In vitro fermentation characteristics of peanut vines and peanut shells in Jilin Province

To evaluate the nutritional value of two kinds of peanut (Arachis hyprogaea) by-products (peanut vines and peanut shells) in the Jilin Province using the in vitro gas production technique, three steppe red cattle with permanent rumen fistulas were used as experimental animals. The cumulative gas production at different time points (2, 4, 6, 8, 12, 24 h) and volatile fatty acid yield content, pH, ammonia nitrogen concentration, and microbial protein content after 24 h of in vitro fermentation of peanut vines, peanut shells, and Chinese leymus (Leymus chinensis) were determined. The results showed as follows: 1) the cumulative gas production, theoretical maximum gas production, and gas production rate when gas production was 1/2 of the maximum for peanut vines were significantly higher than those for peanut shells and Chinese leymus (P < 0.05). The gas production rate and lag time of gas production of Chinese leymus were significantly higher than those of peanut vines and shells (P < 0.05); 2) the pH of Chinese leymus was significantly higher than that of peanut vines and shells (P < 0.05), the total volatile fatty acid yield and propionic acid ratio of the peanut vines were significantly higher than those of peanut shells and Chinese leymus (P < 0.05), and the butyric acid ratio and acetic acid / propionic acid value of Chinese leymus were significantly higher than those of peanut vines and shells (P < 0.05). There was no significant difference in the acetic acid ratio among three groups (P > 0.05); and 3) the microbial protein content of peanut vines was significantly higher than that of peanut shells and Chinese leymus (P < 0.05) and the ammonia nitrogen concentration of Chinese leymus was significantly higher than that of peanut vines and shells (P < 0.05). In conclusion, in vitro fermentation of peanut vines exhibited the best effects and high nutritional value. The utilization rate of peanut shells was low and their proportion in dietary supplementation should not be large.