Theme 5-2: Drought Management and Climate Change--Poster Sessions

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Portable laser methane detectors (LMDs) may be an economical means of estimating CH4 emissions from ruminants. Here, we validated an LMD-based approach and then used that approach to evaluate CH4 emissions from indigenous dairy cows in a dryland area of Ethiopia. First, we validated our LMD-based approach in Simmental crossbred beef cattle (n = 2) housed in respiration chambers and fed either a high- or low-concentrate diet. We found that the exhaled air CH4 concentrations measured by LMD were linearly correlated with the CH4 emissions determined by infrared-absorption-based gas analyzer (r2 = 0.55). On the basis of these findings, we constructed an estimation equation to determine CH4 emissions (y, mg min−1) from LMD CH4 concentrations (x, ppm m) as y = 0.4259x + 38.61. Next, we used our validated LMD approach to examine CH4 emissions in Fogera dairy cows grazed for 8 h d−1 (GG, n = 4), fed indoors on natural-grassland hay (CG1, n = 4), or fed indoors on Napier-grass (Pennisetum purpureum) hay (CG2, n = 4). All the cows were supplemented with concentrate feed. Daily CH4 emissions did not differ among the three groups; however, a numerically greater milk yield was obtained from the CG2 cows than from the GG cows, suggesting that Napier-grass hay might be better than natural-grassland hay for indoor feeding. The CG1 cows had higher CH4 emissions per feed intake than the other groups, without significant increases in milk yield and body-weight gain, suggesting that natural-grassland hay cannot be recommended for indoor-fed cows. These findings demonstrate the potential of using LMDs to rapidly and economically evaluate feeding regimens for dairy cows in areas under financial constraint, while taking CH4 emissions into consideration.

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Quantification of Methane Emissions from Indoor-Fed Fogera Dairy Cows Using Laser Methane Detector

Portable laser methane detectors (LMDs) may be an economical means of estimating CH4 emissions from ruminants. Here, we validated an LMD-based approach and then used that approach to evaluate CH4 emissions from indigenous dairy cows in a dryland area of Ethiopia. First, we validated our LMD-based approach in Simmental crossbred beef cattle (n = 2) housed in respiration chambers and fed either a high- or low-concentrate diet. We found that the exhaled air CH4 concentrations measured by LMD were linearly correlated with the CH4 emissions determined by infrared-absorption-based gas analyzer (r2 = 0.55). On the basis of these findings, we constructed an estimation equation to determine CH4 emissions (y, mg min−1) from LMD CH4 concentrations (x, ppm m) as y = 0.4259x + 38.61. Next, we used our validated LMD approach to examine CH4 emissions in Fogera dairy cows grazed for 8 h d−1 (GG, n = 4), fed indoors on natural-grassland hay (CG1, n = 4), or fed indoors on Napier-grass (Pennisetum purpureum) hay (CG2, n = 4). All the cows were supplemented with concentrate feed. Daily CH4 emissions did not differ among the three groups; however, a numerically greater milk yield was obtained from the CG2 cows than from the GG cows, suggesting that Napier-grass hay might be better than natural-grassland hay for indoor feeding. The CG1 cows had higher CH4 emissions per feed intake than the other groups, without significant increases in milk yield and body-weight gain, suggesting that natural-grassland hay cannot be recommended for indoor-fed cows. These findings demonstrate the potential of using LMDs to rapidly and economically evaluate feeding regimens for dairy cows in areas under financial constraint, while taking CH4 emissions into consideration.