Abstract

PALOMINO-RAMOS, A. R. et al. Postprandial gastrointestinal pH levels in juveniles of Piaractus brachypomus (Serrasalmidae) and Schizodon fasciatus (Anostomidae). Rev. Med. Vet. Zoot. [online]. 2023, vol.70, n.2, pp.192-205.  Epub Apr 16, 2024. ISSN 0120-2952.  https://doi.org/10.15446/rfmvz.v70n2.104565.

A comparative study to determine variations in postprandial pH values along the gastrointestinal tract was performed among juveniles of Piaractus brachypomus (n = 21) and Schizodon fasciatus (n = 21) in rearing conditions. After fasting for 24 hours, the fish were fed three times a day to apparent satiety, with a mixed diet containing pelleted balanced food and chicken heart muscle (ratio 1:1). The evaluation was made before feeding and postprandial (eight hours), where the pH values of the stomach, in the anterior and in the middle portions of the intestine were estimated, using a pH electrode with a lancetype tip. Significant differences (p < 0.05) at the stomach and the middle portions of the intestine, according to the digestion time were observed in both species, while at the anterior portions of the intestine, only S. fasciatus showed significant differences (p < 0.05). In both species, an increase in stomach pH was observed in the first postprandial hour (2,39 to 4,78 in P. brachypomus, 4,47 to 4,73 in S. fasciatus), led by the effect of the ingested food, and the pH values were reduced at the end of the experiment. During the evaluation hours, intestinal pH values for P. brachypomus and S. fasciatus were between 6,68 and 7,47 and 6,86 and 7,60, respectively, increasing distally along the intestine. It is concluded that both species present a permanent stomach acidification, and that the anterior and middle portions of the intestine maintain a slightly neutral pH during digestion and assimilation of food.

Keywords : digestion; pH; gastrointestinal tract; Amazonian fish.

        · abstract in Spanish     · text in Spanish     · Spanish ( pdf )