Study on the appropriate scales of breeding-type family farms from the perspective of quantifying resource losses

ABSTRACT

The appropriate sizes of scale-breeding industries are causing increasing attention in that rational scale-breeding industries may both meet the meat demand of the market and avoid serious environmental problems. In this paper, the appropriate scales of breeding-type family farms were studied from the perspective of quantifying resource losses. The mathematical models about quantifying resource losses were built, and then the evaluation index system of resource losses was established. More than one hundred family farms in Sichuan province and Chongqing city of China located in the subtropics were selected as research cases and were classified as small-, medium- and large-scale family farms, whose unit resource losses and resource loss rates were both evaluated by the index system. Results show that the unit resource losses and the resource loss rate of medium-scale family farms are the lowest among these three kinds of family farms. Therefore, medium-scale farms are moderate, and then are recommended for scale-breeding industries.

Implications: Appropriate sizes are essential for the green development of scale-breeding industries. The external environment factors and internal resource effect should be considered. The unit resource losses and the resource loss rate of medium-scale family farms are the lowest among these three kinds of family farms. Therefore, medium-scale farms are optimistic, and then are recommended for scale-breeding industries. For medium-scale family farms, the scale of 800–999 pigs is optimistic. Furthermore, it is very necessary to adopt green cycle.

Introduction

Scale-breeding family farms are very important in the agricultural economy in that they may increase farmers’ income and alleviate the contradiction between safe food supply and meat market demand. However, they may put pressure on the environment if excessive manures and wastes are not disposed of correctly (Guo 2012). With the rapid development of the breeding industries, more and more scale-breeding farms appear, changing the proportion of smallholder farms in family farms (Ren et al. 2019). Expansive scales and enhanced mechanization level will cause large amounts of wastes and excreta, which must be considered for establishing the balance relationship between scale-breeding and environmental pollution (Zhang and Zhang 2010). Therefore, the appropriate sizes are very important for scale-breeding farms (Zhou 2012). If the breeding farms are too large, then their wastes cannot be recycled thoroughly by farms themselves, indicating that the environment will be polluted, and the agroecology will be demolished. Contrarily, if the breeding farms are too small, then their resource utilization rates may be low, hinting that their unit investments and resource wastes may be too high, so the scale economy effect cannot be reflected correctly (Zhang 2015).

Many researches about the sizes of the breeding farms had been carried on. Hong et al. insisted that management cost is an important factor for choosing the appropriate sizes (Gailhard and Bojnel 2015; Hong, Xu, and Peng 2012; Weng, Luo, and Zheng 2015). Some scholars thought that the livestock and poultry breeding should be based on a mediate scale to keep the balance between farms’ operation activities and external environment (Haan 2013; He 2016; Yuan 2013). Guo et al. suggested that the environmental costs should be internalization for deciding on appropriate sizes (Chen and Xue 2018; Guo 2012; Wang and Wang 2011; Wu, Xu, and Yang 2015). Ma et al. analyzed the determination of mediate scales from the perspective of technology level and labor transferring (Ma and Zhou 2014; Tian and Yao 2018). Environmental regulations are important for breeding farms, the soundness and enforcement of the legal system of environmental protection directly affect the selection of breeding scale (Si 2020; Tian 2019). Internal management should be considered, and environment pollution harmless treatment costs are related to farm size (Larue and Latruffe 2009; Sempore et al. 2016). If the utilization of resources is considered, the economic benefits of medium-sized breeding farms are the best (Du and Liu 2021). However, the above research only focused on one aspect of mediate sizes. In fact, there are many parameters to influence the scale of breeding-type family, so they should be considered comprehensively. Especially, the critical factor, namely the resource consumption, should not be omitted, which is the bridge between the internal management system and the external environment system. So far, few scholars had studied the appropriate sizes of scale-breeding farms and sustainable development from the perspective of resource consumption. Some scholars proposed the accounting methods for environment costs but seldom considered quantifying resource losses. In this paper, the appropriate scales of breeding farms will be studied based on quantitative resource losses and resource efficiency (Lin, Zhao, and Wang 2014; Ren et al. 2019). After the circular economy was considered as background, the estimation model of resource losses was built, and then the index system of resource loss rates was established to assess the influence of the scale on the breeding farms.

