Digestible Met Research Articles

Evaluating growth response of broiler chickens fed diets supplemented with synthetic DL-methionine or DL-hydroxy methionine: a meta-analysis

Methionine (Met) is the first limiting amino acid in corn and soybean meal-based diets (containing L-Met) in broiler chickens, which are often supplemented with synthetic DL-Met or DL-Hydroxy Met (OH-Met). Our objective was to quantitatively assess the efficacy of synthetic Met sources and determine differences in growth rate of broilers fed at or below requirements in response to Met intake. A systematic literature search resulted in building a database containing 480 treatment means from 39 articles published between 1985 and 2019 globally. The database was divided into starter, grower, and finisher subsets based on the age of the broilers. For each subset, linear-plateau and quadratic-plateau models were fitted to determine Met or sulfur amino acid (SAA; Met + Cysteine) requirements using average daily gain as a response variable. For each phase, 4 new subsets were obtained by only retaining records with digestible Met or SAA intake at or below requirement by linear-plateau or quadratic-plateau models. Then, a linear model (without plateau) was fitted for all new subsets for each rearing phase using supplemental digestible synthetic Met or SAA intake (basal Met intake was subtracted from total Met intake) as independent variables. The basal diet was made of only raw materials without supplementation of any synthetic Met source. Finally, the models were extended to evaluate source of synthetic Met effects on the slope parameter. At all stages of model fitting, the inclusion of a random study effect was evaluated for each parameter. All models were fitted within a Bayesian framework, for which minimally informative priors were used. The best models, that is, the most accurate inclusion of random effects, were selected based on at least 10-point difference in leave-one-out cross-validation information criterion. Model selection criteria did not consistently favor either of the linear- and quadratic-plateau models to determine Met or SAA requirements across broiler growth phases. Extending models with covariates (e.g., dietary energy and amino acids) did not improve any model fit. Body weight gain response of broiler chickens to the 2 sources was not different when fed at or below Met requirements for any of the growth phases.

Lactational performance of dairy cows in response to supplementing N-acetyl-l-methionine as source of rumen-protected methionine

The objective of this experiment was to evaluate the effects of supplementing a rumen-protected source of Met, N-acetyl-l-methionine (NALM), on lactational performance and nitrogen metabolism in early- to mid-lactation dairy cows. Sixty multiparous Holstein dairy cows in early lactation (27 ± 4.3 d in milk, SD) were assigned to 4 treatments in a randomized complete block design. Cows were blocked by actual milk yield. Treatments were as follows: (1) no NALM (control); (2) 15 g/d of NALM (NALM15); (3) 30 g/d of NALM (NALM30); and (4) 45 g/d of NALM (NALM45). Diets were formulated using a Cornell Net Carbohydrate and Protein System (CNCPS) v.6.5 model software to meet or exceed nutritional requirements of lactating dairy cows producing 42 kg/d of milk and to undersupply metabolizable Met (control) or supply incremental amounts of NALM. The digestible Met (dMet) supply for control, NALM15, NALM30, and NALM45 were 54.7, 59.8, 64.7, and 72.2 g/d, respectively. The supply of dMet was 88, 94, 104, and 115% of dMet requirement for control, NALM15, NALM30, and NALM45, respectively. Milk yield data were collected, dry matter intake (DMI) was measured daily, and milk samples were collected twice per week for 22 wk. Blood, ruminal fluid, urine, and fecal samples were collected during the covariate period and during wk 4, 8, and 16. Data were analyzed using the GLIMMIX procedure of SAS (SAS Institute) using covariates in the model for all variables except body weight. Linear, quadratic, and cubic contrasts were also tested. Treatments did not affect DMI, milk yield, and milk component concentration and yield; however, feed efficiency expressed as milk yield per DMI and 3.5% fat-corrected milk per DMI were quadratically affected, with greater response observed for NALM15 and NALM30 compared with control. Acetate proportion linearly increased, whereas propionate proportion linearly decreased with NALM supplementation. Blood urea nitrogen linearly decreased with NALM supplementation. Total plasma essential AA concentrations were quadratically affected, as greater values were observed for control and NALM45 than other treatments. Plasma Met concentration was quadratically affected as lower levels were observed with NALM15, whereas Met concentrations increased with NALM45 compared with control. Nitrogen utilization efficiency and apparent total-tract nutrient digestibility were not affected by treatment. Supplementation of NALM at 15 or 30 g/head per day resulted in the greatest improvements in feed efficiency without affecting N metabolism of early- to mid-lactation dairy cows.

