Hunan Fengsheng Biotechnology Co., Ltd.

Introduction of feed additives and their application in the production of laying hens

Issuing time:2024-01-05 10:20

The rise of healthy breeding and brand eggs leads the development of laying chicken industry. Among many additive products, plant-based feed additives well meet the development needs of laying chicken industry. This paper introduces the components and effects of plant-based feed additives to enhance people's cognition of plant-based feed additives, and combines corresponding production data. In order to promote the better application of plant-based feed additives in the production of laying hens.

Key words: plant essential oil, spicy substance, bitter substance, saponin, laying chicken

Antibiotic-free farming is the focus of current livestock production, which is particularly important for laying hens because there are very few antibiotics allowed during the laying period and the market share of branded eggs is increasing. At present, a variety of additives play an important role in the healthy breeding of laying hens, among which plant additives are more concerned. Austria Diglukang Company was founded in 1988, Diglukang Company is committed to the research of plant feed additives, deeply engaged in the research and application of plant feed additives, and has accumulated rich experience in this field. In this paper, Biaozhuang, a poultry product of Diglukang Company, was introduced to provide reference for the application of plant-based feed additives in the production of laying hens.

1. Introduction of common components in plant feed additives

1.1 Plant essential oils - star anise and thyme

Plant essential oil refers to a kind of aromatic oily liquid extracted from plant tissues and organs (Ganli Equality, 2015), and its active components can be divided into phenols, aldehydes and ketones, terpenes, esters, etc., according to their chemical structure. This paper mainly introduces two kinds of plant essential oils, star anise and thyme, which have good application effect in poultry

1.1.1 Star anise essential oil

Star anise is the fruit of the genus of star anise in the star anise family. It is an important economic crop with the same origin of medicine and food in China. Star anise oil has a representative odor color of light yellow or colorless, and its content is generally 5%-12%. The composition of star anise oil is relatively complex, among which the most important active ingredient is trans-anisole, which also contains aldehydes, ketones and eths such as anisaldehyde and artemiseed brain, and terpenes such as α-pinene and β-pinene (Song Zhenshuai, 2014).

1.1.2 Thyme essential oil

Thyme for the lip family thyme genus perennial herbs, also known as thyme, ground pepper and so on. The main active ingredient in thyme essential oil is thymol, which also includes phenols such as Nepetalol and carvacrol, as well as hydrocarbons and terpenes such as para-cymene, γ-terpene, α-pinene (Zhang Youlin et al., 2011).

1.2 Plant saponins

Saponins are secondary metabolites found in some plants, which contain both hydrophilic groups and lipophilic groups. When shaken in aqueous solution, saponins can produce a large number of foams and are natural surfactants. According to their ligand structure, saponins can be divided into two categories, steroid saponins and triterpene saponins (Chen Xuwei et al., 2008).

1.3 Bitter Substances

Bitter substances exist in nature is very rich, it is a self-protection mechanism formed in the long-term evolution of plants, bitter substances have many physiological functions. Common bitter substances are gentian, hops and dandelion. Gentian is a perennial herb mainly distributed in Northeast China. The main active component of Gentian is gentiopicin, which also includes triterpenoids, lignans, flavonoids, alkaloids, benzoates and other chemical components (Chu Bowen et al., 2016). Hop is a perennial climbing plant belonging to the genus Humulones. The main active components of hop are resin components and derivatives of Humulones and humulones, as well as polyphenols such as xanthohumol and isoxanthohumol, and terpenes and terpene oxides (Liu Yumei, 2009). Dandelion is a perennial herb belonging to the asteraceae family. Its active components mainly include flavonoids, terpenes, phenolic acids, phytosterols, etc. (Xie Shenyang et al., 2012).

1.4 Spicy substance

Spicy substance is a general term for substances with spicy and pungent smell, common spicy substances are chili, pepper, ginger and so on. Capsicum belongs to the genus Solanaceae. Capsicum is an annual or perennial herb that can produce capsicum berries. Its main active ingredients include capsaicin, dihydrocapsaicin and other capsaicinoid substances. Lutein and other capsaicin pigment substances, as well as vitamins, phenols and other active ingredients (Liu Yiwei et al., 2014). Pepper is a perennial evergreen vine in the family Piperaceae. Pepper fruit mainly contains volatile oil components such as aldehydes and ketones, terpenes, and alkaloids such as piperine, as well as active and nutritional components such as oleoresin, protein, and minerals (Li Xingping et al., 2013). Ginger is the rhizome of perennial herb ginger, which mainly includes volatile oil components such as terpenes and terpene oxides, gingerol components such as gingerol and gingerol phenols, and active and nutritional components such as diphenylhepane, protein and curcumin (Song Zhenshuai, 2014).

