**2. Materials and Methods**

Field data (n = 979,806) were collected from the Integrated Veterinary Information System (IVIS) and the online application "ARTEMIS" of the Hellenic Agricultural Organization "ELGO-DIMITRA" from 132 approved slaughterhouses, geographically distributed in all 13 regions of the country from years 2011 to 2017. The registration of the data is obligatory based on the national legislation. The data included the gender, the breed and the geographical region of the farm, the date of birth and the date of slaughter, the carcass weight and the SEUROP classification categories.

The EU definition of carcass is ''the whole body of a slaughtered animal as presented after bleeding, evisceration and skinning". According to European legislation [31], the beef carcass is weighed as soon as possible after slaughter and not later than 60 min after the animal has been stuck and the presentation of the beef carcass should be (a) without the head and the feet; the head shall be separated from the carcass at the atloido-occipital joint and the feet shall be severed at the carpametacarpal or tarsometatarsal joints; (b) without the organs contained in the thoracic and abdominal cavities with or without the kidneys, the kidney fat and the pelvic fat; (c)without the sexual organs and the attached muscles and without the udder or the mammary fat.

The EU classification system classified bovine carcasses according to their gender and age into 6 categories using the letters A, B, C, D, E and Z. The definition of each letter is A: carcasses of uncastrated male animals aged from 12 months to less than 24 months; B: carcasses of uncastrated male animals aged from 24 months; C: carcasses of castrated male animals aged from 12 months; D: carcasses of female animals that have calved; E: carcasses of other female animals aged from 12 months and Z: carcasses of animals aged from eight months to less than 12 months. In addition to the latter categories, in European legislation [31] there is one more with the letter V for the carcasses of animals aged less than eight months. The beef carcasses in category V were not obliged to be classified according to SEUROP system. In our study, the category C was not used because there were no carcasses slaughtered in Greece in this category.

The SEUROP system defines six classes in order to classify carcasses according to their muscle conformation. The S class is ''superior"; the E class is ''excellent"; the U class is ''very good"; the R class is ''good"; the O is ''fair" and the P class is ''poor". Regarding to the fat deposit, the EU system classified bovine carcasses into five classes using the numbers 1–5. Specifically, class 1 is low; class 2 is slight; class 3 is average; class 4 is high; class 5 is very high.

The final selected dataset for analysis excluded the crossbred animals and consisted from 323,046 carcasses derived from 24 purebred cattle breeds including all animals with age of slaughter from 210 to 975 days with a sufficient number of observations (>100).

For the statistical processing of carcass weight and age of slaughter data, the analysis of variance was used (one-way ANOVA) in order to detect significant differences between the relative means for breed, gender, slaughter year, slaughter month, farm's geographical region and categories of carcass classification, muscle conformation and fattening. For multiple comparisons, the Bonferroni criterion used was set at significance level of *p* ≤ 0.05. All statistical analyses were performed with the statistical program SPSS Statistics for Windows (IBM SPSS statistics Version 22.0, 2020).

#### **3. Results**

Data showed that a high percentage of carcasses (n = 503,000) resulted from random and unidentified crossbreeding (51.3%). The statistical data processing showed that the carcass weight and the age of slaughter averaged 298.9 ± 0.2 kg and 559.1 ± 0.3 days (about 1.5 years), respectively.
