An assessment of ammonia emissions from dairy facilities in Pennsylvania

1. An assessment of ammonia emissions from dairy facilities in Pennsylvania J.D. Ferguson, Z. Dou, and C.F. Ramberg, Jr. University of Pennsylvania Center for Animal Health and Productivity Abstract A survey of 747 dairy farms in Pennsylvania was used to construct demographics for the average Holstein dairy farm. The average Holstein dairy farm was composed of 69 lactating cows, 11 nonlactating, pregnant cows, and 52 nonlactating, nonparous (heifers) animals. Milk production averaged 27.4 kg (60.2 lb). Crop acres averaged 71.6 hectares. Milk production, crop acres and type and average county yields, and herd animal groups were used to construct a typical feeding program for these farms. Typical rations were constructed for 6 feeding groups (3 milk production groups, 1 nonlactating group, 2 heifer groups) to meet milk production, pregnancy and growth requirements. Rations were constructed based on three forage qualities (excellent, average, and poor) typically observed on PA dairy farms. Data for animal description (milk production, body weight, growth, and pregnancy status) and ration components and amounts consumed for each animal group were input into the excretion model of the Dairy Nutrient Planner computer program (DNP). Excretion of fecal N, urinary N, total P and K, and fecal dry matter were for each animal group was output and used to assess potential volatile losses of N. Work at the Marshak Dairy, New Bolton Center, indicates the majority of urinary N is lost as ammonia rapidly from dairy facilities. Based on this observation, the losses of N as ammonia were estimated to be 4.74, 4.46, and 4.42 metric tons per year for the farms with excellent, average, and poor quality forages. Volatile losses of N may most reduced by controlling levels of urea in urine. Urinary N may be reduced through dietary manipulation of protein and carbohydrate sources. Conversion of urea to ammonia may be reduced by altering the pH of barn floors and gutters. Entrapment of ammonia may be accomplished by acidification of manure slurry. Objective: This study was conducted to determine the potential loss of N from PA dairy farms as ammonia N Background:Data from a survey of management practices on 747 Holstein farms in PA was used to estimate feeding programs on these farms. Previous work at New Bolton Center had identified that N excreted in urine as urea was rapidly converted to ammonia by bacterial activity. Therefore prediction of urinary N would enable estimates of ammonia losses from animal facilities. • Materials and Methods • Farm Selection for manure sampling • Farms with complete data for herd demographics, feed management and selection, manure • handling and storage, and cropping were used for the study from survey data • Ration Construction and Excretion Predicition •  Crop acres and average yield per acre for the county were used to estimate intake of crop dry matter for each animal group •  Herd demographics consisted of three lactating groups (high, medium, low) of a total of 69 cows, 11 adult nonlactating cows, and 52 growing animals •  Rations were balanced using farm grown ingredients and purchased grains and protein supplements based on feeds identified by the farm survey •  Rations were input to the DNP, a computer model which predicts urinary and fecal excretion of N, P and K based on ration composition. • Average rations were used to estimate yearly losses of N, P and K in animal waste. Urinary N was assumed to be converted to ammonia and lost from animal housing

2. The fraction of herds feeding the following feeds were as follows: Feeds Milk cows Dry cows Heifers Corn silage .950 .862 .823 Legume hay .757 .211 .333 Legume haylage .650 .190 .219 Mixed hay .285 .271 .393 Mixed haylage .206 .099 .118 Grass hay .149 .713 .548 Grass haylage .053 .051 .059 Small grain silage .077 .059 .070 Ryelage .168 .100 .138 Sorghum Silage .020 .028 .027 Pasture .687 .748 .715 Feeds Milk cows Dry cows Heifers High moisture corn .519 .284 .252 Dry corn .575 .542 .573 High moisture small grains .031 .014 .015 Dry small grains .363 .307 .348 Dairy feed .172 .137 .120

3. Feeds Milk cows Dry cows Heifers Protein supplements Whole soybeans .406 .084 .077 SBM .618 .405 .414 Distillers dry grains .300 .093 .075 Whole cottonseeds .334 .034 .023 Corn gluten meal .086 .018 .020 Blood meal .065 .009 .007 Fish meal .049 .003 .004 Animal/marine/blend .074 .022 .011 Protein feed .350 .119 .132 Feeds Milk cows Dry cows Heifers Byproducts Soy hulls .144 .050 .028 Wet brewers grains .037 .013 .012 Dried brewers grains .044 .014 .021 Corn hominy .050 .020 .012 Corn gluten bran .008 .001 . Bakery waste .047 .010 .011 Based on acres committed to each crop and forage to concentrate intakes of 50/50 for milk cows and 75/25 for dry cows and heifers, the average forage intake was estimated as follows (lbs of dry matter per cow per day): Milk cows Dry cows Heifers Corn silage 11.92 11.70 7.20 Legume/legume forage 7.93 .90 4.79 Grass forage .92 7.79 .55 Small grain forage .10 .10 .06 Corn 12.96 4.24 2.61 Small grains 1.78 .54 .33 Soybeans 2.09 .68 .42 Soy meal 3.00 1.00 1.00 Distiller's grains 1.50 Protein feeds .75 Crude Protein 16.5% 12.3% 14.5% Forage Quality Influence on Excretion Metric tons/year Excellent Average Poor Fecal N 6.75 6.78 6.89 Urinary N 4.74 4.46 4.42 P 2.25 2.21 2.40 K 10.79 9.46 11.18 Note - all urinary N subject to volatile loss! Conclusion: As much as 40% of excreted N leaves the farm as ammonia prior to manure collection and storage Controlling urinary N through feeding programs could substantially reduce ammonia losses from dairy farms