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Phytogenic feed additives as potential gut contractility modifiers—A review

Mendel, Marta, Chłopecka, Magdalena, Dziekan, Natalia, Karlik, Wojciech
Animal feed science and technology 2017 v.230 pp. 30-46
acetylcholine, antibiotics, diarrhea, displaced abomasum, essential oils, feed additives, feeds, fermentation, gastrointestinal motility, indigestion, intestinal microorganisms, laboratory animals, livestock, methane production, muscles, neutralization, parasympatholytics, plant extracts, rumen, rumen microorganisms, ruminants, saponins, secondary metabolites, smooth muscle, tannins
The increasing requirement for implementing new feed additives in livestock, especially ruminants, results predominantly from two issues: the urgent need of reduction of greenhouse gas emissions and the necessity of finding replacements of antibiotics which must not be preventively used in animals feeding. A group of additives that has gained a progressive interest in recent years consists of plant secondary metabolites and plant-derived extracts. There is extensive knowledge of the effects of phytogenic feed additives on rumen microbial fermentation, rumen methanogenesis and ruminant performance. However, there is little information about their systemic effects. In case of ruminants, the possible impact of employed additives on gut motility should be carefully analyzed due to the special anatomical and physiological features. Therefore, the aim of this review is to present available data on the effects of plant extracts and individual secondary plant metabolites which can be potentially used as feed additives on gastrointestinal motility. The review describes the impact of essential oils, tannins and saponins on gut smooth muscle activity in laboratory animals and livestock, particularly ruminants, under in vivo and in vitro conditions The analysis of gathered data allows to generalize that most essential oils, tannins and saponins which are under consideration as phytogenic feed additives generate myorelaxant effects towards gastrointestinal tissues. Significant antispasmodic effects of plant secondary metabolites can reduce the gastrointestinal smooth muscle basal tone and cause an impaired response of rumen and abomasal muscles to acetylcholine which reflect hypotony and subsequently predispose the animals to some gut disturbances, like abomasal displacement or rotation, and or indigestion. On the other hand, the revealed ability of various plant extracts to reduce acetylcholine-induced contraction could be used to contract gastrointestinal muscle spasm and consequently become beneficial in animals with diarrhea symptoms. Noteworthy, essential oils of numerous plants turned out to act spasmogenic if used in low doses and spasmolytic whenever tested in higher concentrations. This dual character of essential oils should be further analyzed and possible used to treat or prevent hypo- and hypermotility disorders.Bearing in mind, the process of gut microorganisms’ adaptation and their ability to decompose or neutralize various substances, including plant secondary metabolites, the effects of plant-derives substances on gastrointestinal motoric activity are especially expected in a short time after the introduction of a new phytocompound or plant extract to animal feed.