## 1 Introduction  
The livestock and poultry industries are quickly expanding, and harmful gases created during rearing, such as ammonia (NH\({}_{3}\)) and greenhouse gases, are attracting more attention because they constitute a danger to the environment. High concentrations of ammonia and carbon dioxide (CO\({}_{2}\)) affect the broilers' growth, slaughter traits, and animal welfare [1]. At the same time, the public is concerned about the serious pollution of the surrounding environment [2; 3; 4]. A large amount of NH\({}_{3}\) and CO\({}_{2}\) emissions have serious negative impacts on public health and climate change [5], and it is urgent to reduce the production and emissions of NH\({}_{3}\) and CO\({}_{2}\) during livestock and poultry rearing.  
In order to create an improved rearing environment, researchers have conducted [6; 7; 8; 9] a series of modifications. During the broiler rearing, litter is often spread on the ground to prevent animals from directly contacting the ground, which provides a comfortable growth environment for broilers and reduces NH\({}_{3}\) emissions. It has been considered that the bedding materials can change the physicochemical properties of litter, with further effects on its microorganism activity, and finally influence the generation and emissions of NH\({}_{3}\) and CO\({}_{2}\). In chicken manure, 60-75% of nitrogen exists in the form of uric acid nitrogen, and the NH\({}_{3}\) produced is mainly due to the decomposition of uric acid by the uricase generated from microbial activities. Generally, the less active the poultry excrement microorganisms, the less carbon and nitrogenous substances in the excrement will be decomposed. Moreover,the absorption characteristics of litter can also affect gas emissions [10]. Common litters include straw, rice husk, wood shavings, sawdust, etc. [11; 12; 13].  
Tea plantation areas around the globe have reached over 4 million hectares and the yield is more than 6 million tons. Tea is often used for the removal of unpleasant odors, sewage deodorization, and inhibition of odor emissions in solid waste disposal. It has been reported that tea's gas adsorption and deodorization functions might be attributed to its rich tea polyphenol (TP) content, as it contains strong active carboxyl and oxhydryl groups that account for 18-34% of its dry weight [14; 15; 16]. [PERSON] et al. [16] applied composite papers containing waste tea to remove the odor of several gases, such as hydrogen sulfide (H\({}_{2}\)S) and NH\({}_{3}\). [PERSON] et al. [17] found that tea grounds and other tea wastes could serve as low-cost adsorbents to remove part of the pharmaceutical contaminants in a water medium. At present, the utilization rate of tea wastes, such as residues from tea plantations and tea grounds from deep processing, only accounts for about 15% of total tea production. Therefore, we studied whether waste tea could be used as a litter additive to inhibit the emissions of NH\({}_{3}\) and CO\({}_{2}\) during poultry rearing.  
The assessment of the regular emissions during the rearing process is very important in order to reduce them. Before field detection, rearing chamber detection is usually adopted for its easy accessibility [18; 19; 20]. In this work, a digital rearing chamber inspection system was developed for simultaneous monitoring of broiler growth conditions, as well as emissions of NH\({}_{3}\) and CO\({}_{2}\) with waste tea litter or without litter. The aim of this experiment was to determine whether waste tea litter could provide a new technique and method for emission reduction and control of NH\({}_{3}\) and CO\({}_{2}\) in livestock rearing.