Lysine Ratio In Diets Research Articles

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

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

Performance response of increasing the standardized ileal digestible tryptophan:lysine ratio in diets containing 40% dried distiller grains with solubles.

A total of 1,170 pigs (PIC 800 × PIC, initially 38.6 kg) were used in a 98-d grow-finish study to determine the performance response of pigs fed increasing levels standardized ileal digestible (SID) Trp:Lys ratio in diets containing 40% dried distillers grains with solubles (DDGS). Five dietary treatments were fed and consisted of a corn-soybean meal (SBM) diet or diets containing 40% DDGS with SID Trp:Lys ratios of 15%, 18%, 21%, or 24%. Each treatment was replicated 9 times and pens contained 26 pigs with the equal number of gilts and barrows. Data was analyzed as a randomized complete block design with previous nursery treatment as a random blocking factor. Pair-wise comparisons were used to evaluate the impact of diets on performance and carcass traits; specifically to compare the corn-SBM dietary treatment against other dietary treatments. Single degree of freedom orthogonal polynomials were used to evaluate the dose-response of increasing the SID Trp:Lys ratio in 40% DDGS diets. Increasing the SID Trp:Lys ratio in diets containing 40% DDGS increased (linear, P ≤ 0.02) average daily gain (ADG), average daily feed intake (ADFI), final body weight (BW), hot carcass weight (HCW), carcass gain, and daily carcass gain. Increasing the SID Trp:Lys ratio in 40% DDGS diets did not impact (P ≥ 0.65) gain to feed (G:F) for the cumulative period. Pigs fed the corn-SBM diet had greater (P ≤ 0.01) ADG and a heavier (P ≤ 0.01) final BW compared to pigs fed 40% DDGS diets, regardless of the SID Trp:Lys ratio. Diets that contained 40% DDGS with a SID Trp:Lys ratio of 24% had no difference (P|t| = 0.25) in ADFI compared to the corn-SBM dietary treatment. The cumulative G:F of pigs did not differ (P = 0.32) between pigs fed corn-SBM diets and diets containing 40% DDGS regardless of the SID Trp:Lys ratio. However, pigs receiving the corn-SBM diets had heavier HCW, greater carcass yields, total carcass gain, and daily carcass gain (P < 0.01) compared to pigs fed the 40% DDGS diets regardless of SID Trp:Lys ratio. In conclusion, increasing the SID Trp:Lys ratio in 40% DDGS diets improved ADG and ADFI for the overall grow-finish period. However, when compared to a corn-SBM diet, increasing the SID Trp:Lys ratio in 40% DDGS diets did not correct the growth performance or carcass characteristics of pigs.

Methionine plus cystine to lysine ratio in diets for tambatinga fingerlings

ABSTRACT Among a variety of hybrids produced in Brazil, tambatinga is obtained from the crossing of a tambaqui female with a pirapitinga male. Although rapid weight gain in less time is an attractive characteristic from a commercial viewpoint, the information on its nutritional requirements, especially amino acid requirements, is limited. As corn and soybean meal-based diets available for fish contain deficient levels of essential amino acid methionine, our objective was to determine the digestible methionine plus cystine to lysine ratio in diets for tambatinga fingerlings. We used 900 fish with initial weights varying from 1.49 ±0.59 to 4.14 ±1.70 g, and they were fed six types of diets with different digestible methionine plus cystine to lysine ratios (50, 55, 60, 65, 70, and 75%). Performance parameters such as food efficiency, body depositions of protein, fat, and ash, and nitrogen retention efficiency were evaluated. The increase of digestible methionine plus cystine to lysine ratio in the diet improved quadraticly the feed intake, consumption of digestible methionine plus cystine, weight gain, specific growth rate and feed conversion, protein deposition and body ash and retention efficiency nitrogen until the estimated ratios of 57%, 73%, 58%, 58% and 59%, 59%, 58% and 60%, respectively; and reduced linearly the efficiency of using methionine plus cystine for the weight gain. On the other hand, body fat deposition was not affected. We concluded that the digestible methionine plus cystine: lysine ratio in the rations for tambatinga fingerlings is 59%, for provide better performance and body protein deposition.

