O experimento foi conduzido com o objetivo de avaliar cinco planos de nutrição baseados em sequências de lisina digestível verdadeira: 0,90-0,80-0,70; 1,00-0,90-0,80; 1,10-1,00-0,90; 1,20-1,10-1,00 e 1,30-1,20-1,10%, fornecidos dos 60 aos 99, dos 100 aos 129 e dos130 aos 148 dias de idade, respectivamente. Foram utilizadas oitenta leitoas, híbridas comerciais, selecionadas para deposição e carne, com peso inicial de 23,46±0,27kg. Os animais foram distribuídos em delineamento de blocos ao acaso, com cinco tratamentos, oito repetições e dois animais por unidade experimental. Não houve efeito (P>0,05) dos planos nutricionais no consumo de ração diário, no ganho de peso diário e na conversão alimentar. Os planos nutricionais não influenciaram (P>0,05) nenhum dos parâmetros de característica de carcaça avaliados (rendimento de carcaça quente, quantidade de carne e rendimento de carne). O plano nutricional de lisina digestível verdadeira de 0,90-0,80-0,70% fornecido dos 60 aos 99, dos 100 aos dos 129 e 130 aos 148 dias de idade, respectivamente, atende às exigências de lisina digestível verdadeira de leitoas dos 60 aos 148 dias de idade.

The experiment was conducted to evaluate five nutritional plans based on sequences of standardized ileal digestible lysine: 0.90-0.80-0.70, 1.00-0.90-0.80, 1.10-1.00-0.90, 1.20-1.10-1.00, and 1.30-1.20-1.10% fed to gilts from 60 to 99, 129 to 100, and 130 to 148 days of age, respectively. Eighty commercial hybrid gilts, selected for lean gain, with initial weight of 23.46±0.27kg were allotted in a randomized block design, with five treatments, eight replicates, and two pigs per experimental unit. No effect (P>0.05) of the nutritional plans was verified on daily feed intake, daily weight gain and feed conversion. The nutritional plans had no influence (P>0.05) on any of the carcass traits evaluated (carcass yield, meat amount, and meat yield). The nutritional plan of 0.90-0.80-0.70% standardized ileal digestible lysine fed to gilts from 60 to 99, 100 to 129, and 130 to 148 days of age, respectively, meets the standardized ileal digestible lysine requirements of gilts from 60 to 148 days of age.

Foram utilizados 50 suínos machos castrados, com alto potencial genético para deposição de carne magra na carcaça e peso inicial de 60,5 ± 1,58 kg para avaliar diferentes níveis de lisina digestível sobre o desempenho e as características de carcaça. Foi usado o delineamento de blocos ao acaso, com cinco tratamentos, cinco repetições e dois animais por repetição. Os tratamentos consistiram de cinco níveis de lisina digestível (0,600; 0,700; 0,800; 0,900 e 1,000% de lisina) obtidos variando-se a proporção de milho e farelo de soja nas rações. Os animais permaneceram no experimento até atingirem o peso final de 95,8 ± 2,64 kg. Os níveis de lisina influenciaram de forma quadrática a conversão alimentar e a conversão alimentar em músculo, que melhoraram até o nível de 0,85% de lisina digestível, e o rendimento de carne magra, que aumentou até o nível de 0,840% de lisina digestível. O consumo de lisina diário aumentou de forma linear em razão dos níveis de lisina da ração. Não houve efeito dos tratamentos sobre o ganho de peso, consumo de ração, características de carcaça, rendimento de carcaça, rendimento de gordura e rendimento de pernil. Conclui-se que suínos machos castrados, dos 60 aos 95 kg, exigem 0,850% de lisina digestível, correspondente a um consumo diário estimado de 24,2 g de lisina digestível.

Fifty barrows with high genetic potential for lean gain and 60.5 ± 1.58kg of average initial live weight were used in a study to evaluate different lysine levels on performance and carcass traits. A randomized blocks experimental design, with five treatments, five replicates and two animals per replicate was used. Treatments consisted in five digestible lysine levels (0.600; 0.700; 0.800; 0.900; e 1.000%) obtained with the variation of corn and soybean meal proportion. Animals were kept in the experiment until they reached 95.8 + 2.64kg of final live weight. Lysine levels had a quadratic effect on feed conversion and feed conversion in muscle, which improved to the level of 0.85 % digestible lysine , and lean meat yield , which increased up to 0.840 % digestible lysine.The daily lysine intake increased linearly with the elevation of dietary levels of lysine. There was no effect of treatments on weight gain, feed intake, carcass traits, carcass yield, fat yield, and ham yield. It was concluded that barrows from 60 to 95 kg require 0.850% of total lysine, corresponding to a digestible lysine estimated intake of 24.2 g/day.

