not as effective as the corn-SBM diet in supporting BW gain of finisher pigs. However, the results seemed to indicate that pigs fed the corn-FM diet supplemented with the necessary AA can utilize feed and AA for BW gain and lean gain as efficiently as those fed the corn-SBM diet. Further research is needed to explore fully the optimal AA supplementation strategy to effectively utilize FM for pig production.

Growth and intestinal morphology of pigs from sows fed two zinc sources during gestation and lactation.

An experiment was conducted to compare the effects of organic (Zn AA complex, ZnAA) and inorganic Zn (ZnSO4) sources on sows and their progeny during gestation and lactation and on the pigs during the nursery period. The dietary treatments were 1) a corn-soybean meal diet with 100 ppm Zn from ZnSO4 (control); 2) diet 1 + 100 ppm additional Zn from ZnSO4; and 3) diet 1 + 100 ppm additional Zn from ZnAA. Dietary additions were on an as-fed basis. Thirty-one primaparous and multiparous sows were allotted to the treatment diet beginning on d 15 of gestation and continuing through lactation. At weaning (d 17 of age), 202 pigs (63, 55, and 84 pigs for treatments 1 to 3, respectively) were allotted to the same dietary treatment as their dam. The pigs were fed a 3-phase diet regimen during the nursery period: d 0 to 7 (phase I); d 7 to 21 (phase II); and d 21 to 28 (phase III). At weaning and at the end of phase III, 1 gilt per replicate was killed, and the left front foot, liver, pancreas, and entire small intestine were removed. Diet had no effect (P > 0.10) on any response during gestation. During lactation, there was an increase (P < 0.10) in litter birth weight in sows fed ZnAA compared with those fed the control or ZnSO4 diets. The sows fed ZnAA nursed more pigs (P < 0.10) than sows fed the ZnSO4 diet, and they weaned more pigs (P < 0.05) than sows fed the control diet. Jejunal villus height of the weaned pigs from sows fed ZnSO4 was increased (P < 0.05) compared with those from the sows fed the control diet. During the nursery period, growth performance was not affected (P > 0.10) by diet. Pigs fed ZnSO4 had greater duodenal villus width (P < 0.05) than those fed ZnAA, and pigs fed ZnSO4 or the control diet had greater ileal villus width (P < 0.05) than those fed ZnAA. Pigs fed ZnSO4 or ZnAA had more (P < 0.05) bone Zn than those fed the control diet. Liver Zn concentration was greatest in pigs fed ZnSO4, followed by those fed ZnAA, and then by those fed the control diet (P < 0.05). Pancreas Zn was increased (P < 0.05) in pigs fed ZnSO4 compared with those fed the control diet. These results suggest that 100 ppm Zn in trace mineral premixes provides adequate Zn for optimal growth performance of nursery pigs, but that 100 ppm additional Zn from ZnAA in sow diets may increase pigs born and weaned per litter.

Changes in glutathione peroxidase and tissue selenium concentrations of broilers after consuming a diet adequate in selenium.

Three experiments (EXP) were conducted with commercial broilers to develop a low-Se diet for comparing plasma glutathione peroxidase (pGPX3) concentrations and then to compare pGPX3 and plasma and tissue Se concentrations in broilers fed this low-Se diet after being supplemented with sodium selenite (SS) or Se-enriched yeast (SY). With the exception of Se, all diets were nutritionally adequate. The EXP lasted from 0 to 20 or 22 d posthatching, and treatments were replicated with 6 to 8 pens of 6 to 15 chicks per pen. The results of EXP 1 and 2 indicated that a cornstarch-dextrose diet containing 10% torula yeast and 31% soybean meal (SBM) resulted in similar gain as a corn-SBM (C-SBM) diet, but the cornstarch-dextrose-torula yeast-SBM diet with no added Se reduced pGPX3 activity 6-fold. In EXP 3, the treatments were a C-SBM diet with 0 or 0.30 ppm added Se from SS or SY. These diets were fed from 0 to 10 d posthatching. Beginning on d 10, all broilers were fed the cornstarch-dextrose-torula yeast-SBM, low-Se diet. On d 10, 13, 16, 19, and 22, three broilers per replicate were randomly selected for plasma and tissue collection. Treatment differences were significant at P < 0.05. Daily gain, daily feed intake, and gain:feed were not affected by diet during the 0-to-10-d or 0-to-22-d periods. Plasma GPX3 activity and plasma, liver, and breast Se concentrations were greater in broilers previously fed the diets with added Se, regardless of source, than in those fed the C-SBM diet, except for liver Se concentration on d 19 of broilers previously fed the SS diet. The pGPX3 concentrations were not different in broilers previously fed either Se diet on d 10 and 13 but were greater in broilers previously fed the SY diet on d 16, 19, and 22. Plasma Se concentrations were not different in broilers previously fed diets with SS or SY on d 10 and 22 but were greater in broilers previously fed the SY diet on d 13, 16, and 19. Breast Se concentrations were greater in broilers previously fed the SY diet than in those fed the SS diet on each day. Liver Se concentrations were not different in broilers previously fed SS or SY diets on d 19 and 22 but were greater in those previously fed the SY diet on d 10, 13, and 16. These results indicated that SY supplementation in broiler diets resulted in greater tissue Se concentrations than SS and that pGPX3 and tissue Se concentrations remained greater in birds previously fed a diet with SY than in those fed SS after being fed a low-Se diet.