# Optimization of Chinese Chive Juice as a Functional Feed Additive
## 1 Introduction  
The overuse of in-feed antibiotics in farm animal nutrition is one of the main reasons for the rapid emergence of multi-drug resistant (MDR) bacterial strains and the recent advent of strains with reduced susceptibility to antibiotics, which adversely affects both humans and animals [1]. There has been increased interest in exploring the remedial antimicrobial agents derived either from natural products or their combinatorial forms [2, 3]. _Allium_ species, such as onions (_Allium cpa_ L.), garlic (_Allium sativum_ L.), leeks (_Allium amploprasum_ L.), shallots (_Allium ascalonicum_), and chives (_Allium schenoprasumand_ L.), have been shown to confer antimicrobial, antioxidant, antiviral, immune-enhancing, and cholesterol-lowering properties because they are rich in organosulfurcompounds, polyphenols, saponins, and oligosaccharidesacharides [4]. For instance, supplementation with garlic (_A. sativum_ L.) essential oil (5 g/day) has been shown to increase the conjugated linoleic acid in the milk of dairy cattle [5]. Feeding dried garlic or onion (100 mg/day) improved the growth performance of broilers [6]. Dietary supplementation of garlic powder (6 g/kg/day) improved the immunity response and hepatic antioxidant activity in growing rabbits [7]. _A. tuberosum_, commonly known as the Chinese chive (CC), is native to Central Asia and Europe. It is widely used as an edible flavoring vegetable and spice. Aqueous CC extracts have exhibited antibacterial activity against a wide range of foodborne microorganisms, effectively inhibited _Campylobacter_ species at a concentration of 2 mg/mL [8; 9], and also reduced the cell count of penicillin-sensitive _Staphylococcus aureus_ in rats supplemented with 400 mg/kg/day [10]. Recently, fermented CC juice was shown to have broad-spectrum antibacterial activity against poultry pathogens, and notable antioxidant activities [11; 12]. So far, the application of CC as a functional feed additive is relatively less explored. To the best of our knowledge to date, only one study has reported the dietary supplementation of CC oil to reduce _Flavobacterium columnar_-based infections in Nile tilapia [13]. The high moisture content of CC is one of the main determinant factors that limits its further application in animal feed.  
Dehydration is commonly used to preserve vegetables and fruits by reducing the water activity, thus hindering the perishability caused by autochthonous microorganisms and extending their shelf life [14]. However, traditional high-temperature drying may also adversely affect thermally labile bioactive compounds resulting in compromised nutritional or functional qualities [15]. In most cases, heat drying decreases the antioxidant content, which is generally attributed to the oxidation processes or thermal degradation [16]. Soybean meal (SBM) is a common feed ingredient and can be used as a good excipient for CC juice. [PERSON] et al. [17] reported that the addition of SBM in oregano (_Origanum vulgare_ L.) lippie seed oil extract effectively reduced the odorous compounds in swine in vitro. To minimize the influence of high-temperature drying on CC functionality, the drying temperature and duration, as well as the excipient ratio should be carefully tailored. Fractional factorial design (FFD) is used to identify the most influential factors along with their interactions [18], herein, FFD was used to obtain the optimal drying conditions for CC without significant loss of antibacterial activities. Metabolomics is a very useful tool for discovering the changes in specific compounds and to help us understand their correlation with the relevant functionality [12; 19]. Here, we investigated the functional stability of CC with heat treatment and its optimized drying conditions based on antibacterial potential and changes in the relevant active compounds as profiled by untargeted metabolomic analysis.