Effects of Chinese Herbal Medicine Additives on Growth, Immunity and Antioxidation of Chickens

Cui YANG, Sicong LUO, Siqian WU, Limei QIN, Liang WU, Yang LIU, Jiahuang YANG, Qiang WU*

1. Guangxi Agricultural Vocational University, Nanning 530072, China; 2. The Animal Husbandry Research Institute of Guangxi Zhuang Autonomous Region, Nanning 530001, China; 3. Guangxi Analysis and Testing Research Center, Nanning 530000, China

Abstract Chinese herbal medicine additives can not only directly improve the growth performance of chickens, but also indirectly affect the growth of chickens by enhancing the antioxidant capacity, immunity and disease resistance of the body, and eliminating diseases and adverse factors, thereby improving the growth performance of chickens. In the context of the current national prohibition of adding antibiotics to feed, the research and application of Chinese herbal medicine additives are of practical significance to eliminate the long-term use of antibiotics as chicken feed additives and reduce the threat to the environment and human health. For this reason, the research related to the substitution of Chinese herbal medicine for antibiotics is made a brief introduction to provide a reference in research and production practice.

Key words Chinese herbal medicine additives, Chicken, Growth properties, Antioxidant capacity, Immunological functioning, Disease resistance

1 Introduction

Although feed antibiotics have the effect of disease prevention and control and growth promotion for chickens, their long-term and large-scale use will produce drug resistance, double infection, drug residues and environmental pollution, causing serious harm to human health[1-3]. Chinese herbal medicine is an important part of traditional Chinese medicine. The research shows that the proper application of Chinese herbal medicine additives in the ration can not only improve the immunity and disease resistance of chickens, but also have a good growth promoting effect[4-7], and have the advantages of no drug resistance, no harmful residues, no pollution, and no drug-induced diseases[8]. Therefore, the application of Chinese herbal medicine as a chicken feed additive to replace antibiotics has been widely carried out in China in recent years, and some progress has been made.

2 Effects on improving growth performance of chickens

Many Chinese herbal medicines can improve the feed intake and conversion efficiency of chickens, so they can significantly improve the growth performance of chickens. Huang Junetal.[9]used Perillae Folium, Foeniculi Fructus, Cinnamomi Cortex, Achyranthis Bidentatae Radix, Astmgali Radix, Garlic, and Angelicae Sinensis Radix together to form a Chinese herbal medicine additive, and 1.5% of Chinese herbal medicine additive was added in basal diet to feed 1-42 d of AA chicken. Chicken’s feed intake was increased by 6.02% (P<0.01), and feed conversion efficiency was improved by 5.88% (P<0.05), while average daily gain was improved by 12.64% (P<0.05). Zhu Yingmin[10]used the additive composed of Chinese herbal extracts (Astmgali Radix, Cinnamomi Cortex, Codonopsis Radix, Epimedii Folium, Citrus reticulata Blanco, Rhizoma Aractylodis Lanceae, Crataegi Fructus, Medicated Leaven, Asparagi Radix, and Radix Rhizoma Glycyrrhizae) to add in daily ration in the proportion of 0.3% to feed 1-42 d of commercial Avian broilers. The results showed that the feed intake and conversion efficiency were improved by 5.93% and 4.35% when compared with the control group (P<0.05), and average daily gain was also improved by 10.74% (P<0.05). Yang Cuietal.[11]added "Lianhuang" Chinese herbal medicine additive composed of Forsythiae Fructus, Angelicae Sinensis Radix, Astmgali Radix, Crataegi Fructus, Citrus reticulata Blanco, and Radix Rhizoma Glycyrrhizae in ration of Donglan black chicken, and it was added in daily ration to feed Donglan black chicken to 70 d in the proportions of 0.25%, 0.50% and 1.00%. The results showed that except 50-70 d, ADG (average daily gain) in other stages and average body weight in 70 d in 0.25% of additive group were significantly higher than control group (P<0.05). In 22-35 and 1-70 d, the feed conversion efficiency was significantly better than that of the control group (P<0.05). In 36-49 and 1-49 d, it was significantly superior to the control group (P<0.01). Similar groups and results were also reported in the research of Xi Jianzhongetal[12]. It can be seen that this kind of compound Chinese herbal medicine can improve the feed intake and conversion efficiency of chickens, and promote the growth of chickens.

