Abstract: In order to study the efficacy of stress Ning in improving the production performance of commercial broiler chickens. Select 200 healthy 1-day-old AA broiler chickens with similar body weight and randomly divide them into 2 treatments, with 5 replicates per treatment and 20 chickens per replicate (see Table 1). Treatment 1: Control group, broiler chickens were fed a regular diet (NRC recommended nutritional level) without adding any antibiotics to the diet; On the basis of the same diet as treatment 1, supplement stress Ning with 250 mg/kg for treatment 2. The experiment is divided into two stages (0-21d; 22-42d). Experimental chicken cage feeding, feeding pellet feed, with consistent dietary composition and nutritional levels between treatments. At 21 and 42 days, 10 chickens were randomly selected from each treatment (2 chickens per replicate) for slaughter experiments to determine slaughter performance. The measurement results indicate that:

Production performance and European index: Compared with the control group, the addition of stress Ning showed a trend of reducing the feed to weight ratio in the early stage (1-21d) (P=0.065) and throughout the entire period (1-42d) (P=0.077), and a trend of improving the European index (P=0.057). Comparing and analyzing numerically, with the production performance indicators of the control group at 100%, after adding stress Ning, the ADFI, ADG, and feed to weight ratio of commercial broiler chickens in the early stage (1-21d) were 99.4%, 108.3%, and 91.4%, respectively; The ADFI, ADG, and feed to weight ratio of commercial broiler chickens in the later stage (22-42d) were 96.8%, 102.7%, and 94.0%, respectively; The total period (1-42 days) was 97.5%, 104.4%, and 93.3%, respectively; At the same time, the body weight at 21 and 42 days was 107.8% and 104.3%, respectively, and the survival rate and European index increased by 3.6% and 15.8%, respectively.

Slaughtering performance: Compared with the control group, the addition of stress Ning significantly increased the chest muscle rate at 21 days (P<0.01), 21="" 42="" and="" showed="" a="" trend="" of="" increasing="" the="" semi="" clearance="" rate="" at="" days="" p="" there="" was="" no="" significant="" effect="" on="" other="" indicators="">0.05). From a numerical comparison analysis, with the control group's meat production performance indicators set at 100%, the addition of stress Ning increased the chest muscle rate and leg muscle rate by 10.4% and 2.3% respectively after 21 days, reduced the thymus index by 14.5%, increased the abdominal fat rate by 33.8% and reduced the thymus index by 6.8% after 42 days.

Keywords: commodity broiler, stress Ning, production performance, slaughter performance

1. Materials and Methods

1.1 Test Materials

Stress Ning: A high-yield stress additive formula mainly composed of microecological active ingredients. Provided by SD BIOTECH GROUP.

1.2 Experimental animals and design

Select 200 healthy 1-day-old AA broiler chickens with similar body weight and randomly divide them into 2 treatments, with 5 replicates per treatment and 20 chickens per replicate (see Table 1). Treatment 1: Control group, broiler chickens were fed a regular diet (NRC recommended nutritional level) without adding any antibiotics to the diet; On the basis of the same diet as treatment 1, supplement stress Ning with 250 mg/kg for treatment 2. The experiment is divided into two stages (0-21d; 22-42d). Feed the control group diet at 28-35 days of age as an endogenous metabolism test to calculate the true metabolic rate of nutrients.

1.3 Experimental diet

Conventional diet for commercial broiler chickens in Shandong Province (see Table 2).

1.4 Test Method

Feeding experiment: The experiment is divided into two stages: broiler chickens (0-21d) and broiler chickens (22-42d). Experimental chicken cage feeding with powdered feed.

Slaughter experiment: 10 chickens were randomly selected for each treatment (2 chickens/replicate) at 21 and 42 days. Conduct slaughter experiments.

1.5 Measurement indicators

Production performance: Record feed intake daily and weigh at 21 and 42 days. Calculate the average daily feed intake, average daily weight gain, and feed to gain ratio. Record mortality rate, diarrhea rate, stool characteristics, mental state, etc. Calculate the European index.