Dois experimentos foram conduzidos para determinar os efeitos da energia líquida (EL) da ração no desempenho e nas características de carcaça de suínos, recebendo dietas com proteína bruta reduzida (PB). Os suínos (60,0±1,05kg, Exp. 1, 93,0±1,56kg, Exp. 2) foram distribuídos em delineamento de blocos casualizados, com três tratamentos. O Exp. 1 teve seis baias/tratamento e o Exp. 2 teve 8 baias/tratamento e todas as baias tiveram 2 animais. Os tratamentos foram: 199g kg-1 PB e 2566kcal kg-1 NE, 155g kg-1 PB e 2.631kcal kg-1 NE, 155g kg-1 PB e 2.566kcal kg-1 NE no Exp. 1, e 180g kg-1 PB e 2588kcal kg-1 NE, 145g kg-1 PB e 2638kcal kg-1 NE, 145g kg-1 de PB e 2588kcal kg-1 NE, no Exp. 2. No Exp.1, a ração com 155g kg-1 PB e 2566kcal kg-1 EL resultou em maior GPD. Não houve efeito dos níveis PB ou EL sobre os demais parâmetros. No Exp. 2, os melhores resultados de CRD e GDP foram obtidos com 145g kg-1 PB e 2588kcal kg-1 EL. Os suínos alimentados com a dieta com 180g kg-1 PB e 2.588kcal kg-1 NE apresentaram menor quantidade de carne na carcaça. Não houve efeito do conteúdo de PB ou EL da ração na espessura de toucinho. A ração contendo 155g kg-1 PB e 2.566kcal kg-1 NE resultou em maior GPD de suínos dos 60 aos 95kg. Dos 95 aos 120kg, a dieta com 145g kg PB e 2588kcal kg-1 EL resultou em maior GPD e carne na carcaça.

Two experiments were conducted to determine the effects of dietary net energy content (NE) on performance and carcass traits of finishing barrows fed low-crude protein (CP) diets. Pigs (60.0±1.05kg, Exp. 1, 93.0±1.56kg, Exp. 2) were allotted in a randomized block design to 3 dietary treatments. Exp. 1 had 6 pens treatment-1 and Exp. 2 had 8 pens treatment-1 and all pens had 2 pigs. The treatments were: 199g kg-1 CP and 2566kcal kg-1 NE, 155g kg-1 CP and 2631kcal kg-1 NE, 155gk g-1 CP and 2566kcal kg-1 NE in Exp. 1, and 180g kg-1 CP and 2588kcal kg-1 NE, 145g kg-1 CP and 2638kcal kg-1 NE, 145g kg-1 CP and 2588kcal kg-1 NE, in Exp. 2. In Ep.1, except for average daily gain (ADG) there was no effect of dietary CP or NE on any other parameter evaluated. The diet with 155g kg-1 CP and 2566kcal kg-1 NE resulted in greatest ADG. In Exp. 2, the greatest results of ADFI and ADG were obtained with 145g kg-1 CP and 2588kcal kg-1 of NE. Pigs fed the diet with 180g kg-1 CP and 2588kcal kg-1 NE had less carcass meat. There was no effect of dietary CP or NE on backfat. The CP diet containing 2566kcal kg-1 NE resulted in greatest ADG of 60- to 95-kg barrows. For 95- to 120-kg barrows the diet with 145gk g-1 CP and 2588kcal kg-1 of NE resulted in greatest ADG and carcass meat.

This study was conducted to evaluate the effects of digestible lysine levels in diets with and without supplementation of industrial amino acids on performance and fat deposition in the carcass of broilers in the starter phase. One thousand four hundred and forty chickens with initial weight of 168.1±5.0 g were distributed in a completely randomized experimental design, in a 5 × 2 factorial arrangement, composed of five digestible lysine levels (10.0, 11.0, 12.0, 13.0 and 14.0 g/kg) and two types of diet (diet with different proportions of corn and soybean meal and diet supplemented with industrial amino acids to obtain the digestible lysine levels), with eight replications and 18 birds per replication. There was interaction effect only on weight gain and fat deposition in the birds. The lysine levels reduced feed intake linearly in both diets, but caused a linear increase in lysine intake. The lysine levels quadratically affected weight gain and feed conversion, which improved up to the estimated levels of 13.0 and 12.8 g/kg lysine, respectively, when the corn:soybean meal ratio of the diet changed. In the diets supplemented with amino acids, the lysine levels increased weight gain and improved feed conversion linearly. Regardless of the type of diet, protein deposition increased linearly, whereas fat deposition reduced also linearly, as the lysine levels in the diets were increased. The levels of 13.0 and 14.0 g/kg digestible lysine provide, respectively, the best performance in birds fed a diet in which the proportion of corn and soybean meal varies and a diet supplemented with industrial amino acids, in the period from 8 to 21 days of age.

