Essential oil and aromatic plants as feed additives in non-ruminant nutrition: a review

This paper summarizes the current knowledge regarding the possible modes of action and nutritional factors involved in the use of essential oils (EOs) for swine and poultry. EOs have recently attracted increased interest as feed additives to be fed to swine and poultry, possibly replacing the use of antibiotic growth promoters which have been prohibited in the European Union since 2006. In general, EOs enhance the production of digestive secretions and nutrient absorption, reduce pathogenic stress in the gut, exert antioxidant properties and reinforce the animal’s immune status, which help to explain the enhanced performance observed in swine and poultry. However, the mechanisms involved in causing this growth promotion are far from being elucidated, since data on the complex gut ecosystem, gut function, in vivo oxidative status and immune system are still lacking. In addition, limited information is available regarding the interaction between EOs and feed ingredients or other feed additives (especially pro- or prebiotics and organic acids). This knowledge may help feed formulators to better utilize EOs when they formulate diets for poultry and swine.     

饲料添加剂调节畜禽肠道菌群及其生长性状的研究进展

肠道菌群影响畜禽生长发育以及相关多个重要经济性状。就多种饲料添加剂调节畜禽肠道菌群及其生长性状的研究进展进行综述。从生物学机制出发,介绍了饲料添加剂对畜禽肠道菌群及其生长性状的影响和菌群移植影响宿主生长性状的研究进展,总结了通过饲料添加剂影响畜禽肠道菌群、改善畜禽生长性能的应用实践。     

Phenolic compounds as natural feed additives in poultry and swine diets: a review

Due to ban on using antibiotics in feed industry, awareness of using natural feed additives have led to a great demand. The interest of plants phenolic compounds as a potential natural antioxidant source has been considered in research community due to their predictable potential role as feed additives in poultry and swine production.However, the mode of action for their functional role and dosage recommendation in animal diets are still remain indistinct. Taking into account, the present review study highlights an outline about the mode of action of phenolic compound and their experimental uses in poultry and swine focusing on the growth performance, antioxidant function, immune function, antimicrobial role and overall health status, justified with the past findings till to date.Finally, the present review study concluded that supplementation of phenolic compounds as natural feed additives may have a role on the antioxidant, immunity, antimicrobial and overall production performance in poultry and swine.     

Strategies to modulate the intestinal microbiota and their effects on nutrient utilization,performance, and health of poultry

Poultry is widely produced and consumed meat global y. Its demand is expected to continue increasing to meet the animal protein requirement for ever-increasing human population. Thus, the chal enge that poultry scientists and industry face are to produce sufficient amount of poultry meat in the most efficient way. In the past, using antibiotics to promote the growth of poultry and manage gut microbiota was a norm. However, due to concerns over potential fatalistic impacts on food animals and indirectly to humans, their use as feed additives are banned or regulated in several jurisdictions. In this changed context, several alternative strategies have been proposed with some success that mimics the functions of antibiotics as growth promoters and modulate gut microbiota for their beneficial roles. These include the use of probiotics, prebiotics, organic acids, and exogenous enzyme, among others. Gut microbiota and their metabolic products improve nutrient digestion, absorption, metabolism, and overal health and growth performance of poultry. This paper reviews the available information on the effect of feed additives used to modulate intestinal microbiota of poultry and their effects on overal health and growth performance. Understanding these functions and interactions wil help to develop new dietary and managerial strategies that wil ultimately lead to enhanced feed utilization and improved growth performance of poultry. This review wil help future researchers and industry to identify alternative feed ingredients having properties like prebiotics, probiotics, organic acids, and exogenous enzymes.     

Nutritional significance of amino acids,vitamins and minerals as nutraceuticals in poultry production and health – a comprehensive review

Nutraceuticals have gained immense importance in poultry science recently considering the nutritional and beneficial health effects of their constituents. Besides providing nutritional requirements to birds, nutraceuticals have beneficial pharmacological effects, for example, they help in establishing normal physiological health status, prevent diseases and thereby improve production performance. Nutraceuticals include amino acids, vitamins, minerals, enzymes, etc. which are important for preventing oxidative stress, regulating the immune response and maintaining normal physiological, biochemical and homeostatic mechanisms. Nutraceuticals help in supplying nutrients in balanced amounts for supporting the optimal growth performance in modern poultry flocks, and as a dietary supplement can reduce the use of antibiotics. The application of antibiotic growth enhancers in poultry leads to the propagation of antibiotic-resistant microbes and drug residues; therefore, they have been restricted in many countries. Thus, there is a demand for natural feed additives that lead to the same growth enhancement without affecting the health. Nutraceuticals substances have an essential role in the development of the animals’ normal physiological functions and in protecting them against infectious diseases. In this review, the uses of amino acids, vitamins and minerals as well as their mode of action in growth promotion and elevation of immune system are discussed.     