Methods and models

Normative research method

Connotation of resource losses

Here, resources are interpreted as wealthy resources, which were considered by the United Nations Program as the natural elements and conditions for generating economic values and improving human well-being. They are often cataloged as natural, social, information and environmental resources (Luo 2012), which are the general terms for those entering into the production and management processes of the family farms. The losses of resources are embodied in the physical flow accounts (PFA) of the United Nations integrated System of Environmental and Economic Accounting (SEEA), which are defined as unwanted energy in production process. This unwanted energy may come from links of production and consumption. They are eventually discharged into environment. In manufacturing industry, the resource losses mainly refer to three kinds of wastes, namely waste gases, waste water, and residues. These wastes cannot be reused by existing technology. The products of enterprises are classified as positive products and negative products in material flow cost accounting. The positive products are the right products according to design scheme, including finished products, semi-finished products, and by-products. Negative products are incidental to positive production process, including recyclable parts and non-recyclable parts. Using recycling technology, the recyclable parts will be reused and put into the process of production. If the number of non-recyclable parts exceeds the capacity of the recycling system, the redundant will be discharged into natural environment, then resulting in environment costs and resource losses. Resource losses are the monetary expression of destruction degree caused by the negative factors of production (Xu and Wang 2008), which originate from three aspects, namely the low effective utilization rate of resources, the lack of comprehensive utilization ways of wastes, and the excessive consumption of materials (Qu 1997). In this paper, the livestock breeding was selected as the studied subject and it is necessary to make clear the relationship between resource losses and production process.

The production process of livestock breeding is the process of resource consumption, which was shown in Figure 1.

Figure 1. The relationship between resource consumption and farm production.

From Figure 1, many resources will be invested at the beginning of investment, and then these resources will go into the production stage. After processing, the material forms of resources are changed and become agricultural products which will be sold at the market. After customers obtain the products, these resources go into consumption stage, and then the resource value is realized. Furtherly, the emissions will be generated once the consumption is satisfied and wastes will be discharged into environment. The production process of breeding farms is based on their resource flow, and the resource utilization efficiency is related to their sustainable development.

The relationship between resource losses and breeding scales

High resource losses cause great impacts on the external environment. The emissions and losses of nitrogen and phosphorus are both related to the breeding sizes (Wei, Bai, and Wu 2018). For the small-scale family farms, their low breeding technology level, insufficient funds, deficient professional knowledge, and less farmland to absorb waste will result in high resource losses. With the increase of the breeding-scales, investments and the technology level will be improved, and then farms have more different ways to get professional knowledge. Therefore, the wastes will be reused and recycled in scientific ways, and then the resource losses will be less. If the breeding-scales are too large, the amount of the wastes will exceed environmental carrying capacity, which results in more resource losses. Under the background of recycling economy, livestock manure can be recycled. The recycling system may enhance the utility of resources and extend energy transferring chain. The moderate-scale farms have high circular economy level, and its effective utilization degree of feces and urine is high. Considering the profit maximization, the breeding scales with minimum resource losses should be chosen as optimal sizes (He 2016). From the above analysis, the variation trend of resource losses with breeding-scales should be U-type.

Production procession analysis of resource losses

The production procession of resource losses for farms is shown in Figure 2 to analyze material energy cycle of breeding-type family farms, where RL represents the resource losses which include evaporated water, non-recyclable parts of manure, the unused biogas and slurry during incineration, and dead pigs. Pig-breeding family farms are selected as studied objects due to their availability of data and representativeness of results. Resource losses are classified as the following. (1) Ammonia, hydrogen sulfide, methane, nitric oxide and other waste gases; (2) Unused biogas residues and biogas slurry originating; (3) Unused biogas; (4) Dead swine; (5) Others.

Figure 2. The production procession of resource losses for family farms.

