Effects of anti-nutritive factors on ruminants and methods to alleviate them: A review

Abstract

Anti-nutrient substances are compounds originating in most animal feed materials that are toxic to animals and limit the accessibility of nutrients to the animal body. But, some Anti-nutrients substances might exercise useful special effects at lower concentrations in feeding material. Main anti-nutritional factors in eatable forage and fodder contain tannins, saponins, phytic acid, gossypol, lectins, amylase inhibitors, goitrogens and protease inhibitors. The balance between anti-nutritional factors' beneficial plus lethal effects depends on their time of exposure, concentration, biochemical structure, and interaction with other dietary constituents. Numerous anti-nutritional factors and noxious elements are present in various foliage utilized as animal feed. Anti-nutrient substances decrease the maximal use of nutrients, particularly minerals, proteins, and vitamins, therefore inhibiting optimum utilization of the nutrients in the feeds and reducing their nutritive quality. High concentrations of tannins (>5.0 g/100 g DM) can be lethal to animals, especially ruminants feeding on tannin-rich forages. Tannins mostly found in legumes binds with proteins, leading to the activation of numerous digestive enzymes and reduction protein digestibility. It is concluded that numerous anti-nutrient substances that affect protein digestibility and the poisonous effects of these substances in plants can be removed or treated to reduce the negative effects using a variety of processing methods such as boiling, fermentation, soaking, germination, and chemical treatment. From the various studies, processing methods can greatly improve the nutritive value of feeding material as feed for ruminants. This review focuses on various categories of anti-nutritional factors, effects of anti-nutritive factors on ruminants, and likely treating methods that could be employed to lessen these factors in animal feeds. Introduction Anti-nutritional factors are substances that, when present in feed, either directly or through their metabolic products, reduce nutrient accessibility, thereby affecting animal performance (Yacout, 2016) [108]. Anti-nutritional factors are naturally occurring substances found in feeds that may be responsible for decreased nutrient utilization in animals after intake (Jeyakumar et al., 2022) [36]. Plant toxins can be found in the foliage, seeds, bark, and nearly every plant part (D'Mello, 2004) [13]. Chemical constituents in feeds that, by themselves or through metabolic products produced in the system, inhibit feed use, reduce animal performance, or negatively impact animal health (Ramteke et al., 2019) [73]. ANFs are chemical substances produced naturally in plants by the normal metabolism of plant species or by various mechanisms such as metabolic utilization of feed (Akande et al., 2010) [3]. As a result, they are feed additives that inhibit animal growth and performance. The anti-nutritional factors (ANFs) exert an effect contrary to optimal nutrition (Akande et al., 2010) [3]. Anti-nutrients are secondary metabolite substances evolved by plants for their protection (Habtamu & Negussie, 2014) [28] and, therefore, protect the plant from defoliation by insects and animals, especially browsers. There are several classifications of plant toxins. D'Mello, (2004) [13] classified anti-nutrients into heat-labile groups comprising cyanogens, lectins, and proteinase inhibitors and heat-stable groups as condensed tannins, antigenic proteins, saponins, gossypol, and Phyto-oestrogens. According to Aletor (2005) [4] , classification can be based on their chemical structure, specific action when ingested, or biosynthetic origin. The biological effects of these chemicals are complex and diverse (Habtamu & Negussie, 2014) [28]. These factors might not always be harmful, especially when consumed below the lethal dose. However, the balance of harmful