植物提取物添加剂在动物营养中的应用及其机制的研究进展

植物提取物添加剂具有提高动物生产性能、无残留和无抗药性的特点,能够为畜禽养殖业高效生产安全、健康、营养的食品提供保证.本文综述了植物提取物添加剂的抗菌和抗氧化作用,并总结了其在猪禽上的应用研究和影响其使用效果的因素.     

Antibodies: Alternatives to Antibiotics in Improving Growth and Feed Efficiency

The consolidation of poultry since the 1950s largely depended upon two primary management tools: vaccination and antibiotics. These two tools allowed for the prevention of both bacterial and viral infections that could greatly impact poultry raised in large numbers. Antibiotics were also found to improve poultry growth and feed efficiency over 10% when fed below therapeutic levels. Hence, by the late 1950s, the use of antibiotics for improving growth and feed efficiency in consolidated poultry flocks was commonplace. Early in the discovery of antibiotics, the development of resistance was always a concern, particularly in humans’ consuming animal products that were fed antibiotics. While science never conclusively supported this concern, advocate groups persuaded users of poultry products to avoid foods derived from animals fed antibiotics. Scientists studied the theories supporting the mechanism(s) by which antibiotics improve growth. Products to improve animal performance in the absence of antibiotics have included: enzymes, competitive microbial species, precolonization of the gastrointestinal tract with favorable microbial species, and dietary additives that inhibit microbial attachment to the intestinal mucosa. A recent addition to dietary substances that improve growth and feed efficiency in poultry and other species are egg antibodies that specifically target processes involved in the immune regulation of growth. Antibodies to neuropeptides and the rate-limiting enzyme, phospholipase A₂, in eicosanoid synthesis are presented, along with the hypothesized mechanism of action. Evidence suggested that egg antibodies offer a new strategy in improving the efficiency of animal performance.     

Tryptophan in poultry nutrition: Impacts and mechanisms of action

Many studies have shown that productivity, immune system, antioxidant status, and meat and egg quality can be optimized by dietary supplementation with amino acids that are not usually added to poultry diets. Understanding the effects of these amino acids may encourage feed manufacturers and poultry producers to include them as additives. One of these amino acids is tryptophan (Trp). The importance of Trp is directly related to its role in protein anabolism and indirectly related to its metabolites such as serotonin and melatonin. Thus, Trp could affect the secretion of hormones, development of immune organs, meat and egg production, and meat and egg quality in poultry raised under controlled or stressed conditions. Therefore, this review discusses the main roles of Trp in poultry production and its mode (s) of action in order to help poultry producers decide whether they need to add Trp to poultry diets. Further areas of research are also identified to address information gaps.     

Novel and disruptive biological strategies for resolving gut health challenges in monogastric food animal production

Use of feed antibiotics as growth promoters for control of pathogens associated with monogastric food animal morbidity and mortality has contributed to the development of antimicrobial resistance, which has now become a threat to public health on a global scale. Presently, a number of alternative feed additives have been developed and are divided into two major categories, including 1) the ones that are supposed to directly and indirectly control pathogenic bacterial proliferation; and 2) the other ones that are intended to up-regulate host gut mucosal trophic growth, whole body growth performance and active immunity. A thorough review of literature reports reveal that efficacy responses of current alternative feed additives in replacing feed antibiotics to improve performances and gut health are generally inconsistent dependent upon experimental conditions. Current alternative feed additives typically have no direct detoxification effects on endotoxin lipopolysaccharides(LPS) and this is likely the major reason that their effects are limited. It is now understood that pathogenic bacteria mediate their negative effects largely through LPS interactions with toll-like receptor 4, causing immune responses and infectious diseases. Therefore, disruptive biological strategies and a novel and new generation of feed additives need to be developed to replace feed antibiotic growth promoters and to directly and effectively detoxify the endotoxin LPS and improve gut health and performance in monogastric food animals.     

