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and speed of movement ) and ‘ sensitivity ’ ( extent to which behaviour is affected by environmental disturbances ) and more willingness to perform . Young horses were less distressed immediately after weaning , were less flighty and more attentive than weanlings on starch-sugar feeds .
Gut pain from grain and starchy feeds has been linked to behavioural problems . Gut pain occurs less frequently in horses on fibre , oil-enriched feeds and this is likely related to stomach and gut acid levels . The chewing process stimulates the flow of saliva , which in turn lowers stomach acid levels and the horse feels more comfortable – a bit like humans chewing an antacid tablet . One kilogram of hay requires over 3000 chewing movements and results in the production of over 4 litres of saliva . One kilogram of grain requires only 1 / 3 as much chewing and yields only 2 litres of saliva .
GUT HEALTH : the gut-brain axis and the biome : The two-way communication system linking the gut and brain is called the gut-brain axis . There is a clear link between diet , the types of bugs in the gut flora ( biome ) and behaviour . The gastrointestinal tract releases over 20 different hormones and neurotransmitters . Disruption of these has a wider influence on behaviour . Diet plays a key role in affecting the composition of gut microbiota . The horse ’ s gut has over 1,000,000,000 different types of bacteria and over 10,000,000,000 bacteria per gram of contents . Changes in the gut biome on high starch / sugar feeds is associated with increased alertness , reactivity and more unpredictable behaviour . Conversely when the same horses were fed high fibre diets they were more settled and their biome was healthier . Resting heart rates are significantly higher when horses are fed a high-starch diet compared to a high-fibre diet .
BEDDING : The type of bedding material can exacerbate aggressiveness . Horses on straw have reduced aggressiveness because it facilitates time spent lying down , exploration and fibre intake from nibbling straw – all of which affect the gut-brain axis .
MARES AND FILLIES : Blood magnesium levels fall when estrogen rises , as occurs when mares are in season and this may in part explain why they are more prone to tying up , nervousness and muscular soreness at this time . Other symptoms include high sensitivity to touch and sound , abnormally high muscle tone and muscular twitching . Demand for B vitamins from stress and training can also exceed the intestinal production , especially if the diet is high in raw grains as the associated increase in gut acid , wipes out the beneficial bacteria that help horses synthesize their own B-vitamins . Another sign of this is a proneness to lose manure / diarrhea with excitement ,
2021 AQHA YEARBOOK ~ MAY / JUNE ISSUE