ABSTRACT. Leucine (Leu) participates in the activity of cationic amino acid (aa) transporters. Also, branched-chain aa [Leu, isoleucine (Ile), and valine (Val)] share intestinal transporters for absorption. We conducted an experiment with 16 young pigs (body weight of about 16 kg) to determine whether Leu and Ile affect expression of aa transporters b 0,+ and CAT-1 in the jejunum and expression of myosin in muscle, as well as serum concentration of essential aa, and growth performance in pigs. Dietary treatments were: wheat-based diets fortified with Lys, Thr, and Met; basal diet plus 0.50% Leu; basal diet plus 0.50% Ile, and basal diet plus 0.50% Leu and 0.50% Ile. After 28 days, the pigs were sacrificed to collect blood, jejunum, and semitendinosus and longissimus muscle samples. The effects of single and combined addition of Leu and Ile were analyzed. Leu alone or combined with Ile significantly decreased daily weight gain and reduced feed conversion. Leu and Ile, alone or in combination, significantly decreased expression of b 0,+ and significantly increased CAT-1. Ile alone or combined with Leu significantly decreased myosin expression in semitendinosus and significantly decreased it in M. Cervantes-Ramírez et al. 116©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 12 (1): 115-126 (2013) longissimus muscle. Leu alone significantly decreased Lys, Ile and Thr serum concentrations; Ile significantly decreased Thr serum concentration; combined Leu and Ile significantly decreased Thr and significantly increased Val serum concentration. We conclude that dietary levels of Leu and Ile affect growth performance, expression of aa transporters and myosin, and aa serum concentrations in pigs.

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Se realizaron dos experimentos para evaluar el efecto de la adición de fitasa fungal (Aspergillus niger) en la actividad de tripsina y quimotripsina y digestibilidad de nutrientes en cerdos cruzados (Yorkshire x Landrace, 11,5 kg peso vivo). En ambos experimentos se empleó una dieta base formulada con sorgo y pasta de soya; los tratamientos (T) fueron los siguientes: T1, dieta base, y T2, base adicionada con 500 unidades de actividad fitásica (FTU) por kg de alimento. En el exp. 1 se utilizaron seis cerdos canulados en conducto pancreático, los cuales fueron adaptados a las dietas durante 5 d, previo a la colecta de muestras. La colección de jugo pancreático se hizo a intervalos de 15 min, de 08:00 a 20:00 h, durante 5 d. El alimento se ofreció dos veces al día (08:00 y 20:00 h). En el exp. 2 se utilizaron 20 cerdos alimentados con dietas similares del exp. 1 para estimar la digestibilidad total aparente de MS, MO, FDN, P, Ca, Mg, Zn y Fe. La fitasa no tuvo efectos en el peso y la longitud del páncreas, ni tampoco en la actividad de la tripsina y de la quimotripsina. La adición de fitasa incrementó la digestibilidad de la proteína (p