Free faecal liquid in horses: faecal composition and associations with feeding and management

Free faecal liquid (FFL) is a condition where horses show two-phase characteristics of faeces, with one solid phase (faecal balls) and one liquid phase (only free liquid). Causes of this condition are unknown. The aim of this thesis was to characterize horses with FFL, investigate feeding and management factors suggested to be associated with presence of FFL, and to compare faecal composition in horses with (case) and without (control) FFL. Characterisation of horses with FFL showed that all types (e.g. breeds, ages, disciplines performed) of horses could be affected. No specific feeding or management factors were overrepresented among FFL horses. Changes in forage feeding were reported to result in reduced signs of FFL. A comparably high incidence of previous colic was reported in horses showing FFL. Faecal bacterial composition was in general similar, but some specific low abundant bacterial taxa differed between case and control horses. Case horses had a lower concentration and proportion of lactic acid, and lower water holding capacity of faecal compounds, compared with controls. Case horses were reported to be fed lower average amounts of straw, and a higher proportion and amount of concentrates in the diet, compared with controls. Case horses were also reported to have lower daily intake of digestible crude protein and neutral detergent fibre and higher daily intake of starch and water soluble carbohydrates compared with control horses. Overall, this thesis shows that feeding and management may be important for the occurrence of FFL. Further studies are required to establish the clinical relevance of lowabundant taxa in faeces and the impact of specific feed components on FFL.