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

Drackley, J. K. and Reynolds, C. K. ORCID: https://orcid.org/0000-0002-4152-1190 (2021) The impact of improving feed efficiency on the environmental impact of livestock production. In: Baines, R. (ed.) Reducing greenhouse gas emissions from livestock production. Burleigh Dodds Series in Agricultural Science. Burleigh Dodds Science Publishing. ISBN 9781786764393 doi: 10.19103/AS.2020.0077.10

Abstract/Summary

As ruminants, cattle are marvellous bioreactors that, through symbiotic rumen fermentation, convert cellulosic plant biomass and other organic materials inedible to humans into high-quality animal proteins for human nutrition. Nevertheless, the conversion is of course not 100% efficient, and so varying quantities of waste products such as carbon dioxide (CO2), methane (CH4), and reactive nitrogenous compounds are emitted. As such, producers of ruminant livestock must strive to maximise output for each unit of input, both to enhance enterprise profitability and to minimise the environmental impacts of dairy and meat production. A key metric of this system efficiency is feed conversion efficiency (FCE), which for milk production is usually defined as energy-corrected milk divided by feed dry matter intake (DMI) and for meat production is live weight gain divided by feed DMI. FCE per se also has a genetic component, which can be measured by residual feed intake (RFI). RFI is defined as the actual intake minus the feed intake expected to meet requirements for milk production, growth, reproduction and maintenance (Koch et al., 1963). FCE has been widely used in beef production, as well as in pork and poultry production, to monitor the efficiency of feed utilization for growth. The dairy industry also recognizes the importance of the metric in management systems, but in addition to milk yield, there is also a need to account for body tissue loss and gain in calculating the efficiency of a lactating dairy cow (VandeHaar, 1998). Maximising the output of saleable product per unit of resource input is a standard principle of all manufacturing industries that relate directly to profitability. Another way of stating this relationship is that producers must minimise their unit cost of product and optimise their total unit output (Colman et al., 2011). Relative to the reduction of greenhouse gases and contaminants of water, the simple concept is that the more carbon and nitrogen (N) in feedstuffs captured in the product, the less carbon and N are available for conversion into waste products (e.g. CO2, CH4 or urea N). By this principle, increasing milk or meat output from the same feed input requires changes in digestibility or postabsorptive nutrient metabolism with the result that less greenhouse gases and other waste products are produced per unit of milk or meat. The same principles apply to phosphorus and other nutrients that may become pollutants when they escape the animal through feaces or urine. This chapter will focus on the efficiency of milk production by dairy cattle related to nutrition and geneticsfocussing on how improving FCE can decrease the greenhouse gas burden of milk production and how FCE can be improved.

Item Type	Book or Report Section
URI	https://reading-clone.eprints-hosting.org/id/eprint/101160
Item Type	Book or Report Section
Refereed	Yes
Divisions	Life Sciences > School of Agriculture, Policy and Development > Department of Animal Sciences > Animal, Dairy and Food Chain Sciences (ADFCS)- DO NOT USE
Publisher	Burleigh Dodds Science Publishing
Publisher Statement	Recent IPCC reports have highlighted the environmental impact of livestock production as a major source of non-CO2 emissions: methane (CH4), nitrous oxide (N2O) and ammonia (NH3). The livestock sector must react to these reports and develop or implement methods that can reduce greenhouse (GHG) emissions from livestock production. Reducing greenhouse gas emissions from livestock production provides authoritative reviews on measuring GHG emissions from livestock as well as the range of methods that can be applied to reduce emissions, ranging from breeding to animal health and manure management. The collection also reviews nutritional approaches such as improving forage quality and the use of plant bioactive compounds and other feed supplements to limit emissions by modifying the rumen environment. Drawing in an international range of expert authors, Reducing greenhouse gas emissions from livestock production summarises what we can do to make livestock production more sustainable and viable for the future. It will be a major reference for the livestock (particularly dairy) science research community, environmental scientists, government and other agencies tackling the challenge of climate change, as well as companies involved in livestock production and processing of dairy and meat products. Key features A comprehensive review of both the causes of greenhouse gas emissions from livestock and the range of ways these emissions can be reduced Particularly strong focus on the range of nutritional strategies, from forage and silage to feed supplements such as plant bioactive compounds and direct-fed microbials as well as inhibitors and vaccines Covers other approaches such as genetics and selection, improved husbandry as well as manure management
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