2, the efficacy of plant-based feed additives

2.1 Improve nutrient digestion and absorption

Because of its aromatic odor, plant feed additives can promote animal feeding, improve animal feed intake, in addition, it can also improve the digestion and absorption of nutrients. Platel et al. (2000) pointed out that spicy substances such as pepper and ginger can promote the secretion of pancreatic enzymes such as lipase and amylase in rats, and spicy substances can also promote the secretion of cholic acid. This is related to the secretion of cholecystokinin promoted by spicy substances.

2.2 Antioxidant

Under normal circumstances, the animal body is in a state of oxidation and antioxidant dynamic balance, but the current animal growth environment, their own physiological state and other influencing factors, so that this dynamic balance is easy to break, once this balance is broken, it will cause oxidative damage to the animal, further cause oxidative stress. Oxidative stress not only causes metabolic diseases in animals, but also causes lipid damage at the cellular level, ultimately leading to the decline of animal production performance (Ganley Equality, 2015). Among the common components of plant feed additives, plant essential oil has a good antioxidant effect, and its antioxidant effect is mainly through two ways: direct effect and indirect effect. Essential oils rich in phenolic structures in plant essential oils, such as thyme essential oils, have REDOX properties in their phenolic structures and can be used as reducing agents and hydrogen donors to directly absorb oxygen free radicals, thereby reducing the damage of oxygen free radicals to animal bodies (Kahkonen.MP et al., 1999). Essential oils with low content of phenolic structures, such as star anise essential oil, can indirectly exert antioxidant effects by increasing the gene expression of antioxidant enzymes such as superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) (Muller, 2012). The possible pathway is that plant essential oil can release NrF2 from its co-factor with KeaP1, and the released NrF2 can enter the nucleus and bind to the antioxidant reaction element (ARE), which will promote the gene expression of SOD and other antioxidant enzymes, thus improving the antioxidant level of animals (Rubiol. JA et al., 2008). The spicy substances and saponins in plant feed additives also have good antioxidant effects.

2.3 Reduce the production of ammonia

The production of ammonia in animals mainly includes the following ways: the first is the amino acid produced in the process of protein metabolism in animals through various deamination and the ammonia produced by the kidney hydrolysis of glutamine; The second is ammonia produced by excrement uric acid and urea which are metabolized by protein in animal body and decomposed by urease secreted by bacteria in intestinal tract; The third is the ammonia produced by urease decomposition of uric acid and urea in the feces of animal enclosures. This part of ammonia is an important exogenous ammonia and one of the main factors causing environmental pollution in livestock farms (the reaction of urease decomposition of urea to produce ammonia is shown in the figure below).


Plant feed additives reduce ammonia emissions mainly through two aspects: the spicy substance and bitter substance components can promote the secretion of digestive enzymes, improve the efficiency of animal protein utilization, and then reduce nitrogen emissions, but the most important is that its saponin components can effectively reduce the production of ammonia in livestock and poultry houses, mainly through the following aspects: Inhibit the activity of proteinolytic bacteria, bind directly to ammonia, and inhibit urease activity.

2.4 Control pathogenic bacteria

A large number of in vitro tests have proved that the essential oil components of plant feed additives can effectively inhibit bacteria, fungi, viruses and other microorganisms, which can inhibit gram-negative bacteria and Gram-positive bacteria. At present, a lot of researches and exploration have been conducted on the specific mechanism of antibacterial activity of essential oil. The components of essential oil have obvious lipophilicity. After contact with the cell membrane of pathogenic bacteria, the structure of its phospholipid bilayer will be disrupted, the membrane protein will be destroyed, and its permeability will be increased, resulting in the flow of cell contents and the loss of proton motive force. Eventually, pathogenic bacteria die due to their inability to synthesize ATP (Dunn, 2016). Table 1 describes the MIC values of different plant essential oils and their monomer components against different pathogenic bacteria. The MIC value is the minimum antibacterial concentration, which is a quantitative index to measure the antibacterial effect.

Table 1 MIC values of different plant essential oils (μL/mL)


Note: Data from C. Franz(2010)

It can be seen from Table 1 that in order to play a direct antibacterial effect, the amount of plant essential oil added in the full-priced compound feed will be very high, and such a high amount of addition is almost impossible to achieve in actual production. However, some studies have pointed out that when the amount of plant essential oil added is less than the amount of MIC, it still has antibacterial effect, and this antibacterial effect is mainly achieved through quorum sensing inhibition effect. Burt et al. (2014) and Hawrelak et al. (2012) pointed out that pathogenic bacteria communicate through corresponding signaling molecules. Plant essential oil can block this information exchange between pathogenic bacteria, thus preventing pathogenic bacteria from becoming pathogenic. Khan et al. (2009) pointed out that plant essential oil with a lower MIC value can effectively inhibit the production of cyanoviolet pigment by Bacillus cyanoviolet; Muller et al. (2012) also pointed out that rosemary essential oil can reduce the heat-resistant enterotoxin produced by E. coli. Oregano oil and turmeric oil had no effect. At present, there are relatively few reports on the quorum sensing of plant essential oils on pathogenic bacteria, so the blocking of signal molecular communication between plant essential oils needs further research. In addition, compared with synthetic natural equivalents, the active ingredients of pure natural extracted plant essential oils are relatively complex and have synergistic effects to exert antibacterial effects together. Therefore, complex essential oils have better antibacterial effects than single essential oils, and long-term use of single essential oils may lead to drug resistance (Gutierrez et al., 2008; Liu Meng, 2011).