In addition, chickens’ growth can be promoted only by increasing food intake. Wang Jialietal.[13]used compound Chinese herbal medicine additive prepared by Radix Acanthopanacis Senticosl, Hordei Fructus Germinatus, Crataegi Fructus, Rhizoma Woodwardiae Seu Osmundae Seu Cyrtomii, Atractlodis Rhizoma, and Fructus Schisandrae Chinensis in a certain proportion, and feed 1-42 d of AA chicken by 1% of additive amount. The results showed that feed intake was improved by 7.34% during 22-42 d of test period (P<0.05). In whole test period of 1-42 d, feed intake was also improved by 6.33% (P>0.05). However, feed conversion ratio only declined by 1.72%, that is, the improvement of feed conversion efficiency was extremely low, while average daily gain of chicken was improved by 8.14% (P<0.05). Similar research results were also reported by Lei Xiaojunetal[14].

More research shows that the improvement of chicken growth performance is achieved through the improvement of feed conversion efficiency by Chinese herbal medicine additives. Adding compound preparation composed of more than 20 kinds of Chinese herbal medicine in ration of Guixiang chicken in different doses, Gao Yanminetal.[15]found that when 1.0% of Chinese herbal medicine preparation was added to the diet, although the feed intake was not increased, the feed conversion efficiency was increased by 26.6% (P<0.01), while average daily gain was improved by 35.9% (P<0.01). When using additive composed of 11 kinds of Chinese herbal medicine to feed 1-42 d of hybrid broilers, Miao Xuetal.[16]found the feed conversion efficiency of experimental chickens fed with 0.4% or 0.5% of Chinese herbal medicine in the basic diet increased by 11.36% (P<0.05) and 9.55% (P<0.05), while average daily gain was also improved by 10.66% (P<0.05) and 12.63% (P<0.05). Li Ningchuanetal.[17-18]used Chinese herbal medicine additives similar to functional prescriptions to feed test chicken, and similar effects were obtained. The application effect of such Chinese herbal medicine additives in practice should be better, because the effect of improving growth performance can be achieved without increasing feed intake and feed cost.

According to the pharmacology of traditional Chinese medicine, the above Chinese herbal medicines have the effect of promoting growth, such as Crataegi Fructus, Hordei Fructus Germinatus, Medicated Leaven, Codonopsis Radix, Radix Rhizoma Glycyrrhizae, Garlic, Cinnamomi Cortex, Atractlodis Rhizoma, Foeniculi Fructus, and Fructus Schisandrae Chinensis. With the pharmacological functions of strengthening stomach and digestion, strengthening spleen and qi, promoting fluid production and blood circulation,etc., they can enhance the appetite of chickens, improve the feed intake and feed conversion efficiency of chickens. Modern pharmacological research further shows that these Chinese herbal medicines contain polysaccharides, alkaloids, essential oils and other bioactive substances. For example, alkaloids can promote the development of chicken intestinal villus structure, improve the villus height and recess depth of chicken ileum and cecum to a certain extent, and improve the digestion and absorption function of intestinal mucosa. Essential oil and polysaccharide can increase the secretion of endogenous enzymes in the intestinal tract of chicken, improve the activity of digestive enzymes in the intestinal tract, change the shape of feed in the intestinal tract, and reduce the viscosity of intestinal chyme, thus increasing the digestion and absorption of feed nutrients, improving feed conversion efficiency, and effectively improving the growth performance of chicken[15,19-21].

3 Effects on antioxidant performance of chicken

The health level of chickens is the premise to ensure the normal growth of chickens. The essence of chicken antioxidant performance is a process in which a variety of antioxidant active substances in the body continuously eliminate free radicals in the body to protect the body from damage. The antioxidant system has a perfect and complex function, and can be compared with the immune system. The stronger the antioxidant capacity of the body, the healthier the chickens will be and the longer their lives will be. Therefore, the antioxidant function of chicken (organism) is an important factor affecting the health of chicken. The improvement of the antioxidant capacity of chicken can indirectly improve the growth performance of chicken. The research shows that many Chinese herbal medicines have good antioxidant function, such as Ginkgo Folium, Foeniculi Fructus, Astmgali Radix, Crataegi Fructus, Radix Rhizoma Glycyrrhizae, Magnoliae Officmalis Cortex, Scutellariae Radix, Macrocephalae Rhizoma, Citrus Reticulata Blanco, Sophorae Flavescentis Radix, Fructus Ligustri Lucidi, Poria, Salviae Miltiorrhizae, Paeoniae Radix Alba, Scrophulariae Radix, Radix Ophiopogonis, Fritillariae Cirrhosae Bulbus, and Rhei Radix Et Rhizoma[22-24].

