The Effect of Sargassum siliquastrum Supplementation on Growth Performance, Cecal Fermentation, Intestine Histomorphology, and Immune Response of Japanese Quails

SIMPLE SUMMARY: Market demand is predicted to rise as the growing scope of seaweed-based applications, as feed additives for poultry, expands. Seaweeds are a rich source of essential nutrients and bioactive substances, including polysaccharides and trace elements. Seaweeds also have prebiotic properties that help birds perform better and could be utilised instead of antibiotics. Only a few studies have examined the effect of brown seaweed (Sargassum siliquastrum) supplementation on bird performance, but to our knowledge, there have been no studies regarding the effect of S. siliquastrum supplementation on the bird’s cecal fermentation and microbial populations. Hence, this research aimed to evaluate the impact of S. siliquastrum supplementation on performance, cecal fermentation, and microbial populations, as well as on the immunological response in Japanese quails. The results indicated that the studied S. siliquastrum supplement improved the performance, cecal fermentation, microbial populations, intestinal morphology, and immunological response in Japanese quails. Hence, this research implies that a dietary S. siliquastrum supplement for quails could be a viable feed additive alternative. ABSTRACT: This study aimed to investigate the dietary effects of Sargassum siliquastrum on the growth performance, nutrient digestibility, cecal fermentation, microbial populations, antioxidant status, immune response, and intestine histomorphology of Japanese quails. A total of 450 Japanese quails, aged 7 days, weighing 27.35 ± 0.23 g, were randomly distributed to three dietary groups in a 42-day feeding experiment. Five replicates were prepared per group, with each replicate consisting of 30 chicks in a cage. The three dietary groups consisted of a basal diet (0% supplementation, which was the control) and diets supplemented with 1% and 2% of S. siliquastrum. The results showed that the S. siliquastrum-supplemented groups and the control group had similar final body weight (FBW), average body gain (ADG), and average feed intake (ADFI). However, the S. siliquastrum-supplemented groups had a better feed conversion ratio (FCR), as well as a lower mortality rate, compared to the control group. S. siliquastrum supplementation improved the nutrient digestibility of dry matter (DM), organic matter (OM), crude protein (CP), and crude fiber (CF) (p < 0.05). The S. siliquastrum-supplemented groups exhibited the heaviest empty intestine and cecum weights, as well as the longest intestinal and cecal length. Furthermore, the total volatile fatty acid (VFA) and the propionic acid concentrations increased significantly in quails fed S. siliquastrum-supplemented diets (p < 0.05), although the concentration of NH(3)-N decreased (p < 0.05). The dietary inclusion of S. siliquastrum had a beneficial effect on cecal microbial populations, where the Lactobacillus sp. counts increased, and the E. coli and Clostridium perfringens counts decreased. The histopathological examination of the duodenum confirmed that S. siliquastrum dietary supplementation enhanced the height and width of the villi. Quails fed S. siliquastrum-supplemented diet exhibited the highest total antioxidant capacity, superoxide dismutase, glutathione peroxidase, and glutathione reductase activities, but the thiobarbituric acid reactive substance was decreased (p < 0.05). Serum IgA, IgG, and IgM concentrations increased considerably (p < 0.05) in S. siliquastrum-supplemented groups. In conclusion, S. siliquastrum supplementation in the diet of Japanese quail can provide beneficial effects on performance, cecal fermentation, beneficial bacteria populations, and the immune response, and could be considered as an alternative feed additive in poultry production.