Preliminar histological study of the thymus in regularly slaughtered Chianina beef cattle to improve methods for the detection of illicit treatments.

Chianina is an Italian cattle breed appreciated for its meat and resilience skills. No standard values are present in literature regarding Chianina thymic involution. A possible early physiological involution has been reported during the Italian National Residue Plan screening tests. The aim of this work was to perform an anatomo­histopathological study of the thymus in Chianina cattle to improve knowledge about thymic involution in this breed. Forty Chianina bulls (16­24 months old), never treated with corticosteroids and regularly slaughtered in the Umbria region (Italy), were enrolled. Animals aged 19­21 months which received score 3 thymic atrophy had a prevalence of 0.15 (CI 95%: 0.02­0.45%), while the prevalence was 0.29 (CI 95%: 0.10­0.56%) among animals aged 22­24 months. The thymus/carcass weight and thymic cortex/medulla ratio resulted close to those reported in cattle experimentally challenged with corticosteroids. Results suggest that the Chianina breed could be characterized by a physiological premature involution of the thymus gland in comparison to other breeds. These results represent a starting point to increase the reliability of the National Residue Plan histological screening test.