The use of plant bioactive compounds to reduce greenhouse gas emissions from farmed ruminants

This chapter focuses on the opportunity to use plant bioactive compounds in ruminant diets for their potential to mitigate greenhouse gas emissions, particularly enteric methane. Nitrous oxide emissions related to urinary nitrogen waste are addressed when information is available. The main families considered are plant lipids and plant secondary compounds (tannins, saponins, halogenated compounds and essential oils). The effects of these compounds in vivo, their mechanisms of action, and their potential adoption on farms are discussed, and future trends in this research area are highlighted.

Quantifying the contribution of livestock health issues to the environmental impact of their production systems

The focus of this chapter is on the environmental impact consequences of endemic livestock health challenges that lead to deterioration in animal health, and on the potential impacts arising from their mitigations. The first part of the chapter concentrates on the potential of animal health to affect the environmental impact of livestock systems. Subsequently, it reviews the literature to date which has quantified the impact of health challenges for the environmental impacts of livestock systems. The potential of successful health interventions to mitigate negative environmental impacts represents a point of synergy between concerns around environmental sustainability and animal welfare, both of which represent 'hot topics' in the discourse surrounding the livestock industry and its sustainability. The challenges associated with modelling health interventions and their potential to mitigate environmental impacts constitute the last section in the chapter.

The use of feed supplements to reduce livestock greenhouse gas emissions: direct-fed microbials

This chapter aims to outline the strategy of using feed supplements for the reduction of greenhouse gas emissions (GHG) in ruminants, including methane (CH4), carbon dioxide and nitrous oxide, given that feed intake is an important variable in predicting these emissions. Focus will be given to direct-fed microbials, a term reserved for live microbes which can be supplemented to feed to elicit a beneficial response. The viability of such methods will also be analysed for their use in large scale on-farm operations.

The impact of improving feed efficiency on the environmental impact of livestock production

This chapter examines the impact of improving feed efficiency on the environmental impact of livestock production. It starts by discussing the relation between greenhouse gases and dairy production, highlighting how important it is to the dairy sector to find ways of decreasing greenhouse gas output. The chapter then moves on to discuss the origins of methane and reactive nitrogen excretions in ruminants. A section on improving feed conversion efficiency is also included, which is then followed by a review of the nutritional practices that can be used to enhance feed conversion efficiency and decrease methane excretion. The chapter also examines the nutritional practices that can be used to increase milk protein efficiency and nitrous oxide excretion as well. Discussions on genetics and feed conversion efficiency and postabsorptive metabolism and feed conversion efficiency are also provided.

Greenhouse gas emissions from livestock production: modelling methods, methane emission factors and mitigation strategies

This chapter discusses the systems analysis and life cycle assessment modelling approaches and also looks at a range of model applications. These applications include use within the national inventories of various countries across species including discussions around the use of different emission factors. The chapter concludes with applications to quantify emissions at the farm level and a discussion around some of the mitigation strategies that have been modelled previously.

Measuring methane emissions from livestock

This chapter looks at the key techniques used for measurement of CH4 and other gas emissions from livestock production, ranging from individual animal measurements to herd scale measurements for grazing animals and whole farm emissions such as feedlots. Individual animal measurement techniques discussed include whole-animal respiration chambers and head capture measurement. Herd scale measurements include micrometeorological methods and the eddy covariance (EC) technique.

Sustainable nitrogen management for housed livestock, manure storage and manure processing

This chapter reviews sustainable nitrogen management for housed livestock, manure storage and manure processing. The chapter begins by discussing the various forms nitrogen can take, focusing specifically on ammonia, nitrous oxide and di-nitrogen. It then goes on to review livestock feeding and housing for dairy and beef cattle, pigs and poultry. The chapter also examines manure storage, treatment and processing by discussing the principles of emissions produced from these processes as well as mitigation measures that can be used. It also addresses the best practices and priority measures for livestock feeding, housing and manure storage, treatment and processing.

The contribution of animal breeding to reducing the environmental impact of livestock production

Animal production is responsible for 14.5% of total anthropogenic greenhouse gas (GHG) emissions. Approximately half of these emissions originate directly from animal production, whereas the other half comes from feed production. Animal breeding aims at improving animal production and efficient use of resources, which results in a reduction of environmental impact. In this chapter we quantify the contribution of animal breeding to reducing the environmental impact of the four major livestock species in the Netherlands, namely laying hens, broilers and pigs (all monogastrics), and dairy cattle (ruminants). For eggs, and broiler and pig meat we focussed on GHG emissions and nitrogen and phosphorus efficiency, whereas for dairy we focussed on enteric methane emissions, an important contributor to GHG emissions. Results showed that current selection strategies on increased (feed) efficiency indirectly reduces environmental impact per unit of animal product by about 1% per year. If the aim is to directly select on environmental traits, recording of new traits is required; e.g., nitrogen and phosphorus contents of meat and eggs, and methane emission of individual dairy cows.

Developments in anaerobic digestion to optimize the use of livestock manure

The purpose of this chapter is to discuss developments in anaerobic digestion (AD) to optimize use of livestock manure, particularly the use of livestock manure in the production of biogas. It also discusses the use of biogas slurry and residues. The chapter shows the how AD can play an important role in promoting circular agriculture. It includes a case study on the use of AD in practice in Henan Province in China.

Modifying the rumen environment to reduce greenhouse gas emissions

Ruminants were among the first domesticated animals and have been providing food, leather, wool, draft and by-products to humanity for at least 10,000 years. However, rumen methanogens reduce CO2 to CH4 in association with other rumen microbes that generate substrates for methanogenesis. Consequently, other rumen microbiota can directly and indirectly impact the abundance and activity of methanogens. Enteric methanogenesis from ruminants accounts for approximately 6% of total anthropogenic greenhouse gases emissions and can represent from 2 to12% of the host’s gross energy intake. A myriad of strategies to mitigate CH4 emissions have been investigated, but few have been adopted by industry. This chapter reviews rumen- and feed-associated factors affecting CH4 production and outlines the challenges associated with achieving a reduction in enteric CH4 emissions. The pros and cons of these strategies are discussed in an attempt to define the best approaches to mitigate CH4 emissions from ruminant production systems.