Production effects and bioavailability of N-acetyl-l-methionine in lactating dairy cows

Two experiments were conducted to investigate the production effects of N-acetyl-l-methionine (NALM; experiment 1) and to estimate its bioavailability (BA) and rumen escape (RE; experiment 2), respectively, in lactating dairy cows. In experiment 1, 18 multiparous Holstein cows were used in a replicated, 3 × 3 Latin square design experiment with three 28-d periods. Treatments were (1) basal diet estimated to supply 45 g/d digestible Met (dMet) or 1.47% of metabolizable protein (MP; control), (2) basal diet top-dressed with 32 g/d of NALM to achieve dMet supply of 2.2% of MP, and (3) basal diet top-dressed with 56 g/d of NALM to achieve dMet supply of 2.6% of MP. The NALM treatments supplied estimated 17 and 29 g/d dMet from NALM, respectively, based on manufacturer's specifications. In experiment 2, 4 rumen-cannulated lactating Holstein cows were used in a 4 × 4 Latin square design experiment with four 12-d periods. A 12-d period for baseline data collection and 4 d for determination of RE of NALM preceded the Latin square experiment. For determination of RE, 30 g of NALM were dosed into the rumen simultaneously with Cr-EDTA (used as a rumen fluid kinetics marker) and samples of ruminal contents were collected at 0 (before dosing), 1, 2, 4, 6, 8, 10, 14, 18, and 24 h after dosing. Rumen escape of NALM was calculated using the estimated passage rate based on the measured Cr rate of disappearance. Bioavailability of abomasally dosed NALM was determined using the area under the curve of plasma Met concentration technique. Two doses of l-Met (providing 7.5 and 15 g of dMet) and 2 doses of NALM (11.2 and 14.4 g of dMet) were separately pulse-dosed into the abomasum of the cows and blood was collected from the jugular vein for Met concentration analysis at 0 (before dosing), 1, 2, 4, 6, 8, 10, 12, 14, 18, and 24 h after dosing. Supplementation of NALM did not affect DMI, milk yield, feed efficiency, or milk protein and lactose concentrations and yields in experiment 1. Milk fat concentration and energy-corrected milk yield decreased linearly with NALM dose. Plasma Met concentration was not affected by NALM dose. The estimated relative BA of abomasally dosed NALM (experiment 2) was 50% when dosed at 14.4 g/cow (11.2 g/d dMet from NALM) and 24% when dosed at 28.8 g/cow (14.4 g/d dMet from NALM). The estimated RE of NALM was 19% based on the measured kp of Cr at 11%/h. The total availability of ingested NALM was estimated at 9.5% for the lower NALM dose when taking into account RE (19%) and bioavailability in the small intestine (50%). Overall, NALM supplementation to mid-lactation dairy cows fed a MP-adequate basal diet below NRC (2001) recommendations (45 g/d or 1.47% Met of MP) decreased milk fat and energy-corrected milk yields but did not affect milk or milk true protein yields. Further evaluation of BA of NALM at different doses is warranted. In addition, intestinal conversion of NALM to Met needs additional investigation to establish a possible saturation of the enzyme aminoacylase I at higher NALM doses.

Effect of feeding level on the digestibility of alternative protein-rich ingredients for African catfish (Clarias gariepinus)

Apparent digestibility coefficients (ADC) of nutrients and individual amino acids (AA) for 13 feed ingredients as affected by feeding level were determined for African catfish, a species of economic importance in Africa. Results from two trials are reported. In each trial, ADC were determined using a reference diet and test diets with yttrium oxide as indicator. Juvenile African catfish (averaging 53.9 g, trial 1; 40.4 g, trial 2) were stocked in tanks connected to a common recirculation aquaculture system. Ingredients tested included hydrolysed feather meal (HFM), fishmeal (FM), insect meal (IM), soybean meal (SBM), sunflower meal (SFM), poultry meal (PM), corn dried distillers grains with solubles (CDDGS), faba beans (FB), lupine meal (LM), pea protein (PP), guar meal (GM), canola meal (CM) and yeast meal (YM). The effect of feeding level on ADC was determined by feeding fish restrictively (80% satiation) for 5 weeks and subsequently to apparent satiation for 2 weeks. Inclusion of yeast meal at 30% resulted in low palatability. ADC of nutrients were significantly affected by feeding level (except for fat and carbohydrate), but the effect was ingredient-dependent. African catfish was able to digest protein very effectively in almost all tested ingredients with ADC values ranging from 85.6 to 105.1% across feeding periods. Several ingredients tested, including animal protein ingredients and YM had similar high ADC for dry matter as FM. However, the ADC of AA differ among ingredients, indicating a need for digestible amino acid profile data. Methionine (Met) was the first limiting essential amino acid in HFM, FB, and LM with values ranging from 5−6 g/kg, expressed as digestible Met (dMet) per unit of digestible protein (DP), compared to FM (27 g dMet/kg DP). IM had comparable and sometimes higher overall digestible essential AA values compared to FM, except for methionine and lysine. For oilseeds and legumes, SBM tended to be the best quality AA source, as it had the highest digestible essential amino acid profile. These data provide information concerning nutrient and digestible AA values, which will allow a more efficient use of alternative ingredients in African catfish diets. Formulating diets based on the digestible AA in ingredients will aid precise feed formulation, thereby minimising economic losses and reducing the environmental footprint of aquaculture production.