Meat production performance: At 21 and 42 days, 10 chickens were slaughtered for each treatment, and the meat production performance (such as net bore rate, semi net bore rate, leg muscle rate, chest muscle rate, etc.) was measured.

Immune organ index: At 21 and 42 days, 10 chickens were slaughtered for each treatment, and their spleens and thymus were collected to calculate the spleen and thymus indices.

1.6 Data statistics and analysis

The data was analyzed using SAS 9.2 software, and Duncan's multiple range test was used to compare the mean values, with a significance level of p<0.05.

2. Results and Analysis

2.1 Comparative analysis of production performance

The effect of supplementing 250 mg/kg of stress Ning in the diet of commercial broiler chickens on production performance is shown in Table 3. Analysis of variance showed that compared with the control group, adding stress Ning had a trend of reducing feed to weight ratio in the early stage (1-21d) (P=0.065) and throughout the entire period (1-42d) (P=0.077). Comparing and analyzing numerically, with the production performance indicators of the control group at 100%, after adding stress Ning, the ADFI, ADG, and feed to weight ratio of commercial broiler chickens in the early stage (1-21d) were 99.4%, 108.3%, and 91.4%, respectively; The ADFI, ADG, and feed to weight ratio of commercial broiler chickens in the later stage (22-42d) were 96.8%, 102.7%, and 94.0%, respectively; The total period (1-42 days) was 97.5%, 104.4%, and 93.3%, respectively; At the same time, the weight at 21 days and 42 days was 107.8% and 104.3%, respectively. This proves that adding stress Ning to the diet of commercial broiler chickens can reduce feed to weight ratio, improve feed utilization efficiency, and enhance production performance.

2.2 Comparative analysis of European indices

The effect of supplementing 250 mg/kg of stress Ning in the diet of commercial broiler chickens on survival rate and European index is shown in Table 3. The analysis of variance showed that adding stress Ning had a trend of improving the European index (P=0.057). From a numerical comparison analysis, with the European index of the control group being 100%, adding stress Ning increased the survival rate and European index by 3.6% and 15.8%, respectively. From this, it can be seen that Stress Ning can significantly improve the survival rate and European index of broiler chickens, and improve breeding profits.

2.3 Comparative analysis of meat production performance

The effect of supplementing 250 mg/kg of stress Ning in the diet of commercial broiler chickens on production performance is shown in Tables 5 and 6. The analysis of variance showed that compared with the control group, the addition of stress Ning significantly increased the chest muscle rate at 21 days (P<0.01) 21="" 42="" and="" showed="" a="" trend="" of="" increasing="" the="" semi="" clearance="" rate="" at="" days="" p="" but="" had="" no="" significant="" effect="" on="" other="" indicators="">0.05). From a numerical comparison analysis, with the control group's meat production performance indicators set at 100%, the addition of stress Ning increased the chest muscle rate and leg muscle rate by 10.4% and 2.3% respectively after 21 days, reduced the thymus index by 14.5%, increased the abdominal fat rate by 33.8% and reduced the thymus index by 6.8% after 42 days.

3. Conclusion

Compared to the control group:

3.1 Adding stress Ning to commercial broiler chickens reduced feed to weight ratio, increased slaughter weight, and achieved better production performance; Improve European indices and increase aquaculture profits.

3.2 Adding stress Ning to commercial broiler chickens has a trend of improving meat production performance, achieving good 21 day chest and leg muscle rates, with 21 day chest and leg muscle rates increasing by 10.4% and 2.3%, respectively.

Table 1 Experimental Design

Table 2 Experimental Diet Composition and Nutritional Level

Table 3 The Effect of Stress Ning on the Production Performance of Commercial Broiler Chickens

Table 4 The Effect of Stress Ning on the European Index of Commercial Broiler Chickens

Table 5 Effect of Stress Ning on 21 day Meat Production Performance of Commercial Broiler Chickens

Table 6 Effect of Stress Ning on Meat Production Performance of Commercial Broiler at 42 Days