Effects of Nano Chinese Herbal Medicine Feed Additive on Growth Performance, Meat Quality and Disease Resistance of Chickens

Zhenxing ZOU, Nguyen Thi Thanh Hai, Yongling HU

1. Hunan Polytechnic of Environment and Biology, Hengyang 421005, China; 2. Faculty of Animal Husbandry and Veterinary Medicine, Bac Giang Agriculture and Forestry University, Bac Giang 236100, Vietnam

Abstract [Objectives] To explore the effects of nano compound Chinese herbal medicine feed additive on growth performance, meat quality and disease resistance of chickens. [Methods] Chickens were fed with nano compound Chinese herbal medicine feed additive developed by Hunan Polytechnic of Environment and Biology, including 120 chickens in the treatment group and 120 chickens in the control group (CK). The growth performance indices (body weight gain, feed to gain ratio and slaughter index), meat quality indices (pH value, color, drip loss, shear force) and disease resistance indices (morbidity and mortality) of the chickens in the treatment and CK groups were recorded and determined, respectively. [Results] The inclusion of 2% nano compound Chinese herbal medicine feed additive in the diet significantly increased the growth rate, reduced the feed-to-gain ratio and improved the meat quality of the chickens. Supplementing Chinese herbal medicine could increase the pH value and reduce the drip loss and shear force of chicken meat. At the same time, the body’s immune function, antioxidant level and resistance against diseases of the chickens fed with nano compound Chinese herbal medicine feed additive were improved. [Conclusions] The inclusion of nano compound Chinese herbal medicine feed additive in the diet can improve the growth performance, meat quality and disease resistance of chickens.

Key words Compound Chinese herbal medicine feed additive, Chicken, Growth performance, Meat quality, Disease resistance

1 Introduction

Chinese herbal medicine has advantages of green, natural, safe and pollution-free, with both edible and medicinal values. In China, it is widely used as a feed additive in the breeding industry to promote growth and development and disease resistance of animals[1]. However, in Vietnam, the application of Chinese herbal medicine feed additives has not been popularized. In particular, the application of Chinese herbal medicine feed additives made by modern fermentation technology and nanotechnology in Vietnam’s aquaculture industry has not been reported. In this study, through an international cooperation project with Hunan Polytechnic of Environment and Biology, a nano compound Chinese herbal medicine feed additive was introduced into Vietnam, and its effects on chicken growth performance, meat quality and disease resistance were investigated, in order to provide a theoretical basis for the promotion and application of nano compound Chinese herbal medicine feed additives in Vietnam’s aquaculture industry, which is of great significance for promoting China-Vietnam agricultural cooperation and promoting the "Belt and Road" initiative.

2 Materials and methods

2.1 Preparation of nano Chinese herbal medicine feed additiveNano Chinese herbal medicine feed additive was provided by Hunan Polytechnic of Environment and Biology. It was composed of Chinese medicines with heat-clearing, detoxifying, qi-nourishing, yin-nourishing and immunity-improving effects. The main ingredients included Chinese yam, hawthorn, angelica, cowherb seed, astragalus, fleeceflower root, white peony root, motherwort, dodder seed, oriental water plantain, uniflower swisscentaury root, common cnidium fruit and combined spicebush root, etc. Based on the theory of traditional Chinese medicine formula, using modern fermentation and micro-nano technology and process, compound Chinese herbal medicine feed additive with diameters of 3-5 μm was prepared.

2.2 Grouping and feeding management of experimental animalsTotal 240 one-day-old healthy Vietnamese broilers of similar physical condition were randomly and evenly divided into two groups, treatment group and control group (CK). The basic diet for the treatment group and CK group was prepared according to theFeedingStandardofChicken(NY/T 33-2010). The composition and nutritional level of the diet are shown in Table 1. After 3 weeks of pre-feeding, 2% nano traditional Chinese medicine feed additive was supplemented to the basic diet of the treatment group. The experiment lasted for 9 weeks (that is, to the age of 12 weeks old). The chickens were fed twice a day, at 6:00 and 17:00, respectively. They were provided with free access to drinking water and allowed to move freely. The breeding density was 8 chickens/m2, and the immunization program was the same.