2.5 Other Effects

In addition to the above functions, these four common components of plant feed additives also have anti-inflammatory, anti-stress, improve intestinal integrity, promote bone growth, protect the liver, analgesia and other effects.

3, the effect of plant feed additives on the production performance of laying hens

Through the above description of the components and effects of plant-based feed additives, the understanding and cognition of plant-based feed additives are enhanced. Combining the practical application data of plant-based feed additives in the production of laying hens, the theory and practice are combined to better demonstrate the application effect of plant-based feed additives in the production of laying hens.

3.1 Plant-based feed additives improve the production performance of laying hens

According to the data of 100,000 laying hens from 11 trials summarized in Figure 1, plant-based feed additives can significantly improve the production performance of laying hens, including 0.3% increase in feed intake, 1% increase in laying rate, 2% increase in egg weight, and 2.1% decrease in feed to egg ratio. The improvement of plant feed additives on the production performance of laying hens is closely related to its physiological function. The aromatic essential oil components and spicy substances can promote the feed intake of laying hens and increase the intake of nutrients. The essential oil, bitter substances and spicy substances and other components can also promote the secretion of digestive fluid and cholic acid and the secretion of digestive enzymes such as pancreatic enzyme and brush marginal enzyme of laying hens. It can improve the digestion and absorption of nutrients such as fat, protein and amino acids of laying hens (FIG. 2). Plant-based feed additives can also improve the intestinal health of laying hens from two aspects: the first is to reduce intestinal oxidative damage through antioxidant action; the second is to inhibit pathogenic bacteria through quorum sensing inhibition effect, thus improving intestinal health. It further promotes the digestion and absorption of nutrients. It can be concluded that the improvement of plant feed additives on the production performance of laying hens is mainly attributed to two aspects: improving palatability and promoting the secretion of digestive fluid and digestive enzymes, increasing the intake, digestion, absorption and utilization of nutrients; The intestinal health of laying hens was improved by antioxidant, anti-inflammatory and quorum sensing inhibition.

At the later stage of laying, the digestion and absorption of nutrients of laying hens will decrease with the increase of weekly age, and the intestinal health level will also decline. The improvement degree of plant feed additives at this stage may be higher than that at the early stage of laying and the peak of laying. As shown in Figure 3, the adding stage of plant-based feed additives ranged from 58 weeks of age to 67 weeks of age. As can be seen from the egg production curve, the experimental group could effectively delay the decline of laying rate during the experiment, and the plant-based feed additive group could still effectively slow down the decline of laying rate after the experiment.


FIG. 1 Effect of plant-based feed additives on production performance of laying hens


FIG. 2 Effects of plant-based feed additives on nutrient digestion and absorption of laying hens


FIG. 3 Effect of plant-based feed additives on laying rate of laying hens in late laying period

3.2 Plant-based feed additives improve egg quality

Eggshell quality is an important index of egg quality, good eggshell quality is conducive to reducing egg damage, eggshell thickness and eggshell strength is the main index of eggshell quality. According to the data in the table, adding plant-based feed additives to the laying hens' diets during the laying period can significantly improve eggshell strength, which may be related to the promotion of blood alkaline phosphatase secretion by plant-based feed additives, which is achieved through neuroendocrine regulation (Song Zhenshuai, 2014).

Table 2 Effects of plant-based feed additives on egg quality of laying hens


Note: 1 Biaozhuang (BSG) 510 is a plant-based feed additive product designed by Austrian Dilukang Company for the physiological characteristics of poultry

3.3 Plant-based feed additives can improve the coop environment

The odor in livestock and poultry houses is produced by the anaerobic decomposition of feces, anal excretion and animal respiration. There are many components. Among the known adverse gas components, ammonia is considered to be the gas that has the greatest impact on the environment and animal health. Make respiratory mucosa edema, congestion induced trachea, bronchial inflammation, pulmonary edema and other diseases. Plant feed additives can effectively reduce the concentration of ammonia in livestock and poultry houses, the main way of action is that the saponin components of plant feed additives can effectively inhibit the activity of urease, thus reducing the production of ammonia in livestock and poultry houses. In addition, the improvement of the digestion and absorption of nutrients by spicy substances and bitter substances can also reduce the production of ammonia to a certain extent.


FIG. 4 Effect of plant-based feed additives on ammonia concentration in chicken houses

4. Outlook

The above introduction of the composition and mode of action of plant-based feed additives provides a theoretical reference for us to better understand plant-based feed additives, and gradually opens the "black box" of plant-based feed additives. Combined with the corresponding data in the production of laying hens, we believe that post-antibiotics

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