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Eficiencia del uso de treonina para cerdos en fase de crecimiento.

Efficiency of threonine utilization in the growing pigs

INTRODUCCION

La treonina es un aminoacido indispensable para los cerdos y se requiere tanto para su mantenimiento como para su crecimiento. Es el componente fundamental de las inmunoglobulinas y representa una parte significativa de las proteinas secretadas por el intestino delgado (1). No sufre transaminacion y no es sintetizada por los cerdos. Por consiguiente, toda la treonina requerida se debe proporcionar en la dieta.

Se llevaron a cabo muchos experimentos con el fin de determinar los requerimientos nutricionales de treonina y la mayoria de ellos, se realizaron a traves del metodo empirico. Sin embargo, otro metodo que se puede emplear para obtener los requerimientos nutricionales de los cerdos es el factorial. En ese caso, estos requerimientos se definen de acuerdo con factores fisiologicos bien establecidos, tales como el mantenimiento de las estructuras de la proteina y la deposicion de esta (2). Las necesidades estimadas de la treonina por el metodo factorial suponen el conocimiento de los requerimientos de mantenimiento, la tasa de deposicion de la proteina y la eficiencia de utilizacion posterior a la absorcion de la treonina. No toda la treonina ingerida por el cerdo se recupera en las proteinas corporales y esta ineficiencia esta vinculada con procesos fisiologicos, perdidas basales de aminoacidos en los sistemas tegumentario y digestivo, catabolismo del nitrogeno y renovacion de proteinas (3).

El conocimiento de la eficiencia de los aminoacidos para la deposicion de proteina es fundamental para mejorar la nutricion proteica, lo que da lugar a mejoras economicas y a la reduccion de perdidas de nitrogeno en heces y orina. Se han efectuado relativamente pocos estudios para evaluar la eficiencia marginal de la utilizacion de treonina en cerdos. Es por eso que se llevo a cabo un estudio para determinar dicha eficiencia.

MATERIALES Y METODOS

Los animales y las condiciones ambientales. El experimento se llevo a cabo con 12 cerdos castrados, de linea comercial, en la etapa de finalizacion, con un peso vivo promedio de 72 [+ o -] 2 kg. Los animales se alojaron en jaulas metabolicas, con medidas de ancho y altura variables con el fin de ajustar el area de acuerdo al peso del animal, y se mantuvieron en un ambiente controlado para lograr una temperatura promedio de 22[grados] Celsius.

Diseno experimental. El experimento se dividio en dos periodos de 12 dias (siete dias de adaptacion a las condiciones experimentales y cinco dias de recoleccion). Los animales se distribuyeron en cuatro dietas experimentales, a traves de un diseno de transicion balanceado (4), con un total de seis repeticiones por tratamiento y considerando el animal como la unidad experimental.

Caracteristicas de la dieta. Las dietas se prepararon empleando el concepto de proteina ideal con el fin de proveer el 30%, 45%, 60% y 70% de las condiciones nutricionales requeridas (CNR) de treonina (3). La cantidad de los demas aminoacidos se calculo para lograr una relacion de al menos el 15% de sus requerimientos expresados en relacion con la treonina (5). En la Tabla 1 se presenta la composicion centesimal calculada de la dieta experimental.

Procedimiento experimental. La cantidad de alimento se calculo para satisfacer el consumo de 2,6 veces la energia metabolizable de mantenimiento (250 kcal/kg [PV.sup.0,60]), considerando un ajuste en el consumo diario de alimento de acuerdo con el aumento de peso estimado de 0,8 kg por dia. El alimento se distribuyo en cuatro comidas diarias: a las 8:00 h, 11:00 h. 13:00 h, 18:00 h y se proporciono agua a voluntad.

Las heces se recolectaron durante cinco dias de acuerdo con el metodo del indicador, utilizando oxido ferrico como un marcador indigestible. Las muestras se empacaron en bolsas plasticas y se mantuvieron en un congelador a -10[grados]C. Al final del periodo experimental, las heces se homogenizaron y se obtuvieron muestras de 0,5 kg, parcialmente secas y molidas para su analisis posterior.