PSVI-7 Increased consumption of Methionine as DL-Methionine or OH-Methionine improved pigs growing performance and carcass traits under hot conditions

Abstract This study aimed to determine the effects of increasing Methionine (Met) supply on growth performance and carcass traits of growing-finishing pigs under summer conditions in Brazil. A total of 200 barrows and females, 63 d-old (20.43±2.0 kg), were allocated in a 2 x 2 factorial design (two Met sources [DL-Met and OH-Met] and two Met doses [100 and 120% Brazilian Nutritional recommendation) with 10 replicates of 5 animals each. Corn-DDGS-wheat-soya based diets were formulated. Treatments were offered during four phases: growing I (63-93 d old), growing II (94-114 d old), finishing I (115-142 d old) and finishing II (143-160 d old). The recommended digestible Met levels were: 0.32, 0.30, 0.29 and 0.24% respectively for the four phases. Average temperature was 27.12 ± 4.51ºC and relative humidity was 61.72 ± 5.65%. Growth performance was measured for each rearing phase. Carcass yield, back fat height, loin depth, and lean meat yield were measured at the end of the experiment. Data were submitted to a 2-way ANOVA and Tukey test. There was no significant interaction between the Met source and the dose for all performance and carcass traits. Feed intake and feed conversion ratio were similar between treatments (P >0.05). The individual daily weight gain and live weight were better for the highest doses of methionine (P< 0.05) in all phases and on the whole period, except for the finishing II where the weight gain was similar for all treatments. Likewise, carcass yield, lean meat was increased with the highest dose of methionine in comparison to the adequate dose. No significant difference was found between DL-Met and OH-Met on growth performance parameters. OH-Met resulted in a higher loin depth (58.37 mm) in comparison to DL-Met (55.21 mm). Overall, these results demonstrated the interest of increasing Met supply under hot conditions to improving performance and carcass quality traits.

Energia metabolizável e aminoácidos sulfurosos para poedeiras leves no primeiro ciclo de produção

Objetivou-se determinar o nível de energia metabolizável (EM) e de metionina + cistina digestível (M+C) para poedeiras leves de 24 a 44 semanas. O delineamento experimental foi o inteiramente casualizado distribuído em esquema fatorial 3 níveis de M+C digestível (0.603%; 0.670%; e 0.737%) x 3 níveis de EM (2755; 2900 e 3045 kcal/kg), totalizando 9 tratamentos, avaliados por cinco períodos de 28 dias cada. Foi observado interação (P<0,05) dos fatores estudados para as variáveis de consumo de ração, produção de ovos, e para as conversões por massa e por dúzia de ovos. Para qualidade dos ovos houve interação para porcentagem de casca e gema, e em todas as variáveis sorológicas. Nas variáveis histomorfométricas de intestino delgado e útero, só não houve interação para largura de vilosidades intestinais e de dobra uterínica. Recomenda-se a utilização de 0.603% de M+C digestível associado ao nível de 2.900 kcal/kg de EM na dieta de poedeiras leves de24 a 44 semanas.

