Expression of cationic amino acid transporters, carcass traits, and performance of growing pigs fed low-protein amino acid-supplemented versus high protein diets.
Free amino acids (AA) appear to be absorbed faster than protein-bound AA (PB-AA). We conducted an experiment to assess the effect of feeding pigs with a partially free (F-AA) or totally PB-AA diet on expression of selected genes and performance of pigs. The expression of cationic AA transporters b(0,+) and CAT-1 in intestinal mucosa, liver, and longissimus (LM) and semitendinosus (SM) muscles, as well as that of myosin in LM and SM, was analyzed. Twelve pigs (31.7 ± 2.7 kg) were used. The F-AA diet was based on wheat, supplemented with 0.59% L-Lys, 0.33% L-Thr, and 0.10% DL-Met. The PB-AA diet was formulated with wheat-soybean meal. Average daily feed intake was 1.53 kg per pig. The expression of b(0,+) and CAT-1 was analyzed in jejunal and ileal mucosa, liver, LM, and SM; myosin expression was also analyzed in both muscles. Pigs fed the PB-AA diet tended to have higher weight gain and feed efficiency (P < 0.10), and had thinner back fat (P = 0.02). The expression of b(0,+) was higher (P < 0.01) in jejunum but lower (P < 0.01) in the liver of pigs fed the F-AA diet; CAT-1 tended to be lower in liver but higher in LM of PB-AA pigs. Myosin expression was not affected. Intestinal AA absorption was faster in pigs fed the F-AA diet, but AA uptake by the liver seemed to be faster in pigs fed the PB-AA. Performance and expression of AA transporters and myosin suggest that the dietary content of free or protein-bound AA does not affect their availability for protein synthesis in pigs.
Instituto de Ciencias Agrícolas, Universidad Autónoma de Baja California, Mexicali, México.
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Morales
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Grageola
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García
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Araiza
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Zijlstra
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Cervantes
D026923:Amino Acid Transport Systems, Basic / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D004044:Dietary Proteins / Q000008:administration & dosage*; D019587:Dietary Supplements; D005260:Female; D015870:Gene Expression; D007413:Intestinal Mucosa / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism; D009218:Myosins / Q000235:genetics / Q000378:metabolism; D009928:Organ Specificity; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D034421:Sus scrofa / Q000254:growth & development / Q000378:metabolism*
D026923:Amino Acid Transport Systems, Basic; D004044:Dietary Proteins; D012337:RNA, Ribosomal, 18S; D009218:Myosins