Se dreno la orina en contenedores plasticos que contenian 30 ml de acido sulfurico ([H.sub.2]S[O.sub.4] 3,5 M) para impedir la contaminacion bacterial y la volatilizacion del nitrogeno. Se midio el volumen y el pH de la orina cada 12 horas, se recolecto un 5% de la muestra y se almaceno a 4[grados] Celsius. Para cada animal se determinaron los residuos del forraje y los sobrantes, se pesaron y el valor se desconto del consumo de alimento del animal.

Se determino el contenido de aminoacidos del maiz y la soya empleados en las dietas experimentales mediante cromatografia liquida, despues de hidrolisis acida. La materia seca de los ingredientes, heces, forraje y sobrantes junto con los componentes nitrogenados, forraje, heces y orina, fueron determinados segun los metodos descritos por la AOAC (6).

El nitrogeno retenido se obtuvo a partir de la diferencia entre la ingesta de nitrogeno y el nitrogeno eliminado en las heces y en la orina (balance de nitrogeno). La deposicion de proteina se calculo multiplicando el nitrogeno retenido por 0.0625, asumiendo que el nitrogeno constituye el 6.25% del total de proteinas retenidas (3).

La cantidad de treonina retenida se calculo como la diferencia entre la treonina ingerida estandarizada y la treonina retenida, asumiendo que esta constituye el 3,79% de la proteina corporal (7). La eficiencia marginal de utilizacion de treonina se obtuvo mediante el coeficiente angular de la linea originada por la regresion entre la treonina retenida y el consumo de treonina digestible estandarizada (8).

Analisis estadistico. Los datos obtenidos se sometieron a analisis de varianza utilizando el modelo lineal que contiene como efectos principales el animal, el tiempo y el tratamiento. Posteriormente, se llevo a cabo un procedimiento de regresion lineal con las medias ajustadas, utilizando el programa Minitab (9).

Aspectos eticos. El protocolo experimental fue aprobado y revisado por el Comite Etico de Experimentacion Animal de la Universidad Federal de Santa Maria (Dictamen 005/2012).

RESULTADOS

Los animales se mantuvieron saludables durante el periodo experimental. Las muestras de heces y orina fueron obtenidas sin ningun problema.

En nuestro experimento la dieta con la relacion mas alta entre treonina digestible estandarizada y energia metabolizable (TDE:EM) presento un valor de 1.4 g/Mcal. El consumo de materia seca (CMS) fue diferente entre los tratamientos (p<0.001).

Se presentaron diferencias (p<0.001) en el nitrogeno fecal entre tratamientos (Tabla 2) y se observo un incremento lineal (p<0.001) del nitrogeno fecal en funcion del consumo de nitrogeno de acuerdo con la pendiente de la relacion, que es de 0.165 (SE=0.019). El nitrogeno en la orina (NO) se vio afectado por los tratamientos (p<0.001).

El nitrogeno retenido esta linealmente relacionado con su consumo (p<0.001). La pendiente de la linea de regresion relaciona el nitrogeno en la orina (NO) con el consumo de nitrogeno (NC) 0.254 (SE=0.026). La pendiente de relacion entre la treonina retenida (TR) y el consumo de treonina digestible estandarizada (TDE) es de 0,63 (SE=0.033).

DISCUSION

Una importante suposicion en la estimacion empirica de la eficiencia de los aminoacidos es que la prueba de estos debe constituir la primera restriccion nutricional en las dietas experimentales.

La relacion (TDE:EM) es menor que la recomendada para la maxima deposicion de proteina (2.0 g/Mcal) en cerdos con un peso vivo de 70 kg (3). Ademas, se suministraron otros aminoacidos diferentes a la treonina para exceder sus requerimientos. Esto indica que la treonina es el primer factor nutricional limitante para la deposicion de proteina.