Hematology and serum biochemistry of broilers at the initial and growth stages submitted to different levels of digestible sulfur amino acids

ABSTRACT: The objective of this study was to evaluate the effect of digestible methionine and cystine (Met + Cys) levels on the hematological and serum biochemical parameters of broiler chickens during the initial and growth stages. For this, 1,800 male chicks of the Coob 500 strain were used, with 900 chicks in the initial phase (1 to 21 days old) and 900 chicks in the growth phase (22 to 42 days old), distributed in a completely randomized design of five treatments with six replicates of 30 birds. The treatments consisted of 0.545, 0.616, 0.711, 0.782, and 0.853%; and 0.514, 0.571, 0.647, 0.704, and 0.761% digestible Met + Cys for “1 to 21” and “22 to 42” days of breeding, respectively. Results showed that digestible Met + Cys levels in broiler feed altered some hematological parameters (erythrocyte, hematocrit hemoglobin, total leukocytes, heterophile: lymphocyte) and serum biochemistry (uric acid, PST, total LDL, and TG). The digestible Met + Cys levels in the diet of broilers affected the hematological parameters and serum biochemistry, especially at higher levels. From the inclusion level 0.761 of Met + Cist in the broiler diet, red blood cells, hemoglobin and hematocrit changes begin to appear.

Digestible methionine+cysteine in the diet of commercial layers and its influence on the performance, quality, and amino acid profile of eggs and economic evaluation.

This work aimed at evaluating the effects of 4 digestible Met+Cys levels on the diet of commercial layers and their influence on the productive performance, quality, and amino acid profile of eggs and economic viability of the activity. A total of 576 white Lohmann LSL-Lite layers was distributed into 6 replicates of 24 birds for each diet. The experimental design was completely randomized, with 4 treatments defined by levels evaluated in the feed (0.465, 0.540, 0.581, and 0.647%). The productive performance was measured for 30 weeks. The quality (34 and 50 wk old) and the amino acid profile of eggs (43 wk old) also were evaluated. A linear positive response was observed at higher Met+Cys levels for feed intake, number of eggs per housed bird, and digestible Met+Cys intake. Egg production, egg weight, egg mass, feed efficiency, and weight gain had their optimal values determined by the quadratic regression model at 0.638, 0.654, 0.647, 0.644, and 0.613% digestible Met+Cys, respectively. In the 34th wk, eggshell thickness decreased linearly at higher Met+Cys levels. In the 50th week, the optimal levels detected for eggshell thickness and percentage were 0.571 and 0.570% digestible Met+Cys, respectively. The percentages of proteins, branched-chain amino acids (leucine, isoleucine, and valine), histidine, and proline in eggs (albumen+yolk) showed a linear negative response in function of higher Met+Cys levels. Higher digestible Met+Cys levels (>0.630%) led to a good performance of layers, while lower Met+Cys levels improved the eggshell quality of layers in peak production. Optimal Met+Cys levels may change according to the price of the synthetic amino acid.

Available energy and amino acid digestibility of defatted rice bran fed to growing pigs.

This study was conducted to determine and compare available energy and apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of CP and AA in 9 samples of defatted rice bran (DFRB) fed to growing pigs and to generate prediction equations for DE and ME based on chemical analysis. In Exp. 1, 60 crossbred growing pigs (Duroc × Landrace × Yorkshire; 40.7 ± 3.5 kg BW) were fed 1 of 10 diets in a completely randomized design to determine the available energy of DFRB. The diets included a corn-soybean meal-basal diet and 9 experimental diets formulated by replacing the corn and soybean meal with 29.16% DFRB. In Exp. 2, 6 growing pigs (initial BW = 28.5 ± 2.8 kg) were surgically equipped with a T-cannula in the distal ileum and arranged in a 6 × 6 Latin square design with 6 diets and 6 periods. The diets included an N-free diet based on cornstarch and sucrose and 5 experimental diets containing 60% DFRB as the sole source of AA. Chromic oxide (0.3%) was used as an indigestible marker. Among the 9 samples, the concentrations of ether extract (EE), crude fiber (CF), NDF, ADF, starch, Ca, and P averaged 1.33 (0.50% to 4.14%), 14.54 (9.78% to 23.85%), 28.62 (20.19% to 38.85%), 14.22 (9.32% to 23.99%), 38.80% (30.62% to 47.55%), 0.16% (0.09% to 0.24%), and 1.96% (1.11% to 2.28%), respectively. The average DE and ME were 2,643 and 2,476 kcal/kg DM, respectively, and ranged from 2,039 to 3,157 kcal/kg DM and 1,931 to 2,978 kcal/kg DM, respectively. In Exp. 2, there were significant differences in the AID and SID of CP and most AA except for His, Tyr, and Met (P < 0.05). The AID and SID of CP averaged 67.75% and 76.37%, respectively. The digestibility of Met was the greatest, averaging 86.15% and 90.08% for AID and SID, respectively. The AID and SID of Lys ranged from 51.88% to 71.43% (mean = 63.27%) and from 61.93% to 79.98% (mean = 72.97%), respectively. These results indicated that there is significant variability in chemical composition, energy content, and the SID and AID of CP and most AA among the selected DFRB. The DE and ME of DFRB are primarily related to their NDF and starch concentrations.