Digestible trypthophan and digestilbe lysine ratios in diets for growing japanese quails

The objective of this study was to evaluate the effects of different tryptophan and digestible lysine ratios for growing Japanese quails (1 to 40 days of age) with repercussions on the early stage of production (41 to 110 days of age). A total of 1000 one day old Japanese quails were distributed at random, with five tryptophan and digestible lysine ratios, 10 replicates and 20 birds per experimental unit. A tryptophan- deficient basal diet was formulated with 1.48 g of digestible tryptophan /kg, corresponding to a ratio of tryptophan and lysine of 0.14. This basal diet was supplemented with five levels of L-tryptophan (98%), replacing glutamic acid corresponding to the tryptophan and lysine ratio of 0.14 (no supplementation); ratios of 0.16; 0.18; 0.20 and 0.22, being the diets isocaloric and isonitrogenous. The performance of the birds in the growing and egg laying phases was evaluated. Although body weight and weight gain until 40 days of age had increased (P&lt;0,001) and feed intake in the egg laying phase had decreased (P=0,037) in a linear fashion, LRP was the one with the best adjustment for those parameters. The effect was quadratic for feed intake (P=0,0069), feed conversion (P=0,0032) and viability (P&lt;0,001) of the birds in the growing phase. A quadratic effect was found for egg production per bird housed at one day of age (P&lt;0,001), weight gain at 110 days of age (P=0,039) and feed conversion per egg mass (P=0,046) in the laying phase. Intake of tryptophan increased (P&lt;0,001) and egg production per housed bird in the laying phase linearly decreased (P&lt;0,001) with the increase in the ratios between tryptophan and lysine. The digestible tryptophan and digestible lysine ratio is 0.18 (1.88 g of tryptophan/kg and 10.5 g of lysine/kg of diet), corresponding to an intake of 20.63 mg of tryptophan per bird per day, in the diet for growing, provides greater viability of birds in the growing phase and a satisfactory performance of Japanese quails in the laying phase.

Threonine to lysine ratio in diets of tambaqui juveniles (Colossoma macropomum)

The objective of this study was to determine the optimal digestible threonine to lysine ratios in diets of tambaqui (Colossoma macropomum) juveniles. Five-hundred fish with a mean ± SE initial weight of 2.16 ± 0.03 g were used in a completely randomized design, consisting of four treatments, five replicates per treatment, and 25 fish per experimental unit. The treatments consisted of four isoenergetic, isophosphoric, isocalcic, and isolisinic (1.45%) diets, consisting of a basal diet supplemented with four L-threonine levels (1.013, 1.085, 1.158, and 1.230%), resulting in different threonine to lysine ratios (70, 75, 80, and 85%). Fish were maintained in twenty 500-L aquaria with independent water supply, drainage, and aeration systems, and were fed to apparent satiation six times a day for 45 days. Performance, feed efficiency, daily protein and fat deposition, body moisture content, and nitrogen retention efficiency of fish were evaluated. The digestible threonine intake increased linearly, and the efficiency of threonine for weight gain decreased quadratically, with increasing digestible threonine to lysine ratios. Weight gain, specific growth rate, feed:gain ratio, protein efficiency for weight gain, and nitrogen retention efficiency of fish increased in a quadratic manner with increasing digestible threonine to lysine ratios up to the levels of 75.96, 76.06, 76.36, 76.47, and 74.02%, respectively. It was concluded that the digestible threonine to lysine ratio for use in diets of juvenile tambaqui to achieve optimal performance and nitrogen retention efficiency is 76 and 74%, respectively, which corresponds to a digestible threonine level of 1.102 and 1.073%.

Digestible tryptophan-to-digestible lysine ratio in diets for laying hens of 42 to 58 weeks of age

SUMMARY To determine the ideal digestible tryptophan-to-digestible lysine ratio in diets for laying hens of 42 to 58 weeks of age, 240 Hy-Line W-36 hens at 42 weeks of age were distributed in a completely randomized design with five treatments, eight replicates and six birds per experimental unit. At 42 weeks of age, the birds were subjected to experimental treatments that consisted of diets with equal amounts of nutrients, except for the digestible tryptophan level. The digestible tryptophan levels in the experimental diets were 0.149, 0.160, 0.171, 0.182 and 0.193%, generating digestible tryptophan-to-digestible lysine ratios of 21.5, 23.1, 24.6, 26.2 and 27.8%. The digestible lysine level in the diets was sub-optimal (0.694%). The same ratios between lysine and the other amino acids were maintained in all experimental diets. The ideal digestible tryptophan-to-digestible lysine ratio was estimated through the studied parameters using analysis of variance and polynomial regression analysis (α = 0.05). The digestible tryptophan-to-digestible lysine ratio in diets quadratically affected egg production, egg mass, feed conversion per egg mass and use efficiency of digestible lysine for egg mass. However, there were no effect (P&gt;0.05) on egg weight, feed conversion per dozen eggs, use efficiency of digestible lysine for number of eggs produced, percentage of egg components and weight gain. The digestible tryptophan-to-digestible lysine ratio estimated for theses parameters ranged from 23.6 to 24.3%. The digestible tryptophan-to-digestible lysine ratio recommended in diets for laying hens of 42 to 58 weeks of age is 24.3%.