No se habia previsto la diferencia en CMS ya que la cantidad de esta afecta el contenido de perdidas endogenas de aminoacidos. Sin embargo, puesto que la diferencia entre el consumo mas bajo y el mas alto es de solamente 1.3% (Tabla 2), es posible que la perdida de endogenos de treonina y de otros aminoacidos no se vea afectada significativamente.

El nitrogeno encontrado en las heces corresponde a un promedio de digestibilidad aparente en dietas experimentales del 83.5%. El nitrogeno en la orina es consistente con lo esperado ya que esta es la principal via de excrecion de nitrogeno, cuando se encuentra por encima de lo requerido.

Los resultados de la retencion de nitrogeno estan en linea con aquellos encontrados por Libao-Mercado y colaboradores (8) y muestran que la treonina es el primer limitante de la deposicion de proteina en las dietas utilizadas en nuestro experimento.

La pendiente de la linea de regresion que relaciona NO y NC indica que el 25.4% del nitrogeno consumido se elimino a traves de la orina. Ese valor fue mayor al 16% obtenido por Heger y colaboradores (10) y menor que el valor de 33% mencionado por Libao-Mercado (8). Las diferencias pueden estar relacionadas con la composicion de las dietas una vez purificadas con proteina de alto valor biologico como las utilizadas por Heger y colaboradores (10), las cuales tienen la tendencia a producir una menor proporcion de perdidas de consumo de nitrogeno en la orina.

Cuando el NO se relaciona con el consumo de nitrogeno digestible (CND) se observa que el nitrogeno eliminado en la orina debido a la no utilizacion de la deposicion de proteinas es de 0.309 g/kg [PV.sup.0,75] por cada gramo de CND por encima de las necesidades de mantenimiento (Figura 1). El valor es mayor que el 16% obtenido por Heger y colaboradores, quienes utilizaron una dieta purificada que contiene una fuente de proteinas de alto valor biologico. El NO se origina a partir de dietas con nitrogeno que no es empleado para la sintesis de proteina, por el nitrogeno endogeno intestinal secretado y no es reabsorbido hasta el final del intestino delgado y por el nitrogeno absorbido en el intestino grueso. Por lo tanto, estos resultados ponen de manifiesto una vez mas la importancia de la calidad de la proteina para mejorar la utilizacion del nitrogeno en la produccion porcina (12).

El valor de la relacion entre la treonina retenida TR y el consumo de TDE indica que la eficiencia marginal de TDE para la deposicion de proteina es del 63% (Figura 2), la cual es menor al 73.83 y 67% encontrada por de Lange y colaboradores (7), Heger y colaboradores (10) y Heger y colaboradores (13), respectivamente. Estas discrepancias pueden estar explicadas, al menos parcialmente, por las diferencias entre los aspectos metodologicos encontrados en los estudios interrelacionados.

Suponiendo que la eficiencia del consumo de treonina digestible estandarizada para la retencion de proteina en la proteina corporal es el 63%, esto implica que el 37% de la TDE se pierde debido al inevitable catabolismo minimo que ocurre incluso cuando el consumo de treonina limita la deposicion de proteina. Los principales determinantes fisiologicos de este catabolismo de aminoacidos en cerdos en crecimiento son las perdidas de aminoacidos endogenos, perdidas de aminoacidos fisicas con la piel y el pelo y perdidas debido al intercambio proteinico (1). Se considera que la treonina se utiliza con menor eficiencia en la deposicion proteica en comparacion con otros aminoacidos como la lisina y la valina, a modo de ejemplo (5). Normalmente se justifica porque las perdidas endogenas intestinales son las principales contribuyentes del catabolismo inevitable y la treonina es particularmente importante ya que su participacion en la proteina de la mucina intestinal es alta (14, 15).

La informacion acerca de la eficiencia de la deposicion de treonina es fundamental para el desarrollo de las estimaciones de las necesidades mediante el metodo factorial, que a su vez es el metodo preferido para la estimacion de los requerimientos nutricionales de cerdos (16) y se utiliza en la mayoria de los modelos de simulacion de cerdos en crecimiento (17).

