## 3 Results and Discussion
### Limitations, Gapsm, and Challenges for Future Research  
The evaluation and/or characterization of bedding quality in CBP systems was explored in studies carried out in distinct locations (Brazil, Germany, the Netherlands, Italy, Spain, and the United States of America) and periods of the year, as well as considering different facility types, bedding materials, and management, and using different quality indicators. Therefore, some care in relation to the results extrapolation is necessary. As the selected articles used different parameters for evaluating and/or characterizing bedding quality in CBP systems, a meta-analysis was not performed. Consequently, it was not possible to assess the quality of the studies, which could influence the results achieved. Studies in which peer review was uncertain (annals of events and book chapters) and/or published in languages other than English were excluded, as it was not possible to critically assess the methods and results. However, it was not possible to determine to what extent these exclusions affected the results achieved. Even though bedding management practices have been described (at least partially) in the selected studies, it is understood that future studies need to provide more detail on such routines, highlighting information such as types and characteristics of equipment used for bedding turning; number, times, and duration of turning operations; and frequency and volume of bedding replacements. Additionally, it is important that future studies specify information such as density, breed and size of housed animals, facility types and ventilation systems present, as well as climatic and topographic characteristics of the place where they were carried out. These and other factors can directly influence the efficiency of the composing process and therefore have the potential to be used as a background in the assessment of bedding quality in CBP systems [32]. Specifically regarding bedding turning, [PERSON] et al. [11] observed that increasing the turning depth also makes it possible to increase the temperature in the bedding subsurface due to greater aeration. Despite this, it is estimated that knowledge about the interrelationships between operations and depth of turning, environmental conditions, and bedding temperature in composing, is still limited. Therefore, conducting studies on this topic is, even today, of unique importance. Many of the studies carried out on this subject had the objective of characterizing average conditions in CBP systems, in terms of thermal comfort and bedding quality, without worrying about the distribution variability of physicochemical variables of the bedding along the resting area. Admittedly, the use of spatialization tools makes it possible to identify regions with management failures and/or more affected by external conditions and, therefore, to propose ways of improvement (localized or not), to homogenize the thermal environmental conditions and physicochemical bedding properties. Therefore, carrying out new monitoring studies over time, using these tools and considering different practical conditions encountered at the field level (in terms of facility types, climatic and geographic conditions, ventilation systems, materials and bedding management practices, size, and breed of housed animals, among others) is also important for the advancement of knowledge in the area. Due to the proposed objective, this review study did not correlate the welfare and health conditions of the animals housed in CBPs with physicochemical bedding quality. However, current knowledge on the subject indicates that bedding conditions in CBPs are directly associated with the welfare and health of housed animals [5; 12; 46; 57; 58; 59; 60; 61; 62; 63]. Therefore, it is important that new studies (experiments and reviews of the state of the art) be conducted to have a greater understanding of the potential synergies between the physicochemical bedding quality and the welfare and health of dairy cattle housed at CBPs.