Feed Restriction Improves Lipid Metabolism by Changing the Structure of the Cecal Microbial Community and Enhances the Meat Quality and Flavor of Bearded Chickens

Non-targeted metabolomics identifies biomarkers in milk with high and low milk fat percentage

Milk is widely recognized as an important food source with health benefits. Different consumer groups have different requirements for the content and proportion of milk fat; therefore, it is necessary to investigate the differential metabolites and their regulatory mechanisms in milk with high and low milk fat percentages (MFP). In this study, untargeted metabolomics was performed on milk samples from 13 cows with high milk fat percentage (HF) and 13 cows with low milk fat percentage (LF) using ultra-high performance liquid chromatography coupled with mass spectrometry (UHPLC-MS/MS). Forty-eight potential differentially labeled compounds were screened using the orthogonal partial least squares-discriminant analysis (OPLS-DA) combined with the weighted gene co-expression network analysis (WGCNA) method. Amino acid metabolism was the key metabolic pathway with significant enrichment of L-histidine, 5-oxoproline, L-aspartic acid, and L-glutamic acid. The negative correlation with MFP differentiated the HF and LF groups. To further determine the potential regulatory role of these amino acids on milk fat metabolism, the expression levels of marker genes in the milk fat synthesis pathway were explored. It was noticed that L-histidine reduced milk fat concentration primarily by inhibiting the triglycerides (TAG) synthesis pathway. L-aspartic acid and L-glutamic acid inhibited milk fat synthesis through the fatty acid de novo and TAG synthesis pathways. This study provides new insights into the mechanism underlying milk fat synthesis and milk quality improvement.

Beneficial Effects of Bacillus amyloliquefaciens D1 Soy Milk Supplementation on Serum Biochemical Indexes and Intestinal Health of Bearded Chickens

This study investigated the effects of dietary supplementation with Bacillus amyloliquefaciens D1 (B. amyloliquefaciens D1) on growth performance, serum anti-inflammatory cytokines, and intestinal microbiota composition and diversity in bearded chickens. To investigate the effects of Bacillus amyloliquefaciensa and fermented soy milk, 7-day-old broilers were orally fed different doses of Bacillus amyloliquefaciens D1 fermented soy milk for 35 days, with the unfermented soy milk group as the Placebo group. This study found that B. amyloliquefaciens D1 fermented soy milk improved the intestinal microbiota of broilers, significantly increasing the abundance of beneficial bacteria and decreasing the abundance of harmful bacteria in the gut. B. amyloliquefaciens D1 fermented soy milk also significantly reduced the serum lipopolysaccharide (LPS) content. The body weight and daily weight gain of broilers were increased. In conclusion, the results of this study are promising and indicate that supplementing the diets of bearded chickens with B. amyloliquefaciens D1 fermented soy milk has many beneficial effects in terms of maintaining intestinal microbiota balance and reducing inflammation in chickens.

Castration alters the cecal microbiota and inhibits growth in Holstein cattle

To determine the effects of castration on growth performance, serum hormone levels, cecal microbiota composition, and metabolites in cattle. A total of 18 Holstein bulls and steers were divided into bull and steer groups and randomly assigned to 3 pens (3 cattle per pen, and each cattle were separated by a fence) to determine the average daily gain (ADG), daily dry matter intake (DMI), and feed efficiency (G/F). After the finishing trial, six cattle per group were randomly slaughtered. Serum was collected to measure the hormone concentration, and the cecal content was collected to measure the pH, short-chain fatty acids, and digestive enzyme activities. Metagenome sequencing and untargeted metabolomics were used to investigate the microbiota composition, functional profiles, and differential metabolites of the cecal contents. We found that castration significantly decreased ADG, DMI, and G/F in cattle (P < 0.05). The serum testosterone, thyroxine, growth hormone (P < 0.05), and triiodothyronine (P < 0.01) concentrations significantly decreased in the steer group when compared to those of the bull group. The activities of cellulase, xylanase, pectinase, and β-glucosidase (P < 0.05) significantly decreased in the steer group, whereas the activities of lipase and α-amylase significantly increased. Moreover, castration significantly decreased the relative abundance of Ruminococcaceae_bacterium, Treponema_porcinum, Oscillibacter_sp. (P < 0.05), and Alistipes_senegalensis (P < 0.01), whereas the relative abundance of Phocaeicola_plebeius (P < 0.05) was significantly increased. Also, the relative abundance of Phocaeicola_plebeius was negatively correlated with testosterone levels, and the function of the cecal microbiota was enriched in the GH29 and GH97 families in the steer group. Metabolomic analysis indicated that castration increased the levels of L-valine, L-phenylalanine, L-aspartic acid, L-isoleucine, L-lysine, methionine, L-glutamic acid, and L-leucine, while decreasing the levels of α-ketoglutaric acid through the 2-oxocarboxylic acid metabolism pathway. In addition, α-ketoglutaric acid was negatively correlated with Oscillibacter_sp. (P < 0.01). Overall, castration can inhibit cattle growth by altering the composition of the cecal microbiota. Therefore, this study provides a theoretical and practical basis for improving the growth performance of steers.

Effects of Yeast Culture Supplementation in Wheat-Rice-Based Diet on Growth Performance, Meat Quality, and Gut Microbiota of Growing-Finishing Pigs

The aim of this study was to investigate the effects of yeast culture (Saccharomyces cerevisiae) supplementation on the growth performance, meat quality, gut health, and microbiota community of growing−finishing pigs. A total of 45 growing−finishing pigs were randomly allocated to three treatments: a corn−soybean-based diet (CON, n = 15), a wheat−rice-based diet (GRA, n = 15), and GRA supplemented with 500 mg/kg yeast culture (YC, n = 15). The results show that compared to the CON group, the GRA group exhibited no significant differences in feed intake, daily gain, or feed conversion ratio, but had significantly reduced feed cost per kilogram BW gain of the finishing pigs (p < 0.05). Compared to that of the CON group, the GRA and YC groups showed an increase in the dressing percentage (p < 0.1). The meat color redness of the YC group increased (p < 0.1), whereas the b* value at 24 h decreased (p < 0.1). Meanwhile, the addition of YC significantly increased total superoxide dismutase activity on day 30 and catalase activity on day 60 (p < 0.05), and decreased serum urea nitrogen content on day 60 (p < 0.05). Furthermore, YC supplementation increased the gene expression of the duodenal anti-inflammatory factor IL-10 (p < 0.05), while it significantly decreased the gene expression of the ileal pro-inflammatory factor IL-8 (p < 0.05). The intestinal microbial identification results show that compared to the CON group, the YC group showed an increase in the relative abundances of Lactobacillus, Streptococcus, and Clostridium in the colon, and a decrease in the relative abundances of Bacteroidea, Clostridae, and Prevotella in the cecum. In conclusion, the growth performance of pigs on a wheat−rice-based diet was similar to that of pigs on a corn−soybean-based diet. Supplementation of 0.5% YC in the wheat−rice-based diet could improve the dressing percentage and meat color of growing−finishing pigs, which might be due to the increase in nitrogen utility and antioxidant capacity, and the improvement of the immune system and changes in microbiota communities.