Table 1 Composition and nutritional level of basic diet (0-20 weeks old)

2.3 Sample collectionThe body weight of the chickens was measured at the ages of 1 d, 1 week and 12 weeks, respectively. The feed intake and illness situation were recorded. The body weight gain, morbidity and mortality were calculated. At the age of 12 weeks, 10 chickens were selected randomly from each group and slaughtered for measurement of meat production index and meat quality.

2.4 Index measurement

2.4.1Determination of slaughter index. After 12 weeks of age, 10 chickens, half male and half female, were selected randomly from each group and slaughtered for measurement of live weight, eviscerated weight, leg muscle weight and breast muscle weight. The percentage of eviscerated yield, percentage of leg muscle and percentage of breast muscle were calculated according to the following formulas:

Percentage of eviscerated yield (%) = Eviscerated weight (g)/Live weight (g) ×100%.

Percentage of leg muscle (%) = Leg muscle weight (g)/Eviscerated weight (g) ×100%.

Percentage of breast muscle (%) = Breast muscle weight (g)/Eviscerated weight (g) ×100%.

2.4.2Measurement of meat quality. The color of leg muscle and breast muscle was measured using Minota CR-410 (Japan). The measurement parameters included: brightness (L), yellowness (b) and redness (a). The shear force of muscle was determined with Warner-Bratzler 2000 (USA). The pH of chicken meat 15 and 24 h after slaughter was measured by directly inserting the pH meter into the meat, about 0.5-1.0 cm from the surface. The drip loss of chicken meat was determined by pressurized gravimetric method.

2.5 Data processing and analysisExperimental data were processed initially with Excel 2010, and then subjected to one-way ANOVA using SPSS 20.0 statistical software. The results are expressed as mean±standard deviation. WhenP<0.05, difference is considered to be significant.

3 Results and analysis

3.1 Effect of nano compound Chinese herbal medicine feed additive on growth performance of chickensAs shown in Table 2, from week 1 to week 4, the differences in chicken body weight between the treatment group and the CK group were insignificant (P>0.05). After the chickens in the treatment group were fed with nano compound Chinese herbal medicine feed additive for one week, that is, from week 5 on, the body weight of the treatment group was significantly higher than that of the CK group (P<0.05). The feed to grain ratio of the treatment group was 2.52∶1, and that of the CK group was 2.68∶1. It indicates that the inclusion of nano compound Chinese herbal medicine feed additive in the diet significantly improved the growth performance of the chickens and the utilization efficiency of the feed.

Table 2 Effect of nano compound Chinese herbal medicine feed additive on growth performance of chickens g

3.2 Effect of nano compound Chinese herbal medicine feed additive on slaughter index of chickensAs shown in Table 3, the live weight of the treatment group was higher than that of the CK group. The results about slaughter index show that the percentage of eviscerated yield of the treatment group was 3.02% higher than that of the CK group (P<0.05); the percentage of leg muscle of the treatment group was 1.42% higher than that of the CK group (P<0.05); and the percentage of breast muscle of the treatment group was 1.78% higher than that of the CK group (P<0.05), indicating that the supplementation of nano compound Chinese herbal medicine feed additive significantly improved the meat production performance of the chickens.

Table 3 Effect of nano compound Chinese herbal medicine feed additive on slaughter index of the chickens

3.3 Effect of nano compound Chinese herbal medicine feed additive on meat quality of chickensAfter 15 and 24 h of slaughter, no significant difference was observed in leg muscle pH value or breast muscle pH value between the two groups (P>0.05). In terms of meat color, the L, a and b values of the leg muscle and breast muscle in the CK group were all better than those in the treatment group (P>0.05). The drip losses of the leg muscle and breast muscle of the treatment group were both lower than those of the CK group (P<0.05). There were significant differences in shear forces of leg muscle and breast muscle between the two groups (P<0.05) (Table 4). The results above suggest that the inclusion of nano compound Chinese herbal medicine feed additive in the diet could improve the pH value, color, drip loss and shear force of the meat of the chickens.

