9. Livestock Management

Improved feeding practices: Methane emissions can be reduced by feeding more concentrates, normally replacing forages (Blaxter and Claperton, 1965; Johnson and Johnson, 1995; Lovett et al., 2003; Beauchemin and McGinn, 2005). Although concentrates may increase daily methane emissions per animal, emissions per kg-feed intake and per kg-product are almost invariably reduced. The magnitude of this reduction per kg-product decreases as production increases. The net benefit of concentrates, however, depends on reduced animal numbers or younger age at slaughter for beef animals, and on how the practice affects land use, the N content of manure and emissions from producing and transporting the concentrates (Phetteplace et al., 2001; Lovett et al., 2006).

Other practices that can reduce CH4 emissions include: adding certain oils or oilseeds to the diet (e.g., Machmuller et al., 2000; Jordan et al., 2006); improving pasture quality, especially in less developed regions, because this improves animal productivity, and reduces the proportion of energy lost as CH4 (Leng, 1991; McCrabb et al., 1998; Alcock and Hegarty, 2006); and optimising protein intake to reduce N excretion and N2O emissions (Clark et al., 2005).
 
Longer-term management changes and animal breeding: Increasing productivity through breeding and better management practices, such as a reduction in the number of replacement heifers, often reduces methane output per unit of animal product (Boadi et al., 2004). Although selecting cattle directly for reduced methane production has been proposed (Kebreab et al., 2006), it is still impractical due to difficulties in accurately measuring methane emissions at a magnitude suitable for breeding programmes. With improved efficiency, meat-producing animals reach slaughter weight at a younger age, with reduced lifetime emissions (Lovett and O'Mara, 2002). However, the whole-system effects of such practices may not always lead to reduced emissions. For example in dairy cattle, intensive selection for higher yield may reduce fertility, requiring more replacement heifers in the herd (Lovett et al., 2006). [1]