En conclusion, el valor de la eficiencia marginal de utilizacion de 0,63 se puede utilizar para calcular los requerimientos nutricionales de treonina por el metodo factorial.

INTRODUCTION

Threonine is an indispensable amino acid for pigs and is required for both maintenance and growth. It is the primary amino acid constituent of immunoglobulins and represents a significant portion of the proteins secreted by the small intestine (1). Threonine does not undergo transamination and there is no synthesis of threonine by the pigs. Consequently, all the threonine required by pig must be provide in the diet.

Many experiments were performed in order to determine the nutritional requirements of threonine, and most of them, through the empirical method. However, another method that might be employed to obtain the nutritional requirements of pigs is the factorial one. In that case, the animal's nutritional requirement is defined according to well laid out physiological factors, such as the maintenance of protein structures and protein deposition (2). The estimated requirements for threonine by the factorial method suppose knowledge about maintenance requirement, rate of protein deposition and the post-absorptive utilization efficiency of threonine. Not all the threonine ingested by pig is recovered in body protein and the inefficiency is linked to the physiological processes, basal losses of amino acids of the integumentary and digestive system, nitrogen catabolism and protein turnover (3).

The knowledge of the amino acid efficiency for protein deposition is crucial to improve protein nutrition, which can result in economic improvements and reducing nitrogen losses in feces and urine. There are relatively few studies conducted to evaluate the marginal efficiency of threonine utilization by pigs. Thus, one study was conducted to determine the marginal efficiency of threonine utilization in pigs.

MATERIAL AND METHODS

Animals and ambient condition. The experiment was performed with 12 castrated pigs of commercial line, in the finishing phase, and with an average live weight of 72 [+ or -] 2 kg. The animals were housed in metabolic cages, with variable widths and heights in order to adjust the area to the weight of the animal, and kept in a controlled environment in order to achieve the average temperature of 22[degrees] Celsius.

Experimental design. The experiment was divided into two periods of 12 days (seven days of adaptation to the experimental conditions and five days of collection). The animals were distributed through a balanced changeover design (4) in four experimental diets, with a total of six replications per treatment and considering the animal as the experimental unit.

Diet characteristic. The diets were prepared using the concept of ideal protein in order to meet 30%, 45%, 60% and 70% of threonine nutritional conditions suggested by the NRC (3). The other amino acids were calculated to achieve a ratio of, at least, 15% of their requirements expressed in relation to the threonine (5). The calculated and centesimal composition of the experimental diet is presented in table 1.

Experimental procedure. The amount of feed was calculated to meet the consumption of 2.6 times the metabolizable energy for maintenance (250 kcal [kg.sup.-1] [BW.sup.0.60]), considering an adjustment on daily feed intake according to the estimated weight gain of 0.8 kg per day. The food was distributed into four meals a day: at 08h:00, 11h:00, 13h:00, 18h:00 and water was provided ad libitum.

The feces were collected for five days according to the marker-to-marker approach using ferric oxide as an indigestible marker. The samples were packed into plastic bags and maintained in a freezer at -10[degrees C. At the end of the experimental period, the feces were homogenized and samples of 0.5 kg were obtained, partially dried and grounded for further analysis.

The urine was drained into plastic containers containing 30 ml of sulfuric acid (H2SO4 3.5 M) to prevent bacterial contamination and nitrogen volatilization. The volume and urinary pH were measured every 12 hours, and a sample of 5% was collected and stored at 4[grados] Celsius. The waste of feed and leftovers was determined to each animal. Subsequently, the feed leftovers were weighed, and the value was discounted from the animal's feed intake.

The content of corn and soybeans amino acids used in the experimental diets were determined by liquid chromatography after acid hydrolysis. The dry matter of the ingredients, feces, feed and leftovers along with the nitrogen ingredients, feed, feces and urine, were determined by the AOAC methodology (6).

The retained nitrogen was obtained by the difference between the nitrogen intake and nitrogen eliminated in feces and urine (nitrogen balance). The protein deposition was calculated by multiplying the retained nitrogen by 0.0625 assuming that nitrogen constitutes 6.25% of the retained proteins (3).