Superoxide dismutase (SOD) is an antioxidant metal enzyme existing in organisms. It can catalyze the disproportionation of superoxide anion free radicals to produce oxygen and hydrogen peroxide, and plays a vital role in the balance between oxidation and antioxidation. The free radicals generated during the metabolic process of some normal substances and the metabolic changes of some drugs or poisons in the body can cause lipid peroxidation (LPO), and the intermediate product malondialdehyde (MDA) can destroy biological macromolecules. Therefore, it is significant to reduce the content of serum malondialdehyde. Fu Shuaietal.[25]added Chinese herbal medicine preparation composed of Radix Rhizoma Glycyrrhizae,Ginkgobilobaleaf extract, Crataegi Fructus, Astmgali Radix, Forsythiae Fructus, Lonicerae Japonicae Flos, Herba Origani, and Zingiberis Rhizoma to feed 1-42 d of AA chicken in basal diet in the proportions of 50, 100 and 150 g/t. The results displayed that test chicken fed with ration added in 100 g/t of Chinese herbal medicine preparation significantly improved total antioxidant capacity (T-AOC) and superoxide dismutase activity (T-SOD) of 21 and 42 d (P<0.05), also significantly improved glutathione (GSH) peroxidase activity of 42 d of broilers (P<0.05), and obviously declined serum malondialdehyde content (P<0.05). It can be seen that the application of the additive has significantly improved the antioxidant capacity of the experimental chicken. Therefore, it has also improved the growth performance of the chicken to a certain extent. Qiu Yulangetal.[26]used Chinese herbal medicine additive composed of Astmgali Radix extract, Andrographis Herba extract, and Citrus reticulata Blanco to feed 1-42 d of AA chicken, and the total antioxidant capacity, superoxide dismutase and glutathione peroxidase activities of experimental chickens were significantly increased (P<0.05), while the content of malondialdehyde was obviously reduced (P<0.05); the daily average weight gain and feed conversion efficiency were significantly improved (P<0.05), and the test results were very similar to Fu Shuai’s research results. Yang Cuietal.[27]added Kuxuanshen granules in rations of Guangxi Hongguang yellow chicken. Among 0.125%, 0.25% and 0.50% of additive amounts, test chicken in 0.25% of additive amount significantly improved total antioxidant capacity, glutathione content and total superoxide dismutase activity. It can be seen that the addition of Kuxuanshen granules in the diet has significantly improved the overall antioxidant performance of Hongguang yellow chicken. Qiao Hongxingetal.[28]added fermented Astmgali Radix in the basic diet of AA chicken, and Zhu Yongyietal.[29]added fermentedG.bilobaleaves in the diet of yellow broilers, both of which have achieved good results in significantly enhancing the antioxidant capacity of chickens and significantly improving the growth performance of chickens.

Oxidative stress of chicken is a problem often caused by large-scale and high-density breeding in chicken industry. The oxidative stress of the body is caused by the excessive accumulation of peroxides (free radicals) in the body, which exceeds the body’s antioxidant defense capacity, breaks the oxidation-antioxidant balance, and causes damage to some tissues and organs or physiological functions of the body, thus reducing production performance[30]. Therefore, the essence of antioxidation is a process in which a variety of antioxidative active substances (such as superoxide dismutase, glutathione, catalase,etc.) in the body continuously eliminate free radicals in the body to protect the body from damage. It can be seen that the stronger the antioxidant capacity of the body, the higher the health level of the body and the better the growth performance.

Some Chinese herbal medicine additives can significantly improve the antioxidant function and growth performance of chickens, because these Chinese herbal medicines contain a large number of polyphenols, polysaccharides, alkaloids, saponins and other active substances. Most of these active substances are scavengers of oxygen free radicals in the body. For example, phenols can directly remove oxygen free radicals due to the hydrogen ions released by them, and destroy or stop the peroxide produced in the oxidation process of oil, making the reaction of decomposing oil into aldehyde or ketone (low molecular substances) cannot continue. At the same time, these active substances can also effectively improve the activity of antioxidant enzymes and the content of other antioxidant substances[31], so they can enhance the antioxidant capacity of the body, eliminate the damage of free radicals or other peroxides (such as malondialdehyde, nitric oxide,etc.) to the body, and promote the growth of chickens.

