The intestinal physiology and mechanisms involved in nutrient transport are not well established in quails (Coturnix coturnix japonica). The present study assessed the growth performance, morphological development, duodenal density and the expression of Sglt1 and Glut2 of female Japanese quails from 1 to 49 days of age. The three small intestine segments were sampled weekly from 1 to 49 days of age to evaluate villus height, crypt depth and villus: crypt ratio, and goblet cell counts. Scanning electronic microscopy was used to determine duodenal villus density, and real-time polymerase chain reaction (qPCR) was used to study the sodium/glucose cotransporter-1 Sglt1 and glucose transporter Glut2 in the jejunum. Villus height and crypt depth in the duodenum, jejunum and ileum increased with age until 42 and 49 days of age (P < 0.001), and regression analysis evidenced a quadratic effect (P < 0.0001), indicating increasing values to a maximum and then a decrease afterwards. Goblet cell counts increased (P < 0.001) in duodenum, jejunum and ileum from 1 to 42 days, decreasing at 49 days, which was also corroborated by the regression analysis. Villus density in the duodenum was greater in the first week, decreased with age and increased again at 42 days, probably due to the proximity with egg production onset. The expression of Sglt1 and Glut2 mRNA in the jejunum varied with age. In conclusion, the intestinal mucosa of female Japanese quail developed morphologically until 42days and functionally until earlier ages, indicating an adaptation to the exogenous diet during the first weeks of life.
Keywords: Gene expression; Glut2; Intestinal development; Japanese quail; Sglt1; Small intestine.