Desempenho e rendimento de carcaça em frangos de corte de um a 46 dias alimentados com dietas contendo diferentes níveis de valina e reduzido teor proteico

Este estudo teve como objetivo avaliar as relações de valina:lisina digestíveis em dietas com teor reduzido de proteína bruta (PB) e os efeitos dessa redução sobre desempenho e rendimento de carcaça em frangos de corte. Foram utilizados 1200 pintos machos seguindo modelo inteiramente ao acaso, com seis tratamentos de seis repetições (exceto controle, com 10 repetições), compostos por 30 aves cada. O tratamento controle (T1) foi formulado conforme os níveis de proteína bruta e aminoácidos (AAs) recomendados por Rostagno et al . (2011), e os demais tratamentos (T2 a T6) tiveram seus níveis de PB reduzidos (4% em relação ao controle) e variaram em função da relação valina:lisina digestíveis, com cinco níveis equidistantes em intervalos de 0,07:1, variando de 0,63:1 e 0,91:1 (dietas até 21 dias) e de 0,64:1 e 0,92:1 (dietas após 21 dias). As seguintes características de desempenho foram avaliadas: ganho de peso, consumo de ração, conversão alimentar, viabilidade criatória e índice de eficiência produtiva. Aos 46 dias de idade, seis animais por repetição foram abatidos para determinação de rendimento de carcaça e de cortes comerciais. As diferentes relações valina:lisina digestíveis não influenciaram o desempenho dos animais (P&gt;0,05) para nenhuma característica avaliada. A redução proteica piorou a conversão alimentar dos animais (P≤0,05) até os 21 dias. Os resultados sugerem que os níveis de valina utilizados não afetam o desempenho dos animais, apenas o rendimento de peito e que, portanto, a redução proteica não é recomendada durante as três primeiras semanas de criação.

An Elevated Dietary Cysteine to Methionine Ratio Does Not Impact on Dietary Methionine Efficiency and the Derived Optimal Methionine to Lysine Ratio in Diets for Meat Type Chicken

Optimal dietary methionine (Met) to lysine (Lys) ratio in presence of elevated dietary cysteine (Cys) levels was derived for meat type growing chicken. Twelve averaged weighed Ross 308 birds (each 50% of male and female per dietary treatment) were utilized in N balance trials. During starter (d10 - 20) and grower period (d25 - 35) five dietary treatments were used. Diets based on uniform mixtures of maize, wheat, soybean meal, potato protein and fish meal were supplemented with crystalline amino acids (AA). In diets 1 - 3, the dietary Cys to Met ratio was set as 85, 95 and 105 to 100, respectively. Diet 4, at a Cys to Met ratio of 105 to 100, was additionally supplemented with betaine (BET) as methyl group donor. Diets 1 - 4 were limiting in Met, diet 5 without L-Lys·HCl addition was limiting in Lys. Individual N-balance data per treatment were utilized for assessing protein quality and efficiency of dietary Met (Diets 1 - 4) or Lys (Diet 5) based on “Goettingen approach”. Elevated dietary Cys supply and supplemented BET failed to improve both dietary protein quality and Met efficiency. The established optimal Met to Lys ratio was on average 34 to 100 for growing chicken during starter and grower period, respectively.

