Zhijun GE, Liqiang TIAN, Yiyao LI, Dongpu FENG*

1. School of Agriculture, Ningxia University, Yinchuan 750021, China; 2. Pioneer College, Inner Mongolia University, Hohhot 010000, China; 3. School of Civil and Hydraulic Engineering, Ningxia University, Yinchuan 750021, China

Abstract [Objectives] The aim of this paper was to reveal the changes of large livestock industry and their influence on animal husbandry economy in Guyuan City of Ningxia. [Methods] The linear trend method was employed to quantify the change trends of the indicators for large livestock industry, and the ridge regression model was conducted to analyze their impacts on the gross output value of animal husbandry (GOVAH). [Results] The numbers of sold and slaughtered cattle and sheep in Guyuan presented a significant upward trend, while the number for hog had a significant downward trend, during 2000-2019. The GOVAH in Guyuan and its 5 counties had increased by 2-3 times in recent 20 years, which was mainly driven by large-scale livestock breeding. The cattle and sheep breeding sectors had positive effects on GOVAH, while the hog breeding sector had negative effect. [Conclusions] This study provides a reference for the structural adjustment and large-scale development of animal husbandry.

Key words Livestock breading industry, Linear trend method, Ridge regression model, Guyuan City

1 Introduction

The global demand for meat products has generally shown an upward trend in recent 40 years[1]because of the development of social economy and the improvement of living standards. The large livestock breading industry provides beef, mutton, pork, milk, and wool skin, which is an important part of the animal husbandry. The livestock breading industry is the basic branches of agricultural economy in pastoral area and agro-pastoral transition zone in China. Large animal husbandry plays an important role in improving the economic level of local people and getting rid of poverty, in Northern China[2]. Wangetal.[3]analyzed the data of China’s animal husbandry from 2003 to 2017. The results show that Jilin, Heilongjiang, Shaanxi, Shanxi, Inner Mongolia, Guizhou, Ningxia, Tibet and Xinjiang are areas with advantages in animal husbandry industry and competitiveness. Wang Binglongetal[4], through investigation and analysis, found that the beef cattle industry in Guyuan increased by 5.8% in 2017 compared with 2016, and the cattle farmers in Guyuan reached 61.3% of the total farmers. Yang Jinboetal.[5]predicted the development trend of animal husbandry in Ningxia in the future according to the price of large livestock in Ningxia from 2017 to 2019. Ma Xiaomingetal.[6]pointed out that the scale of sheep industry in Ningxia has gradually expanded and has become a local pillar industry.

Although some achievements have been made, there is still defects and deficiencies on animal husbandry of Guyuan, such as the lack of long series data and reliable attribution analysis. Guyuan city is not only a traditional agro-pastoral ecotone, but also a poverty-stricken area. Moreover, the large livestock industry accounts for a large proportion in the output value of animal husbandry. Therefore, it is vital to understand the development trend of large livestock industry and its influence on animal husbandry economy. In this paper, we selected the number of sold and slaughtered large livestock (NSSLL) and the gross output value of animal husbandry (GOVAH) as direct indicators to explore the issue. Based on the long series data, we analyzed the change trends of three kinds of large livestock in Guyuan and their impact on the economic income of animal husbandry through linear regression and ridge regression. In this study, we intended to evaluate the roles of different livestock in improving the local economic level and provide a reference for a more reasonable animal husbandry structure.

2 Materials and methods

2.1 Site description and data sourcesGuyuan City (105°19′-106°57′ E and 35°14′-36°31′ N) is in the south of Ningxia Hui Autonomous Region, China. It is located in the warm and semi-arid climate area of the Loess Plateau, which is an agro-pastoral ecotone. The total area is 10 500 km2and the urban area is only 52.33 km2. The residence population of Guyuan is 1 458 600 by the end of 2019.

The annual GDP of Guyuan is 35.246 billion yuan in 2020. Among them, the added value of the primary, the secondary and the tertiary industry was 7.195, 6.913 and 21.138 billion yuan, respectively. Animal husbandry is the local pillar and characteristic advantageous industry, and it has brought many jobs and income to herdsmen.

