Cause, conseguenze e strategie di mitigazione Proponiamo il primo di una serie di articoli in cui affronteremo l’attuale problema dei mutamenti climatici. Presentiamo il documento redatto, votato e pubblicato dall’Ipcc - Comitato intergovernativo sui cambiamenti climatici - che illustra la sintesi delle ricerche svolte su questo tema rilevante.

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Climate Change 2007: The Physical Science Basis.

Climate change 2014 - Synthesis Report

Beginning with Emlen (1966) and MacArthur and Pianka (1966) and extending through the last ten years, several authors have sought to predict the foraging behavior of animals by means of mathematical models. These models are very similar,in that they all assume that the fitness of a foraging animal is a function of the efficiency of foraging measured in terms of some "currency" (Schoener, 1971) -usually energy- and that natural selection has resulted in animals that forage so as to maximize this fitness. As a result of these similarities, the models have become known as "optimal foraging models"; and the theory that embodies them, "optimal foraging theory." The situations to which optimal foraging theory has been applied, with the exception of a few recent studies, can be divided into the following four categories: (1) choice by an animal of which food types to eat (i.e., optimal diet); (2) choice of which patch type to feed in (i.e., optimal patch choice); (3) optimal allocation of time to different patches; and (4) optimal patterns and speed of movements. In this review we discuss each of these categories separately, dealing with both the theoretical developments and the data that permit tests of the predictions. The review is selective in the sense that we emphasize studies that either develop testable predictions or that attempt to test predictions in a precise quantitative manner. We also discuss what we see to be some of the future developments in the area of optimal foraging theory and how this theory can be related to other areas of biology. Our general conclusion is that the simple models so far formulated are supported are supported reasonably well by available data and that we are optimistic about the value both now and in the future of optimal foraging theory. We argue, however, that these simple models will requre much modification, espicially to deal with situations that either cannot easily be put into one or another of the above four categories or entail currencies more complicated that just energy.

Citation classic - optimal foraging - a selective review of theory and tests

Anaerobic digestion of energy crops, residues, and wastes is of increasing interest in order to reduce the greenhouse gas emissions and to facilitate a sustainable development of energy supply. Production of biogas provides a versatile carrier of renewable energy, as methane can be used for replacement of fossil fuels in both heat and power generation and as a vehicle fuel. For biogas production, various process types are applied which can be classified in wet and dry fermentation systems. Most often applied are wet digester systems using vertical stirred tank digester with different stirrer types dependent on the origin of the feedstock. Biogas is mainly utilized in engine-based combined heat and power plants, whereas microgas turbines and fuel cells are expensive alternatives which need further development work for reducing the costs and increasing their reliability. Gas upgrading and utilization as renewable vehicle fuel or injection into the natural gas grid is of increasing interest because the gas can be used in a more efficient way. The digestate from anaerobic fermentation is a valuable fertilizer due to the increased availability of nitrogen and the better short-term fertilization effect. Anaerobic treatment minimizes the survival of pathogens which is important for using the digested residue as fertilizer. This paper reviews the current state and perspectives of biogas production, including the biochemical parameters and feedstocks which influence the efficiency and reliability of the microbial conversion and gas yield.

Biogas production: current state and perspectives

Framework Convention on Climate Change

Methane Emissions by Cattle Grazing Tannin-Containing Legumes

1205 Estimating farm-gate ammonia emissions from Canadian beef production in 1981 as compared with 2011

\n Ruminant production systems need to embrace the challenge of reducing greenhouse gas emissions to be in sync with other sectors of society that are adopting net-zero emission goals. The major greenhouse gas from ruminants is enteric methane, which contributes 3% to 5% of total global greenhouse gases. A broad range of potential mitigation strategies has been proposed to decrease methane emissions from ruminants. One promising strategy is the investigational methane inhibitor 3-nitrooxypropanol (3-NOP; DSM Nutritional Products Ltd., Kaiseraugst, Switzerland), which when fed to beef cattle, has decreased methane yield (g methane/kg dry matter intake) by 20% to 80%, depending upon the diet composition and dose. Furthermore, the decrease in methane production persists over several months. 3-NOP reduces methanogenesis in the rumen by inactivating the enzyme methyl-coenzyme M reductase used by archaea. 3-NOP is most effective when incorporated into a total mixed ration. Some advantages of 3-NOP are: only a small dose is required (1–2 g/d); no negative effects on digestibility, animal health or carcass characteristics; rapid degradation to compounds naturally occurring in the rumen (e.g., nitrate, nitrite and 1,3-propanediol); sustained efficacy over time; and risk assessments indicate residues in meat and milk are unlikely. However, 3-NOP is not yet approved for commercial use. Research studies in small pens indicate up to 5% improvement in gain:feed ratio for backgrounding and finishing cattle, although recently completed studies at a commercial feedlot indicate improvements in feed conversion may be less. This presentation will highlight the current findings of beef cattle research using 3-NOP to decrease methane emissions, with emphasis on its potential for decreasing the carbon footprint of beef.

68 Utility of 3-NOP in Beef Production Systems

Pretreatment of crop residues by ammonia fiber expansion (AFEX) alters the temporal colonization of feed in the rumen by rumen microbes.

Active dry yeast and yeast cultures based on Saccharomyces cerevisiae are widely used in commercial dairy production in North America and Europe to improve milk yield. These products have been extensively evaluated in corn-based diets, but their effectiveness may depend on the type of diet. The objective of this study was to determine the potential benefits of supplementing barley-based dairy diets with yeast for milk yield and production efficiency in dairy cows. Forty lactating Holstein dairy cows were randomly assigned to 1 of 2 treatments: 1) a control diet (no yeast) or 2) a yeastsupplemented diet. All cows were fed the control diet for 3 wk, followed by a 6-wk period on their assigned diets. The control diet consisted of 23% barley silage, 23% alfalfa silage, 6% alfalfa hay, and 48% of a ground barley-based concentrate (DM basis). For the treatment diet, an active dry yeast (Levucell SC-1077, Lallemand Animal Nutrition, Milwaukee, WI) was added to the concentrate to provide 0.5 g Levucell/d per animal (1 × 10

Karen A. Beauchemin

Papers

Methane Emissions by Cattle Grazing Tannin-Containing Legumes

1205 Estimating farm-gate ammonia emissions from Canadian beef production in 1981 as compared with 2011

68 Utility of 3-NOP in Beef Production Systems

Pretreatment of crop residues by ammonia fiber expansion (AFEX) alters the temporal colonization of feed in the rumen by rumen microbes.

S upplementing Barley- Based Dairy Cow Diets with