Digestible threonine to lysine ratio in diets for laying hens aged 24-40 weeks

Two-hundred sixteen white laying hens were used to assess the ideal ratio of digestible threonine:lysine in diets for laying hens at 24 to 40 weeks of age. Birds were assigned to a randomized block design, with six treatments, six replicates per treatment and six birds per experimental unit. The cage was used as the blocking criterion. Experimental diets contained different digestible threonine:digestible lysine ratios (65, 70, 75, 80, 85 and 90%) with 142 g/kg of crude protein. Experimental diets were formulated to be isonitrogenous and isocaloric with different contents of L-glutamic acid. Feed intake (g/hen/d), egg production (%), egg weight (g), egg mass (g/hen/d), feed conversion ratio (kg/dozen and kg/kg egg), eggshell weight (g), albumen weight (g), yolk weight (g) and body weight gain (g) were assessed. The maximum egg production was observed at 78% digestible threonine:digestible lysine ratio, while the best values of feed conversion ratio (kg/dozen egg) and feed conversion ratio (kg/kg of egg) were observed at 77.6% and 75%, respectively. Feed intake, egg mass and egg contents (yolk, albumen and eggshell) were not affected by treatments. The estimated digestible threonine:digestible lysine ratio of Hy-Line W36 laying hens at 24 to 40 weeks of age is 78%, corresponding to 5.70 g/kg of dietary digestible threonine.

Ideal digestible isoleucine: digestible lysine ratio in diets for laying hens aged 24-40 weeks

Two hundred fifty-two Hy-Line W36 laying hens were allotted in a randomized block design with 6 treatments, 7 replicates and 6 hens per experimental unit in order to determine the ideal digestible isoleucine: digestible lysine (Ile:Lys) ratio for laying hens aged 24-40 weeks. Experimental diets contained 5.92, 6.33, 6.73, 7.14, 7.54 and 7.95 g/kg of digestible isoleucine, resulting in different Ile:Lys ratios (0.73:1, 0.78:1, 0.83:1, 0.88:1, 0.93:1 and 0.98:1). Experimental diets were isonitrogenous, with different dietary contents of glutamic acid, and made isocaloric by adjusting the levels of cornstarch. All essential amino acids were provided proportionally to digestible lysine. Feed intake, egg production, egg weight, egg mass, feed conversion ratio per egg mass, feed conversion ratio per dozen eggs, albumen, yolk and eggshell content were assessed. Feed intake, egg production, egg mass and feed conversion ratio were influenced by Ile: Lys ratios quadratically. The egg weight was not affected by Ile: Lys ratio. No differences were observed in the egg quality according to Ile: Lys ratios. The data indicates that the optimum digestible isoleucine: digestible lysine ratio for laying hens aged 24-40 week is 0.84:1, corresponding to the consumption of 681 mg of isoleucine and 811 mg of lysine/hen day-1.

Digestible tryptophan:digestible lysine ratio in diets for laying hens from 24 to 40 weeks of age

The objective of this study was to determine the ideal digestible tryptophan:digestible lysine ratio in diets for laying hens from 24 to 40 weeks of age. Two hundred and forty Hy-Line W-36 laying hens at 24 weeks of age were distributed in a completely randomized design, with five treatments, eight replicates and six birds per experimental unit. The digestible tryptophan levels in the experimental diets were 1.57; 1.68; 1.79; 1.90 and 2.01 g/kg, providing ratios of digestible tryptophan:digestible lysine of 0.215; 0.230; 0.245; 0.260 and 0.275. The increase in the levels of digestible tryptophan in the diet linearly improved the feed intake, digestible tryptophan intake, digestible lysine intake, egg production, egg mass, feed conversion per egg mass and utilization efficiency of digestible lysine for eggs mass. There were quadratic effects from the digestible tryptophan levels on egg weight. For the efficiency of utilization of digestible lysine for egg mass, there was better adjustment of the data to the LRP model. The level of digestible tryptophan in the diet from which the plateau occurred was 0.184%. This level corresponded to the intake of 142 mg/bird/day of digestible tryptophan and digestible tryptophan:digestible lysine ratio of 0.252. The ideal digestible tryptophan:digestible lysine ratio recommended in diets for laying hens from 24 to 40 weeks of age is 0.252 (25.2%).