This study was conducted to verify the effects of dietary crude protein reduction on growth and carcass performance of 22-42-day-old broilers reared under different temperatures. Treatments were set up in a five by two factorial arrangement, with five crude protein levels (220, 210, 200, 190 and 184 g/kg) and two temperatures (21.6 and 32.2 ºC). Diets were isocaloric and essential amino acid-to-lysine ratio was maintained constant in all treatments. There was no interaction between crude protein reduction and environmental temperature for any of the parameters evaluated. Crude protein had no influence on feed intake. Nevertheless, weight gain and feed conversion ratio were linearly influenced by crude protein reduction. Worse performance was also observed in birds exposed to heat stress as compared with birds kept under thermoneutral temperature. There was no effect of crude protein reduction on breast and legs. Birds kept under heat stress had lower breast yield and higher leg yield as compared with broilers reared at 21.6 ºC. Any crude protein reduction in the range of 220 to 184 g/kg for 22 to 42-day-old broilers has a negative effect on their performance. Heat stress worsens broiler performance and breast yield.

Four trials were conducted to determine the requirements of available phosphorus (aP) of female broiler chicks from 1 to 10 (exp.1), 11 to 21 (exp.2), 22 to 33 (exp.3), and from 34 to 46 (exp.4) days of age, keeping the calcium:available phosphorus ratio equal to 2:1. In each trial, 480 Cobb broilers were randomly allotted in a completely randomized design with 6 treatments, 8 replicates and 10 birds per pen. The levels of aP ranged from 2.0 to 5.5 g/kg (Exp. 1), 1.9 to 5.4g/kg (exp. 2), 1.8 to 5.3 g/kg (exp. 3) and 1.7 to 5.2 g/kg of diet (exp. 4), in increments of 0.7 g/kg. The experimental diets were formulated using corn and soybean meal and the available phosphorus was considered 33% of total phosphorus. The characteristics evaluated were body weight gain, feed intake, feed conversion ratio and bone parameters. For female broiler chicks from 1 to 10; 11 to 21; 22 to 33; and from 34 to 46 days of age, the levels of available phosphorus and calcium recommended are 4.59 and 9.18; 3.88 and 7.76; 3.58 and 7.16; and 2.56 and 5.12 g/kg of diet, respectively.

The objective of this study was to evaluate the inclusion of yeast extract as a partial replacemer of blood plasma in piglet diets and its effect on the performance and intestinal morphometry of pigs weaned at 21 days of age. One hundred and twenty animals were randomized into blocks, with five diets (4.0% blood plasma; 2.0% blood plasma with 0.0; 1.0; 2.0 or 3.0% yeast extract), six replicates and four pigs per experimental unit. At 35 days of age, one pig per experimental unit was slaughtered in order to evaluate duodenal and jejunal morphometry. The levels of yeast extract had a quadratic impact on daily feed intake and final weight, which increased up to the estimated level of 1.91%. Daily weight gain and feed conversion rate were not affected. A comparison between diets containing different levels of yeast extract and the basal diet showed that the diets containing 2.0% and 1.0% yeast extract provided the highest final weight and the worst feed conversion rate, respectively. Duodenal villus height and crypt depth were quadratically affected by yeast extract levels and the best results were achieved with the estimated levels of 1.64 and 1.16%, respectively. The levels of yeast extract provided a linear increase in the duodenal villus:crypt ratio, but did not change the morphometric variables of the jejunum. No difference was found in the morphometric variables of the duodenum and jejunum when diets containing different levels of yeast extract were compared with the basal diet. The results suggest that the inclusion of 1.91% yeast extract allows for a partial replacement for plasma in the diet, decreasing plasma inclusion from 4.0 to 2.0%.