Protein and amino acid bioavailability of extruded dog food with protein meals of different quality using growing mink () as a model.

The present study evaluated growing mink () as a model for dietary protein quality assessment of protein meals used in extruded dog foods. Three foods with similar CP content but of different protein quality were produced using different protein meals. The protein meals varied with respect to CP digestibility and AA composition and included lamb meal (LBM), poultry meal (PM), and fish meal (FM) with low, intermediate, and high protein quality, respectively. Nitrogen balance, BW gain, protein efficiency ratio (PER), and apparent total tract digestibility (ATTD) were used as measures of protein and AA bioavailability in growing mink. Standardized ileal digestibility (SID) was used to measure protein and AA bioavailability in adult dogs (). The mink study (3 × 3 Latin square design) included 12 kits aged 8 to 11 wk. The dog study included 12 dogs divided in 3 groups allocated to 1 of the experimental diets. The growing mink responded in accordance with the different AA supply between diets, as determined by the first limiting AA. The LBM diet deviated from the other diets with lower ( < 0.001) values for N retention, BW gain, and PER, and the diets differed ( < 0.001) in ATTD of CP and all AA, except for hydroxyproline. Retention of N was 0.66, 1.04, and 1.18 g·kg·d; BW gain was 8.2, 26.8, and 35.3 g/d; PER was 0.38, 1.39, and 1.71; and ATTD of CP was 66.8, 73.8, and 82.1% for the LBM, PM, and FM diets, respectively. In dogs, SID of CP and AA differed ( ≤ 0.017) between diets and was generally lowest for the LBM diet, intermediate for the PM diet, and greatest for the FM diet. For CP, SID was 71.5, 80.2, and 87.0% for the LBM, PM, and FM diets, respectively. The contents of digestible CP and AA (based on SID) covered the minimal requirement for adult dogs set by the NRC for all diets, except for the content of digestible Met + Cys in the LBM diet. Despite this, dietary content of Met + Cys in the LBM diet agreed with the recommended level set by the NRC and the Association of American Feed Control Officials for adult dogs but was below the level recommended by the European Pet Food Industry Federation. It was concluded that growth studies with mink kits can provide valuable information in protein quality assessment of extruded dog foods. Furthermore, the study showed that to ensure nutritional adequacy of dog food and to be able to compare protein quality of dog foods, information on AA composition and digestibility is crucial.

Requirement of Digestible Sulfur Amino Acids in Laying Hens Fed Sorghum- and Soybean Meal-Based Diets

Two experiments were done to evaluate the effect of increasing levels of dietary digestible methionine (Met) and Met:cysteine (Met:Cys) ratio on the productivity of Hy-Line W-36 laying hens fed sorghum- and soybean meal-based diets. In Exp. 1, 160 hens from 68 to 75 weeks of age were assigned to four dietary levels of digestible Met (0.20 0.24, 0.28 and 0.32%). The digestible total sulfur amino acids:Lysine (TSAA:Lys) ratios were: 62, 68, 76 and 84%. In Exp. 2, 192 hens from 76-83 weeks of age were assigned to four dietary digestible Met:Cys ratios (160, 116.7, 85.7 and 62.5%). The digestible TSAA:Lys ratio was kept constant across diets (80%). Results were subjected to ANOVA and linear regression analyses. In Exp. 1, optimal egg production, egg mass, and feed efficiency responses were observed at 0.30 and 0.50% of dietary digestible Met and TSAA, respectively (quadratic effect, p<0.05). Live performance was maximized with digestible Met and TSAA in takes of 288 and 478 mg/hen/d, respectively. In Exp. 2, optimal egg production and feed efficiency responses were observed at 151 and 150% of dietary digestible Met:Cys ratios, respectively (quadratic effect, p<0.05). The digestible Met, Cys and TSAA intake to maximize egg production and feed efficiency were 313, 207 and 510 mg/hen/d, respectively. The requirements for sulfur AA in Hy-Line W-36 hens from 68 to 83 weeks of age fed sorghum- and soybean meal-based diets fell inside the range of the requirements previously estimated in hens fed corn-soybean meal based diets.