Determination of digestible isoleucine: lysine ratio in diets for laying hens aged 42-58 weeks

Two hundred and fifty-two Hy-Line W36 laying hens were allotted in a completely randomized design with 6 treatments, 7 replicates and 6 hens per experimental unit in order to determine the ideal ratio of isoleucine (Ile) in relation to lysine (Lys) to laying hens aged 42-58 weeks. Experimental diets contained digestible Ile at different levels, resulting in different Ile:Lys ratios (0.73:1; 0.78:1; 0.83:1; 0.88:1; 0.93:1 and 0.98:1). A basal diet was formulated to provide Isoleucine in levels below recommendations. This diet was supplemented with L-isoleucine to make up the 6 diets. Each diet was made isonitrogenous by varying the dietary contents of glutamic acid and isocaloric by adjusting the contents of cornstarch. All essential amino acids were provided proportionally to lysine. Egg production, egg weight, egg mass, feed conversion ratio, albumen, yolk and eggshell contents were recorded and compiled at every 28-day period. No differences were observed in the performance over a wide range of dietary isoleucine concentrations from 5.76 to 7.73 g/kg corresponding to 0.73:1 to 0.98:1 Ile:Lys ratios. The lowest Ile:Lys ratio (0.73:1) was sufficient to ensure satisfactory performance of birds, corresponding to the consumption of 534 mg of isoleucine and 731 mg of lysine/day.

Determining the effects of standardized ileal digestible tryptophan:lysine ratio and tryptophan source in diets containing dried distillers grains with solubles on growth performance and carcass characteristics of finishing pigs (2012)

A total of 2,290 pigs (PIC 1050 × 337; initially 157 lb) were used to determine the effect of tryptophan source (L-tryptophan vs. soybean meal) and increasing SID tryptophan:lysine ratio in diets containing 30% dried distillers grains with solubles (DDGS) on finishing pig performance. Pens of pigs were balanced by initial weight and randomly allotted to 1 of 7 dietary treatments in a completely randomized design with 26 to 28 pigs per pen and 10 to 13 replications per treatment. Treatments were arranged as a 2 × 3 factorial with main effects of tryptophan source (L-tryptophan or soybean meal) and SID tryptophan:lysine ratio (18, 20, and 22% of lysine). The seventh treatment was a negative control diet formulated to a 16% SID tryptophan:lysine ratio.; Swine Day, Manhattan, KS, November 15, 2012

Determining the effects of tryptophan:lysine ratio in diets containing dried distillers grains with solubles on growth performance of finishing pigs (2011)

A total of 1,235 pigs (PIC 1050 × 337; initially 149 lb) were used in a 71-d study to determine the effects of tryptophan:lysine ratio in diets containing 0, 20, or 40% dried distillers grains with solubles (DDGS) on growth performance of finishing pigs raised in a commercial environment. Pens of pigs were balanced by initial weight and randomly allotted to 1 of 6 dietary treatments in a completely randomized design with 26 to 28 pigs per pen and 7 to 8 replications per treatment. Treatments were arranged as a 2 × 3 factorial with main effects of standardized ileal digestible (SID) tryptophan:lysine ratio (16.5 or 20% of lysine) and DDGS (0, 20, or 40%). Overall (d 0 to d 71), no differences occurred in growth performance due to SID tryptophan:lysine ratio. Increasing DDGS resulted in poorer F/G (linear, P = 0.02), but did not influence other growth performance criteria. For carcass characteristics, increasing the SID tryptophan:lysine ratio increased (P = 0.02) carcass yield percentage with the greatest improvement in yield observed when diets contained high levels (20 and 40%) of DDGS (tryptophan × DDGS interaction, P = 0.07). Pigs fed high levels of DDGS had reduced loin depth (linear, P = 0.02); however, the lowest loin depth was at 40% DDGS for 16.5% SID tryptophan:lysine ratio and at 20% DDGS for 20% SID tryptophan:lysine ratio resulting in a tryptophan × DDGS interaction (quadratic, P = 0.02). A tendency of tryptophan × DDGS interaction (linear, P = 0.08) was observed for lean percentage, with lean percentage decreasing as DDGS increased in diets containing the 16.5% SID tryptophan:lysine ratio and no change in lean percentage as DDGS increased in diets containing the 20% SID tryptophan:lysine ratio. The tendency of interactions for yield and lean percentage indicate an advantage to increasing the SID tryptophan:lysine ratio in diets with high levels of DDGS, but no effects on growth performance were observed due to SID tryptophan:lysine ratio.; Swine Day, Manhattan, KS, November 17, 2011

Determining the effects of tryptophan:lysine ratios in diets containing 30% dried distillers grains with solubles on growth performance of 157- to 285-lb pigs (2011)