With the objective of evaluating available phosphorus (aP) levels in diets for barrows selected for lean meat deposition, eighty commercial hybrid pigs with initial weight of 94.05±1.05 kg were used in this experiment. Pigs were allotted in a completely randomized block design, with five treatments (0.092, 0.156, 0.220, 0,284, and 0.348% of aP), eight replicates and two pigs per experimental unit. The average daily weight gain of pigs increased and the feed conversion improved quadratically with increasing aP in the diets up to the estimated levels of 0.21 and 0.20%, respectively. There was no effect of the dietary aP on average daily feed intake. However, aP intake, bone strength and concentration of phosphorus in the bones increased linearly with increasing aP in the diets. The levels of aP did not affect carcass traits; however, the alkaline phosphatase activity was improved and the values of serum inorganic phosphorus increased quadratically up to the estimated levels of 0.26 and 0.27% of aP, respectively. The available phosphorus levels of 0.21, 0.27, and 0.35%, corresponding to daily aP intakes of 6.34, 8.13, and 10.44 g result, respectively, in greatest performance, blood and bone parameters of 95 to 120 kg barrows selected for lean gain.

Utilizaram-se 50 leitoas de alto potencial genético para deposição de carne magra na carcaça, com peso inicial de 30,17 ± 2,03, a fim de avaliar o efeito de níveis crescentes de lisina digestível sobre o desempenho e características de carcaça. Os animais foram distribuídos em delineamento experimental de blocos ao acaso, com cinco tratamentos (0,83; 0,93; 1,03; 1,13 e 1,23% de lisina digestível), cinco repetições e dois animais por unidade experimental. Na distribuição dos animais dentro de cada bloco foi adotado como critério o peso inicial dos animais. Não foi observado efeito dos níveis de lisina digestível sobre o consumo de ração diário e ganho de peso diário. Observou-se efeito quadrático dos tratamentos sobre a conversão alimentar, que melhorou até o nível estimado de 1,11% de lisina digestível. Foi observado efeito linear dos níveis de lisina sobre a taxa de deposição de proteína diária, entretanto, o modelo Linear Response Plateau foi o que melhor se ajustou aos dados e estimou o nível de 1,09% de lisina digestível para melhor deposição de proteína diária. Não foi observado efeito dos tratamentos sobre a taxa de deposição diária de gordura. Conclui-se que o nível de 1,11% de lisina digestível proporciona os melhores resultados de desempenho e de taxa de deposição de proteína diária na carcaça de fêmeas suínas de alto potencial genético para deposição de carne magra na carcaça, dos 30 aos 60kg.

Fifty gilts were used, with initial weight of 30.17 ± 2.03kg, to evaluate the effect of increasing levels of digestible lysine on performance and carcass characteristics. The animals were distributed in a random block experimental design, with five treatments (0.83; 0.93; 1.03; 1.13 and 1,23% of digestible lysine), five replicates and two animals which were considered one experimental unit. The criteria for the formation of the blocks were the animals initial weight. There was no effect of levels of digestible lysine on daily feed intake and daily weight gain. A quadratic effect was observed on feed conversion that improved until an estimated level of 1.11% of digestible lysine. A linear effect was observed on daily protein deposition, however, the data were adjusted through the Linear Response Plateau model, which indicated the estimated level of 1.09% of digestible lysine for best daily protein deposition. No effect was observed on daily fat deposition among the treatments. It conclude that the level of 1.11% of digestible lysine provided the best performance and daily protein deposition results for gilts with high potential for lean deposition, from 30 to 60kg.

With the objective to evaluate levels of available phosphorus (aP) in diets with or without ractopamine, 112 gilts with high genetic potential for meat deposition with initial weigh of 94.0±2.28 kg were allotted in a completely randomized block design, in a 4 × 2 factorial arrangement (0.109, 0.209, 0.309, and 0.409% aP and 0 or 5 ppm of ractopamine), with eight treatments, seven replicates, and two gilts per experimental unit. There were no interactions between aP levels and ractopamine. The levels of available phosphorus influenced both daily weight gain and daily phosphorus intake, which increased linearly. Feed conversion improved in a quadratic way up to the estimated level of 0.330% aP maximum response. Daily weight gain increased and feed conversion improved by adding ractopamine to the diets. Serum alkaline phosphatase activity decreased linearly by increasing the levels of available phosphorus. Bone strength, ash, calcium, and phosphorus contents in the bones also increased quadratically with maximum responses at 0.320, 0.270, 0.277, and 0.295% aP, respectively. The available phosphorus level of 0.330%, corresponding to a daily intake of 8.67 g of aP is suitable for 94 to 125 kg gilts selected for meat deposition fed diets with or without ractopamine.

