Productivity gains and greenhouse gas emissions intensity in dairy systems

A previous study showed the additive methane (CH 4 )-mitigating effect of nitrate and linseed fed to non-lactating cows. Before practical application, the use of this new strategy in dairy cows requires further investigation in terms of persistency of methanogenesis reduction and absence of residuals in milk products. The objective of this experiment was to study the long-term effect of linseed plus nitrate on enteric CH 4 emission and performance in dairy cows. We also assessed the effect of this feeding strategy on the presence of nitrate residuals in milk products, total tract digestibility, nitrogen (N) balance and rumen fermentation. A total of 16 lactating Holstein cows were allocated to two groups in a randomised design conducted in parallel for 17 weeks. Diets were on a dry matter (DM) basis: (1) control (54% maize silage, 6% hay and 40% concentrate; CON) or (2) control plus 3.5% added fat from linseed and 1.8% nitrate (LIN + NIT). Diets were equivalent in terms of CP (16%), starch (28%) and NDF (33%), and were offered twice daily. Cows were fed ad libitum, except during weeks 5, 16 and 17 in which feed was restricted to 95% of dry matter intake (DMI) to ensure complete consumption of meals during measurement periods. Milk production and DMI were measured weekly. Nitrate and nitrite concentrations in milk and milk products were determined monthly. Daily CH 4 emission was quantified in open circuit respiration chambers (weeks 5 and 16). Total tract apparent digestibility, N balance and rumen fermentation parameters were determined in week 17. Daily DMI tended to be lower with LIN + NIT from week 4 to 16 (−5.1 kg/day on average). The LIN + NIT diet decreased milk production during 6 non-consecutive weeks (−2.5 kg/day on average). Nitrate or nitrite residuals were not detected in milk and associated products. The LIN + NIT diet reduced CH 4 emission to a similar extent at the beginning and end of the trial (−47%, g/day; −30%, g/kg DMI; −33%, g/kg fat-and protein-corrected milk, on average). Diets did not affect N efficiency and nutrients digestibility. In the rumen, LIN + NIT did not affect protozoa number but reduced total volatile fatty acid (−12%) and propionate (−31%) concentrations. We concluded that linseed plus nitrate may have a long-term CH 4 -mitigating effect in dairy cows and that consuming milk products from cows fed nitrate may be safe in terms of nitrate and nitrite residuals. Further work is required to optimise the doses of linseed plus nitrate to avoid reduced cows performance.

Section: Measurements and Analysesmentioning

confidence: 99%

Long-term effect of linseed plus nitrate fed to dairy cows on enteric methane emission and nitrate and nitrite residuals in milk

Guyader

Doreau

Morgavi

et al. 2016

“…Mitigation options that reduce Ei only by increasing herd productivity (e.g. animal husbandry, genetics and health management) while keeping herd GHG output constant (or increasing it proportionally less than productivity) are not included in this review, despite their great relevance among low-intensity ruminant systems (Gerber et al, 2011;FAO, 2013a and2013b).…”

Section: Introductionmentioning

confidence: 99%

Technical options for the mitigation of direct methane and nitrous oxide emissions from livestock: a review

Gerber

Hristov

Henderson

et al. 2013

324

218

Although livestock production accounts for a sizeable share of global greenhouse gas emissions, numerous technical options have been identified to mitigate these emissions. In this review, a subset of these options, which have proven to be effective, are discussed. These include measures to reduce CH 4 emissions from enteric fermentation by ruminants, the largest single emission source from the global livestock sector, and for reducing CH 4 and N 2 O emissions from manure. A unique feature of this review is the high level of attention given to interactions between mitigation options and productivity. Among the feed supplement options for lowering enteric emissions, dietary lipids, nitrates and ionophores are identified as the most effective. Forage quality, feed processing and precision feeding have the best prospects among the various available feed and feed management measures. With regard to manure, dietary measures that reduce the amount of N excreted (e.g. better matching of dietary protein to animal needs), shift N excretion from urine to faeces (e.g. tannin inclusion at low levels) and reduce the amount of fermentable organic matter excreted are recommended. Among the many 'end-of-pipe' measures available for manure management, approaches that capture and/or process CH 4 emissions during storage (e.g. anaerobic digestion, biofiltration, composting), as well as subsurface injection of manure, are among the most encouraging options flagged in this section of the review. The importance of a multiple gas perspective is critical when assessing mitigation potentials, because most of the options reviewed show strong interactions among sources of greenhouse gas (GHG) emissions. The paper reviews current knowledge on potential pollution swapping, whereby the reduction of one GHG or emission source leads to unintended increases in another.