A total of 2,298 pigs (half gilts and half barrows, PIC TR4 × 1050; initially 157 lb) were used in a 52-d study to determine the effects of increasing tryptophan:lysine ratios in diets containing 30% dried distillers grains with solubles (DDGS) on the growth performance of finishing pigs raised in a commercial environment. Pens of pigs were balanced by initial weight and randomly allotted to 1 of 6 dietary treatments in a completely randomized design within gender; each pen contained 23 pigs and each treatment had 16 to 17 replications. Treatments were arranged as a 2 × 6 factorial with main effects of gender (gilts or barrows) and standardized ileal digestible (SID) tryptophan:lysine ratio (2 positive control diets with no DDGS containing SID tryptophan:lysine ratios of 17 or 21% of lysine and 4 diets containing 30% DDGS with SID tryptophan:lysine ratios of 15, 17, 19, or 21% lysine).

Effects of standardized ileal digestible tryptophan:lysine ratio in diets containing 30% dried distiller grains with solubles on the growth performance and carcass characteristics of finishing pigs in a commercial environment (2010)

Two experiments were performed to determine the effects of increasing standardized ileal digestible (SID) tryptophan to lysine (trp:lys) ratio in growing-finishing pig diets containing 30% dried distillers grains with solubles (DDGS). In both experiments, soybean meal replaced crystalline lysine and threonine to alter the dietary SID trp:lys concentrations while maintaining minimum ratios of other amino acids. In Exp. 1, a total of 638 pigs (PIC 1050 x 337, initially 80.0 lb) were used in a 105-d trial with 26 to 27 pigs per pen and 6 pens per treatment. Pens of pigs were randomly allotted to 1 of 4 dietary treatments with standardized ileal digestible trp:lys ratios of 14.0, 15.0, 16.5, and 18.0%. All diets were fed in meal form and treatments were fed in 4 phases. For the overall trial, ADG and ADFI increased (linear; P < 0.001) as trp:lys increased through 18%; however, the response tended to be quadratic from d 0 to 42, with optimal ADG and ADFI at 16.5% SID trp:lys. Feed efficiency was not influenced by SID trp:lys ratio. Although feed cost per pig increased (linear; P < 0.001) as SID trp:lys ratio increased, so did (linear; P < 0.04) final live weight, HCW, income per pig, and income over feed cost (IOFC). The results of this experiment indicated the optimal SID trp:lys ratio was 16.5% from 80 to 160 lb, but at least 18% from 160 to 265 lb. In Exp. 2, a total of 1,214 pigs (PIC 1050 x 337, initially 146.2 lb) were used in a 73-d finishing trial with 25 to 28 pigs per pen and 9 pens per treatment. Pens of pigs were randomly allotted to 1 of 5 treatment groups. Pigs were fed common diets before the start of the experiment. Dietary treatments included corn-soybean meal-based diets with SID trp:lys ratios of 15.0, 16.5, 18.0, and 19.5, and the 15.0% diet with L-tryptophan added to achieve 18.0% SID trp:lys ratio. Overall (d 0 to 73), ADG, ADFI, F/G, final weight, and HCW improved (linear; P < 0.03) as dietary SID trp:lys increased through 19.5%. Increasing SID trp:lys increased (linear; P < 0.001) feed cost per pig, but also increased (P < 0.01) total income per pig. While there were no differences on an IOFC basis, pigs fed the highest level of SID trp:lys had numerically the greatest IOFC. Overall, there were no significant differences between the diet with 18.0%

Crude protein reduction and digestible methionine+cystine and threonine to digestible lysine ratios in diets for Nile tilapia fingerlings

The objective of the present study was to investigate crude protein reduction and the methionine+cystine and threonine to lysine ratios in diets for reversed Nile tilapia fingerlings (Oreochromis niloticus), Thai strain. Four hundred and twenty Nile tilapia fingerlings with an average initial weight of 1.83 ± 0.02 g were placed in a completely randomized design, with five treatments, seven replications per treatment and 12 fish per experimental unit, for 37-days. Two crude protein (CP) levels were evaluated (32 and 28%). The diet with 32% CP had methionine+cystine:lysine and threonine:lysine ratios of 63 and 74%, respectively. Three diets with 28% CP had methionine+cystine:lysine and threonine:lysine ratios of 63 and 74%, 60 and 74% and 60 and 69%, respectively. The diet with 28% CP and had methionine+cystine:lysine ratio of 63% and threonine:lysine of 74% and was supplemented with 0.3% glutamic acid. The fish were kept in thirty-five 130 L aquariums supplied with single-pass flow-through water, individual aeration and fed ad libitum six times per day. Fish fed the diet with 32% CP had lower protein efficiency ratios and nitrogen efficiency ratios. The diet CP level was 28% and the methionine+cystine and threonine to lysine ratios were 60 and 69%, respectively.

