Ermers Colette, McGilchrist Nerida, Fenner Kate, Wilson Bethany, McGreevy Paul
School of Environment and Rural Science, University of New England, Armidale, NSW 2351, Australia.
Equilize Horse Nutrition Pty Ltd., Tamworth, NSW 2340, Australia.
Animals (Basel). 2023 Apr 20;13(8):1414. doi: 10.3390/ani13081414.
Failure to meet the minimum forage requirement of 1.5% of the horse's bodyweight and the opportunity for foraging for a minimum of 8 h a day (not going without this opportunity longer than four to five consecutive hours) can have both physiological and behavioural consequences. To provide an energy source for horses, rations often include starch rather than fibre. This can result in health issues related to the gastrointestinal tract (GIT) in the horse. In the stomach, the main concern is equine gastric ulcer syndrome (EGUS) and, more specifically, equine squamous gastric disease (ESGD). Ulcerations are caused either by increasing acidity in the stomach (from starch ingestion and reduced saliva production) or splashing of acidic juices caused by a lack of a forage barrier prior to exercise or prolonged periods without fibrous feed intake, which allows the stomach to collapse and spread acidic gastric fluids into the upper squamous regions of the stomach. In the hindgut, starch that has escaped digestion in the small intestine causes microbial instability and increased production of volatile fatty acids (VFA) and lactic acid. This puts horses at great risk for acidosis and subsequent laminitis. Shifts in the hindgut microbiota will also affect a horse's behaviour via the gut-brain axis, as well as potentially compromise immune function. Reduced fluid intake caused by reduced saliva production can result in colic. Choosing a fibrous alternative for starch in a high-energy diet greatly reduces the risk of EGUS and acidosis and improves digestion, GIT pH, body condition, behaviour, immune functions, and performance. Providing hay can reduce crib-biting, wood-chewing, coprophagia, the consumption of bedding, aggression, and stress, and subsequently increase social bonding and affiliation with conspecifics. Adequate fibre intake is related to reduced clinical signs of EGUS, reduced reactivity, and better adaptation to weaning. Lignophagia (wood chewing) has also been observed in horses that are foraging, and this is thought to reflect low fibre content in the available forage (for example, early vegetative, lush pasture).
未能满足马匹体重1.5%的最低草料需求，以及每天至少8小时的采食机会（连续不超过四到五个小时没有这个机会），可能会产生生理和行为上的后果。为马匹提供能量来源时，日粮通常包含淀粉而非纤维。这可能导致马匹出现与胃肠道（GIT）相关的健康问题。在胃中，主要问题是马胃溃疡综合征（EGUS），更具体地说是马鳞状胃病（ESGD）。溃疡的产生要么是由于胃内酸度增加（因摄入淀粉和唾液分泌减少），要么是由于运动前缺乏草料屏障或长时间不摄入纤维饲料导致酸性汁液飞溅，使胃塌陷并将酸性胃液扩散到胃的上部鳞状区域。在肠道后部，未在小肠消化的淀粉会导致微生物不稳定，并增加挥发性脂肪酸（VFA）和乳酸的产生。这使马匹面临酸中毒和随后蹄叶炎的巨大风险。肠道后部微生物群的变化也会通过肠脑轴影响马匹的行为，并可能损害免疫功能。唾液分泌减少导致的液体摄入量减少会引发绞痛。在高能量日粮中选择纤维替代淀粉可大大降低EGUS和酸中毒的风险，并改善消化、胃肠道pH值、身体状况、行为、免疫功能和表现。提供干草可以减少咬栏、嚼木、食粪、啃食垫料、攻击行为和应激反应，随后增加与同种动物的社交联系和归属感。充足的纤维摄入量与EGUS临床症状的减轻、反应性降低以及更好地适应断奶有关。在采食的马匹中也观察到了啃木现象，这被认为反映了可用草料中纤维含量较低（例如，早期营养丰富、茂盛的牧场）。
