Life-cycle comparisons of economic and environmental consequences for pig production with four different models in China

China, the world's largest consumer and producer of pork in the world, is attracting increasing attention due to the environmental impacts of its pig production. Previous studies seldom comprehensively compare the environmental impacts of the pig production system with different models, resulting in different intensities of environmental impacts. We aim to comprehensively evaluate Chinese pig production with different breeding models and explore a more sustainable way for pig production. We use life cycle assessment (LCA) to evaluate and compare environmental impacts of pig production system with four main breeding models in China from 1998 to 2020: domestic breeding, small-scale breeding, medium-scale breeding, and large-scale breeding. The life cycle encompasses fertilizer production, feed production, feed processing, pig raising, waste treatment, and slaughtering. The impact categories including energy consumption (EN), global warming (GWP), acidification (AP), eutrophication (EU), water use (WD), and land occupation (LO) are expressed with "100 kg live weight of fattening pig at farm gate." The results show that driven by governmental support, growing meat demand, and cost advantage, the scale breeding especially large-scale breeding simultaneously yielded greater net economic benefit and less environmental impact compared to other breeding models especially the domestic breeding. Due to mineral fertilizer application, feed production contributed over 50% of the total environmental impacts. Notably, the composition of feeds exerted significant influence on the environmental impacts arising from fertilizer production and feed processing. Furthermore, attributable to the substantial use of electricity and heat, as well as the concomitant emissions, pig raising contributed the largest GWP, while ranking second in terms of AP and EU. Notably, waste management constituted the third-largest EU, AP, and WD. In addition to promote scale breeding, we put forth several sustainable measures encompassing feed composition, cultivation practices, fertilizer utilization, and waste management for consideration.

Assessment of Livestock Water Productivity in Seno and Yatenga Provinces of Burkina Faso

The expected increase in livestock production to meet its increasing demand could lead to increased water depletion through feeds production. This study aimed at estimating the amount of water depletion through feeds and its corresponding productivity in livestock within the three dominant livestock management systems namely sedentary-intensive, sedentary-extensive, and transhumance in Yatenga and Seno provinces in the Sahelian zone of Burkina Faso. Using a participatory rapid appraisal and individual interview, beneficial animal products, and services were estimated, and consequently, livestock water productivity (LWP) as the ratio of livestock products and services to the amount of water depleted. Our results showed feed resources are mainly natural pasture and crop residues are common in all the management systems though the proportion of each feed type in the feed basket and seasonal preferences varied. Consequently, water depleted for feed production was similar across the systems in both provinces and ranged from 2,500 to 3,200 m−3 ha−1 yr−1. Values for milk (40 US$US$/household) and flock offtake (313 US$/household) derived from the transhumant system were higher (P < 0.05) than those from other systems in the Seno province. With higher returns from the beneficial outputs, LWP was higher (0.11 US$ m−3) in the transhumant system than other systems in Yatenga, but similar with sedentary-intensive in Seno Province Multiple regression analysis results showed that LWP had a significant positive relationship with flock offtake in Yatenga but milk and flock offtake in Seno. The study concluded that sedentary-intensive and transhumant system with more market-oriented beneficial outputs and much dependence on less-water-depleted feed resources will improve livestock water productivity in dry areas. Besides, interventions to improve livestock water productivity through beneficial outputs must recognize the unique socio-cultural context of the livestock farmers.

BOARD-INVITED REVIEW: Quantifying water use in ruminant production

The depletion of water resources, in terms of both quantity and quality, has become a major concern both locally and globally. Ruminants, in particular, are under increased public scrutiny due to their relatively high water use per unit of meat or milk produced. Estimating the water footprint of livestock production is a relatively new field of research for which methods are still evolving. This review describes the approaches used to quantify water use in ruminant production systems as well as the methodological and conceptual issues associated with each approach. Water use estimates for the main products from ruminant production systems are also presented, along with possible management strategies to reduce water use. In the past, quantifying water withdrawal in ruminant production focused on the water demand for drinking or operational purposes. Recently, the recognition of water as a scarce resource has led to the development of several methodologies including water footprint assessment, life cycle assessment, and livestock water productivity to assess water use and its environmental impacts. These methods differ with respect to their target outcome (efficiency or environmental impacts), geographic focus (local or global), description of water sources (green, blue, and gray), handling of water quality concerns, the interpretation of environmental impacts, and the metric by which results are communicated (volumetric units or impact equivalents). Ruminant production is a complex activity where animals are often reared at different sites using a range of resources over their lifetime. Additional water use occurs during slaughter, product processing, and packaging. Estimating water use at the various stages of meat and milk production and communicating those estimates will help producers and other stakeholders identify hotspots and implement strategies to improve water use efficiency. Improvements in ruminant productivity (i.e., BW and milk production) and reproductive efficiency can also reduce the water footprint per unit product. However, given that feed production makes up the majority of water use by ruminants, research and development efforts should focus on this area. More research and clarity are needed to examine the validity of assumptions and possible trade-offs between ruminants' water use and other sustainability indicators.

