Impact of dietary manipulation on nutrient flows and greenhouse gas emissions in cattle

Abstract

-The growing global demand for meat and particularly in countries such as Brazil is expected to increase intensive animal production. Consequently the main pollutants of interest are nitrogen (N), phosphorus (P) and greenhouse gases (GHG). Nitrogen can be a problem through nitrate leaching to water bodies, ammonia, and nitrous oxide emissions to air. Phosphorus loading in soil from manure application can be the main issue due to the tendency of P to accumulate in soil and leach to groundwater and rivers. The sources of agricultural GHG emissions include methane from enteric fermentation, manure storage and spreading, and nitrous oxide mainly from application of manure on land. Dietary manipulation has proven to be an effective tool to reduce nutrient/mineral pollution and GHG emissions. Several studies have shown that decreasing crude protein in the diet could reduce N excretion and ammonia volatilization substantially without compromising productivity.Similarly, reducing P intake in dairy cattle has been shown to reduce P excretion by up to 10%. Changing the type of N and P consumed and energy level of diet has also been reported to affect the amount and type of N and P excreted. Dietary manipulation also has an impact on the amount of GHG emissions, particularly, from enteric fermentation. Feeding cattle with a high starch and low fiber diet, for example, reduces acetate production in the rumen, and leads to lower methane production. Emissions from stored manure from high fiber fed animals tend to be higher. Evidence is also available that diet affects emissions from manure applied soil. As level of production is increased to meet global demand for ruminant meat and milk products, dietary manipulation will be useful in addressing environmental concerns.Key Words: methane, nitrogen, phosphorus, pollution, ruminants Impacto da manipulação dietética sobre os fluxos de nutrientes e as emissões de gases de efeito estufa na pecuária RESUMO -A crescente demanda global por carne, em particular no Brasil, deverá aumentar a produção animal intensiva.Por conseguinte, os principais poluentes são o nitrogênio (N), fósforo (P) e gases de efeito de estufa (GEE). O nitrogênio pode ser um problema devido à lixiviação de nitrato para os corpos d'água, amônia e emissões de óxido nitroso para o ar.Carga de fósforo no solo decorrente da aplicação de esterco pode ser o problema principal, devido à tendência de o P acumular no solo e atingir os lençóis freáticos e rios. As fontes de emissões de GEE agrícolas incluem metano proveniente da fermentação entérica, armazenagem e e distribuição de estrume e óxido nitroso principalmente da aplicação de adubo na terra. A manipulação dietética tem demomstrado eficiência na redução da poluição de nutrientes/minerais e das emissões de GEE. Vários estudos têm demonstrado que a diminuição de proteína bruta na dieta podem reduzir substancialmente a excreção de N e a volatilização de amônia, sem comprometer a produtividade. Da mesma forma,a redução da ingestão de P em bovinos leiteiros pod...

Modeling the trade-off between diet costs and methane emissions: A goal programming approach

“…Although representative, it is important to point out that the agriculture sector as a whole is only responsible for 8.1% of total US GHG emissions, and its main contributor is agricultural soil management (EPA, 2014). In this context, several studies have been conducted to identify and review technical options for mitigating CH 4 emissions (e.g., Boadi et al, 2004;Martin et al, 2010;Gerber et al, 2013;Hristov et al, 2013), and dietary manipulation has been suggested as a key mitigation tool (Kebreab et al, 2010). Recently, interest has increased on practical aspects related to the implementation of mitigation strategies and also on the associated mitigation costs (e.g., Doreau et al, 2014;Pacheco et al, 2014).…”

Greenhouse Gas Emissions from Housing and Manure Management Systems at Confined Livestock Operations

“…An effective tool to reduce nutrient/mineral pollution and GHG emissions is proven to be dietary manipulation. Numerous studies have revealed that reducing crude protein in the diet could substantially lessen nitrogen excretion and ammonia volatilization without compromising productivity [89][90][91][92][93]. Hao et al [94] studied the effects of DDGS on feces and manure composition in feedlot cattle and revealed that as the ratios of wheat DDGS (e.g., 0, 20, 40, and 60%) in animal diet increased (40 and 60% wheat DDGS), the likelihood of volatile fatty acids (VFAs) also increased.…”

“…Furthermore, dietary manipulation also impacts the amount of GHG emissions, particularly from enteric fermentation. For example, feeding cattle with a high starch and low fiber diet reduces creation of acetate in the rumen and leads to lower methane production [93]. As a proportion of energy intake, a higher proportion of concentrate in the diet leads to a reduction in CH4 emissions.…”

“…A lower N content of pasture or silage would reduce N excretion by animals and NH3 volatilization loss [43]. Excretal N could be reduced by using grass grown with moderate fertilizer application [93].…”

Fermentação ruminal e produção de metano in vitro de dietas contendo torta de algodão

“…De fato, o metano produzido no rúmen não só afeta a eficiência de utilização de energia pelos animais, mas também contribui significativamente para a poluição ambiental. Assim, alimentos alternativos que por anos têm sido estudados com vistas a melhorar o desempenho dos animais e aumentar as margens da atividade, recentemente passaram a ser investigados também quanto ao potencial para redução nas emissões de metano entérico (HOPKINS; DEL PRADO, 2007;KEBREAB et al, 2010;LASCANO;CÁRDENAS, 2010).…”