In addition, some of Chinese herbal medicines which can improve the body’s antioxidant capacity are also directly related to the growth performance of chickens, such as reduced glutathione (GSH). The research showed that GSH had good growth promotion on fattening pig[32], mutton sheep[33]and some fish[34-35]. Wei Jianfuetal.[36]added GSH in basal diet to feed yellow broiler. The results found that GSH also had a good promoting effect on chicken growth. Liu Lietal.[36]used GSH to cultivate chicken intestinal epithelial cellsinvitro. The research results displayed that GSH can not only significantly increase the proliferation of chicken intestinal epithelial cells, but also improve the glucose absorption and the activity of cell membrane enzymes.

4 Effects on improving immunity of chickens

The decrease of immunity or disease resistance of chickens is an important reason that affects the health level and growth performance of chickens. However, the high scale, intensive or industrialized high-density breeding of chicken production and the resulting stress often lead to a serious decline in the immunity or disease resistance of chickens, thus affecting the growth performance of chickens. Therefore, it is particularly important to ensure that chickens have good immunity or disease resistance to ensure the normal production of chickens. Many Chinese herbal medicines with pharmacological functions such as clearing away heat and toxic substances, tonifying qi and yang, benefiting the body and strengthening the exterior can improve or enhance the immunity and disease resistance of chickens. Modern pharmacological research also shows that this kind of Chinese herbal medicine has good biological effects such as anti-bacterial, anti-inflammatory, anti-virus, anti-stress,etc.

Jia Yugangetal.[37]used the additive composed of more than 10 kinds of Chinese herbal medicine to feed Tibetan chicken, which obviously improved the contents of serum immunoglobulin IgG and IgM in Tibetan chicken (P<0.05) and cell factors IL-2, IL-4 and INF-γ (P<0.05). Meanwhile, body weight of Tibetan chicken in 6, 12 and 18 weeks (P<0.05) and average daily gain (P<0.05) were significantly improved, and chicken mortality was obviously declined (P<0.05). Su Jiliangetal.[38]used Chinese herbal medicine additives with 3 different formulas to feed 21 d of yellow broiler in the dose of 0.5%. The results found that the formula A composed of Isatidis Radix, Phellodendri Chinensis Cortex, Crataegi Fructus, Codonopsis Radix, Artemisiae Argyi Folium, Radix Acanthopanacis Senticosl, Rhizoma Woodwardiae Seu Osmundae Seu Cyrtomii, and Astmgali Radix significantly increased thymus and bursal index of experimental chickens (P<0.05). The immunoglobulin IgG, IgM and adhesion molecules CD4 and CD8 in serum were significantly (P<0.05) or extremely significant (P<0.01) higher than those in the control group, and the antibody titer of chicken blood against Newcastle disease was also significantly higher than that of the control group (P<0.05). Meanwhile, the growth performance of the experimental chickens was significantly better than that of the control group, and the average daily gain and feed conversion efficiency were significantly improved (P<0.05). Yang Cuietal.[39]added "Lianteng" Chinese herbal medicine additive composed of 6 kinds of Chinese herbal medicines in a certain proportion in the ration of Guangxi Sanhuang chicken. The results displayed that in test chicken of 0.1% and 0.2% of additive amount, serum albumin content and interleukin-2 level were obviously improved. It can be seen that this additive can also improve the immune performance of chickens to a certain extent. Many other similar studies have shown similar results[40-43].

It can be seen that the proper use of this kind of Chinese herbal medicine additive in the diet can significantly improve the immune function and the growth performance of chickens. These Chinese herbal medicines contain flavonoids, saponins, tea polyphenols, polysaccharides, alkaloids, organic acids, plant essential oils and other bioactive substances, which can promote the development of immune organs, effectively promote the transformation of lymphocytes, enhance the phagocytic function of macrophages, improve the level of cellular and humoral immunity, enhance the immunity and disease resistance of the body, and eliminate the impact of diseases and other harmful factors on the growth of chickens[44]. At the same time, it can also promote the development of the intestinal tract, improve the immune function of the intestinal tract and intestinal health, and promote the secretion of digestive enzymes[19], so it can improve feed digestion and utilization efficiency and promote the growth of chickens. Therefore, it is of practical significance to properly apply such Chinese herbal medicine additives in chicken production practice.

5 Conclusions

Chinese herbal medicine not only has the pharmacological function of enhancing appetite and digestive function, thus it can improve the feed intake and conversion efficiency to improve the growth performance of chickens, but also can improve the immune and antioxidant performance of the body, so it can eliminate the damage of diseases to the body and indirectly improve the growth performance of chickens. Therefore, the research and application of Chinese herbal medicine additives to replace antibiotics in production practice is of great significance for the development of chicken industry in the region and even in China.