Maternal dietary linoleic acid altered intestinal barrier function in domestic pigeons (Columba livia)
Abstract Linoleic acid (LA) is predominantly essential for poultry. Poultry lacking linoleic acid showed retarded growth and reduced disease resistance. Intestinal barrier function plays an important role in pigeon squab growth, whereas research on the effects of LA on intestinal health in altrices is scant. Considering that squabs are fed by their parents, the purpose of this study was to explore the effects of maternal dietary LA on the intestinal morphology, gene expression of tight junction proteins, immune cytokines, and microbial flora in squabs. A completely randomized design with a control group, 1% LA supplementation group, 2% LA supplementation group, and 4% LA supplementation group were used. Six squabs from each treatment were randomly sampled at 21 days post hatching. The results indicated that LA supplementation improved intestinal morphology, as reflected by the increased villus height, villus area and the ratio of villi to crypts. In addition, 1% LA supplementation elevated the density of goblet cells in the intestine, and strengthened tight junctions by upregulating claudin-3 and occludin gene expression but downregulating claudin-2 gene expression. Moreover, 1% LA supplementation reduced the secretion of proinflammatory cytokines and partly increased anti-inflammatory cytokines. The diversity of the intestinal microbiota in the 1% LA supplementation group was higher than that in the other groups. As beneficial bacteria, butyrivibrio was the biomarker of 1% LA supplementation. However, excessive (4%) LA supplementation led to adverse impacts on intestinal immunity and microbiota. In conclusion, maternal dietary LA might alter intestinal barrier function in pigeon squabs in a dose-dependent manner. Supplementation with 1% LA was suggested in parental pigeons.