In the first phase, namely preparation phase, factory, equipment and piglets, feeds, medicine, etc. are prepared and invested. In the second stage, fattening pigs are cultivated, and then much more other resources such as labor, hydroelectricity and depreciation are supplied. According to material flow theory, positive and negative products are both produced during the fattening period. Positive products are fattening pigs, while negative products include the manure, urine, dead pigs, and waste gases. Positive products may be sold in market. Negative products may be classified as recycled and the non-recycled parts. The recycled parts are misplaced resources that may be reused. Non-recycled parts are always discharged into the environment, resulting in pollution and resource losses.

Manure and urine can produce biogas and anaerobic fermentation residues by composting and anaerobic fermentation processing. Biogas can be used as fuel for heating, lighting and cooking. The anaerobic fermentation residues may be used in vegetable or crops planting. If emissions of the anaerobic fermentation residues and biogas exceed the carrying capacity of the environment, resource losses happen. The dead pigs are negative products. According to the rules about dead pigs in China, the pigs that die from sickness are not allowed to be slaughtered and sold. They should be harmlessly processed by incineration and chemical process. The process of incineration will result in the costs including the labor wages, transportation costs, piglet fee, feeding expenses, etc. During the chemical process, oil, organic fertilizer, and fuel are produced, which can be recycled during pig-breeding and planting sectors. The evaporated water and other non-recycled parts are considered as resource losses.

Quantitative model of resource losses for breeding-type family farms

There are three steps to quantify the resource losses of scale-breeding farms here. Firstly, the negative product costs are defined. Secondly, the non-recyclable and unused parts of negative products are calculated. Thirdly, the resource losses of non-recycle products are evaluated. Negative products of pig-breeding farms mainly include manure, urine, flushing sewage, waste gases and dead pigs. If the unused negative products overload the capability of environment, then the resource losses happen.

The major factor for the formation of pig-manure is fodder, and the excretion rate is 35% (Stein 2012; Yang 2004). Pig-manure comes mainly from the live pigs and dead pigs. The wasted gases should be considered due to incomplete digestion, so the feed expense $F_f$ corresponding to those absorbed by pigs may be given by the formula (1),

(1) $F_f=(Q_n\bullet S_q\bullet D\bullet p_s+Q_b\bullet S_{bq}\bullet D_b\bullet p_s)\times (1-t)$(1)

(2) $F_{FP}=F_f\times h$(2)

where $Q_n$ and $Q_b$ are the number of fattening pigs and dead pigs, respectively. $S_q$ and $S_{bq}$ are daily fodder consumption of per fattening pig and dead pig, respectively. $D_b$ means the number of breeding days for sick pigs. $p_s$ is the market price of fodder.$h$ infers the ratio of the manure to the sum of wastes. The digestion rate is given as 72%, 40%, 76%, 60%, 51.75%, 75%, 86% and 80%, for wheat bran, soybean meal, fine wheat bran, rice in husk, sorghum, crushed bones, and shell powder, respectively. The digestion rate of the fodder is determined as 65% (Stein 2012; Yang 2004). $t$ is the feed digestion and absorption rate. $F_{FP}$ refer to the feed costs of pigs’ manure. The unit feed costs of pig-manure may be obtained by dividing the amount of excretion.

The components of pig-urine are mainly water, nitrogen, phosphorus and organic substances. Costs of urine may be accounted by water expense. The pig-urine costs come mainly from slaughtered pigs and dead pigs. The urination coefficient is 48.501% (Guo 2012). The price of drinking water can be obtained from the market. Therefore, the pig urine costs $F_u$ may be written as

(3) $F_u=(Q_n\times D+Q_b\times D_b)\times W_q\times p_w\times t_u$(3)

where $W_q$ is daily water consumption per pig. $p_w$ is the market price of drinking water. $t_u$ is the proportion of urine to the total excrement.

From investigation and literature, family farms always clean the piggery twice a day. There is a comprehensive cleaning and disinfection once a week. The rinse wasted water daily emission $W_{wq}$ is about 0.01 m³/(head·d), so farm irrigation sewage costs $F_{ww}$ can be accounted by Yuan 2013.

