GLOBAL WARMING Distribution of solar radiation entering the atmosphere –20% reflected by the atmosphere –20% absorbed by the atmosphere –51% is absorbed by the earth –9% is reflected by the earth and dust Distribution of emitted infrared radiation –17% escapes atmosphere –83% is held and re-emitted Maintains atmospheric temperature Increased concentrations of CO 2, CH 4 and other gases increase amounts of infrared radiation that is trapped and re-emitted –Increases atmospheric temperature

UNDERSTANDING GLOBAL WARMING

EVIDENCE FOR GLOBAL WARMING Since 1860 –CO 2 concentration in atmosphere has increased by 24% –CH 4 concentration in atmosphere has doubled –Mean global temperature has increased by 2 o F 10 hottest days on record have occurred since 1980

ENVIRONMENTAL EFFECTS OF GLOBAL WARMING Average temperature will increase by 2 to 6 o F in next century An increase in extreme weather events –Droughts, floods etc. –Concern for insurance industry Sea levels will increase.5 to 3 feet –Threaten coastal resources, wetlands, and islands –Saline water will pollute water supplies of coastal cities Increased range of diseases associated with tropical climates –Malaria, dengue fever, and yellow fever will occur at higher latitudes Heat stress and death of humans and animals –Particularly a concern in elderly Increases air conditioning needs –Angus cattle? Rapidly reproducing species of weeds, rodents, insects, bacteria and viruses may occur at higher latitudes Crop may be susceptible to new insect and disease problems Reduced forest health and changes in tree species

GASES ASSOCIATED WITH GLOBAL WARMING Current Rate of Half % of US GHG Relative concentration increase life GHF contribution GH effect ____Gas____ (ppmV) (%/yr) _(yr)_ emissions __%__ ( /kg) (_/mole) Carbon dioxide Methane Nitrous oxide Fluorinated hydrocarbons Water vapor Sources –Carbon dioxide Hydrocarbon combustion –Methane Livestock, manure, wastewater treatment, landfills and fuel production –Nitrous oxide Hydrocarbon combustion, industrial processes, denitrification of manure and soil N –Fluorinated hydrocarbons Refrigeration, dry cleaning, chemical manufacturing –Water vapor Increased temperature from other GHG

LIVESTOCK AGRICULTURE’S ROLE IN GREENHOUSE GASES Nitrous oxide –Difficult to determine amount –Likely to be high in animals that excrete high concentrations of Nitrogen N 2 O emissions are 10 times greater from fields with manure application compared to unfertilized fields N 2 O emissions can be considerable from fields or pastures with soil compaction under wet conditions

Methane CH 4 % of million metric % of anthropogenic Sources tons/yr total sources Natural Wetland Oceans Termites Burning Industrial Gas and oil Coal Charcoal Landfills Waste water treatment Agricultural Rice Livestock Manure Burning

Implications –Anthropogenic sources contribute 66% of all methane emissions –Livestock production and manure are the largest anthropogenic sources –Methane emissions from anthropogenic sources are increasing 1%/yr Methane emissions from livestock in Iowa Direct emissions Manure % of total tons/year Cattle 352,000 14, Swine 22, , Poultry NA 1,770.4 Sheep 4, Horse

GREENHOUSE GAS PRODUCTION IN LIVESTOCK Methane –Produced by anerobic fermentation of carbohydrates in the rumen, large intestine, or stored manure –Represents a loss of 4 to 10% of the dietary energy in ruminant animals

Methane production Starch Cellulose (In grains) (In plant fiber) Digested by bacterial enzymes Glucose (a simple sugar) In aerobic organisms run through electron transport to produce Metabolized by bacteria through ATP and H 2 O Glycolysis NADH 2 Pyruvate (a 3-C intermediate) In anerobic organisms In aerobic organisms run through TCA cycle producing more NADH 2 used NADH 2 used for ATP production in electron transport Acetic acid Propionic acid Butyric acid CH 4 (Volatile fatty acids) (Belched gases by eructation)