&lt;b&gt;Digestible lysine levels for laying hens and their effects on egg quality&lt;/b&gt;

Egg quality of semi-heavy laying hens fed on low protein diets (14.0% CP) and on different lysine levels is evaluated, while maintaining the same ratio of digestible amino acids / digestible lysine. Four hundred and twenty commercial strain Isa Brown laying hens, 28 weeks old, were divided into 42 experimental plots. A completely randomized design with six treatments and seven replicates was employed in four production cycles of 28 days each. Treatments comprised Control - 16.92% CP; 0.750% digestible lysine. Treatments 1 to 5, with CP levels 14% and digestible lysine levels 0.600, 0.675, 0.750, 0.825 and 0.900% respectively. Levels of Treatments 1 and 2 (0.546 and 0.640% digestible Met + Cys / 0.600 and 0.675% digestible lysine) provided smaller egg size. On the other hand, eggs had higher shell percentage when compared to control diet. When compared to other digestible amino acids, digestible lysine requirement may be estimated at 0.750% in a diet with 14% CP, which corresponds to the average daily intake of 876 mg dig. lysine hen -1 day -1 and 798 mg dig. Met + Cys hen -1 day -1 , without jeopardizing performance and eggs' internal and external quality.

Comparison of ileal and total tract nutrient digestibility of dry dog foods1

The apparent total tract and ileal digestibility assays to measure AA absorption in commercial canine diets were compared in the present study. Five ileal cannulated dogs were fed 5 commercial dry canine foods selected to contain 19 to 30% CP in a 5 × 5 Latin square design. Ileal and total tract digestibility (apparent and standardized) of DM, OM, CP, crude fat (CF), carbohydrate, and AA (including reactive Lys) were calculated using Cr2O3 as an indigestible marker. Greater apparent total tract digestibility values were found for DM, OM, and CP (P ≤ 0.034) compared with ileal digestibility values; however, CF (P = 0.058) had a greater ileal apparent digestibility. Apparent and standardized CP digestibility values were, respectively, 5.7 and 7.4 percentage units greater when measured over the total digestive tract compared with measurement at the ileum (P = 0.034 and 0.011, respectively). Ileal apparent digestibility for N of AA (P = 0.009) and most AA (P < 0.05), except for Met, Ile, Lys, Phe, and Ala, was decreased if measured at the ileum. However, correction for endogenous losses showed only Met digestibility did not differ between measurement sites. Differences between sites in excess of 15 percentage units were recorded for AA. Apparent and standardized ileal reactive Lys digestibility was 3.1 to 15.3 percentage units greater than corresponding total tract digestibility values. For several indispensable AA, the bioavailability estimates currently used by the 2006 NRC and the 2011 Association of American Feed Control Officials to derive allowance estimates for canine adult maintenance were greater than the digestibility values of these AA in the commercial dog foods evaluated. Although the canine large intestine is relatively short, the total tract digestibility assay in dogs can overestimate the digestibility of dietary AA and CP and may not be an accurate method for the measurement of absorption. In this study, bioavailability estimates of AA appeared to be less than those used to derive allowance estimates for commercial dog foods. Further work is required if current recommendations warrant adjustment.

Apparent dry matter, energy, protein and amino acid digestibility of four soybean ingredients in white shrimp Litopenaeus vannamei juveniles

Dry matter, energy, protein and amino acid apparent digestibility coefficients (ADC) were determined in Pacific white shrimp juveniles (6 g average initial weight) for four soybean products: full fat soybean meal (FFSBM, 38% CP in dry matter), solvent extracted soybean meal (SBM, 52% CP), soybean protein concentrate (SPC, 71% CP) and soybean protein isolate (SPI, 89% CP), obtained from soybeans processed by different manufacturers in USA and México. The test diets included 30% of the test ingredients and 70% of a ground commercial diet supplemented with 1% chromic oxide and 1% sodium alginate. Amino acid contents in the ingredients, diets and feces were analyzed by HPLC at Evonik-Degussa laboratory. Amino acid profiles of the four soybean product samples were quite similar except for a lower content of methionine and cystine in SPI. In general, nutrient digestibility values were far higher in the soy products than in the fish meal-based reference diet. Dry matter and energy ADCs were significantly higher for SPI (92 and 98%, respectively) than for FFSBM, SBM and SPC (83 and 89%, respective averages). Crude protein ADC was not significantly different among FFSBM, SBM and SPI, but SPC had significantly a lower value (93 vs 96%). Total amino acid (92 vs 97%) and essential amino acid (91 vs 96%) digestibility profiles were almost identical for FFSBM, SBM and SPI, while the SPC profile was parallel but 3.5 to 7 percentage units lower. Cys and Thr were the least digestible amino acids in all samples, while Gly and Arg were generally the most digested. Compared to the ADC of crude protein, the ADCs for Thr and Cys were 3–4% lower, while arginine ADC was 2–3% higher. The ADCs for Lys and Met were similar to that of crude protein, although Lys and Met digestibility may be overestimated due to their high solubility in seawater.