As shown in Fig.1, Guyuan City has 5 subordinate counties. The overwhelming majority of large livestock in Guyuan and its 5 subordinate counties are cattle, sheep, and hog. The data of GOVAH and NSSLL in Guyuan and its subordinate counties are fromNingxiaStatisticalYearbook(2000-2019)[7].

Fig.1 Location and administrative division of Guyuan City

2.2 MethodologyLinear trend method[8]is a method to quantify the trends of time series data by linear regression. The regression coefficientbis also called tendency value, and its size reflects the tendency of the variablexto rise and fall. As the annual data were used in this study,bmeans the annual change rate. The Pearson correlation coefficientRindicates the significance of the linear correlation. The greater the absolute value ofR, the significant the correlation. In this study, we selected different significance levels (a=0.1,a=0.05 anda=0.01) to analyze the change trend.

Some indicators have the collinearity problem in multiple linear regression, so we conducted the ridge regression to solve the problem. At the expense of a small amount of information and accuracy, the ridge regression[9]is more practical and reliable than traditional multiple linear regression. The data analysis was carried out in the statistical software SPSS[10], and the specific principles and formulas are shown in reference[11].

3 Results and analysis

3.1 Change trends of NSSLLAs is shown in Table 1, the mean values of NSSLL, the number of sold and slaughtered cattle (NSSC), the number of sold and slaughtered sheep (NSSS) and the number of sold and slaughtered hogs (NSSH) in 2000-2019 are 1 057 500, 195 400, 657 800 and 204 300, respectively. The difference between the maximum and the minimum of NSSLL is 1.2 million, and for NSSS it is up to 1 million. However, for the NSSC and NSSS, they are only 210 000 and 122 000, respectively. The variation coefficients and standard deviations indicate that NSSS and NSSC are more discrete, and the data of hogs are less discrete. Fig.2a presents the trend of the NSSL, which showed a significant upward trend at the significance levela=0.01, as well as the NSSC and NSSS. According to the linear regression, the annual change rates of the NSSL, NSSC and NSSS in Guyuan are 54 500, 13.83 and 42 470 annually, respectively. On the contrary, NSSH showed a significant downward trend, decreasing by 1 730 annually. Taking 2016 as the turning point, the change trends of the NSSL, NSSC and NSSS can be divided into two parts: rapid development period and slow decline period.

In terms of the breeding scale of 5 subordinate counties of Guyuan, the cattle industry in Xiji, Pengyang and Yuanzhou is significantly larger than that in other counties and districts (Fig.2b). The sheep industry in Yuanzhou, Pengyang and Xiji is larger (Fig.2c), meanwhile the hog industry in Yuanzhou, Pengyang and Longde is significantly larger than others (Fig.2d). The change trends of NSLL, NSSC, NSSS and NSSH in subordinate counties are very similar to the trend of the whole Guyuan, except for the sheep slaughter in Jingyuan. On the one hand, the NSSC and NSSS indicated that the cattle and sheep breeding industries are rapidly developed in all the subordinate counties of Guyuan; on the other hand, the NSSH suggested that the hog breeding industry was transferred to Yuanzhou. The large livestock industry has increased by 2-3 times in last 20 years. By optimizing the breeding structure, a professional breeding industry with certain scale and local characteristics has been formed.

Note: (a) NSSLL denotes the number of sold and slaughtered large livestock, (b) NSSC denotes the number of sold and slaughtered cattle, (c) NSSS denotes the number of sold and slaughtered sheep, (d) NSSH denotes the number of sold and slaughtered hogs.

3.2 Temporal changes of GOVAHFrom 2000 to 2019, the mean of GOVAH in Guyuan was 1 623 million yuan, the minimum was 298.7 million yuan in 2000 and the maximum was 3 742.1 million yuan in 2019 (Table 2). Fig.3 showed a significant upward trend, with an annual increase of 190.1 million yuan (Table 2). The GOVAH in subordinate counties of Guyuan can be divided into 2 levels: the high level is about 1 000 million yuan (Pengyang, Yuanzhou and Xiji), and the low level is within 500 million yuan (Jingyuan and Longde), at the end of 2019. The significant upward trends were detected in all counties, with great annual growth rate.

