Synergistic effect of corn straw and mulberry leaves fermantation in vitro and effects on growth performance and antioxidant capacity of sheep.

Abstract

This study was to determine the synergistic effect of corn straw and mulberry leaves in sheep diet. Corn straw and mulberry leaves were mixed as culture substrate for six groups: 100:0 (T0), 80:20 (T20), 60:40 (T40), 40: 60 (T60), 20:80 (T80) and 0:100 (T100). The in vitro culture indicated that mulberry leaves exhibited a positive correlation with theoretical gas production (GP), cumulative GP, microbial crude protein concentration, and organic matter digestibility. At 72 h, total volatile fatty acids and acetic acid were significantly higher in the T60, T80, and T100 groups (P < 0.05). Moreover, at 6 h, 12 h, and 72 h, the ammonia nitrogen of T60, T80, and T100 groups was significantly higher (P < 0.05). The combination of T20, T60, and T80 were selected for sheep feeding, and T60 got an highest increase in the average daily feed intake (P < 0.05). In addition, the thickness of the rib and back was notably increased in the T80 (P < 0.05). The water holding capacity of the longissiums dorsi muscle was higher and drip loss lower by feeding combination feed, especially in T20 and T60 groups (P < 0.05). The blood urea nitrogen decreased with the increase of mulberry leaf content (P < 0.05). Additionally, the T60 and T80 groups demonstrated higher DPPH and ABTS free radical scavenging ability (P < 0.05). Furthermore the combination resulted in a notable enhancement of catalase and glutathione peroxidase activity in the sheep liver (P < 0.05). In conclusion, the combination of corn straw and mulberry leaves had a positive synergistic effect in improving feed intake, muscle thickness, muscle water retention and liver antioxidant capacity of sheep, which provides a practical way for utilizing agricultural waste.