(4) $F_{ww}=\left(Q_n\times D+Q_b\times D_b\right)\times W_{wq}\times p_w$(4)

During pig-breeding, the main exhausted gases are ammonia, H₂S and N₂S. Ammonia and H₂S are major components of the stink originating from the decomposition and metabolism of crude protein. Under the current technology conditions, these wasted gases cannot be recycled, and then they are defined as resource losses. The amount of exhausted gases depends mainly on the amount of undigested fodder. Therefore, costs of exhausted gases $F_{wg}$ may be obtained by the following model,

(5) $F_{wg}=F_f\times \frac{{\sum }_{l=2}^5{r}_l}{{\sum }_{l=1}^5{r}_l}$(5)

where $r_l$ is the rate of wasted gases to the total excrement. $l=1,2,3,4,5$ correspond to the fecal, NH₃, H₂S, CH₄ and NO₂, respectively.

Costs of dead pigs include the piglet, fodder, labor, fuel, depreciation, water and electricity. After harmless processing of dead pigs, the costs of non-recyclable parts are defined as resource losses. The calculation method is similar to that of fattening pigs.

The disposal methods of wasted water and excrement include returning directly to field, aerobic composting and anaerobic methane treatment. Resource losses are different for different disposal methods. For returning directly to field, the saturated carried amount of pig-manure for each acre farmland is 33000 kg per year. The bearing capacity of an acre water surface is 3478 kg manure excreted by about six pigs (Chang et al. 2013; Du, Cheng, and Zhang 2007; Huang 2011; Zhu, Hm, and Sh 2006). After the amount of discarded fresh manure exceeding the carrying capacity of the farmland and water surface multiplies the unit feed cost, the resource losses $R{L}_{(1a)}$ can be got. For compost and returning directly to field, the method of composting is microbial decomposition of manure with substance that crop unfavorable. The dry matter of fecal is decomposed to produce heat and water evaporation, and then dry pathogenic bacteria, parasite eggs and weed seed are all promoted. Afterwards, the fertilizer is shaped. The bearing capabilities of farmlands and fishponds are 15000 kg and 15306 kg per acre, respectively (Hai 2007). The amount of composting exceeding the bearing capability of farmlands and fishponds is defined as resource losses $R{L}_{(1b)}$. For biogas treatment and returning to field, biogas and biogas fertilizer will be produced after biogas being handled by the anaerobic chemical method. Considering the actual gas production rate, the annual biogas yield may be calculated (Hai 2007). Unused biogas costs are also considered as resource losses. About 14.5725 tons biogas fertilizer will be generated per cubic meter methane tank a year. The amount of biogas fertilizer exceeding the environmental capacity of farmlands and fishponds is defined as resource losses $R{L}_{(1c)}$. For biogas treatment, composting and returning to field, the manure may be treated in methane tank. The resulting compost and manure will be applied to water and farmland as fertilizer. When the fertilizer reaches the environmental absorptive capacity, the excessive emissions are looked on as resource losses $R{L}_{(1d)}$.

Waste gases include NH₃, H₂S, CH₄ and NO₂ etc. These waste gases are difficult to collect and utilize, so the exhausted gases are always discharged into nature directly, and then are defined as resource losses $R{L}_{(2)}$. Exhausted gases are caused by crude protein contained in fodder, which are not decomposed and metabolized fully. The more undigested fodder, the more exhausted gases. Single wasted gas costs may be got by the undigested feed costs multiplying the ratio of waste gases to total amount of emission. Furthermore, the total waste gases costs can be got after summing up all single waste gas costs.

The dead livestock and poultry can be processed by incineration method. The negative products such as incineration oil, organic fertilizer and fuel will be produced, which may be recycled and reused during pig-breeding and crop planting. If the negative products exceed the capacity of the crop planting, the unnecessary parts will be regarded as the pollution, and then be included into resource losses $R{L}_{(3)}$ which is divided into three parts as $R{L}_{(3\mathrm{a})}$ meaning the emissions of incineration oil over the farm operation, $R{L}_{(3b)}$ indicating the emissions of organic fertilizer over carrying capacity of cultivated land and $R{L}_{(3c)}$ referring to the emissions of fuel over the need of pig production. Thus, the total resource losses of scale-breeding farms can be got by formula.