Homocysteine Remethylation in Young Broilers Fed Varying Levels of Methionine, Choline, and Betaine

Methionine is critical in amino acid nutrition for chickens, yet details of the flux of Met metabolites in the avian system are lacking. This study explored the interactions among dietary choline (CHO), betaine (BET), and sulfur amino acid levels on growth and hepatic homocysteine (HCY) remethylation. Graded levels (0, 0.07, 0.11, and 0.24%) of DL-Met were added to diets adequate in CHO and deficient in sulfur amino acids (0.26% digestible Met, 0.26% digestible Cys). Each Met level was tested alone or with the addition of CHO (0.25%) or BET (0.28%). Broilers were reared from 8 to 22 d in raised wire floor battery cages, and the 12 dietary treatments were fed to 3 replicate pens containing 5 birds per pen. Weight gain and feed efficiency were maximized (P < 0.05) with addition of 0.11% supplemental Met, whereas feed intake was maximized (P < 0.05) with addition of 0.07% supplemental Met. Overall, growth parameters were not affected (P > 0.05) by CHO or BET addition. Hepatic tissue primed by the different dietary treatments was subjected to a newly developed stable isotope methodology and HPLC-mass spectrometry to quantify the impact of diet on HCY remethylation. Dietary Met level did not (P > 0.05) affect HCY remethylation, but remethylation through the Met synthase pathway was increased (P < 0.05) by addition of CHO or BET to diets containing deficient or excess levels of Met. Minimal changes in hepatic HCY remethylation through the betaine-homocysteine methyltransferase pathway occurred in response to dietary changes; therefore, data failed to support previous suggestions that BHMT might have a regulatory role when diets containing deficient or excess Met levels are fed. In contrast to previous suppositions based on enzyme activity, under most dietary conditions, the quantity of HCY remethylated by Met synthase appeared to exceed that remethylated by the alternate betaine-homocysteine methyltransferase pathway.

Hepatic and renal betaine-homocysteine methyltransferase activity in pigs as affected by dietary intakes of sulfur amino acids, choline, and betaine.

In Exp. 1, young pigs were fed a basal diet containing .17% methionine (Met) (.14% digestible Met), and .48% cystine (.38% digestible cystine) for 14 d (34 to 48 d of age). Treatment additions were .25% DL-Met, .34% betaine, .30% choline, or .25% DL-Met and .34% betaine. Methionine, but not betaine or choline supplementation, increased (P < .05) weight gain and feed efficiency. Hepatic betaine-homocysteine methyltransferase (BHMT) activity was increased (P < .05) by betaine and choline supplementation but was not affected by Met deficiency. Renal BHMT activity was increased (P < .05) by Met deficiency and was further increased (P < .05) by betaine supplementation. In Exp. 2, 10-kg pigs were fed the basal diet from Exp. 1 supplemented with enough DL-Met to bring the total basal Met to .24% (.20% digestible Met). Treatment additions consisted of .20% DL-Met or .34% betaine, and diets were fed for 16 d (34 to 50 d of age). Feed efficiency increased (P < .05) in response to Met, but not to betaine, supplementation. Hepatic BHMT activity increased (P < .05) in response to betaine and Met, but no changes in renal BHMT activity occurred. Although statistically significant changes in hepatic and renal BHMT activity occurred in both experiments, the magnitude of the responses was probably not physiologically important. Therefore, in contrast to previous findings with rats and chicks, it does not seem that hepatic and renal BHMT activity in pigs is influenced substantially by Met deficiency, or by surfeit levels of choline or betaine.

Sulfur Amino Acid Requirement and Cystine Replacement Value of Broiler Chicks During the Period Three to Six Weeks Posthatching