Para avaliar o efeito de níveis de lisina digestível sobre o desempenho e as características de carcaça de suínos machos castrados dos 60 aos 100 dias de idade, foram utilizados 300 animais com peso médio de 25±0,52 kg, distribuídos em delineamento experimental de blocos ao acaso, com 5 tratamentos (0,65; 0,75; 0,85; 0,95 e 1,05% de lisina digestível), 5 repetições e 12 animais por unidade experimental. Não houve efeito dos níveis de lisina digestível sobre o consumo médio diário de ração. O consumo de lisina digestível aumentou de forma linear com o aumento desse aminoácido na ração. O ganho de peso médio diário aumentou e a conversão alimentar melhorou de forma quadrática com o aumento dos níveis de lisina digestível da ração. Não foi observado efeito dos níveis de lisina digestível sobre a espessura de toucinho dos animais, entretanto, o rendimento de carcaça e a quantidade de carne aumentaram de forma quadrática com o aumento dos níveis de lisina digestível. Os níveis de 0,96 e 0,92% de lisina digestível, correspondentes aos consumos estimados de 18,69 e 17,69 g/dia, proporcionam os melhores resultados de ganho de peso e conversão alimentar, enquanto os níveis de 0,89 e 0,90%, correspondentes aos consumos estimados de 17,28 e 17,52 g/dia, propiciam os melhores resultados de rendimento e quantidade de carne na carcaça de suínos machos castrados dos 60 aos 100 dias de idade.

In order to evaluate digestible lysine levels on the performance and carcass traits of castrated male pigs from 60 to 100 days of age, 300 barrows with initial weight of 25.0±0.52 kg were allotted in a completely randomized block design with five treatments (0.65, 0.75, 0.85, 0.95, and 1.05% digestible lysine levels), five replicates, and 12 pigs per experimental unit. There was no effect of digestible lysine levels on average daily feed intake. The average daily gain increased and feed conversion improved quadratically with increasing dietary digestible lysine levels. There was no effect of the digestible lysine levels on pig backfat thickness; however the carcass yield and quantity of meat increased quadratically with increasing digestible lysine levels in the diets. The levels of 0.96 and 0.92% digestible lysine, corresponding to the estimated intakes of 18.69 and 17.69 g/day provide the best results of weight gain and feed conversion, while levels of 0.89 and 0.90%, corresponding to the estimated intakes of 17.28 and 17.52 g/day, provide the best results of yield and quantity of meat in the carcass of barrows from 60 to 100 days of age.

This study was developed to evaluate the effects of adding L-glutamine and L-glutamate in diets with no lactose or with 4.0 or 8.0% lactose inclusion for piglets weaned at 21 days old. One hundred and eight piglets with initial weight of 6.12±0.70 kg were allotted in a complete randomized block design, in a 3 × 2 factorial arrangement, with six treatments, six replicates, and three piglets per experimental unit. The experimental diets were supplied from 21 to 35 days. From 36 to 49 days, animals received the same diet with no lactose inclusion, but the animals in the treatments with L-glutamine + L-glutamate in the previous phase continued to receive diets containing these ingredients. There was no interaction between the level of lactose and the inclusion of L-glutamine + L-glutamate on the parameters evaluated. The levels of lactose did not affect the performance of piglets in either of the two periods. Adding L-glutamine and L-glutamate in the diet positively influenced the weight gain of pigs from 21 to 49 days of age and increased the villous height in the duodenum, jejunum and ileum. Inclusion of L-glutamine + L-glutamate in diets for piglets weaned at 21 days of age improves the performance and the intestinal mucosa morphology, regardless of lactose addition.