VOLATILE FATTY ACIDS In animals –Absorbed through wall of the rumen in ruminants or large intestine of ruminants and nonruminants –Metabolized by the animal for energy Main source of energy for ruminants –Provide 70% of the energy in ruminants –Production of different VFAs and methane vary with diet In manure –Volatile fatty acids contribute to manure odor Acetic acid and propionic acid smell like vinegar Butyric acid smells like rancid butter

FACTORS AFFECTING METHANE AND VFA PRODUCTION IN THE RUMEN OF RUMINANTS Dietary factors –High forage levels of diet Promotes cellulose digesting bacteria in rumen Increases production of acetic acid and methane Decreases production of propionic acid –High grain levels of diet Promotes starch digesting bacteria in rumen Increases production of propionic acid Decreases production of acetic acid and methane –Fine grinding or pelleting of forage Decreases the amount of time the cattle spend chewing Decreases saliva flow and secretion of the buffer, sodium bicarbonate. Allows rumen pH to decrease Decreases growth of cellulolytic bacteria Decreases production of acetic acid and methane Increases production of propionic acid

–Increasing forage maturity Causes more chewing Increases saliva flow and secretion of buffer, sodium bicarbonate Increases rumen pH Increases growth of cellulolytic bacteria Increases production of acetic acid and methane Decreases production of propionic acid –Feeding fats containing unsaturated fatty acids An unsaturated fatty acid is a fatty acid that has one or more double bonds in the chain The rumen bacteria use hydrogens to saturate (replace double bonds with hydrogens) unsaturated fatty acids Example H H H + H H H H H C C C C COOH H H H H H H H H Unsaturated fatty acid Saturated fatty acid Results –Decreased acetic acid and methane production –Increased propionic acid production Important to feed no more than 5% fat to ruminants

–Feeding ionophores Antibiotics that include –Monensin, sold as Rumensin –Lasalocid, sold as Bovatec Increase propionic acid production Decrease acetic acid and methane production Production factors –Rate of gain Regardless of diet, ruminants produce methane each day at a maintenance level –Every day the cattle or sheep is on the farm, they produce more methane The faster an animal grows or the more milk is produced, the lower the amount of methane produced per unit of meat or milk produced

N 2 O PRODUCTION N 2 O is produced during denitrification of NO 3 –Occurs under anerobic conditions Wet, compacted soils Anerobic lagoons –Amount associated with livestock production is directly related to amounts of N excreted.

FACTORS AFFECTING N 2 O PRODUCTION Diet –Nonruminants Amounts of protein fed –Increased protein = increased N excretion Amino acid balance –Poor amino acid balance = increased N excretion –Ruminants Amounts of protein fed –Increased protein = increased N excretion Ratio of degraded to undegraded protein in the rumen –Increased protein degraded in rumen = increased N excretion Ratio of degradable protein to digestible carbohydrate in the rumen –High proportion of degradable protein to digestible carbohydrate = increased N excretion »Digestible carbohydrate is needed to convert degraded NH 3 into microbial protein Amino acid balance –Poor amino acid balance = increased N excretion Manure handling –Storage losses Anerobic Lagoons > Slurries > Compost

STRATEGIES TO REDUCE GHG EMISSIONS ASSOCIATED WITH LIVESTOCK PRODUCTION Production system manipulation –Limit management approaches that just maintain ruminant animals with little production Example - Backgrounding cattle –Maximize reproductive efficiency –Maximize disease control and herd health Dietary manipulation –Nonruminants Manage diet to minimize N excretion and waste –Review N section »Do not feed excess protein »Balance for amino acids »Use crystalline amino acids to create the ‘ideal’ protein »Use phase feeding with 4 or more phases »Use split sex feeding »Limit feed waste »Promote lean growth through genetic manipulation or feed additives: Ractopamine

–Ruminants Maximize the proportion of grain in the diet –Effects »Reduces CH 4 production »Increases incorporation of NH 3 into microbial protein Reduces urinary N »Increases rate of gain Reduces lb GHG/lb gain –Maximum proportions of grain »Beef feedlot – 90% »Lactating dairy cows – 50% »Consequences of excess grain feeding Beef feedlot - Acidosis, Liver abscesses Dairy cows – Low milk fat, Displaced abomasum, Laminitis –Limitation of strategy »Amount of CO 2 released during production of N-fertilizer used to produce grain Processing feeds –Grinding and pelleting »Reduces CH 4 by 20% –Steam-flaking »Reduces CH 4 by 40%