The amount of threonine retained was calculated through the difference between the ingested standardized threonine and deposited threonine, assuming that it constitutes 3.79% of the body protein (7). The marginal efficiency of utilization of threonine was obtained by the angular coefficient of the line originated through the regression between the threonine retained and standardized digestible threonine intake (8).

Statistical analysis. The obtained data were submit to variance analysis by using a linear model containing animal, time and treatment as main effects. Subsequently, it was performed a procedure of linear regression with the adjusted means, and the use of the Minitab program (9).

Ethical aspects. The experimental protocol was reviewed and approved by the Ethics Committee on Animal Experimentation of the Federal University of Santa Maria (Opinion 005/2012).

RESULTS

The animals remained healthy during the experimental period. Feces and urine samples were obtained without any problem.

In our experiment the diet containing the highest ratio between standardized digestible threonine and metabolizable energy (STD: ME) presented a value of 1.4 g Mcal-1. The dry matter intake (DMI) differed between the treatments (p<0.001).

There were differences (p<0.001) in fecal nitrogen among treatments (Table 2) and was observed increased linearly (p<0.001) in fecal nitrogen according to nitrogen intake with the slope of relationship being of 0.165 (SE=0.019). The nitrogen in urine (NU) was influenced by treatments (p<0.001).

The N retention was linearly (p<0.001) associated with N intake. The slope of regression line relating NU and NI 0.254 (SE=0.026). The slope of relation between retained threonine (RT) and standardized digestible threonine (SDT) intake was 0.63 (SE=0.033).

DISCUSSION

One important assumption in empirical estimate of amino acids efficiency is that the amino acid test must be the first nutritional constraint in the experimental diets.

The ratio STD:ME is lower than the recommended for maximum protein deposition (2.0 g Mcal-1) of pigs with a live weight of 70 kg (3). In addition the amino acids others than threonine were supplies to exceed their requirements. This indicates that threonine was the first limiting nutritional factor for protein deposition.

The difference in DMI was not planned because the amount of DMI influences the content of endogenous losses of amino acids. However, since the difference between the lowest and highest consumption was only 1.3 % (Table 2), it is possible that the endogenous loss of threonine and other amino acids were barely affected.

The N found in feces indicating mean apparent N digestibility of experimental diets was 83.5%. The N in urine was according to the expectations since the urine is the main route of nitrogen excretion ingested in excess of requirements.

The results of N retention are in agreement with Libao-Mercado et al (8) and show that the threonine was first limiting to protein deposition in diets used in our experiment.

The slope of regression line relating NU and NI indicated that 25.4% of nitrogen consumed were eliminated through the urine. That value was bigger than 16% obtained by Heger et al (10) and smaller than value of 33% mentioned by LibaoMercado (8). The differences may be associated with the diet composition once purified diets with protein of high biology value as used by Heger et al (10) has a trend to result a lesser proportion of nitrogen intake losses in urine.

When NU was associated with digestible nitrogen intake (DNI) we observed that the N eliminated in the urine due to non-use for protein deposition was 0.309 g [kg.sup.-1] BW0 75 for each gram of DNI above of maintenance needs (Figure 1). The value was bigger than 16% obtained by Heger et al (11) who used purified diet containing a protein source of high biological value. The NU has origin from diet N that's not used to protein synthesis, intestinal endogenous N secreted and no reabsorbed until the end of small intestine and N absorbed in large intestine. Therefore, these results emphasize again the importance of protein quality on improve N utilization in pig production (12).

The value of the relation between RT and STD intake indicates that marginal efficiency of SDT for protein deposition is 63% (Figure 2) which is lower than 73, 83 and 67 % found by de Lange et al (7), Heger et al (10) and Heger et al (13), respectively. These discrepancies can be explained at least partially because the differences in the methodological aspects found inter studies.