Livestock and feed water productivity in the mixed crop-livestock system

Recently with limited information from intensified grain-based farming systems in developed countries, livestock production is challenged as being huge consumer of freshwater. The smallholder mixed crop-livestock (MCL) system which is predominant in developing countries like Ethiopia, is maintained with considerable contributions of crop residues (CR) to livestock feeding. Inclusion of CR is expected to reduce the water requirement for feed production resulting improvement in livestock water productivity (LWP). This study was conducted to determine feed water productivity (FWP) and LWP in the MCL system. A multistage sampling procedure was followed to select farmers from different wealth status. Wealth status dictated by ownership of key farm resources such as size of cropland and livestock influenced the magnitude of livestock outputs, FWP and LWP. Significant difference in feed collected, freshwater evapotranspired, livestock outputs and water productivity (WP) were observed between wealth groups, where wealthier are relatively more advantaged. Water productivity of CR and grazing land (GL) analyzed separately showed contrasting differences where better-off gained more on CR, whereas vice versa on GL. These counterbalancing of variations may justify the non-significant difference in total FWP between wealth groups. Despite observed differences, low WP on GL indicates the need of interventions at all levels. The variation in WP of CR is attributed to availability of production factors which restrained the capacity of poor farmers most. A linear relationship between the proportion of CR in livestock feed and FWP was evident, but the relationship with LWP was not likely linear. As CR are inherently low in digestibility and nutritive values which have an effect on feed conversion into valuable livestock products and services, increasing share of CR beyond an optimum level is not a viable option to bring improvements in livestock productivity as expressed in terms of LWP. Ensuring land security, installing proper grazing management, improved forage seed supply and application of soil and water conservation are expected to enhance WP on GL. Given the relationship of production factors with crop biomass and associated WP, interventions targeted to improve provision of inputs, credit, extension and training support due emphasis to the poor would increase CR yield and reduce part of water use for feed production. Optimizing feed value of CR with treatment and supplementation, following water efficient forage production methods and maintenance of healthy productive animals are expected to amplify the benefits from livestock and eventually improve LWP.

Strategies for improving water use efficiency of livestock production in rain-fed systems

Livestock production is a major consumer of fresh water, and the influence of livestock production on global fresh water resources is increasing because of the growing demand for livestock products. Increasing water use efficiency of livestock production, therefore, can contribute to the overall water use efficiency of agriculture. Previous studies have reported significant variation in livestock water productivity (LWP) within and among farming systems. Underlying causes of this variation in LWP require further investigation. The objective of this paper was to identify the factors that explain the variation in LWP within and among farming systems in Ethiopia. We quantified LWP for various farms in mixed-crop livestock systems and explored the effect of household demographic characteristics and farm assets on LWP using ANOVA and multilevel mixed-effect linear regression. We focused on water used to cultivate feeds on privately owned agricultural lands. There was a difference in LWP among farming systems and wealth categories. Better-off households followed by medium households had the highest LWP, whereas poor households had the lowest LWP. The variation in LWP among wealth categories could be explained by the differences in the ownership of livestock and availability of family labor. Regression results showed that the age of the household head, the size of the livestock holding and availability of family labor affected LWP positively. The results suggest that water use efficiency could be improved by alleviating resource constraints such as access to farm labor and livestock assets, oxen in particular.

Livestock and water: understanding the context based on the 'Comprehensive Assessment of Water Management in Agriculture'

The recently completed ‘Comprehensive Assessment of Water Management in Agriculture’ (CA) assessed the benefits, costs and impacts of the past 50 years of water development. It highlighted important trends that frame the challenges in water resources management of today and into the future, and critically evaluated solutions that people have developed to cope with these challenges. Important past trends include increases in food production that have outpaced population growth, much of this due to a doubling of the global irrigated area between 1961 and 2003, and accompanying declines in the health of aquatic ecosystems resulting from demands for, and impacts of, water use in agriculture. The future will bring new pressures on water resources and ecosystems as demands from sectors other than agriculture increase (including water for biofuel production), populations rise and become more wealthy, which leads to demand for foods that are more water intensive to produce, and climate change increases uncertainty and risk in our agricultural systems. Modelling predictions and analysis of scenarios show that water demand may rise from between only 20 up to 90% over the next 50 years, depending on how we choose to manage water in agricultural systems in the future. Owing to the importance of meat in changing diets and the role of livestock in managing land degradation, livestock is central to many of the issues that will determine whether or not optimistic scenarios (minimised increased demand for agricultural water in the future) can be achieved. This paper briefly summarises the insights and results of the CA, and highlights the areas where livestock management is most closely related to major water challenges and global recommendations of the CA. The purpose of this introductory paper is to set the context within which the importance of enhancing livestock water productivity in mixed farming systems can be appreciated.

