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

Abstract

Objective: This study aimed to investigate the synergistic effects of corn straw and mulberry leaves on the growth performance and antioxidant capacity of sheep.

Methods: Corn straw and mulberry leaves were mixed in six different ratios as culture substrates: 100:0 (T0), 80:20 (T20), 60:40 (T40), 40: 60 (T60), 20:80 (T80) and 0:100 (T100). Rumen fluid from small-tailed Han sheep was collected, and artificial saliva was prepared. Gas production (GP) parameters, volatile fatty acids (VFAs), ammonia nitrogen (NH3-N), microbial crude protein (MCP) and additional indicators of in vitro rumen fluid fermentations were measured over 72 h. Combinations with a positive multiple-factors associative effect index were chosen for a 65 d in vivo feeding experiment, during which the growth performance, carcass traits, meat quality, and liver antioxidant function were evaluated.

Results: Mulberry leaves exhibited a positive correlation with in vitro theoretical maximum GP, cumulative GP, MCP, and organic matter digestibility. At 72 h, total VFA and acetic acid were significantly higher in the T60, T80, and T100 groups (p<0.05). Additionally, at 6 h, 12 h, and 72 h, the NH3-N of the T60, T80, and T100 groups were significantly higher (p<0.05). The T20, T60, and T80 combinations were selected for sheep feeding, and T60 got the highest increase in average daily feed intake (p<0.05). Moreover, the thickness of the rib and back muscle were notably increased in the T60 and T80 groups (p<0.05). Water-holding capacity of the longissimus dorsi muscle was higher and drip loss was lower in the combination-fed groups, particularlly in the T20 and T60 groups (p<0.05). Blood urea nitrogen levels decreased with increasing mulberry leaf content (p<0.05). Furthermore, the T60 and T80 groups demonstrated higher α,α-diphenyl-β-picrylhydrazyl and 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) free radical scavenging ability (p<0.05). Catalase and glutathione peroxidase activities in the sheep liver were also notably enhanced (p<0.05).

Conclusion: The combination of corn straw and mulberry leaves had a positive synergistic effect on improving feed intake, muscle thickness, muscle water retention, and the liver antioxidant capacity in sheep. The ratios of 40:60 corn straw to mulberry leaves showed the most beneficial effects. This combination provides a practical method for utilizing agricultural waste and optimizing sheep diets.