Ammonia, nitrous oxide and methane emissions from excreta of cattle receiving rumen undegradable protein

Abstract

We hypothesized that supplementation with rumen undegradable protein (RUP) during the rearing phase mitigates nitrous oxide (N 2 O), methane (CH 4 ), and ammonia (NH 3 ) emissions from excreta of Nellore animals in Urochloa brizantha 'Xaraés' pasture. The treatments applied to soil were urine and dung of animals supplemented without RUP or with RUP in the middle and end of the rearing phase. We assessed N 2 O and CH 4 emissions using a static closed chamber and NH 3 emissions using the semi-open static chamber method. No effects were observed for supplement, excreta type, period, or interaction on N 2 O emissions. The mean emission factor was 0.03% of N in the excreta lost as N 2 O. Higher NH 3 losses were observed for the urine treatments in the end period, regardless of the supplement type. The mean NH 3 emission factor for urine was 2.96 and 13.8% for the middle and end periods, respectively, while the mean value for dung was 3.9%. The type of supplement did not affect CH 4 emissions, and the mean dung emission factor was 0.12 kg CH 4 head -1 year -1 . In summary, the supplementation of beef cattle in pastures with RUP did not mitigate NH 3 , N 2 O, and CH 4 emissions from excreta. The excreta emission factors for the GHGs measured, regardless of differences in the type of excreta, type of supplement, and period, were lower than the default value of Intergovernmental Panel on Climate Change revised guidelines. Further studies will be needed to fully understand the mechanisms underlying the effects of RUP on greenhouse gas emissions.

Emission of Greenhouse Gases and Ammonia from the Excreta of Nellore Bulls Submitted to Energy and Tannin Supplementation

“…While in the urine, N volatilization was significantly higher, with an average of 15% (Table 6). The range of N excreta lost as NH 3 in the present study was in the range of 2-21% observed in previous studies in the tropical region [10,12,30]. However, they were lower than the IPCC default emission factor of 21% from the national guidelines for greenhouse gas emissions [1,8].…”

“…Nitrification is a microbial process that oxidizes ammonia (NH 3 ) to nitrate, while denitrification is an anaerobic process that reduces nitrate to gaseous dinitrogen (N 2 ) [9,10]. Butterbach-Bahl et al [11] stated that N 2 O produced from the nitrification process can be used in denitrification or diffused in the next soil layer before being released into the atmosphere, which may decrease the N 2 O emissions.…”

“…The amount of N 2 O produced is regulated by the N availability, while the soil moisture and temperature drive the microorganism activity [12,13]. The lack of synchronism between N and energy in the ruminant diet may lead to increases in N-ammoniacal production and its excretion via urine, which increases N availability in the soil pasture to be lost as N 2 O [7,10,14].…”

“…According to Carvalho et al [10], volatilization is the loss of soil N in the form of NH 3 ; it comes from fertilization with nitrogen fertilizers and N mineralization of animal excreta. NH 3 will be volatilized directly into the atmosphere from ammonium (NH 4 + ).…”

“…One option to address this environmental impact is supplementation with supplements that increase the efficiency of N usage by the animals. Animal supplementations have been shown to affect feed digestibility and N metabolism in the animal, providing a better ruminal fermentation and absorption of nutrients such as nitrogen (N), thus reducing emissions from animal excreta [10,18,19].…”