The goal of this review was to analyze published data related to mitigation of enteric methane (CH 4 ) emissions from ruminant animals to document the most effective and sustainable strategies. Increas- ing forage digestibility and digestible forage intake was one of the major recommended CH 4 mitigation practices. Although responses vary, CH 4 emissions can be reduced when corn silage replaces grass silage in the diet. Feeding legume silages could also lower CH 4 emissions compared to grass silage due to their lower fiber concentration. Dietary lipids can be effec- tive in reducing CH 4 emissions, but their applicabil- ity will depend on effects on feed intake, fiber digest- ibility, production, and milk composition. Inclusion of concentrate feeds in the diet of ruminants will likely decrease CH 4 emission intensity (Ei; CH 4 per unit animal product), particularly when inclusion is above 40% of dietary dry matter and rumen function is not impaired. Supplementation of diets containing medium to poor quality forages with small amounts of concen- trate feed will typically decrease CH 4 Ei. Nitrates show promise as CH 4 mitigation agents, but more studies are needed to fully understand their impact on whole-farm greenhouse gas emissions, animal productivity, and animal health. Through their effect on feed efficiency and rumen stoichiometry, ionophores are likely to have a moderate CH 4 mitigating effect in ruminants fed high-grain or mixed grain-forage diets. Tannins may also reduce CH 4 emissions although in some situations intake and milk production may be compromised. Some direct-fed microbials, such as yeast-based products, might have a moderate CH 4 -mitigating effect through increasing animal productivity and feed efficiency, but the effect is likely to be inconsistent. Vaccines against rumen archaea may offer mitigation opportunities in the future although the extent of CH 4 reduction is like- ly to be small and adaptation by ruminal microbes and persistence of the effect is unknown. Overall, improv- ing forage quality and the overall efficiency of dietary nutrient use is an effective way of decreasing CH 4 Ei. Several feed supplements have a potential to reduce CH 4 emission from ruminants although their long-term effect has not been well established and some are toxic or may not be economically feasible.

/pdf/special-topics-mitigation-of-methane-and-nitrous-oxide-3picl514fh.pdf

Special topics--Mitigation of methane and nitrous oxide emissions from animal operations: I. A review of enteric methane mitigation options.

Prepartum behavior and dry matter intake identify dairy cows at risk for metritis

Invited review: The welfare of dairy cattle--key concepts and the role of science.

Animal production is a significant source of greenhouse gas (GHG) emissions worldwide. Depending on the accounting approaches and scope of emissions covered, estimates by various sources (IPCC, FAO, EPA or others) place livestock contribution to global anthropogenic GHG emissions at between 7 and 18 percent. The current analysis was conducted to evaluate the potential of nutritional, manure and animal husbandry practices for mitigating methane (CH4) and nitrous oxide (N2O) – i.e. non-carbon dioxide (non-CO2) – GHG emissions from livestock production. These practices were categorized into enteric CH4, manure management and animal husbandry mitigation practices. Emphasis was placed on enteric CH4 mitigation practices for ruminant animals (only in vivo studies were considered) and manure mitigation practices for both ruminant and monogastric species. Over 900 references were reviewed; and simulation and life cycle assessment analyses were generally excluded. In evaluating mitigation practices, the use of proper units is critical. Expressing enteric CH4 energy production on gross energy intake basis, for example, does not accurately reflect the potential impact of diet quality and composition. Therefore, it is noted that GHG emissions should be expressed on a digestible energy intake basis or per unit of animal product (i.e. GHG emission intensity), because this reflects most accurately the effect of a given mitigation practice on feed intake and the efficiency of animal production. EntErIC CH4 MItIgAtIon prACtICEs Increasing forage digestibility and digestible forage intake will generally reduce GHG emissions from rumen fermentation (and stored manure), when scaled per unit of animal product, and are highly-recommended mitigation practices. For example, enteric CH4 emissions may be reduced when corn silage replaces grass silage in the diet. Legume silages may also have an advantage over grass silage due to their lower fibre content and the additional benefit of replacing inorganic nitrogen fertilizer. Effective silage preservation will improve forage quality on the farm and reduce GHG emission intensity. Introduction of legumes into grass pastures in warm climate regions may offer a mitigation opportunity, although more research is needed to address the associated agronomic challenges and comparative N2O emissions with equivalent production levels from nitrogen fertilizer. Dietary lipids are effective in reducing enteric CH4 emissions, but the applicability of this practice will depend on its cost and its effects on feed intake, production and milk composition. High-oil by-product feeds, such as distiller’s grains, may offer an economically feasible alternative to oil supplementation as a mitigation practice, although their higher fibre content may have an opposite effect on enteric CH4, depending on basal diet composition. Inclusion of concentrate feeds in the diet of ruminants will likely decrease enteric CH4 emissions per unit of animal product, particularly when above 40 percent of dry matter intake. The effect may depend on type of ‘concentrate’ inclusion rate, production response, impact on fibre digestibility, level of nutrition, composition of the basal diet and feed processing.

Mitigation of greenhouse gas emissions in livestock production - A review of technical options for non-CO2 emissions

http://www.remugants.cat/2/upload/etologia_comportament_animal_alimentacia_jdsci_2005.pdf

M.I. Rind

Papers

The effects on production and behavior of mixing uniparous and multiparous cows.

The effects of social dominance on the production and behavior of grazing dairy cows offered forage supplements.

The effects of frequency of feeding a total mixed ration on the production and behavior of dairy cows.