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.

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 water productivity: feed resourcing, feeding and coupled feed-water resource data bases

While water requirement for livestock is widely perceived as daily drinking water consumption, ~100 times more water is required for daily feed production than for drinking water. Increasing livestock water productivity can be achieved through increasing the water-use efficiency (WUE) of feed production and utilisation. The current paper briefly reviews water requirements for meat and milk production and the extent of, and reason for, variations therein. Life-cycle analysis (LCA) can reveal these variations in WUE but LCA are not tools that can be employed routinely in designing and implementing water-use-efficient feed resourcing and feeding strategies. This can be achieved by (1) choosing agricultural by-products and crop residues where water applications are partitioned over several products for example grain and straw (or food and fodder) contrary to planted forage production where water and land have to be exclusively allocated to fodder production, (2) select and breed WUE crops and forages and exploit cultivar variations, (3) increase crop productivity by closing yield gaps; and (4) increase per animal productivity to reduce the proportion of feed (and therefore water) allocated for maintenance requirement rather than productive purposes. Feed-mediated WUE of dairy buffalo production on almost completely (94%) by-product-based feeding systems could be reduced from 2350 to 548 L of water per kg of milk by the combined effect of increasing basal ration quality in a total mixed ration, which resulted in increased milk yield of ~30%, and by increasing crop productivity from 1 t (actual crop yield) to 3 t (potential crop yield). Exemplary, multi-dimensional sorghum improvement using staygreen quantitative trait loci (QTL) introgression for concomitant improvement of WUE of grain and stover production and stover fodder quality showed opportunities for further linked improvement in WUE of crop and livestock production. Metabolisable energy (ME) yield under water stress conditions measured in lysimeters, (which measure crop water transpired) ranged QTL dependent from 16.47 to 23.93 MJ ME per m3 H2O. This can be extrapolated to 8.23–11.97 MJ ME per m3 H2O evapotranspired under field conditions. To mainstream improvement in WUE of feed resourcing and feeding, the paper suggests the combination of feed resource databases with crop–soil–meteorological data to calculate how much water is required to produce the feed at the available smallest spatial scale of crop–soil–meteorological data available. A framework is presented of how such a tool can be constructed from secondary datasets on land use, cropping patterns and spatially explicit crop–soil–meteorological datasets.

Livestock water productivity in the Blue Nile Basin: assessment of farm scale heterogeneity

A recent study of the livestock water productivity (LWP), at higher spatial scales in the Blue Nile Basin, indicated strong variability across regions. To get an insight into the causes of this variability, we examined the effect of farm households’ access to productive resources (e.g. land, livestock) on LWP in potato–barley, barley–wheat, teff–millet and rice farming systems of the Gumera watershed (in the Blue Nile Basin, Ethiopia). We randomly selected 180 farm households. The sizes of the samples, in each system, were proportional to the respective system’s area. Then we grouped the samples, using a participatory wealth ranking method, into three wealth groups (rich, medium and poor) and used structured and pre-tested questionnaires to collect data on crops and livestock management and applied reference evapotranspiration (ET0) and crop coefficient (Kc) approaches to estimate depleted (evapotranspiration) water in producing animal feed and food crops. Then, we estimated LWP as a ratio of livestock’s beneficial outputs to water depleted. Our results suggest strong variability of LWP across the different systems: ranging between 0.3 and 0.6 US$ m−3 year−1. The tendency across different farming systems was comparable with results from previous studies at higher spatial scales. The range among different wealth groups was wider (0.1 to 0.6 US$ m−3 year−1) than among the farming systems. This implies that aggregating water productivity (to a system scale) masks hotspots and bright spots. Our result also revealed a positive trend between water productivity (LWP and crop water productivity, CWP) and farm households’ access to resources. Thus, we discuss our findings in relation to poverty alleviation and integrated land and water management to combat unsustainable water management practices in the Blue Nile Basin.

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.

Livestock water productivity: implications for sub-Saharan Africa

Water is essential for agriculture including livestock. Given increasing global concern that access to agricultural water will constrain food production and that livestock production uses and degrades too much water, there is compelling need for better understanding of the nature of livestock–water interactions. Inappropriate animal management along with poor cropping practices often contributes to widespread and severe depletion, degradation and contamination of water. In developed countries, diverse environmental organisations increasingly voice concerns that animal production is a major cause of land and water degradation. Thus, they call for reduced animal production. Such views generally fail to consider their context, applicability and implications for developing countries. Two global research programs, the CGIAR ‘Comprehensive Assessment of Water Management and Agriculture’ and ‘Challenge Program on Water and Food’ have undertaken studies of the development, management and conservation of agricultural water in developing countries. Drawing on these programs, this paper describes a framework to systematically identify key livestock–water interactions and suggests strategies for improving livestock and water management especially in the mixed crop–livestock production systems of sub-Saharan Africa. In contrast to developed country experience, this research suggests that currently livestock water productivity compares favourably with crop water productivity in Africa. Yet, great opportunities remain to further reduce domestic animals’ use of water in the continent. Integrating livestock and water planning, development and management has the potential to help reduce poverty, increase food production and reduce pressure on the environment including scarce water resources. Four strategies involving technology, policy and institutional interventions can help achieve this. They are choosing feeds that require relatively little water, conserving water resources through better animal and land management, applying well known tools from the animal sciences to increase animal production, and strategic temporal and spatial provisioning of drinking water. Achieving integrated livestock–water development will require new ways of thinking about, and managing, water by water- and animal-science professionals.