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°C) Temperatures
- Lifeng Lia,
- Joby Cyriacb,
- Katharine F. Knowltonb,
- Linsey C. Marrc,
- Susan W. Gayd,
- Mark D. Haniganb and
- Jactone Arogo Ogejo *a
- a Dep. of Biological Systems Engineering, Virginia Polytechnic Institute and State Univ., Blacksburg, VA 24061
b Dep. of Dairy Science, Virginia Polytechnic Institute and State Univ., Blacksburg, VA 24061
c Dep. of Civil and Environmental Engineering, Virginia Polytechnic Institute and State Univ., Blacksburg, VA 24061
d current address, 179 Hunters Path, Bellefonte, PA 16823
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.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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