Dietary supplementation of Astragalus flavonoids regulates intestinal immunology and the gut microbiota to improve growth performance and intestinal health in weaned piglets.

Astragali Radix (AS) is a widely used herb in traditional Chinese medicine, with calycosin as its main isoflavonoid. Our previous study discovered that calycosin triggers host defense peptide (HDP) production in IPEC-J2 cells. The aim of this study is to investigate the alleviation effects of AS total flavone and AS calycosin on growth performance, intestinal immunity, and microflora in weaned piglets. Sixty-four piglets were assigned randomly to 4 treatment groups, (1) CON: the basal diet, (2) P-CON: the basal diet plus antibiotics (1 g/kg), (3) AS-TF: the basal diet plus AS total flavone at 60 mg/day per piglet, (4) AS-CA: the basal diet plus AS calycosin at 30 mg/day per piglet. Each treatment consists of 4 replicates with 4 piglets per replicate. Results showed that treatment with AS-TF and AS-CA enhanced average daily growth and average daily feed intake compared to the CON group (P < 0.01), while AS-CA significantly reduced the diarrhea rate (P < 0.05). Both AS-TF and AS-CA significantly increased serum immunoglobulin (Ig) A and IgG levels, with AS-CA further boosting intestinal mucosal secretory IgA levels (P < 0.05). Histological analysis revealed improvements in the morphology of the jejunum and ileum and goblet cell count by AS-TF and AS-CA (P < 0.05). Supplementation of AS-TF and AS-CA promoted the expression of several intestinal HDPs (P < 0.05), and the effect of AS-CA was better than that of AS-TF. In addition, the AS-TF and AS-CA regulated jejunal microbial diversity and composition, with certain differential bacteria genera were showing high correlation with serum cytokines and immunoglobulin levels, suggesting that the intestinal flora affected by AS-TF and AS-CA may contribute to host immunity. Overall, AS CA and AS TF all improved growth performance and health, likely by enhancing nutrition digestibility, serum and intestinal immunity, and intestinal microbial composition. They showed the similar beneficial effect, indicating AS CA appears to be a major compound contributing to the effects of AS TF. This study demonstrated the positive effect of AS flavonoids on weaned piglets and provided a scientific reference for the efficient use of AS products.

Phytogenic feed additives as natural antibiotic alternatives in animal health and production: A review of the literature of the last decade.

The use of antibiotics in animal production raises great public safety concerns; therefore, there is an urgent need for the development of substitutes for antibiotics. In recent decades, plant-derived feed additives have been widely investigated as antibiotic alternatives for use in animal health and production because they exert multiple biological functions and are less likely to induce resistance development. This review summarizes the research history and classification of phytogenic feed additives and their main functions, potential modes of action, influencing factors, and potential negative effects. Further, we highlight the challenges in developing sustainable, safe, and affordable plant-derived antibiotic alternatives for use in livestock production.

Effects of dietary protein levels on production performance, meat quality and flavor of fattening pigs.

This study aimed to evaluate the effects of dietary protein level on the production performance, slaughter performance, meat quality, and flavor of finishing pigs. Twenty-seven Duroc♂ × Bamei♀ binary cross-bred pigs (60.86 ± 2.52 kg body weight) were randomly assigned to three groups, each group has three replicates, and each replicate has three pigs. Three groups of finishing pigs were fed 16.0, 14.0, and 12.0% crude protein levels diets, and these low-protein diets were supplemented with four limiting amino acids (lysine, methionine, threonine and tryptophan). The results showed that the pigs fed low-protein diets increased (P < 0.05) loin eye muscle area, and reduced (P < 0.05) heart weight, lung weight. The feed-weight ratio of the 14.0% protein group was reduced (P > 0.05); Dietary protein levels significantly affected the luminance (L24h), yellowness (b45min and b24h) (P < 0.05), reduced shear stress, muscle water loss, drip loss, the levels of crude fat (P < 0.05), and increased marbling score (P < 0.05) in the muscle of finishing pigs; The low-protein diets improved PUFA/TFA, PUFA/SFA (P > 0.05), and increased hexanal, E-2-heptenal, 1-octen-3-ol, EAA/TAA in the muscle of finishing pigs (P < 0.05); The results indicated that reduced the crude protein levels of dietary by 2.0-4.0%, and supplementation with four balanced limiting amino acids had no significant effects on the production performance and slaughter performance of finishing pigs, and could effectively improve meat quality and flavor.