(6) $RL=R{L}_{(1)}(R{L}_{(1a)},R{L}_{(1b)},R{L}_{(1c)},R{L}_{(1d)})+R{L}_{(2)}+R{L}_{(3)}(R{L}_{(3a)},R{L}_{(3b)},R{L}_{(3c)})$(6)

Divided total resource losses by the invested resources, the resource loss rates may be obtained. The resource loss rates are often used to analyze the efficiency of resource usage. Comparing the resource loss rates of different production links, the operational improvement points will be found, and then many practical policies may be made for the sustainable development of breeding industry.

Evaluation index of resource losses

Activities of pig-breeding include producing livestock products and processing negative product (manure, wasted gases and dead pigs). The input and output of production process of family farms are shown in Figure 3. During pig-breeding stage, resource expenses (M₁) including labor, water, electricity, depreciation and medicine expense plus site rent are inputted, and then positive products (P_p) and negative products (P_N) will be produced. The Positive products will enter into the meat market, but the negative product will be disposed. To change the manure into fertilizer and biogas, which may be reused in breeding process, the investments for composting (M₄) and biogas treatment (M₅) should be input. If these fertilizer and biogas are not used up, the surplus will be wasted, and then defined as resource losses.

Figure 3. The input and output of production process of family farms.

By analyzing links of production flow, the index system of resource losses assessment may be built and shown in Figure 4. Then, the relationship between the sizes of family farms and resource losses will be obtained. The scales with the lowest resource loss rates should be moderate scales.

Figure 4. Index system of resource loss rates.

Empirical analysis

Statistic data were obtained from questionnaires. The information of samples was from December 31^st, 2017 to December 31^st, 2018. The sampled family farms are located in Sichuan province and Chongqing City in China. A total of 500 questionnaires were issued, and 380 copies were recovered. Contents of questionnaires included locations of farms, environmental conditions, breeding scales, operation mode, clearing manure methods, disposal waste methods, feeding activities, epidemic prevention method, annual income, expenses, resource investments and usage. Among sampled family farms, 123 copies were selected due to their similar production technology level and circular operation model. In this paper, sampled family farms were classified into three categories: small, medium, and large scales. Farms whose scales are less than 500 pigs, between 500 and 999 pigs, and more than 1000 pigs are defined as small-scale, medium-scale and large-scale family farms, respectively. Circular agriculture is a comprehensive management mode that organically links planting, animal husbandry, fishery and processing industry. In this manuscript, the background of resource loss accounting is agricultural circular economy. All sample farms adopt circular operation models. Different cycle modes produce different resource input-output benefits, and different resource losses. From the recovered questionnaires, there are 17, 106 and 20 family farms adopting the circular model as “composting and planting”, “biogas and planting”, “biogas and fisheries and planting”, respectively. The number of family farms corresponding to small, medium and large scales is 27, 70 and 26, respectively, which are shown in Table 1.

Table 1. Descriptive statistics of samples.

Scale of farms θ(pigs)	Sampled number	Circular operation model	Sampled number
$\theta <500$	27	Composting and planting	17
$500\le \theta <1000$	70	Biogas and planting	106
$\theta \ge 1000$	26	Biogas and fishery and planting	20

Based on the above estimation models quantifying resource losses, the resource losses of sampled farms were calculated with the Matlab software and are shown in Figure 5. The average value resource losses of manure with medium-sized farms are lower than those of the small-scale and large-scale farms. The main reason is that medium-scale family farms have more healthy feeding patterns, better environment, and higher breeding technology level than small-scale family farms. Owing to current disease prevention constrains and low combination level of planting and breeding, the emissions exceed the environment carry capability, the resource losses of large-scale farms are high.

Figure 5. Resource losses of all sampled pig-breeding family farms.

There are many factors leading to dead pigs including variety, nature, breeding environment, feeding patterns and disease. With the expansion of scales, pigs are vulnerable to get sick in concentrated large-scale breeding. Supervision and punishment are the most influential factors for the harmless treatment of sick and dead pigs on farms (Wu et al. 2017). The high treatment costs and low revenue make farmers lose interest in recycling dead pigs, so the resource losses of dead pigs are on the rise with increasing scale of pig-breeding.