Assuming that 63% is the efficiency of standardized digestible threonine intake to protein retention in body protein implies that 37% of standardized digestible threonine is lost due to inevitable minimum catabolism that occurs even when the threonine intake limits protein deposition. The main physiologic determinants of inevitable minimum catabolism of amino acids in growing pigs are amino acid endogenous losses, physical amino acids losses with skin and hair and losses due to protein turnover (1). It is assumed that threonine is used with lower efficiency to protein deposition compared with other amino acids like lysine and valine, for example (5). Normally it is justified because the intestinal endogenous losses is the major contributing to inevitable catabolism and threonine is particularly important since its participation in intestinal protein mucin is high (14, 15).

The information about threonine deposition efficiency is essential to the development of requirement estimates by the factorial method, which in turn is the preferred method for estimating the nutritional requirements of pigs (16) and used in most of the simulation models of growth pigs (17).

In conclusion the marginal efficiency of utilization of 0.63 can be used to calculate the nutritional requirements of threonine by the factorial method.

REFERENCES

(1.) Zhu CL, Rademacher M, de Lange CFM. Increasing dietary pectin level reduces utilization of digestible threonine intake, but not lysine intake, for body protein deposition in growing pigs. J Anim Sci 2005; 83(5):1044-1055.

(2.) Hauschild L, Pomar C, Lovatto PA. Systematic comparison of the empirical and factorial methods used to estimate the nutrient requirements of growing pigs. Animal 2010; 4(5):714-723.

(3.) NRC. National Research Council. Nutrient Requirements of Swine, 11th ed. Washington, D.C.: National Academy Press; 2012.

(4.) van den Borne JJGC, Schrama JW, Heetkamp MJW, Verstegen MWA, Gerrits WJJ. Synchronising the availability of amino acids and glucose increases protein retention in pigs. Animal 2007; 1(5):666-674.

(5.) van Milgen J, Valancogne A, Dubois S, Dourmad J, Seve B, Noblet J. InraPorc: A model and decision support tool for the nutrition of growing pigs. Anim Feed Sci Tech 2008; 143(1-4):387-405.

(6.) AO AC. Association of Official Analytical Chemists. Official methods of analyses. Ass Agric Chem 18th ed. Washington: AOAC; 2005.

(7.) de Lange CFM, Gillis AM, Simpson GJ. Influence of threonine intake on whole-body protein deposition and threonine utilization in growing pigs fed purified diets. J Anim Sci 2001; 79(12):3087-3095.

(8.) Libao-Mercado AJ, Leeson S, Langer S, Marty BJ, de Lange CF. Efficiency of utilizing ileal digestible lysine and threonine for whole body protein deposition in growing pigs is reduced when dietary casein is replaced by wheat shorts. J Anim Sci 2006; 84(6):1362-1374.

(9.) Minitab Statistical Software. 2013. Release 16.1 for windows. Minitab inc. State College PA: USA.

(10.) Heger J, Krizova L, Sustala M, Nitrayova S, Patras P, Hampel D. Individual response of growing pigs to sulphur amino acid intake. J Anim Physiol Anim Nutr 2007; 92(1):18-28.

(11.) Heger J, Krizova L, Sustala M, Nitrayova S, Patras P, Hampel D. Individual response of growing pigs to lysine intake. J Anim Physiol Anim Nutr 2008; 93(5):538-546.

(12.) van Milgen J, Dourmad J. Concept and application of ideal protein for pigs. J Anim Sci Biotechnol 2015; 15 (6):1-11.

(13.) Heger J, van Phung T, Krizova L. Efficiency of amino acid utilization in the growing pig at suboptimal levels of intake: Lysine, sulphur amino acids and tryptophan. J Anim Physiol Anim Nutr 2002; 86(5-6):153-165.

(14.) Blank B, Schlecht E, Susenbeth A. Effect of dietary fibre on nitrogen retention and fibre associated threonine losses in growing pigs. Arch Anim Nutr 2012; 66(2): 86-101.

(15.) Morel PCH, Melai J, Eady SL, Coles GD. Effect of non-starch polysaccharides and resistant starch on mucin secretion and endogenous amino acids losses in pigs. Asian Australas J Anim Sci 2005; 18(11):1634-1641.

