Abstract :
[en] Peanut meal (PNM), a byproduct of the peanut oil extraction process, is a valuable source of protein and energy in animal feed. Nevertheless, its utility is hindered by an uneven amino acid profile, particularly concerning essential amino acids such as Lys, Met, and Thr. PNM also contains anti-nutritional factors (ANFs) that negatively impact its nutritional value and digestibility. For instance, phytic acid in PNM forms complexes with minerals, reducing their bioavailability to animals. The high fiber content in PNM can also lead to digestive issues and reduced nutrient absorption. Furthermore, PNM is susceptible to contamination by potent toxins known as aflatoxins, produced by Aspergillus fungi, posing a risk to animal health. In addressing these challenges, fermentation techniques exhibit promise, having demonstrated their capacity to enhance feed ingredient nutritional value by degrading ANFs, optimizing amino acid profiles, and augmenting nutrient accessibility. Additionally, fermentation can yield beneficial metabolites and enzymes that bolster animal health and improve performance.
To initiate fermentation, the selection of appropriate microorganisms is crucial. A strain of Bacillus velezensis LB-Y-1 was screened based on the nutritional characteristics of PNM. This strain, identified through a targeted screening regimen, showcased remarkable potential for the production of multiple enzymes, including protease, cellulase, and phytase. This capability enabled it to break down large protein molecules, convert amino acids, and reduce cellulose and phytic acid content in PNM. Additionally, incorporating LB-Y-1 into the diet positively influenced the growth performance and tibia mineralization of chicken broilers. Analysis of the intestinal microbiota revealed an abundance of beneficial genera such as Parasutterella and Rikenellaceae, while the opportunistic pathogen Escherichia-Shigella was significantly reduced in the LB-Y-1 supplemented group. These findings collectively suggest that LB-Y-1 holds potential as a viable strain for further applications as a starter culture for fermentation processes.
Furthermore, we also screened a potential probiotic strain LC-9-1, which was screened from the intestines of healthy animals, was identified as Pediococcus acidilactici. This strain exhibited exceptional properties, such as efficient acid production, antibacterial activity, and antioxidant capability. When applied in the fermentation of PNM, it effectively reduced the pH of the fermentation product, resisted contamination from pathogenic microorganisms, and enhanced the product's antioxidant capacity. Moreover, experimental studies conducted on broilers revealed that dietary supplementation with LC-9-1 was safe. Additionally, it led to a reduction in abdominal fat deposition and improvements in antioxidant capacity and intestinal immunity in broilers.
The solid-state fermentation was conducted by utilizing the aforementioned bacteria and employing conventional techniques. Significant changes in the nutritional composition of PNM were observed after fermentation. The levels of crude protein, TCA-soluble protein, and L-lactic acid were significantly increased, while the concentrations of crude fiber, phytic acid, and aflatoxin B1 were notably decreased. In addition, solid-state fermentation resulted in an increase in the free amino acid content and improved the balance of hydrolyzed amino acids in PNM. We conducted an assessment of the nutritional value of FPNM in broilers. The results showed that feeding on FPNM resulted in higher apparent ileal digestibility (AID) and standardized ileal digestibility (SID) values for essential amino acids, including Met, Lys, Leu and Phe. Additionally, the AID and SID values for non-essential amino acids in FPNM were higher compared to PNM, except for Pro. However, fermentation did not have a significant effect on the apparent metabolizable energy (AME) value.
In the final study, a feeding trial was conducted, where different gradients of PNM and FPNM (5%, 10%, and 15%) were added to broiler diets. The results revealed that compared to the corn-soybean meal diets, supplementation of 10% PNM led to decreased levels of Lys, Met, and Thr in the breast muscle. However, the supplementation of 10% FPNM mitigated these changes. Furthermore, the broilers in the 10% FPNM group exhibited notable improvements in meat quality parameters such as meat color (redness, a*), pH24 hour values, and oxidative stability. Additionally, the 10% FPNM group showed enhanced antioxidant capacity, as indicated by higher levels of total antioxidant capacity (T-AOC) and superoxide dismutase (SOD), along with lower levels of malondialdehyde (MDA) compared to the 10% PNM group. In conclusion, FPNM positively influenced broiler growth performance, meat quality, and oxidative stability. Taking all performance indicators into consideration, the optimal outcomes were obtained when the addition amount of FPNM was 10%.