Practical starter pig amino acid requirements in relation to immunity,gut health and growth performance

Immune system activation begins a host of physiological responses. Infectious agents are recognized by monocytes and macrophages which in turn stimulate cytokine production. It is the hormone-like factors called cytokines that orchestrate the immune response. The classic responses observed with immune system activation and cytokine production include： anorexia, fever, lethargy, recruitment of other immune cells, and phagocytosis. While production of immune system components is known to require some amino acids, increases in amino acid requirements are more than offset by the associated decrease in protein accretion and increased muscle protein degradation that also accompanies immune system activation. However, the biggest impact of cytokine production is a decrease in feed intake. Therefore, as feed intake decreases, the energy needed to drive protein synthesis is also decreased. This suggests that diets should still be formulated on a similar calorie：lysine ratio as those formulated for non-immune challenged pigs. The evidence is sparse or equivocal for increasing nutrient requirements during an immune challenge. Nutritionists and swine producers should resist the pressure to alter the diet, limit feed, or add expensive feed additives during an immune challenge. While immune stimulation does not necessitate changes in diet formulation, when pigs are challenged with non-pathogenic diarrhea there are potential advantages on gut health with the increased use of crystalline amino acids rather than intact protein sources （i.e., soybean meal）. This is because reducing crude protein decreases the quantity of fermentable protein entering the large intestine, which lowers post weaning diarrhea. It also lowers the requirement for expensive specialty protein sources or other protein sources such as soybean meal that present immunological challenges to the gut. The objective of this review is two-fold. The first is to discuss immunity by nutrition interactions, or lack thereof, and secondly, to review amino acid re     

Practical starter pig amino acid requirements in relation to immunity,gut health and growth performance

Immune system activation begins a host of physiological responses. Infectious agents are recognized by monocytes and macrophages which in turn stimulate cytokine production. It is the hormone-like factors called cytokines that orchestrate the immune response. The classic responses observed with immune system activation and cytokine production include: anorexia, fever, lethargy, recruitment of other immune cells, and phagocytosis. While production of immune system components is known to require some amino acids, increases in amino acid requirements are more than offset by the associated decrease in protein accretion and increased muscle protein degradation that also accompanies immune system activation. However, the biggest impact of cytokine production is a decrease in feed intake. Therefore, as feed intake decreases, the energy needed to drive protein synthesis is also decreased. This suggests that diets should still be formulated on a similar calorie:lysine ratio as those formulated for non-immune challenged pigs. The evidence is sparse or equivocal for increasing nutrient requirements during an immune challenge. Nutritionists and swine producers should resist the pressure to alter the diet, limit feed, or add expensive feed additives during an immune challenge. While immune stimulation does not necessitate changes in diet formulation, when pigs are challenged with non-pathogenic diarrhea there are potential advantages on gut health with the increased use of crystalline amino acids rather than intact protein sources (i.e., soybean meal). This is because reducing crude protein decreases the quantity of fermentable protein entering the large intestine, which lowers post weaning diarrhea. It also lowers the requirement for expensive specialty protein sources or other protein sources such as soybean meal that present immunological challenges to the gut. The objective of this review is two-fold. The first is to discuss immunity by nutrition interactions, or lack thereof, and secondly, to review amino acid requirement estimates for nursery pigs.     

Herbal plants and their derivatives as growth and health promoters in animal nutrition

The purpose of this review is to summarize the effectiveness, modes of action and commercial application of herbal plants and their derivatives as growth promoters for animal. Feed supplements are a group of feed ingredients that can cause a desired animal response in a non-nutrient role such as pH shift, growth, or metabolic modifier (Hutjens, 1991). Common feed additives used in animal diets include immunostimulators, antimicrobials, antioxidants, pH control agents and enzymes. Herbal plants, are a new class of growth promoters and in recent years this feed additives have gained extensive attention in the feed industry. They are a wide variety of herbs, spices, and products derived thereof, and are mainly essential oils. Although numerous reports have demonstrated antioxidative and antimicrobial and immune stimulation efficacy in vitro, respective experimental in vivo evidence is still quite limited. A limited number of experimental comparisons of herbal plants feed additives with antibiotics or organic acid have suggested similar effects on the animal gut microflora. Gut microflora has significant effects on host nutrition, health, and growth performance by interacting with nutrient utilization and the development of gut system of the host. In addition, some phytogenic compounds seem to promote intestinal mucus production. However, the future of using herbs in animal feeding will in great measure depend on the knowledge of chemical structure, their value and characteristics of practical herbs or their extract physiological needs and well-being of animal, and, above all on consumer’s preferences and expectations.     

Dietary plant bioactives for poultry health and productivity

1. Plants and their biologically active chemical constituents, sometimes called secondary metabolites or bioactives, present numerous opportunities for the improvement of livestock production by inclusion in the diet. 2. Many such plant derived materials have well established therapeutic values in man; however, their potential as feed additives in animal production, particularly of poultry, remains largely unexploited. 3. There is increasing evidence indicating that they can be efficient in controlling diseases, and plant bioactives may also influence production parameters such as feed efficiency and product quality. 4. It has been reported that they may even replicate some of the effects of antibiotic growth promoters, which were banned from use in Europe from 2006. 5. This review assesses the status of plant bioactives in poultry production and their mode of action on avian physiology, particularly in the digestive tract.     

