title: Effects of reducing dietary nitrogen on ammonia emissions from manure on the floor of a naturally ventilated free stall dairy barn at low (0-20 degrees C) temperatures.
abstract: This study was conducted to determine the potential for reducing ammonia (NH3) emissions from manure deposited on the floor of a naturally ventilated free stall barn by mid-lactation dairy cows fed reduced or normal N diets. Two crude protein (CP) diets (178 g kg(-1) [high] and 159 g kg(-1) [low] dry matter ), were used. The diets were fed to 48 Holstein cows in a replicated crossover design with two pens per diet. The NH3 emitted from the manure deposited on the floor was measured using a dynamic flux chamber. The NH3 emissions were 2.7 (+/-2.0) and 2.9 (+/-1.8) g N cow(-1) d(-1) for high and low CP diets, respectively. Ammonia emission rates were significantly affected by manure pH, TKN, and ambient air temperature (P<0.05). Dietary CP affected the feed N intake (8.7 and 7.1 kg pen(-1) d(-1) for high and low CP, respectively), but did not affect milk yield (500 and 489 kg pen(-1) d(-1) for high and low CP, respectively) and milk CP content (30 g kg(-1) for both the high and low CP diets). The N utilization efficiency was 29.0% and 32.7% for the high and low CP diets, respectively. Reducing dietary CP reduced total Kjeldahl N (TKN) in manure, but did not affect the total ammoniacal N (TAN) in manure and had no significant effect on the ammonia emission rates from the barn floor.
authors.affiliation: Department of Biological Systems Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
authors.forename: Lifeng
authors.initials: L
authors.lastname: Li
authors.forename: Joby
authors.initials: J
authors.lastname: Cyriac
authors.forename: Katharine F
authors.initials: KF
authors.lastname: Knowlton
authors.forename: Linsey C
authors.initials: LC
authors.lastname: Marr
authors.forename: Susan W
authors.initials: SW
authors.lastname: Gay
authors.forename: Mark D
authors.initials: MD
authors.lastname: Hanigan
authors.forename: Jactone Arogo
authors.initials: JA
authors.lastname: Ogejo
mesh_terms: D000393:Air Pollutants / Q000032:analysis* / Q000378:metabolism; D000641:Ammonia / Q000032:analysis* / Q000378:metabolism; D000822:Animal Husbandry; D000818:Animals; D002417:Cattle; D003080:Cold Temperature; D003612:Dairying; D004032:Diet; D005260:Female; D006863:Hydrogen-Ion Concentration; D007774:Lactation; D008372:Manure / Q000032:analysis; D008892:Milk / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*
chemical_list: D000393:Air Pollutants; D008372:Manure; D000641:Ammonia; D009584:Nitrogen