Methane emission in yellow cattle fed diets based on NaOH treated rice straw, cassava root and leaf meal,  supplemented with sodium nitrate or urea as sources of non-protein nitrogen

Do Thi Thanh Van, Duong Nguyen Khang and T R Preston

 National Institute of Animal Sciences, Hanoi, Vietnam
dothanhvan@hotmail.com

Abstract

The objective of this study was to assess methane output in yellow cattle fed diets based on NaOH treated rice straw supplemented with different non-protein nitrogen sources. In this study, eight growing local yellow cattle with mean initial body weight of 140kg (SD=14,2) were randomly alloted into two treatments according to two sources of non-protein nitrogen as sodium nitrate or urea. The animals were fed a total mixed ration (TMR) including 25% NaOH treated rice straw, 8% molasses, 33% dried casava leaves and 34% cassava root meal. Levels of sodium nitrate and urea were adjusted to vive a level equivalents to 12% crude protein (CP) in dry matter (DM) of TMR. The experimental time was 21 days with 14 days of adaptation and a-7days for data collection. The CH₄ /CO₂ ratio was measured at the first day of data collection period by GASMET portable equiment. The results showed that non-protein nitrogen sources had no effect on daily DM intake or CP intake  (Figure 1) but significantly reduced the methane;cabon dioxide ratio (Figure 2.).

Figure 1: Daily DM and CP intake of yellow cattle fed sodium nitrate or urea as NPN sources in basal diet of NaOH treated rice straw	Figure 2: Ratios of methane to carbon dioxide in rumen gas from yellow cattle fed diets consisting of NaOH treated rice straw, dried cassava leaves, cassava root  meal, molasses with sodium nitrate