During the pig-breeding, wasted gases such as ammonia, hydrogen sulfide, methane and carbon monoxide are discharged into the environment. These wasted gases cannot be reused because the recycling technical level is low. The more the wasted gases, the more resource losses of gas as shown in Figure 5.

From Figure 6, the unit resource losses quickly decrease at first, and then increases slowly with the expansion of scales, indicating that it is the largest for small-scale family farms and the lowest for medium-scale family farms. Therefore, the positive production rate is largest for medium-scale family farms. To study the medium-scale family farms more deeply, sampled medium-scale family farms were further divided into five groups including 500–599, 600–699, 700–799, 800–899 and 900–999. Variations of the unit resource losses of medium-scale farms with scales are shown in Figure 7. The unit resource losses are lowest and the corresponding impact on the environment is minimal for the scale 800–899 pigs from Figure 7.

Figure 6. Variation of unit resource losses of pig-breeding family farms with sizes.

Figure 7. The unit resources loss of medium-scale family farms vary with the scale.

Resource usage may be analyzed by the resource loss rates, which are shown in Table 2. There are 100 farms whose resource loss rates of manure RLR_e are less than or equal to zero. Furthermore, the RLR_e of about 22 family farms are more than zero. Some farms adopt biogas digester to treat manure, but others refuse to do so. Results may be classified into four types as RLR_e > 0, RLR_e ≤ 0, V_dg > 0 and V_dg = 0, respectively. For RLR_e ≤ 0, the average values of total resource loss rates RLR of medium-scale farms are lower than those of other types. If the biogas digester’s volume is more than zero, the RLR of all farms is about 5.24%, which is lower than those of farms whose V_dg is equal to zero. Then, the relationship between the sizes of family farms and the resource loss rates may be obtained. Comparing the RLR of all types of farms, the RLR of the medium-scale family farms’ is lowest. If family farms adopt methane tank to process the pollutants, the RLR_e are lower than that of farms who have no methane tank. The mean biogas resource loss rates RLR_b of the medium-scale family farms are also lowest among three types of farm sizes.

Table 2. Resource usage of family farms.

Items	Farm’s scale θ	$RLR$ mean	$RL{R}_e$ mean	The number of samples	Notes
$RL{R}_e>0$	$\theta <500$	15.94%	19.55%	24	$RL{R}_e$ is manure resource loss rate. $RLR$ is total resource loss of farms; $RL{R}_e\le 0$ means these farms have enough fields to absorb the excrement; There is a strong demand for manure to be used for fertilization. $RL{R}_b$ is the resource loss of biogas.
	$500\le \theta <1000$	3.88%	12.32%	55
	$\theta >1000$	4.75%	15.33%	21
$RL{R}_e\le 0$	$\theta <500$	5.38%	-	2
	$500\le \theta <1000$	3.50%	-	15
	$\theta >1000$	4.54%	-	5
items	Farm’s scale θ	$RLR$ mean	$RL{R}_e$ mean	$RL{R}_b$ mean	Samples’ number	Notes
Biogas digester volume > 0	$\theta <500$	11.33%	11.32%	41.16%	18	Biogas digester volume > 0 means adopting biogas digester to deal with manure and urine; Biogas digester volume = 0 means farmers didn’t adopt biogas digester to depose,excrement
	$500\le \theta <1000$	3.69%	7.18%	24.58%	62
	$\theta >1000$	4.71%	12.38%	31.84%	26
Biogas digester volume = 0	$\theta <500$	21.40%	29.50%	-	9
	$500\le \theta <1000$	4.62%	29.08%	-	8

Many family farms adopt non-hazardous treatment methods to handle dead pigs. Chemical processing is a major treatment way. Correspondingly, their effective utilization rates of dead pigs are about 10% and the average resource losses are 89.83%. Wasted gases are not recycled, so the resource loss rates of wasted gases are 100%.

Results and discussion

The sizes of pig-breeding family farms are critical for agricultural environment and meat supply. Variations of the resource loss rates and the unit resource losses of pig-breeding family farms with different scales are studied in this paper. Results show that the resource loss rates and the unit resource losses of medium-scale family farms are both the lowest among three kinds of family farms. For medium-scale family farms, the scale of 800–999 pigs is moderate.