Three experiments were conducted with commercial broiler chicks to determine the SAA requirement during the growth period 3 to 6 wk posthatching. A 20% CP corn-peanut meal basal diet (3,200 kcal MEn/kg) was analyzed to contain 0.23% Met and 0.28% cystine. True digestibility assessment in cecectomized cockerels revealed that Met and cystine in the basal diet were 81 and 75% digestible, respectively. Therefore, the basal diet contained 0.19% digestible Met and 0.21% digestible cystine. When fully fortified with DL-Met, growth rate and feed efficiency of chicks fed the corn-peanut meal diet were equal to that of chicks fed a 20% CP Met-fortified corn-soybean meal diet. In the SAA requirement assay, Ross × Hubbard male chicks were fed graded increments of DL-Met (0.03%) and L-cystine (0.03%) to achieve digestible SAA concentrations of 0.40, 0.46, 0.52, 0.58, 0.64, and 0.70%. Weight gain and feed efficiency responded quadratically (P < 0.01) to increasing doses of SAA. The estimated requirement for maximal feed efficiency was higher than that for maximal weight gain. Both visual appraisal and curve fitting procedures suggested a requirement of close to 0.61% digestible SAA. When extrapolated to a corn-soybean meal diet where SAA true digestibility is 87.5%, the total SAA requirement calculates to be 0.70% of the diet. However, because commercial corn-soybean meal diets typically contain supplemental Met, which is only 81% efficient (wt:wt) in furnishing cystine, the estimated total SAA requirement for chicks fed 20% CP Met-fortified corn-soybean meal diets with 3,200 kcal of ME/kg would probably approximate 0.72% of the diet. A DL-Met vs L-cystine supplementation assay suggested that digestible cystine can supply no more than 52% of the total requirement for digestible SAA of chicks during the 3- to 6-wk growth period.

Methionine requirement of pigs between 5 and 20 kilograms body weight.

Four nursery experiments were conducted using a methionine (Met)-deficient feather meal-corn-soybean meal-dried whey basal diet (20% CP; 3,250 kcal of ME/kg, .11% choline, .19% Met, 1.00% cystine) supplemented with lysine, tryptophan, and histidine to determine the Met requirement of 5- to 10- and 10- to 20-kg pigs. Based on a true Met digestibility value of 81.6% estimated by a pig ileal digestibility assay, the Met-deficient basal diet contained .155% of digestible Met. A preliminary experiment (Exp. 1) indicated that pigs fed the Met-deficient basal diet when fortified adequately with Met could produce weight gains similar to those of pigs fed a 20% CP practical corn-soybean meal-dried whey diet. In Exp. 2 and 3, crossbred pigs weighing 5.8 kg initially were fed diets containing graded levels of digestible Met between .195 and .355%. Average daily gain increased quadratically (P less than .05) as the level of Met increased. When the data of Exp. 2 and 3 were examined together, the digestible Met requirement of 5- to 10-kg pigs was estimated to be .255% of the diet. In Exp. 4 and 5, crossbred pigs averaging 10 kg were fed digestible Met concentrations ranging from .155 to .315%. Average daily gain increased quadratically (P less than .05). The digestible Met requirement of 10- to 20-kg pigs was estimated at .255% for maximal weight gain, which was similar to that of 5- to 10-kg pigs. Assuming an 89% digestibility of Met in practical corn-soybean meal diets, the total Met level needed in practice would be .29%.(ABSTRACT TRUNCATED AT 250 WORDS)

Methionine Requirement of the Finishing Pig

Two pig experiments were conducted using a methionine (Met)-deficient feather meal-corn-soybean meal basal diet (13% CP; 3,400 kcal ME/kg diet, .126% Met, 456% cystine) supplemented with an amino acid mixture (lysine, tryptophan, histidine, threonine and phenylalanine) to determine the Met requirement of finishing pigs between 50 and 80 kg live weight. Using young chicks in a Met bioavailability growth assay and cecectomized adult cockerels in a Met digestibility assay, the Met-deficient basal diet was found to contain .115% bioavailable and .110% digestible Met. These results gave a bioavailability estimate (relative to DL-Met set at 100%) of 91.3 +/- 2.5% and a true digestibility estimate of 87.0 +/- 2.2% for Met in the basal pig diet. In Exp. 1, 21 crossbred pigs averaging 61 kg initially were individually fed diets containing .115, .165 or .215% bioavailable Met for 21 d. Average daily gain and gain:feed ratio increased quadratically (P less than .05) as level of Met increased. In Exp. 2, 30 crossbred pigs averaging 53 kg were individually fed diets containing .115, .135, .155, .175 or .195% bioavailable Met for 27 d. Daily gain and gain;feed ratio responded linearly (P less than .01) as Met level increased. Based on the results of Exp. 2, the bioavailable Met requirement of finishing pigs in the weight range 50 to 80 kg was estimated to be .182% of the diet. Assuming an 88% bioavailability of Met in commercial diets based on corn and soybean meal, the total Met level needed in practice would be .207%. If 55% of the finishing pig's sulfur amino acid need can be furnished by cystine, the total sulfur amino acid requirement would be .45% of the diet.