(16.) Pomar C, Hauschild L, Zhang G, Pomar J, Lovatto PA. Applying precision feeding techniques in growing-finishing pig operations. R Bras Zootec 2009; 38(spe):226-237.

(17.) Wecke C, Libert F. Optimal dietary lysine to threonine ratio in pigs (30-110 kg bw) derived from observed dietary amino acid efficiency. J Anim Physiol Anim Nutr 2010; 94(6):1-9.

Marcos S Ceron, [1] M.Sc, Vladimir de Oliveira, * [2] Ph.D, Arlei B de Quadros, [2] Ph.D, Clovis E Gewehr, [3] Ph.D, Leonardo T Rocha, [2] Zootec, Debora A Alves, [2] Zootec.

[1] Federal University of Santa Maria (UFSM), Zootecny Departament, Roraima Avenue no. 1000, University City, Camobi District, Zip-code 97105-900, Santa Maria, RS, Brazil. [2] Federal University of Santa Maria, Zootecny Departament. [3] University of the State of Santa Catarina (UDESC), Animal production departament, Luiz de Camoes Avenue, no. 2090, Conta Dinheiro District, Zip-code 88520000, Lages, SC, Brazil. * Correspondence: vladimir.oliveira@ufsm.br

Received: November 2014; Accepted: August 2015.

Caption: Figure 1. Relationship between digestible nitrogen intake and nitrogen in urine.

Caption: Figure 2. Relationship between standardized digestible threonine intake and threonine retention in pigs fed with increasing levels of threonine.
Table 1. Calculated and centesimal composition
of pigs diets fed with increasing levels of
standardized and digestible threonine.

Ingredients                 Level of threonine
                            (% of requirements)

                              30              45

                                              %

Corn                        15.600          21.840
Soybean meal                10.400          14.560
Starch                      59.870          48.930
Sugar                       10.000          10.000
Soybean Oil                  1.000          1.500
L Lysine                     0.060          0.080
DL Methionine                0.050          0.070
L_ Tryptophan                0.015          0.020
Bicalcium Phosphate          1.500          1.500
Limestone                    0.900          0.900
Salt                         0.400          0.400
Vitamin and mineral          0.200          0.200
  premix
Total                       100.000        100.000

                            Nutritional values
                              calculated

ME (Kcal [kg.sup.-1])        3430            3421
CP (%)                       6.35            8.60
Threonine (%) (a)       0.18b (100) (c)   0.25 (100)
Lysine (%)                0.32 (178)      0.44 (176)
Methionine (%)             0.12 (67)      0.16 (64)
MET + Cystine (%)         0.19 (106)      0.26 (104)
Tryptophan (%)             0.06 (33)      0.09 (36)
Isoleucine (%)            0.20 (111)      0.28 (112)
Valine (%)                0.23 (128)      0.32 (128)
Leucine (%)               0.41 (228)      0.57 (228)
Phenylalanine (%)         0.28 (156)      0.39 (156)
PHENYL + TYR (%)          0.41 (228)      0.57 (228)
Histidine (%)              0.12 (67)      0.16 (64)
Arginine (%)              0.25 (139)      0.35 (140)

Ingredients                Level of threonine
                           (% of requirements)

                            60           70

Corn                      27.760       33.850
Soybean meal              18.510       22.560
Starch                    38.500       27.810
Sugar                     10.000       10.000
Soybean Oil               2.000        2.500
L Lysine                  0.100        0.120
DL Methionine             0.090        0.115
L_ Tryptophan             0.025        0.035
Bicalcium Phosphate       1.500        1.500
Limestone                 0.900        0.900
Salt                      0.400        0.400
Vitamin and mineral       0.200        0.200
  premix
Total                    100.000      100.000