Optimum tryptophan: Lysine ratio in diets for growing pigs: Analysis of literature data

Optimum tryptophan supply in diets for growing pigs shows considerable variation between studies; therefore, an attempt was made to analyse all available data reported in the literature. Due to the fact that, in most studies, lysine was the second-limiting amino acid, which means that lysine limits growth at a certain level of tryptophan intake, optimum supply has to be expressed as a ratio to lysine. The database was too small to give optimum supply as a concentration in the diet or as a daily amount. In total, 33 experiments were found, where tryptophan intake was offered in graded levels resulting in a tryptophan-dependent and -independent response phase. An additional 13 experiments showed either no dependent or no independent phase, which did not allow an optimum determination. The optimum tryptophan : lysine ratio (T : L opt) was defined as the beginning of the plateau response-phase in feed intake or body weight gain. Mean T : L opt was 0.174 (SD = 0.023; n = 33) and seemed to be unaffected by body weight, growth rate, lysine and protein concentration in the diet, or genetic improvement of the animals. However, precise detection of the optimum ratio is generally restricted due to the relatively large intervals between the ratios tested in the respective studies. Mean difference between T : L opt and the nearest T : L ratio tested below (T : L opt − 1 ) was 0.028 (SD = 0.011; n = 32). Therefore, it is likely that the true optimum ratio is below 0.174, and that the mean of both ratios ((T : L opt + T : L opt − 1 ) / 2) can be taken as a good estimation (mean = 0.160; SD = 0.024; n = 33). With respect to feed formulation for growing pigs, it was concluded that a figure of 0.17 for the optimum T : L ratio includes a safety margin large enough to cover most of the biological variations.

Influence of dietary total sulfur amino acids and methionine on growth performance and carcass characteristics of finishing gilts.

We conducted three experiments to determine the sulfur amino acid (SAA) and methionine requirements of finishing gilts. Gilts (PIC Line 326 x C-15, Exp. 1; Line 326 x C-22, Exp. 2 and 3) were blocked by initial weight in randomized complete block designs. In Exp. 1, 64 gilts (initially 54 kg) were fed diets containing either .56 or .44% apparent digestible lysine with increasing SAA levels (63, 70, and 77% of apparent digestible lysine) in a 2 x 3 factorial. A lysine x SAA interaction (P < .10) was observed for ADG and ADFI. Increasing SAA:lysine ratios from 63 to 70% in diets containing .56% apparent digestible lysine increased ADG and ADFI; however, increasing the SAA:lysine ratio in diets containing .44% apparent digestible lysine decreased ADG and ADFI. Pigs fed .56% apparent digestible lysine had higher (P < .05) ADG and gain:feed ratio (G/F) and lower 10th rib fat depth than pigs fed .44% apparent digestible lysine. Increasing the SAA:lysine ratio had no effect on G/F or carcass characteristics. In Exp. 2, 80 gilts (initially 74 kg) were fed diets containing .225, .25, .275, .30, or .325% apparent digestible SAA (45, 50, 55, 60, or 65% of .50% apparent digestible lysine, respectively). Increasing SAA concentrations decreased ADG and G/F (linear, P < .06). In Exp. 3, 105 gilts (initially 72 kg) were fed diets containing .20% apparent digestible cystine and .10, .125, or .15% apparent digestible methionine (20, 25, or 30% of .50% apparent digestible lysine). Increasing digestible methionine increased ADG, ADFI, plasma methionine concentrations (linear, P < .01), and G/F (quadratic, P < .03). The greatest increases in ADG and G/F were observed when apparent digestible methionine was increased from .10 to .125%. Based on these results, the apparent digestible methionine requirement is no greater than 25% of apparent digestible lysine, in diets containing excess cystine. This equates to an apparent digestible SAA:lysine ratio that is no greater than 50%.

Determining the optimal isoleucine:lysine ratio in diets for the segregated early-weaned pig

Determining the optimal isoleucine:lysine ratio in diets for the segregated early-weaned pig