A possible correlation between the blood leukocyte formula and the use of glucocorticoids as growth promoters in beef cattle

Clinical analyses designed to set welfare parameters were performed on bloo d drawn from the caudal vein of 14 groups of cattle (young bulls and heifer s) (n = 10) from 480 to 550 kg b.w., each group representative of a differe nt farm. The leukocyte formula exhibited a lymphocytopenia in four groups c ompared with the values from a control group (n = 50). This finding was rel ated to the possible illicit use of corticoids as growth promoters in meat production. The individual plasmas tested negative by two different ELISA k its for corticosteroids, but chemical analyses by LC-MS/APCI (detection lim it 0.5 ng/ml) on the pooled plasma of each of the 14 groups revealed the pr esence of beclomethasone and fluocinolone acetonide in 3 of the 4 suspect f arms. These corticosteroids are not always efficiently screened by commerci ally available immunoassays. The epidemiological reliability of blood analy sis as a screening test for such drugs is discussed in the light of the nee d for duality certification of the whole meat production processes 'from fa rm to fork', and for enhanced animal welfare.