Milk urea concentration as an indicator of ammonia emission from dairy cow barn under restricted grazing
| Autor: | G. André, G. van Duinkerken, M.C.J. Smits, L.B.J. Sebek, Jan Dijkstra |
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| Jazyk: | angličtina |
| Rok vydání: | 2011 |
| Předmět: |
Time Factors
manure stores Animal Nutrition animal diseases Randomized block design Pasture Eating Ammonia chemistry.chemical_compound Animal science ventilation rate Grazing Genetics Animals Urea dietary nitrogen volatilization nitrogen-excretion geography geography.geographical_feature_category Volatilisation model Research Temperature food and beverages Housing Animal Diervoeding livestock buildings Milk Agronomy chemistry cattle Slurry WIAS Environmental Pollutants Animal Science and Zoology protein Barn (unit) Wageningen Livestock Research houses Food Science Onderzoek |
| Zdroj: | Journal of Dairy Science, 94(1), 321-335 Journal of Dairy Science 94 (2011) 1 |
| ISSN: | 0022-0302 |
| DOI: | 10.3168/jds.2009-2263 |
| Popis: | Bulk milk urea concentration was evaluated to assess its potential as an indicator of ammonia emission from a dairy cow barn in a situation with restricted grazing. An experiment was carried out with a herd of, on average, 52 Holstein-Friesian dairy cows. The cows were housed in a naturally ventilated barn with cubicles and a slatted floor, were fed ensiled forages and feed supplements, and each day were allowed 8.5 h of grazing. The experiment was a balanced randomized block design, replicated 3 times. The experimental factor was the bulk milk urea level, which was adjusted to levels of 15, 35, and 55 mg of urea per 100 g of milk, respectively, by changing the level of nitrogen fertilization of the pasture, the herbage mass and grass regrowth age, and the level and type of feed supplement. Ammonia emission from the barn was measured using sulfur hexafluoride as the tracer gas. Ammonia emission generally increased upon an increase in adjusted milk urea levels. A dynamic regression model was used to predict ammonia emission from bulk milk urea concentration, temperature, and a slurry mixing index. This model accounted for 66% of the total variance in ammonia emission and showed that emission increases exponentially with increasing milk urea concentration. At levels of 20 and 30 mg of urea per 100 g of milk, ammonia emission increased by about 2.5 and 3.5%, respectively, when milk urea concentration increased by 1 mg/100 g. Furthermore, emissions from the barn increased 2.6% when temperature increased by 1°C. The study showed that bulk milk urea concentration is a useful indicator for ammonia emissions from a dairy cow barn in a situation with restricted grazing. |
| Databáze: | OpenAIRE |
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