Table 4 Effect of nano compound Chinese herbal medicine feed additive on meat quality of the chickens

3.4 Effect of nano compound Chinese herbal medicine feed additive on disease resistance of chickensTable 5 shows that respiratory and digestive diseases occurred in the chickens of the CK group. The total morbidity rate was 15% and the mortality rate was 11.67%. In contrast, the morbidity and mortality rates of the treatment group were both 0. The results show that the supplementation of nano compound Chinese herbal medicine feed additive to the diet could improve the disease resistance of the chickens.

Table 5 Effect of nano compound Chinese herbal medicine feed additive on disease resistance of the chickens

4 Discussion

4.1 Effect of nano compound Chinese herbal medicine feed additive on growth performance of chickensChinese herbal medicine feed additives have both nutritional and medicinal functions[2]. The proteins, lipids, minerals and vitamins contained in Chinese herbal medicines can provide nutrients for growth of animals. In particular, biologically active substances contained in Chinese herbal medicines have functions of nourishing the spleen, strengthening the stomach and promoting digestion, and can stimulate the growth of livestock and poultry and increase their slaughter rate. The results of this experiment show that supplementing 2% nano compound Chinese herbal medicine feed additive to the diet could significantly improve the growth and development performance, reduce the feed to gain ratio, and improve the meat production performance of chickens, consistent with the results of Kimetal.[3]and Yuan Xiaoxia[4].

4.2 Effect of nano compound Chinese herbal medicine feed additive on meat quality of chickensChinese herbal medicine are rich in various nutrients required by animal body, and they can supplement and improve the nutritional content of the diet, and promote the deposition of beneficial ingredients in muscle tissues when used as feed additives for chickens, thus increasing the accumulation of flavors in chicken meat and improving the production and quality of chicken meat[5].

The value of pH can affect color, drip loss and tenderness of meat. The pH value of meat is related to the decomposition of lactic acid in muscle and the degradation of muscle glycogen, and it can reflect the changes in protein and nutritional value[6]. After adding nano compound Chinese herbal medicine additive to the feed, the pH values of meat of slaughtered chickens in the treatment group were higher than those in the CK group. It indicates that the inclusion of Chinese herbal medicine in the feed could increase the pH value of meat to a certain extent, consistent with the research results of Gao Haixiaetal[7]. Meat color is the appearance of changes in muscle physiology, biochemistry and microbiology, related to the presence of muscle pigments (myoglobin, hemoglobin and colored metabolites), the light reflection and the intensity of oxidation. The brightness of the meat in the treatment group increased, which might be caused by the supplementation of Chinese herbal medicine to increase the content of myoglobin in muscle.

Drip loss is an important indicator to measure the hydraulic power of the muscle system. It directly affects the organization state, texture, flavor and taste of muscles. In this study, the drip loss of the treatment group was lower than that of CK group, which is consistent with the results of Jiang Heetal[8]. This may be due to the fact that nano Chinese herbal medicines are rich in vitamins and phenolic compounds which have the effect of scavenging free radicals and reducing oxidative substances in the body, thereby inhibiting muscle oxidation and meat rancidity that lead to the reduction of drip loss. Shear force is an important indicator to measure the tenderness of meat, and it can indirectly reflect the meat fiber structure and fat content and distribution. The shear force values of leg muscle and breast muscle in the treatment group were lower than those in the CK group, proving that the addition of Chinese herbal medicine to the feed improved the tenderness of the chicken breasts and leg muscles, consistent with research results of Bui Huu Doan[9].

4.3 Effect of nano compound Chinese herbal medicine feed additive on disease resistance of chickensMany Chinese herbal medicines have antibacterial, antiviral, insect repellent and immunity enhancement effects[10]. Especially after modern fermentation and nano-process treatment, their intestinal absorption rate can be improved, and the antibacterial and bactericidal effects become more prominent. At the same time, through the traditional Chinese medicine mechanism of strengthening the body resistance to eliminate pathogenic factors, Chinese herbal medicine can improve the disease resistance, anti-oxidation level and defense function of the body, so as to achieve the effect of resisting disease[11]. The morbidity and mortality of the chickens in the treatment group were both 0, which fully reflects that the addition of compound Chinese herbal medicine to the feed could improve the disease resistance of the chickens.

5 Conclusions

The inclusion of nano compound Chinese herbal medicine feed additive to the diet can improve the growth performance, meat quality and disease resistance of chickens.