This study aimed to determine the moderate size of breeding farms from the perspective of resource consummation. The resource loss rate can be used to measure the resource utilization. The results revealed that the relationship between breeding scale and resource usage. In this paper, resource losses can be quantified, and the resource loss rates, and the unit resource losses of medium-scale family farms are the lowest among three types of scales. The findings support the results of Tian (2019) and Tian (2021) who suggested that the operation size be affected by environment and resource., and the results of this study are also consistent with Xu et al. (2020) who believe that there is U-type relationship between pig-breeding scale and environmental pollution.

The previous study (He 2015) highlighted that the modest scale of pig-breeding farms can be determined by external environmental costs, and operators would like to choose the breeding scale where the external environment costs are lowest. Tian (2019) and Si (2020) insist that environmental regulations and government subsidies have impacts on breeding scale of farms. All the views presented are based on the external factors of breeding-scale, internal resource utilization is ignored.

This study quantified the resource losses and built the resource losses index system to measure the utilization of usage of different breeding scales. The logic relationship between resource and pollution is studied, and resource losses rates are used to determine the moderate scale. Based on the thought routes of resource losses-external environmental pollution-modest breeding scale, the conclusion is obtained.

Implications

The findings of this study identified that resource usage is important for the development of breeding farms. The unit resource losses and the resource loss rate of medium-scale family farms are the lowest among these three kinds of family farms. Therefore, medium-scale farms are moderate, and then are recommended for scale-breeding industries. For medium-scale family farms, the scale of 800–999 pigs is optimal.

Some enlightenment may be given based on the above analysis. ① In order to develop sustainable scale breeding industry, the farms may focus on the internal to improve the utilization rate of resources, optimize the allocation of resources, and then reduce the loss of resources. ② It is necessary to adopt circular economy mode for maximum utilization of resources, including combination of breeding and planting to make full use of resources. Biogas digester is suggested to treat the manure in order to reduce the influence of environment.

Limitation and future study

In this study, quantifying the resource loss is important for choosing optimal size, and there are many factors to consider for building models, some of which need to be measured in various ways, such as big data and remote sensing technologies. Future investigation should look at the relationships among environmental essential factors and focus on the dynamics of environmental carrying capabilities. Future exploration should approach the association between external environmental costs and resource losses. This paper made pig-breeding farms as study objects, future thoughts may consider cattle, sheep, chicken, fish and so on.

Author contributions

Shuai Wang prepared the data, carried out the theoretical analysis, and Zheng-Tao He did the empirical analysis and wrote the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Data used in this study are from questionnaire, and none of the data were deposited in an official repository. https://mail.qq.com/cgi-bin/frame_html?sid=zMuj1VL1I14DJCZC&r=f8d4c691072f2dbf2f1caf3b6da6913c&lang=zh

Additional information

Funding

Supported by three projects: state scholarship fund of China scholarship council [201808505088]; the social science planning project of Chongqing city [2016BS031], Chongqing educational science planning project [2017 G×266].

Notes on contributors

Zheng-Tao He

Zheng-Tao He, is a Lecturer at the School of Economics and Management, CQUPT, and visiting scholar at the George Fox University, U.S. She is a U.S. certified public accountant (USCPA) and member of China Internal Audit Association. She received a Ph.D. in management from the School of Economics and Management, Southwest University. Her academic areas are environment accounting, auditing, and performance evaluation. She has presided over and participated in nearly 10 national and provincial level projects, and published more than 20 academic papers.

Shuai Wang

Shuai Wang, is an Associate Professor, Master Instructor, and Visiting Scholar at Stony Brook University, U.S. Her main research fields include finance and accounting in capital market, corporate governance, company information disclosure,and green accounting. She has taken charge of 3 China Projects supported by the Social Science and Humanity of the Ministry of Education and Fundamental Research Funds for the Central Universities, and participated in more than 10 national, provincial, and ministerial scientific research projects as the main participants. She has published more than 20 academic papers.