## 1 Introduction  
_M. synovoiae_ is a member of the genus _Mycoplasma_ of the class _Mollicutes_, a group of wall-less Gram-positive bacteria causing economic losses in the poultry industry. It is one of the major avian pathogenic agents and has a multifactorial etiology that involves complex interactions amongst pathogen, host, and environmental factors [1]. Poultry healthcare problems in this global industry associated with _M. synovoiae_ infections are related to respiratory infections, arrhythmia problems, and strains causing eggshell pathology [1, 2, 3, 4]. Eggs with eggshell apex abnormalities (EAAs) have a clear demarcation zone on the top zone of the egg, up to approximately 2 cm from the apex. Eggshell pathologies are also characterized by a roughened shell surface, shell thinning, increased translucency, cracks, and breaks [3, 4].  
Egg quality is important to the commercial egg industry. The deterioration in the quality of eggshells causes significant losses in the egg industry [5, 6]. Any infection of the reproductive system of a laying hen can affect the quality of the eggs and eggshells [7]. The eggshell plays a crucial role in the development of the embryo, protecting it from mechanical damage, regulating gas exchange, and providing a source of nutrients. The eggshell protects the egg from contamination by bacteria and other pathogens, ensuring healthy embryo development [8].  
_M. synovoiae_ is vertically transmitted and can cause egg infertility, embryonic death, poorly developed embryos, and weak poults, sometimes even without overt signs of active infection in the parent flock [9; 10]. The occurrence of clinical signs may be related to many factors, such as high levels of ammonia, inadequate ventilation, high stocking densities, and extremes of temperature. Infections with other microorganisms, such as _E. coli_, infectious bronchitis virus, Newcastle disease virus, and _Ornithobacterium rhinotracheale_, are also often involved in the etiology of these diseases [11].  
Mycoplasmas are important causes of disease and loss of production in intensively reared poultry, particularly in those that are under environmental stress [12].  
The disease caused by MS is among the diseases for which the OIE must be notified [13]. As MS can be transmitted via the respiratory tract and egg, the main method of controlling MS infections is to maintain MS-free breeder flocks [14]. Routine diagnosis for the detection of MS may be based on serological, culture, and molecular tests. Sera collected from the flock can be tested for the presence of antibodies using the serum plate agglutination test (SPA), enzyme-linked immunosorbent assay (ELISA), and, rarely, hemagglut inhibition (HI) [15; 16]. The culture method requires the use of PPLO broth and is expensive and time-consuming (28 days). The most frequently used and more sensitive method is the detection of DNA using polymerase chain reaction (PCR) and its modifications, real-time PCR, multiplex PCR, and LAMP [17; 18; 19; 20]. A quick and sensitive method is polymerase spiral reaction (PSR) [21]. The method is 100 times more sensitive than PCR and has a higher positive rate (69.9%) than ELISA (65.3%).  
Optical methods can be used to classify eggs as being from healthy or MS-infected hens using spectroscopy in transmitted light [22]. The authors obtained the best results for a group of brown shells, attaining 88% accuracy. With the destruction method, an egg is required because the measurement is taken through a single eggshell piece. To overcome this disadvantage, we propose a significant change to the spectroscopic data acquisition process.  
The proposed approach for spectroscopic data acquisition is based on the detection of reflected VIS light. Since the eggs are not destroyed, this method can be used on the production line for egg analysis.