## 1 Introduction  
Horsemeat has a strictly defined group of consumers, and the demand for this food varies depending on the country and region. Currently, in Europe, the consumption of horsemeat holds significant importance in countries such as Spain, Belgium, France, and Italy [1]. The quality of the slaughter material obtained at collection centers is highly diverse, which is attributable, in part, to a large age range of the horses (from foals to horses over 20 years of age) and a significant variation in the ante-slaughter weight of horses. Taking into account the characteristics of horse carcasses and meat quality, as well as nutritional value and fatty acid composition, foals are the most extensively studied slaughter category. Numerous research studies [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18] demonstrated the effect of horse age on the slaughter value and quality of horsemeat. It should be emphasized that the age of horses contributes significantly to the diversification of the obtained raw material.  
As an animal ages, not only does the tissue composition of the obtained carcasses change, but the structure of the proteins in muscle and connective tissues, as well as the quality of adipose tissue, also varies [5]. Moreover, the content of basic components in horsemeat is influenced by the age of the animal; specifically, as animals age, the water content in the meat decreases, while the protein and fat content increases [5].  
In comparison with other conventional types of meat, such as beef, chicken, or pork, horsemeat consumption is marginal [19; 20]. Although horsemeat is commercialized in a minority market, it boasts excellent nutritional properties [8]. These properties include low levels of fat and cholesterol; very high contents of protein, vitamins, and minerals; and relatively high concentrations of \(n\)-3 fatty acids and heme iron. These attributes suggest that the consumption of horsemeat may offer health benefits [10; 14; 16; 21; 22; 23; 24; 25; 26; 27; 28].  
In recent years, few studies in the literature have focused their attention on the evaluation of the slaughter value of horses, the tissue composition of carcasses, and the quality of horsemeat in terms of the age of the animal. Most of the research work on the evaluation of the slaughter value of horses and the quality of horsemeat dates back 20 years and some studies in this area are even older [7; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40]. It should be noted that over the course of these years, the environmental, nutritional, and genetic conditions could have changed. These changes could, in turn, result in the differentiation of the characteristics of the slaughter value, as well as the tissue and chemical composition of this raw material [35; 38; 41; 42].  
Given that Poland is a large exporter of horsemeat, the usefulness of Polish horse breeds, compared with other foreign breeds, in terms of slaughter value and chemical composition of the meat may prove to be more favorable [5; 38].  
In this context, the aim of this study was to show the influence of the age of horses in contemporary use in Poland on the tissue composition of carcasses and the quality of horsemeat. This will make it possible to demonstrate new nutritional and health aspects of horsemeat, especially for gourmets of this type of product.