Harnessing benefits from improved livestock water productivity in crop–livestock systems of sub-Saharan Africa: synthesis

The threat of water scarcity in sub-Saharan Africa is real, due to the expanding agricultural needs, climate variability and inappropriate land use. Livestock keeping is the fastest growing agricultural sector, partly because of increasing and changing demands for adequate, quality and diverse food for people, driven by growing incomes and demographic transitions. Besides the economic benefits, rising livestock production could also deplete water and aggravate water scarcity at local and global scales. The insufficient understanding of livestock–water interactions also led to low livestock productivity, impeded sound decision on resources management and undermined achieving positive returns on investments in agricultural water across sub-Saharan Africa. Innovative and integrated measures are required to improve water productivity and reverse the growing trends of water scarcity. Livestock water productivity (LWP), which is defined as the ratio of livestock outputs to the amount of water depleted, could be improved through: (i) raising the efficiency of the water inputs by integrating livestock with crop, water and landscape management policies and practices. Improving feed water productivity by maximising transpiration and minimising evaporation and other losses is critical; (ii) increasing livestock outputs through improved feed management, veterinary services and introducing system-compatible breeds; and (iii) because livestock innovation is a social process, it is not possible to gain LWP improvements unless close attention is paid to policies, institutions and their associated processes. Policies targeting infrastructure development would help livestock keepers secure access to markets, veterinary services and knowledge. This paper extracts highlights from various papers presented in the special issue of The Rangeland Journal on technologies and practices that would enable improving water productivity at various scales and the premises required to reverse the negative trends of water depletion and land degradation.

Factors affecting livestock water productivity: animal scale analysis using previous cattle feeding trials in Ethiopia

Availability and access to fresh water will likely constrain future food production in many countries. Thus, it is frequently suggested that the limited amount of water should be used more productively. In this study we report the results of our investigation on effects of feed, age and weight on livestock water productivity (LWP). The main objective is to identify technologies that will help enhance LWP. We combined empirical knowledge and literature values to estimate the amount of water depleted to produce beef, milk, traction power and manure. We estimated the LWP as the ratio of livestock products and services to the depleted water. In the feeding trials, various combinations of maize and oat stover, vetch, lablab and wheat bran were combined in different proportions to make 16 unique rations that were fed to the experimental animals of different age and weight groups. We observed differences of LWP across feed type, age and weight of dairy cows. The value of LWP tended to increase with increasing age and weight: the lowest LWP (0.34 US$/m3) for cows less than five years whereas the highest LWP value was 0.41 US$/m3 for those cows in the age category of 8 years and above. Similarly, there was an increase in LWP as weight of the animal increased, i.e. LWP was lowest (0.32 US$/m3) for lower weight groups (300–350 kg) and increased for larger animals. There were apparent impacts of feed composition on LWP values. For example, the highest LWP value was observed for oat, vetch and wheat bran mixes. Taking livestock services and products into account, the overall livestock water productivity ranged from 0.25 to 0.39 US$/m3 and the value obtained from a cow appeared to be higher than for an ox. In conclusion, some strategies and technological options such as improved feeds, better herd management, appropriate heard structure can be adapted to enhance LWP.

Changes in water flows and water productivity upon vegetation regeneration on degraded hillslopes in northern Ethiopia: a water balance modelling exercise

The establishment of exclosures (i.e. areas closed for grazing and agriculture) is a common practice to reverse land degradation through vegetation regeneration in the semiarid highland areas of northern Ethiopia. In order to assess the effect of exclosures on water flows, the water balance components for different vegetation regeneration stages were assessed through field measurements and modelling. Successful model calibration and validation was done based on soil water content measurements conducted during 2 years in 22 experimental plots. In the protected areas, vegetation regeneration leads to an increase in infiltration and transpiration and a more productive use of water for biomass production. In areas where additional lateral water (runon) infiltrates, source–sink systems are created. Here, up to 30% of the annual rainfall percolates through the root-zone towards the groundwater table. Increased biomass production in exclosures leads to possibilities for wood harvesting and cut and carry of grasses for livestock feeding. Together with water conservation and more productive use of water, the latter contributes to increased livestock water productivity. At the landscape scale, the creation of vegetation filters, capturing resources like water and nutrients, reinforces the rehabilitation process and healthy landscape functioning.

Enabling the uptake of livestock - water productivity interventions in the crop - livestock systems of sub-Saharan Africa

Livestock–water productivity (LWP) refers to a set of innovations that could contribute towards reducing the amount of water needed per unit of output generated. But what does it take to get these ideas adopted by livestock keepers in crop–livestock systems? In this paper, we treat LWP as an innovation, and consider in what ways it may be introduced and/or developed among the crop–livestock agricultural systems by drawing on successful examples of change. In the first part of this paper, we introduce relevant tenets of the innovation systems literature, and introduce a three-component conceptual framework for the adoption of LWP technologies. In the second part, we describe three successful cases of resources use change. In the final section, we identify what we consider to be necessary components in successful change, and relate these to LWP. We argue that, in the under-regulated crop–livestock systems of eastern Africa, key areas for focus include social institutions, political systems, gender and leadership.