HESTEFORSK 'Hösilageintolerans' hos häst? H-15-47-063

During the last decade, a condition of horses, in public named 'haylage-intolerance' has gained attention in Sweden and Norway as well as some other countries. The condition manifests as two phase faeces with one solid phase (faecal balls) and one liquid phase. The latter may be voided together with the solid phase or separately, and sometimes together with excessive gas. Affected horses may discomfort when voiding faeces by tail swishing and/or nervous trampling with their hindlegs, but do not show other signs of illness. The constant presence of faecal liquid may however result in skin lesions around anus and the inside of the hindlegs. Also, the condition causes additional work with cleaning. The cause of ?haylage intolerance? is not known, although both feed components and individual horse factors (coat colour, rank, temperament) has been suspected. However, no systematic mapping of feeding, management, horse characteristics, associated health problems or faecal composition of affected vs un-affected horses has previously been performed. The aim of the project was therefor to a) map the presence of ?haylage intolerance? in Sweden and Norway through an internet survey, to b) compare feeding and management, including hygienic and nutritive composition of wrapped forages offered to case and control horses in a field study, and to c) map and compare faecal microbial, biochemical and physical composition in affected vs un-affected horses in a field case/control study. The survey study revealed that the general appearance of FFL among Swedish and Norwegian horses is approximately 10%. It may appear in horses from a large variety of breeds, ages, geographic area, stable systems, training disciplines, as well as horses with all kind of coat colours, body condition scores and tempers. Moreover, the described condition not only appears in horses offered haylage, but also in horses offered hay. For some horses offered haylage, the faecal appearance may be normalized by changing from wrapped forage to hay, but not for all. This means, ?Haylage Intolerance? is an incorrect term, and the condition is now designated 'Free faecal liquid' (FFL). Data from the survey also showed that 23% of the horses had had a previous history of colic, which was comparably high as general colic incidence has been reported to less than 10%. This implies a possible connection between colic and FFV, which is new knowledge. The case-control study revealed that case horses on average were fed lower proportions of roughage and higher proportions of concentrates in their total feed rations compared to the control horses. Both nutritive value and hygienic quality of the forage varied among stables. However, as the paired case and control horses were offered the same forages, possible correlations between forage quality and FFV could not be examined in this study. The biochemical composition of the faeces of case horses appeared to differ from that of the control-horses as well as from what was expected according to a higher proportion of concentrates in the diet offered to the case horses compared to the control horses. Part of the explanation for this result may be present in the microbial composition of faeces. Such analyses are still not completed. Cases horses also had higher volumes of free liquid and higher volume of sand in the faeces compared to control horses. As case and control horses were managed equally and offered the same forage, this difference may be due to individual differences in soil ingestion. Faecal sand concentration may be of further interest for finding causes of FFV as presence of sand in the large intestine has been associated with chronical diarrhoea and sand cholic. In conclusion, the project has reveal that presence of FFL cannot be generally attributed to feeding wrapped forages such as haylage to horses. However, horses with FFL differed from controls in some hindgut variables, indicating that FFV may be related to some inndividual factors such as eating behaviour or gastrointestinal responses to feeds or feed components, not identified in this study.

Prosjektet har bidratt til økt kunnskap om utbredelsen av og årsaken til fri fekal væske (FFV) hos hester. Det er dokumentert at FFV forekommer hos alle typer hester, og at lyse hester og hester med lav rang ikke er mer disponert for FFV enn andre, slik det har vært spekulasjoner om. Videre er det avdekka at også hester som får vanlig høy, kan ha FFV. Følgelig er høyensilasje på generelt grunnlag ikke årsak til FFV. Det er grunn til å anta at individuelle forskjeller i evnen til å omsette og fordøye fôr er medvirkende årsak til FFV. Følgelig kan det oppnås bedring hos noen hester ved å bytte fra ett fôr til et anna, men ikke hos alle. Videre studier av hvordan hestens tjukktarmsfordøyelse påvirkes av ulike fôrkomponenter er avgjørende for å finne svar på fortsatt ubesvarte spørsmål og for o mulig forebygge fordøyelsesforstyrrelser som FFV og kolikk. Bruk av metoder som på ulike måter beskrive den mikrobielle aktiviteten i tjukktarmen, vil i slike studier være av avgjørende betydning.

I dette prosjektet vil ein finne ut meir om det som tilsynelatande er 'intoleranse' mot høyensilasje hos somme hestar. Intoleransen gir seg uttrykk med diareliknande avføring med to separate fraksjonar - ein fast og ein blaut. Årsaka til denne tilstanden som ikkje er beskrive for hestar som spiser andre fôrmiddel, er ukjent. Det er heller ikkje kjent om hestar som har denne tilstanden er meir utsette for andre og alvorlege tarmforstyrringar enn hestar som ikkje reagerer negativt på høyensilasje. Gjennom en "case-control" studie (30 par) skal ein registrere utfôring, fôrkvalitet og avføringskonsistens hos affekterte og ikkje-affekterte hestar som står i same stall og som blir fôra og stelt likt. Avfôringa skal analyserast for mikrobiell samansetjing ved hjelp av molekylærgenetiske metodar, samt for biokjemisk/kjemisk samansetjing. Träckens mikrobsammansättning undersöks med molekylärgenetiska metoder samt analyseras med avseende på biokemisk/kemisk sammansättning. Fodrets sammansättning analyseras, och utfodring och hälsa kartläggs. På så sätt kan ev avvikelser hos de affekterade hästarna identifieras, vilket ger möjlighet att hitta lösningar på problemet.