an increasing trendP = 0.098
Volatile fatty acids As shown in Table 9 , when the dietary Lys level was 0.50%, the levels of butyric acid ( P = 0.008) and total volatile fatty acids (linear P = 0.018) in the colonic contents of Ningxiang pigs significantly increased, while the propionic acid content also showed an increasing trend ( P = 0.098).