“…It is (negatively) associated to the productivity of the system, measured in terms of output per animal, or on a whole herd basis, and based on the fact that more efficient systems or processes create less waste (including GHGs) per unit of output (Gerber et al, 2011). For example, increasing efficiency would require fewer animals and/or animals with shorter lifetimes to produce the same quantity of product.…”

Section: Contribution Of Livestock To Global Greenhouse Gas Emissionsmentioning

confidence: 99%

“…A promising approach for reducing relative CH 4 emissions per unit of output from livestock is by improving the nutrient use efficiency (Gerber et al, 2011). This can be achieved either by adding more digestible feed ingredients (e.g.…”

Section: Contribution Of Livestock To Global Greenhouse Gas Emissionsmentioning

confidence: 99%

Current available strategies to mitigate greenhouse gas emissions in livestock systems: an animal welfare perspective

Llonch

Haskell

Dewhurst

et al. 2017

115

Livestock production is a major contributor to greenhouse gas (GHG) emissions, so will play a significant role in the mitigation effort. Recent literature highlights different strategies to mitigate GHG emissions in the livestock sector. Animal welfare is a criterion of sustainability and any strategy designed to reduce the carbon footprint of livestock production should consider animal welfare amongst other sustainability metrics. We discuss and tabulate the likely relationships and trade-offs between the GHG mitigation potential of mitigation strategies and their welfare consequences, focusing on ruminant species and on cattle in particular. The major livestock GHG mitigation strategies were classified according to their mitigation approach as reducing total emissions (inhibiting methane production in the rumen), or reducing emissions intensity (Ei; reducing CH 4 per output unit without directly targeting methanogenesis). Strategies classified as antimethanogenic included chemical inhibitors, electron acceptors (i.e. nitrates), ionophores (i.e. Monensin) and dietary lipids. Increasing diet digestibility, intensive housing, improving health and welfare, increasing reproductive efficiency and breeding for higher productivity were categorized as strategies that reduce Ei. Strategies that increase productivity are very promising ways to reduce the livestock carbon footprint, though in intensive systems this is likely to be achieved at the cost of welfare. Other strategies can effectively reduce GHG emissions whilst simultaneously improving animal welfare (e.g. feed supplementation or improving health). These win-win strategies should be strongly supported as they address both environmental and ethical sustainability. In order to identify the most cost-effective measures for improving environmental sustainability of livestock production, the consequences of current and future strategies for animal welfare must be scrutinized and contrasted against their effectiveness in mitigating climate change.Keywords: animal welfare, climate change, livestock, mitigation, sustainability ImplicationsLivestock is a major contributor to climate change. In the context of an expected increase in the consumption of animal products, livestock producers must reduce their impact on the environment. A number of strategies have been proposed to reduce greenhouse gas (GHG) emissions from livestock, including ruminants. These strategies are based on changes in feeding, breeding and management practices. However, their implications for the animal's health and welfare still need to be explored. This paper tabulates and discusses the potential welfare hazards and benefits of implementing the most prominent strategies and identifies the most costeffective (GHG reduction v. welfare) strategies to mitigate climate change. Contribution of livestock to global greenhouse gas emissionsThe global livestock sector contributes significantly to anthropogenic GHG emissions. Direct emissions (through enteric fermentation and losses from manure) from livest...