欧盟禁用饲料药物添加剂的历史和法规

欧盟考虑到抗生素耐药性的发展和抗生素耐药基因可能从动物到人微生物的转移,决定从2006年1月1日起禁止抗生素作为生长促进剂,甚至还建议禁止在动物饲料中全面使用所有的抗菌剂。收集和整理欧盟饲料药物添加剂的禁用清单和法规,介绍欧盟禁用饲料药物添加剂的历史及其对动物健康的影响,以期为中国饲料药物添加剂的使用和管理提供借鉴和参考。     

药物递送载体及其在饲料添加剂领域中的研究进展

在全面禁止使用促生长类药物饲料添加剂的形势下,畜禽传染性疾病对我国畜牧生产造成潜在威胁,开发绿色饲料添加剂迫在眉睫,但当下抗生素替代产品往往因稳定性差而限制了其使用空间。药物递送系统可以将兽药及饲料添加剂包裹于载体内部,靶向缓释,具有靶向性、稳定性及高效性等多方面的优势,是解决粪便抗生素残留、中的研究进展,以期为畜禽健康养殖提供新的思路和借鉴。     

替代抗生素饲料添加剂研究进展

抗生素作为主要的饲料添加剂在几十年的广泛应用过程中造成了致病菌耐药性增强、动物免疫力降低、影响动物疫苗的效价、通过食物链影响人体健康等亟待解决的问题。我国农业农村部已发布公告,自2020年起我国饲料全面禁止添加使用抗生素类添加剂,饲料行业正式进入“无抗时代”。长期以来,研究人员积极寻求研发各种抗生素替代品及绿色无害的饲料添加剂,以消除或减轻禁用抗生素带来的一系列影响。就目前主要抗生素替代品的抗菌特点及抗菌机理进行综述,旨在为“禁抗”后抗菌性添加剂在饲料中的应用提供参考。     

The use of inulin in poultry feeding: a review

Since the European Union enforced the ban on antibiotic growth promoters in 2006, the research has been focused on natural feed additives which would have a proven positive impact on both production and animal health. Inulin is both the most commonly used and the most effective probiotic additive. The mechanism of inulin interactions with the avian body is complex, multidirectional and not fully understood. Despite a number of unresolved issues, many authors have demonstrated the positive impact of inulin on the host organism. Dietary supplementation of poultry feeding with inulin contributes to the modulation of intestinal microbiota through favouring a quick proliferation of beneficial Bifidobacterium and Lactobacillus strains and inhibiting the growth of pathogenic microbes. There are indications that inulin‐provoked changes in the host gut microbiota in poultry may alter the structure and histomorphology of the intestinal mucosa and improve its absorption capacity in poultry. It has also been demonstrated that inulin may affect the immune system and the systemic metabolism of minerals and lipids. The reports on inulin effects on the body and performance of poultry are often contradictory, as the effectiveness of this prebiotic is strongly dependent on the type and dose used, and the duration of its administration.     

The application of antimicrobial peptides as growth and health promoters for swine

With the widespread ban on the use of antibiotics in swine feed,alternative measures need to be sought to maintain swine health and performance.Antimicrobial peptides(AMPs) are part of the nonspecific defense system and are natural antibiotics produced by plants,insects,mammalians,and micro-organisms as well as by chemical synthesis.Due to their broad microbicidal activity against various fungi,bacteria and enveloped viruses,AMPs are a potential alternative to conventional antibiotics for use in swine production.This review focuses on the structure and mechanism of action of AMPs,as well as their effects on performance,immune function and intestinal health in pigs.The aim is to provide support for the application of AMPs as feed additives replacing antibiotics in swine nutrition.     

Phytate and phytase in fish nutrition

Phytate formed during maturation of plant seeds and grains is a common constituent of plant-derived fish feed. Phytate-bound phosphorus (P) is not available to gastric or agastric fish. A major concern about the presence of phytate in the aquafeed is its negative effect on growth performance, nutrient and energy utilization, and mineral uptake. Bound phytate-P, can be effectively converted to available-P by phytase. During the last decade, phytase has been used by aqua feed industries to enhance the growth performance, nutrient utilization and bioavailability of macro and micro minerals in fish and also to reduce the P pollution into the aquatic environment. Phytase activity is highly dependent on the pH of the fish gut. Unlike mammals, fish are either gastric or agastric, and hence, the action of dietary phytase varies from species to species. In comparison to poultry and swine production, the use of phytase in fish feed is still in an unproven stage. This review discusses effects of phytate on fish, dephytinisation processes, phytase and pathway for phytate degradation, phytase production systems, mode of phytase application, bioefficacy of phytase, effects of phytase on growth performance, nutrient utilization and aquatic environment pollution, and optimum dosage of phytase in fish diets.