Este estudo foi realizado com o objetivo de avaliar níveis de zeólita em dietas para suínos e seus efeitos no desempenho, nas características de carcaça e nos parâmetros sanguíneos e histopatológicos do parênquima hepático desses animais nas fases de crescimento e terminação. Foram utilizados 84 suínos machos castrados, híbridos comerciais de alto potencial genético para deposição de carne, com peso inicial de 30,34±1,14 kg, distribuídos em delineamento experimental de blocos ao acaso, com sete níveis de adsorvente (0,0-0,0; 1,0-0,5; 1,0-1,0; 2,0-1,0; 2,0-2,0; 3,0-1,5; 3,0-3,0, respectivamente, nas fases de crescimento e terminação), com seis repetições e dois animais por baia (unidade experimental). Utilizou-se o sorgo como fonte de contaminação natural por micotoxinas. Os níveis de adsorvente das dietas experimentais foram obtidos a partir da inclusão de zeólita em substituição à areia lavada das dietas sem adsorvente. Não houve efeito dos níveis de zeólita nas dietas sobre o consumo diário de ração, o ganho de peso diário, a conversão alimentar e as características carcaça avaliadas. Os níveis de zeólita nas dietas também não influenciaram os parâmetros sanguíneos e histopatológicos nem os teores ósseos de cálcio e fósforo dos suínos. Devido ao bom índice de desempenho e às características de carcaça, bem como à normalidade dos outros parâmetros estudados dos animais que receberam dieta sem adsorvente, pode-se inferir que as dietas continham baixo grau de contaminação por micotoxinas. Os níveis de zeólita avaliados não influenciam o desempenho, as características de carcaça nem os parâmetros sanguíneos e histopatológicos do parênquima hepático de suínos nas fases de crescimento e terminação recebendo dietas com baixo nível de contaminação por micotoxinas.

This study was conducted to evaluate levels of inclusion of zeolite in diets for pigs on performance, carcass characteristics, blood and liver histopathological parameters of these animals in their growing-finishing phases. Eighty-four barrows from commercial hybrids of high genetic potential for meat deposition, with initial weight of 30.34±1.14 kg were distributed in randomized blocks design, with seven levels of adsorbent (0.0-0.0; 1.0-0.5; 1.0-1.0; 2.0-1.0; 2.0-2.0; 3.0-1.5; 3.0-3.0, respectively, on growing and finishing phases), six replicates with two animals per pen, which was considered the experimental unit. Sorghum was used as naturally contaminated source of mycotoxins. The different levels of adsorbent in the diets were obtained by the supplementation of zeolite in the basal diet. The inclusion of zeolite in the diet did not affect the daily feed intake, daily weight gain, feed conversion or the carcass characteristics of the pigs. In the same way blood parameters, liver histopathological examination and the bone concentration neither calcium nor phosphorus were affected by the different levels of zeolita. Due to the good performance and carcass characteristics, as well as the normality of the other parameters of the animals fed diets without adsorbents analyzed, it can be inferred that the diets had low levels of mycotoxin contamination. The levels of zeolite do not affect the performance, carcass characteristics, blood parameters or liver histopathological examination in growing-finishing pigs fed diets with low level of contamination by mycotoxin.

The objective of this study was to evaluate the effects of increasing dietary digestible tryptophan levels on performance and carcass traits of growing pigs. Fifty crossbred castrated male pigs, with average initial and final body weight of 29.0 ± 1.20 kg and 60.4 ± 1.95 kg were allotted in a completely randomized block design, with five treatments (0.125, 0.133, 0.141, 0.149, and 0.157% of digestible tryptophan, corresponding to digestible tryptophan:lysine relations of 15.0, 16.0, 17.0, 18.0, and 19.0%, respectively) and five replicates, with two pigs per experimental unit, which was represented by the pen. Experimental diets and water were supplied ad libitum throughout the experimental period. Averages of minimum and maximum temperatures inside the facility were of 24.3 ± 0.87 ºC and 28.0 ± 1.82 ºC, respectively. Feed intake and body weight gain increased linearly with increasing dietary tryptophan levels. However, there was no effect of digestible tryptophan on feed conversion or protein deposition of pigs. The highest tryptophan level evaluated (0,157%), corresponding to a digestible tryptophan:lysine relation of 19.0%, provided the greatest weight gain of 30 to 60 kg castrated male pigs.

Ninety-six barrows from 63 to 103 days of age were used to evaluate the effects of dietary digestible lysine levels on performance and carcass traits of two genetic lines selected for lean deposition. Pigs with initial body weight of 23.800 ± 1.075 kg were allotted in a completely randomized block design, within a 4 × 2 factorial arrangement (four digestible lysine levels: 0.80, 0.90, 1.00, 1.10%, and two genetic lines), with six replicates and two pigs per experimental unit. There was no interaction between genetic and digestible lysine levels. The digestible lysine levels also did not influence performance or carcass traits of pigs; however, average daily lysine intake increased with increasing digestible lysine level in the experimental diets. Pigs from genetic line B had better carcass traits when compared with those from genetic line A. The level of 0.80% digestible lysine corresponding to a daily intake of 16.60 g digestible lysine meets the nutritional requirement of pigs from both genetic lines evaluated, from 63 to 103 days of age.