                          Nutritional values
                              calculated

ME (Kcal [kg.sup.-1])      3414         3407
CP (%)                    10.74        12.95
Threonine (%) (a)       0.31 (100)   0.38 (100)
Lysine (%)              0.56 (181)   0.68 (179)
Methionine (%)          0.21 (68)    0.26 (68)
MET + Cystine (%)       0.33 (106)   0.41 (108)
Tryptophan (%)          0.11 (35)    0.14 (37)
Isoleucine (%)          0.36 (116)   0.44 (116)
Valine (%)              0.41 (132)   0.50 (132)
Leucine (%)             0.72 (232)   0.88 (232)
Phenylalanine (%)       0.50 (161)   0.60 (158)
PHENYL + TYR (%)        0.73 (235)   0.89 (234)
Histidine (%)           0.21 (68)    0.25 (66)
Arginine (%)            0.44 (142)   0.54 (142)

CP = crude protein; ME = metabolizable energy; MET =
methionine; PHENYL = phenylalanine; TYR = tyrosine. (a)
Values expressed as standardized digestible amino acid.
(b) Values obtained by multiplying the coefficient of
standardized digestibility by the values of amino acids
analyzed in corn and soybean bran. (c) Values in
parentheses represent the relation between lysine and
other amino acids in this experiment.

Table 2. Dry matter intake, metabolizable energy
intake and nitrogen balance of pigs consuming
diets with increasing levels of standardized
and digestible threonine (values expressed
per day).

Levels of threonine in the diet (% of
requirements)

                                         30      45      60

Observations                              6       6       6
MBW ([BW.sup.0.75])                     24.28   24.47   24.63
DMI (g [kg.sup.-1] [BW.sup.0.75])       92.31   91.06   91.60
MEI (Kcal [kg.sup.-1] [BW.sup.0.75])    56.9    354.8   353.4
NI (g [kg.sup.-1] BW0.75)               1.09    1.47    1.84
NF (g [kg.sup.-1] [BW.sup.0.75])        0.06    0.17    0.25
NU (g [kg.sup.-1] [BW.sup.0.75])        0.31    0.34    0.50
NE (g [kg.sup.-1] BW0.75)               0.47    0.52    0.75
NA (g [kg.sup.-1] [BW.sup.0.75])        1.02    1.30    1.59
NR (g [kg.sup.-1] BW0.75)               0.71    0.96    1.09
PD (g [kg.sup.-1] [BW.sup.0.75])        3.81    4.93    6.08

                                         70     EPM    Prob. *

Observations                              6      --      --
MBW ([BW.sup.0.75])                     25.06   0.13    0.019
DMI (g [kg.sup.-1] [BW.sup.0.75])       91.27   0.12    0.001
MEI (Kcal [kg.sup.-1] [BW.sup.0.75])    351.4   0.48    0.001
NI (g [kg.sup.-1] BW0.75)               2.21    0.01    0.001
NF (g [kg.sup.-1] [BW.sup.0.75])        0.29    0.02    0.001
NU (g [kg.sup.-1] [BW.sup.0.75])        0.57    0.03    0.001
NE (g [kg.sup.-1] BW0.75)               0.86    0.01    0.001
NA (g [kg.sup.-1] [BW.sup.0.75])        1.93    0.03    0.001
NR (g [kg.sup.-1] BW0.75)               1.35    0.02    0.001
PD (g [kg.sup.-1] [BW.sup.0.75])        7.46    0.11    0.001

MBW = metabolic body weight; DMI = dry matter intake;
MEI = metabolizable energy intake; NI = nitrogen intake;
NF = nitrogen in feces; NU = nitrogen in urine; NE =
nitrogen excreted; NA = nitrogen absorbed; NR = nitrogen
retained; PD = protein deposition; EPM = mean standard
error; BW = body weight; Prob. = Probability. * means
adjusted to the treatment effects.
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Title Annotation:ORIGINAL
Author:Ceron, Marcos S.; de Oliveira, Vladimir; de Quadros, Arlei B.; Gewehr, Clovis E.; Rocha, Leonardo T.
Publication:Revista MVZ (Medicina Veterinaria y Zootecnia)
Date:Jan 1, 2016
Words:5359
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