A reconnaissance survey of farmers' awareness of hypomagnesaemic tetany in UK cattle and sheep farms.

Hypomagnesaemic tetany (HypoMgT) in ruminants is a physiological disorder caused by inadequate intake or impaired absorption of magnesium (Mg) in the gut. If it is not detected and treated in time, HypoMgT can cause the death of the affected animal. A semi-structured questionnaire survey was conducted from July 2016-2017 to assess farmers' awareness of HypoMgT in cattle and sheep in the UK. The questionnaire was distributed to farmers at farm business events and agricultural shows, and through a collaborative group of independent veterinary practices to their clients. Farmers were asked about (i) the incidence of presumed HypoMgT (PHT); (ii) their strategies to treat or prevent HypoMgT; (iii) mineral tests on animals, forage and soil, and (iv) farm enterprise type. A total of 285 responses were received from 82 cattle, 157 mixed cattle and sheep, and 46 sheep farmers, of whom 39% reported HypoMgT in their livestock, affecting 1-30 animals. Treatment and/or prevention against HypoMgT was reported by 96% respondents with PHT and 79% of those without. Mineral tests on animal, forage, and soil was conducted by 24%, 53%, and 66% of the respondents, respectively, regardless of PHT. There was a highly significant association between the use of interventions to tackle HypoMgT and the incidence of PHT (p < 0.01). The top three treatment/prevention strategies used were reported as being free access supplementation (149), in feed supplementation (59) and direct to animal treatments (drenches, boluses and injections) (45) although these did vary by farm type. Although some (9) reported using Mg-lime, no other pasture management interventions were reported (e.g., Mg-fertilisation or sward composition). Generally, the results indicate that UK farmers are aware of the risks of HypoMgT. A more integrated soil-forage-animal assessment may improve the effectiveness of tackling HypoMgT and help highlight the root causes of the problem.