Feed ionophores –Compounds »Monensin, sold as Rumensin Do not feed to sheep »Lasalocid, sold as Bovatec –Reduces CH 4 by 28% Addition of fats to ruminant diets –Reduces CH 4 by 33% –Can’t feed more than 5% of the diet »Greater amounts adversely affect fiber digestion and feed intake Forages should be grazed or harvested when immature –Effects »Immature forages are more digestible and have less fiber than mature forages Reduces CH 4 –Implications »Use rotational grazing Reduces CH 4 by 22 to 50% compared to continuous grazing »Incorporate legume forage species in pastures Reduces CH 4 by 25% compared to grass

Utilization of production-enhancing agents –Types »Beef cattle Steroid implants (Trenbolone acetate, Estradiol) Ractopamine »Dairy cattle Bovine somatotropin –Effects »Increases incorporation of amino acids into animal protein Reduce N excretion »Reduces GHG/lb product by increasing production Reduces CH 4 /lb product by 4% Manage protein nutrition to minimize N excretion –Review N strategies –Strategies »Reduce CP of diet Reducing CP concentration of dairy cow from 17.5 to 12.5% CP: Reduce N 2 O by 78% »Lower the Rumen Degradable Protein:Undegradable protein ratio »Increase energy concentration of the diet »Use crystalline amino acids to balance amino acids of lactating dairy cows

Manipulation through manure handling and storage –Effects of manure storage method Anerobic Slurry Stockpiled lagoon earthen pond Deep litter Compost Relative emissions CH Total GHG Very high Dominant gas CH 4 CH 4 CH 4 & N 2 O N 2 O –Effects related to: C:N ratio of the manure Separated Farm yard Deep litter manure without manure with bedding bedding C:N CH 4 (g/cow/7 weeks) 26 3 N 2 O (mg/cow/7 weeks) GHG (CO 2 equiv./cow/7 wk) O 2 exposure –Reduces CH 4 Surface area –Increased surface area increases gas release –Covers reduce gas release

–Methane capture and use Requirements –Anerobic, air-tight structure –pH control »pH 6.8 – 7.0 –High temperature »95 o F –Can not have a high concentration of NH 3 –Expense »$400 - $500/animal for large dairies (<3700 cows) »$1200/animal for small dairies (<500 cows) Production Swine Dairy Beef Poultry Gas yield, cubic ft/lb solids Energy production, BTU/hr/animal Animals needed to heat a 1500 ft 2 house

Manipulation through manure application –Frequent application of manure Prevents anerobic decay Traps C in soil organic matter or released to atmosphere as CO 2 –Timing of manure application Avoid application in later winter and early spring –Plant growth is slow »Little uptake of NO 3 –Soils are water-logged »Anerobic conditions promote denitrification of NO 3 to N 2 O –Method of application Injection of manure reduces all N emissions by 90% Band application of surface produces more N 2 O than uniform surface application

Manipulation of GHG through carbon sequestration –Plants sequester C, reducing atmospheric CO 2 –Amounts of C sequestered Crop tons C/acre Pasture 1.0 Range.12 Hay land.5 Grain 2.0 Trees 3.7 –Potential U.S. grazing lands = 524 million acres C sequestered = 60 million tons = 1.6 x all C emissions from all agriculture –C sequestered may be increased by: Incorporation of legume forage species in pastures – ton/acre/year Improved grazing management (Weed control, alternate water sites) – ton/acre/year Rotational grazing –25% increase

–Producers may economically benefit from increased C sequestration by selling C credits to industries producing Greenhouse Gases 1 C credit = 1 ton C sequestered beyond a base value before improved management = 3.67 tons CO 2 removed from the atmosphere Credits sold through markets –Chicago Climate Exchange To date, few trades because of voluntary market