Effects of Co-Fermented Feed Using Lactobacillus acidophilus, Limosilactobacillus reuteri and Lactiplantibacillus plantarum on Growth, Antioxidant Capacity, Fatty Acids and Gut Microbiota of Largemouth Bass (Micropterus salmoides)

Abstract

The effects of diets fermented with compound probiotics, namely Lactobacillus acidophilus, Limosilactobacillus reuteri and Lactiplantibacillus plantarum, on the growth performance, physiological and biochemical indexes, fatty acid composition and intestinal health of juvenile largemouth bass (Micropterus salmoides) were investigated. Three hundred healthy juvenile M. salmoides (5.29 ± 0.02 g) were selected and randomly divided into two groups with triplicates for each. The basic diet was set as the control group (CON), and fermentation of the basic diet with a mixed bacterial solution (1.8 × 109 cfu/mL, L. acidophilus:L. reuteri:L. plantarum = 1:1:1) was set as the fermentation group (FER). Fish were hand fed to satiation for 56 days and two-thirds of the culture water was renewed every 3 days. The results showed that feed intake of fish in the FER group was significantly lowered, thereby increasing feed efficiency (FE) and protein efficiency (PER) (p < 0.05). Serum alanine aminotransferase (ALT) activity was significantly decreased, and catalase (CAT) activity was significantly increased in the FER group (p < 0.05). The liver superoxide dismutase activity (SOD) was significantly enhanced, and intestinal trypsin was significantly increased in the FER group (p < 0.05). Being fed with the fermentation diet significantly increased the content of n-3 polyunsaturated fatty acids (PUFA), docosahexaenoic acid (DHA) and the n-3/n-6 PUFAs ratios in the liver (p < 0.05). Intestinal histology showed that villus height and width of the intestine and the number of goblet cells were significantly increased in the FER group (p < 0.05). Those fed with fermentation diets had limited diversity of gut microbiota. Compared to the CON group, the relative abundance of Aeromonas decreased significantly (p < 0.05), while the relative abundance of Fusobacteria, Cetobacteria and Lactobacillusis in FER increased greatly in the gut microbiota of the FER group. In conclusion, fermented feed with the three probiotics effectively improved the feed utilization and antioxidant capacity, promoted digestion and absorption of dietary protein, improved the ability of synthesize DHA and n-3 PUFAs in the liver and reduced the abundance of pathogenic bacteria in the gut. Therefore, the present research provided a new way of co-fermented feed with three probiotics for the aquaculture of M. salmoides.

Fermentation of Plant-Based Feeds with Lactobacillus acidophilus Improves the Survival and Intestinal Health of Juvenile Nile Tilapia (Oreochromis niloticus) Reared in a Biofloc System

“…During fermentation, digestive and antioxidant enzymes are produced by L. acidophilus [22,82,127], although their contribution to the host's condition is doubtful. Dietary inclusion of fermented ingredients may improve the activity of digestive [35] and antioxidant enzymes in fish [128], but changes in these activities are not always observed [82,102,129]. In this study, it is worth highlighting that enzymatic activity was not negatively affected by any treatment, even by the CPB diet, especially when considering that soybean meal may contain enzyme inhibitors that could have negatively affected the digestive process [130] and antioxidant response [131].…”

“…This result, however, may vary for different species. For example, fermentation of conventional diets for largemouth bass reduced their ingestion rate [102]. Regarding the current study's promising results, more studies are still needed to identify the palatability enhancers present in fermented feeds and evaluate their effect on fish feeding behavior.…”

“…The use of fermented soybean meal in fish diets has shown evidence of improvement in intestinal health, but survival is generally not affected [99][100][101]. In a recent study, the use of a fermented feed with a co-culture of LAB did not affect the survival of largemouth bass Micropterus salmoides [102]. By expanding the benefits of fermenting the complete feed, the effects of fermenting were able to be maximized.…”

“…Aromatic organic compounds are released during the fermentation process, improving the palatability of feeds, and promoting fish ingesta [109]. This is the first study conducted with fermented plant-based feeds, but it has already been demonstrated that soybean meal fermented with LAB can partially replace fishmeal without impairing feed intake and fish performance [100][101][102][103][104][105][106][107][108][109][110]. This result, however, may vary for different species.…”

The Effects of Unconventional Feed Fermentation on Intestinal Oxidative Stress in Animals

“…Through these effects, fermented feed can maintain the balance and stability of the intestinal flora, promote the growth and reproduction of beneficial bacteria, and inhibit the reproduction of harmful bacteria, thereby improving the intestinal health of animals. This combined effect helps to improve the digestion and absorption capacity of animals, enhance immunity, and reduce the occurrence of intestinal diseases such as diarrhea [ 144 ]. Fermented feed is rich in organic acids, amino acids, and small peptides after decomposition; these components have a role in regulating dysbiosis [ 145 , 146 ].…”