McEvoy J D, McCaughey W J, Cooper J, Kennedy D G, McCartan B M
Department of Agriculture for Northern Ireland, Stormont, Belfast, UK.
Vet Q. 1999 Jan;21(1):8-15. doi: 10.1080/01652176.1999.9694984.
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.
诺龙（β-NT）是欧盟禁止用于家畜生产的一种激素型生长促进剂。注射后，牛体内的主要代谢产物是17α-差向异构体（α-NT）。然而，这种物质在怀孕母牛体内也天然存在。目前尚不清楚α-NT在未阉割或已阉割的公牛体内是否也是内源性的。开展了三项调查，以评估α-NT是否在这部分牛群中天然产生。在屠宰时收集了来自366个牛群的总共1281头牛（73头公牛和1208头阉牛）的胆汁样本，最初使用带有多分析物免疫亲和色谱（IAC）净化的半自动酶免疫分析（EIA）进行筛选。另外38头雄性牛（10头公牛和28头阉牛）的胆汁样本采用经IAC预处理的高分辨率气相色谱-质谱联用仪（GC-MS）进行分析。仅对α-NT含量超过2 ng/ml的样本进行GC-MS分析。以2 ng/ml的α-NT作为确证检测的阈值，筛选EIA的假阳性率为1.8%。来自政府养殖场（共2个）且未接受外源β-NT处理的公牛（n = 16）和阉牛（n = 179），其胆汁中未检测到可测量浓度的α-NT。从无非法生长促进剂滥用史的牛群（共204个）中选取的公牛（n = 35）和阉牛（n = 606），其胆汁中也未检测到α-NT。从未知处理史的牛群（共160个）中选取的32头公牛和451头阉牛中，来自19个牛群的56头阉牛经GC-MS确证其α-NT浓度高于该检测方法的定量限（LOQ，0.7 ng/ml）。在这些动物中，有2头有含β-NT的注射部位，5头有β-激动剂克伦特罗和马布特罗的残留。对56头确证为阳性的动物的移动和所有权历史进行检查，强烈表明在当前养殖场曾使用过外源β-NT。结论是，α-NT并非这部分牛群的内源性物质，在公牛和阉牛胆汁中检测到这种激素构成了滥用的证据。
