Nortestosterone is not a naturally occurring compound in male cattle.

Nortestosterone (beta-NT) is a hormonal growth promoter banned from livestock production in the EU. Following injection, the major metabolite in cattle is the 17 alpha-epimer (alpha-NT). However, this also occurs naturally in pregnant cattle. It is not known whether alpha-NT is also endogenous to intact or castrated male cattle. Three surveys were undertaken to assess whether alpha-NT is naturally produced in this subset of the population. Bile samples from a total of 1,281 cattle (73 bulls and 1,208 steers) from 366 herds were collected at slaughter and initially screened by using a semi-automated EIA with multi-analyte immunoaffinity chromatography (IAC) clean-up. Bile samples from a further 38 male cattle (10 bulls and 28 steers) were analysed by high-resolution gas chromatography-mass spectrometry (GC-MS) with IAC pretreatment. Only samples containing more than 2 ng/ml alpha-NT were subjected to GC-MS. With 2 ng/ml alpha-NT as a threshold for confirmatory testing, the false positive rate of the screening EIA was 1.8%. Bulls (n = 16) and steers (n = 179) from government farms (n = 2) and which were not treated with exogenous beta-NT, did not have measurable concentrations of alpha-NT in their bile. Bulls (n = 35) and steers (n = 606) taken from herds (n = 204) which had no previous history of illegal growth promoter abuse also did not have alpha-NT in their bile. Of 32 bulls and 451 steers of unknown treatment history sampled from herds (n = 160), 56 steers from 19 herds contained GC-MS confirmed concentrations of alpha-NT higher than the limit of quantification of the assay LOQ (0.7 ng/ml). Of these animals, two had beta-NT-containing injection sites and five had residues of the beta-agonists clenbuterol and mabuterol. Examination of the animal movement and ownership histories of the 56 confirmed positive animals strongly suggested that exogenous beta-NT had been administered at the presenting farm. It is concluded that alpha-NT is not endogenous to this subset of the cattle population and that detection of this hormone in bile from bulls and steers constitutes evidence of abuse.

Tick infestations on livestock in the Yemen Arab Republic and their potential as vectors of livestock diseases.

A survey of ticks on cattle, camels, sheep, goats and donkeys in four different geographical locations of the Yemen Arab Republic (YAR) was carried out to provide more information on the possible risk of tick-borne diseases to imported exotic cattle included in the YAR's plans for livestock development. The most abundant ticks were Hyalomma spp. particularly on camels. Ticks found on cattle included Hyalomma spp., Amblyomma variegatum, Boophilus annulatus and Rhipicephalus spp. In general with the exception of camels tick burdens on all species of domestic livestock were very low. Two hundred and ninety eight serum samples from miscellaneous adult cattle throughout the country were negative to a test for Anaplasma marginale antibodies. It is speculated that tick burdens in the YAR are too low for significant disease transmission and the implications of the findings are discussed.