## 1 Introduction  
The global sheep flock reached approximately 1.36 billion individuals in 2019. The highest percentage of sheep population is in Asia (42.3%), followed by Africa (31.7%), Europe (11.0%), Oceania (8.3%) and America (6.8%). Livestock farming, especially sheep production, is the cornerstone of sustainability for rural communities in China. By 2050, agriculture was challenged to increase sheep production by over 60% to meet global food requirements [1]. Worldwide, sheep production systems are generally extensive, semi-intensive, or grazing with variable supplementation. Nearly all grazing animals on pasture-based systems are exposed to helminths. Gastrointestinal nematode (GINs) infection is a major factor limiting profitability for grazing sheep [2]. In addition to direct adverse effects on growth performance and health, GINs infection also indirectly reduces meat quality, including changed fatty acid composition and flavor of muscle, lighter meat color, increased tenderness, causing poor conformation of sheep carcasses, increased meat fatiness, decreased polyunsaturated fatty acid content and lighter meat color [3; 4]. Therefore, it is necessary to decrease GIN infection in sheep to improve meat quality. Synthetic anthelmintics were widely used for decades to prevent and treat GINs. However, there are several disadvantages, including environmental pollution, resistant parasite populations, and especially chemical residues in meat. Consequently, alternative strategies are needed to control GIN infection in sheep. Many studies have focused on controlling GIN infections by means of nutritional regulation. For example, acacia (_Acacia Mill._) extracts containing tannins were found to be effective in killing GINs in sheep [5] and it was suggested that feeding tannin-rich plants could control GIN infection [6]. Recently, biologic control of GINs in small ruminants is becoming more common, especially using nematode predatory fungi to kill nematodes [7]. _Duddingtonia flagrans_ produce a large number of thick-walled chlamdospores to prevent them from being digested in sheep gastrointestinal tract, those spores could germinate into hyphae and produce a predatory trap to capture and digest nematodes [8]. In addition to _D. Flagrans_, some fungi with similar functions were explored. Nematode-trapping fungi (_Arthrobotrys oligospora_) can control nematodes [9] by absorbing urea and forming ammonia, which in turn initiates the lifestyle switch to form trap structures that capture and kill nematodes. In recent years, white-rot fungi (WRF) were found having antiparasitic activity. The potential mechanisms conclude that the mycelium of white-rot fungi (WRF), a heterogeneous group of fungi, often grew on the eggs of nematode (_Deladenus siricidicola_) in medium and prevented these eggs from hatching, significant reducing numbers of juveniles [10]. In addition, an aqueous extract of _Agaricus blazei_ Murril suppressed fecal egg count of nematode in sheep [11]. However, whether the presence of WRF or their metabolites in diets can improve meat quality by reducing GINs burden in sheep remains unknown. China is the largest agricultural country in the world with abundant biomass resources, including \(>\)800 million tons of plant residue (straw) produced annually, nearly one-third of global production. This includes up to 280 million tons of corn straw, although it has a low utilization rate due to low protein content and poor digestibility. Of the many approaches to the improvement of straw digestibility, biologic fermentation techniques seem to be the best. Compared to physical and/or chemical treatments, biologic treatment has definite advantages in terms of energy consumption and avoidance of toxic chemicals [12]. The WRF are commonly used for straw pretreatment to increase fiber digestibility, probably due to their secreted oxidative ligninolytic enzymes including lacase, manganese peroxidase and lignin peroxidase to decompose lignin [13].