Guyuan has made great efforts to develop animal husbandry in recent 20 years. In Fig.3 the GOVAH has increased significantly from 298.7 million yuan (in 2000) to 1 623 million yuan (in 2019), which experienced an increase of about 3 times. The change in the economic indicator coincides with the growth of cattle and sheep breeding industry.

Fig.3 Gross output value of animal husbandry of Guyuan and its subordinate counties in 2000-2019

3.3 Impacts of NSSLL on GOVAHIn the data analysis, a collinearity problem was detected. Therefore, the ridge regression was employed to effectively remove the impact of collinearity. The optimal value for ridge regression parameterkwas recommended by SPSS. The GOVAH was selected as the dependenty, while NSSC, NSSS and NSSH were the independent variablesx1,x2, andx3, respectively. As shown in Table 3,R2andFtests indicated that the regression equations of Guyuan City and all counties and districts are statistically significant. In terms of regression effect, Xiji’s regression equation is the best (R2=0.82), which means that by the regression equation the NSSC, NSSS and NSSH can explain 82% of the change in the GOVAH. The worst one is the equation of Jingyuan, which can only explain 38% of the GOVAH change. Multiple linear regression equations can be obtained according to constants and non-standardized regression coefficients, to predict the dependent variables through independent variables.

Table 1 Statistical analysis of livestock sold and slaughtered in Guyuan and its subordinate counties in 2000-2019 (103)

Table 2 Statistical analysis of gross output value of animal husbandry of Guyuan and its subordinate counties in 2000-2019 (106 yuan)

Table 3 Results of ridge regression analysis of the gross output value of animal husbandry (y) in Guyuan in 2000-2019

Based on the standardized regression coefficient, we analyzed the importance of the changes of different kinds of livestock to the GOVAH. The factors with positive regression coefficient have a positive impact on the GOVAH, andviceversa. The absolute value of standardized regression coefficient represents the impact of factors. If the coefficient passes the significance test, then the conclusion is statistically acceptable. The result of Guyuan show that the cattle and sheep breeding industry had a significant positive impact on the output value of animal husbandry, while the hog breeding industry had a negative influence. Moreover, the stand-ardization coefficient showed that the importance ranking was cattle > sheep > hog. The reason is that Guyuan livestock husbandry has promoted the breeding of cattle and sheep and reduced the hog sector. In the analysis of each county, sheep industry, cattle and sheep sectors had a positive impact, and the influence of cattle is greater than that of sheep, except in Jingyuan. The hog industry was increased in Yuanzhou and reduced in other counties, which caused a positive influence on the husbandry economy in Yuanzhou, but a negative influence in other counties. The influence ranking for Yuanzhou was hog > cattle > sheep. This means that there are some differences in the structure of animal husbandry in 5 subordinate counties of Guyuan.

4 Conclusions

Based on the statistical analysis of the NSSLL (including NSSC, NSSS and NSSH) and the GOVAH in Guyuan and its subordinate counties in 2000-2019, we reached the following conclusions.

(i) The NSSC and NSSS in Guyuan and its subordinate counties showed a significant upward trend, the NSSH showed a significant downward trend in the whole Guyuan and its subordinate counties except Yuanzhou.

(ii) The GOVAH in Guyuan and its subordinate counties showed a significant upward trend, increasing by 2-3 times, in recent 20 years. The annual change rates of GOVAH were 22.7-190.1 million yuan per year in Guyuan and its subordinate counties. The scales of GOVAH were divided to high level (1 000 million yuan) and low level (500 million yuan) in 2019. Pengyang, Yuanzhou and Xiji were in the high level.

(iii) The sharp increase of large livestock breeding industry in Guyuan is the main reason for the growth of animal husbandry economy. The increase of cattle and sheep breeding industry is the main reason to the dramatic growth GOVAH, while the hog industry has a negative influence on GOVAH in Guyuan, except Yuanzhou, where the hog industry had a positive infuence. The importance of influence ranking in other counties was cattle > sheep > hog. This also indicates that Guyuan has gradually formed an intensive, large-scale, and professional breeding mode by adjusting the animal husbandry industrial structure according to the local characteristics.