Browsing by Author "Liu, Kuan-Ling"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Delayed access to feed affects broiler small intestinal morphology and goblet cell ontogeny
    Liu, Kuan-Ling; Jia, Meiting; Wong, Eric A. (2020-11)
    Broilers are often deprived of feed and water for up to 48 h after hatch. This delayed access to feed (DAF) can inhibit small intestine development. The objective of this study was to determine the effects of DAF on small intestinal morphology, mRNA abundance of the goblet cell marker Muc2 and absorptive cell marker PepT1, and the distribution of goblet cells in young broilers. Cobb 500 chicks, hatching within a 12-h window, were randomly allocated into 3 groups: control with no feed delay (ND), 24-h feed delay (DAF24), and 36-h feed delay (DAF36). Morphology, gene expression, and in situ hybridization analyses were conducted on the duodenum, jejunum, and ileum at 0, 24, 36, 72, 120, and 168 h after hatch. Statistical analysis was performed using a t test for ND and DAF24 at 24 h. A 2-way ANOVA and Tukey's HSD test (P < 0.05) were used for ND, DAF24, and DAF36 from 36 h. At 24 to 36 h, DAF decreased the ratio of villus height/crypt depth (VH/CD) in the duodenum but increased VH/CD in the ileum due to changes in CD, whereas at 72 h, DAF decreased VH/CD due to a decrease in VH. The mRNA abundance of PepT1 was upregulated, while Muc2 mRNA was downregulated in DAF chicks. Cells expressing Muc2 mRNA were present along the villi and in the crypts. The ratio of the number of goblet cells found in the upper half to the lower half of the villus was greater in DAF chicks than in ND chicks, suggesting that DAF affected the appearance of new goblet cells. The number of Muc2 mRNA-expressing cells in the crypt, however, was generally not affected by DAF. In conclusion, DAF transiently affected small intestinal morphology, upregulated PepT1 mRNA, downregulated Muc2 mRNA, and changed the distribution of goblet cells in the villi. By 168 h, however, these parameters were not different between ND, DAF24, and DAF36 chicks.
  • Thumbnail Image
    Delayed access to feed affects broiler small intestinal morphology and intestinal cell ontogeny
    Liu, Kuan-Ling (Virginia Tech, 2019-08-01)
    In the broiler industry, chicks are often deprived of feed and water up to 48 h posthatch. This delayed access to feed (DAF) has been found to inhibit small intestinal development, compromising growth of the chick. To further understand the impact of DAF on small intestines at the molecular level, many developmental genes that regulate intestinal development were investigated. The objective of this study was to determine the effect of DAF on early posthatch broiler small intestinal morphology, which includes villus height (VH) and crypt depth (CD), and to quantify changes in regulatory genes, such as Olfactomedin 4 (Olfm4), Marker of Ki-67 (Ki-67), Peptide Transporter 1 (PepT1), and Mucin 2 (Muc2), in response to DAF. The Olfm4 mRNA can clearly identify stem cells in the intestinal crypt, which allows VH and CD to be measured, while Ki-67 marks the proliferating cells. The peptide transporter PepT1 is located on intestinal epithelial cells and plays a critical role in transporting di- and tripeptides. Muc2, which is secreted from goblet cells, forms mucus that lines the intestinal epithelial cells acting as a layer of protective coating. Cobb 500 chicks, hatching within a 12 h window, were randomly allocated into three experimental groups: control with no feed delay (ND), 24 h feed delay (D24), and 36 h feed delay (D36). Quantification of Olfm4, Ki-67, PepT1, and Muc2 mRNA abundance were investigated by quantitative PCR, in duodenum, jejunum, and ileum at 0 h, 24 h, 36 h, 72 h, 120 h, and 168 h posthatch. Additionally, localization of cells expressing each gene was visualized using in-situ hybridization at all listed times except 168 h posthatch. Statistical analysis was performed using JMP Pro 14, and significant differences between treatments within a collection day were determined by t-test and one-way ANOVA (P < 0.05). In the ND group, duodenal CD at 0 h was greatest compared to all other time points. With DAF, the duodenal VH of D36 chicks was lower at 36 h (P < 0.001) and 72 h (P = 0.002) compared to ND chicks. In the jejunum and ileum, the VH of D36 chicks was lower at 120 h (P = 0.005) and 72 h (P = 0.03), respectively, compared to ND chicks. In contrast, the VH of D24 chicks at 24 h was greater than ND (P = 0.004) in the jejunum. There was no difference between treatments by 168 h in all intestinal segments. The CD was also lower in DAF groups compared to ND but only in the jejunum and ileum. In contrast, duodenal CD was greater in D24 chicks at 24 h (P = 0.039) and in D36 chicks at 36 h (P < 0.0001) compared to ND chicks, but the difference was no longer significant by 72 h. The VH/CD ratio was lower in all three segments, except the ileum displayed a greater VH/CD ratio in D24 and D36 chicks at 24 h and 36 h, respectively, compared to ND chicks. The mRNA abundance of Olfm4 and Ki-67 was greater in DAF groups upon refeeding, but not until 120 h. The PepT1 mRNA abundance was greater in DAF groups while the abundance of Muc2 mRNA was lower. This difference in mRNA abundance level was more prominent in the duodenum and jejunum. From the analysis of number and distribution of goblet cells found in the upper half and lower half of the villi, expressed as a ratio (VU/VL), a greater ratio was observed in delayed groups compared to ND. In summary, while DAF resulted in altered small intestinal morphology with an effect more pronounced in D36 than D24 chicks, upon refeeding, some genes important to intestinal development were upregulated as a response to the treatment.