Effect of dietary crude protein modification on ammonia and nitrous oxide concentration on a tie-stall dairy barn floor

Abstract

Dietary crude protein (CP) reduction is considered a useful strategy to minimize cow N excretion and NH(3) and N(2)O emissions. The aim of the current work was to relate dietary CP modification to whole-animal N balance and subsequent NH(3) and N(2)O concentrations on a tie-stall barn floor. The effect of temperature on NH(3) and N(2)O concentration was also studied. Three Holstein mid to late lactating cows were confined in separate tie-stalls and randomly assigned to 3 diets with varying CP content [low CP (LCP): 14.1%; moderate CP (MCP): 15.9%; high CP (HCP): 16.9%]. Increasing N intake (from 438.6 to 522.8 g of N/d) improved milk yield (from 22.1 to 24.2 kg/d). However, N use efficiency tended to decrease with increasing dietary CP, as shown by milk N use efficiency (from 23.9 to 22.6%), milk urea N (from 15.4 to 18.7 mg/dL), and excreted N per milk yield unit (from 14.7 to 16.4 g of N/kg of milk). Because of higher N excretion, NH(3) concentration on the dairy barn floor increased (LCP: 7.1mg of NH(3)/m(3); MCP: 10.4 mg of NH(3)/m(3); HCP: 10.8 mg of NH(3)/m(3)). In contrast, N(2)O concentration did not respond to dietary manipulation (mean 1.1mg of N(2)O/m(3)). Temperature, which ranged between 12.6 and 18.0 degrees C, did not affect NH(3) and N(2)O concentrations at the stall level. However, when fecal and urinary samples were incubated at 4, 19, and 29 degrees C in the laboratory, ammonia concentration increased for all diets, especially for the MCP and HCP diets, as the temperature increased. In contrast, N2O concentration was negatively related to increasing temperature. In conclusion, data from the current trial demonstrate that lowering dietary CP minimizes NH(3) concentration on dairy stall floors although temperature controls the rate of NH(3) volatilization. On the other hand, N(2)O concentration is not affected by dietary treatments on tie-stall floors.

Nitrogen Isotope Fractionation and Origin of Ammonia Nitrogen Volatilized from Cattle Manure in Simulated Storage

“…Nitrous oxide emission is expected to be negligible in conditions as those utilized in the current study due to the lack of nitrifying and denitrifying microorganisms in cattle feces [14] and relatively short storage time. Adviento-Borbe et al [15] and Arriaga et al [16], for example, reported insignificant N 2 O emissions off the barn floor in dairy farms. In an experiment related to this study, N 2 O emissions were negligible from dairy manure stored in laboratory conditions or during the first 100 h following soil application [17].…”

Evaluating the potential of dietary crude protein manipulation in reducing ammonia emissions from cattle and pig manure: A meta-analysis

“…Firstly, these quantifications are based on studies that measure the impacts of reduced CP on NH 3 emissions for different animal types (e.g., pigs, cattle) and categories (e.g., gilts, barrows, boars, etc.) (Hansen et al 2007;Le et al 2009;Arriaga et al 2010). Furthermore, emission reductions are reported at different stages of the manure management chain (Portejoie et al 2004;Madrid et al 2013) and vary in initial and final CP levels from and to which CP is reduced (Portejoie et al 2004).…”

“…This oversupply of CP leads to a greater percentage of N in manure, and a subsequent increase in NH 3 emissions (van Vuuren et al 2015). Research has shown that it is possible to reduce dietary CP in animal diets without affecting animal performance and health, resulting in lower NH 3 emissions (Hansen et al 2007;Agle et al 2010;Arriaga et al 2010). This has been made possible by carefully matching the diets with the requirements of the animals.…”

Towards improving the manure management chain

“…and NUE ranges between 22-25%, Tables S10-11), compared to countries with low milk yields (FCR ranges between 1.3-1.4; and NUE ranges between 17-20%). Our NUE estimates for dairy cows are similar to estimates derived from studies at dairy farms in Spain (mean NUE of 22%; Arriaga et al, 2010) and The Netherlands (NUE ranged from 23-26%; .…”