SAC Sustainable Livestock Systems Group

Edinburgh, United Kingdom

SAC Sustainable Livestock Systems Group

Edinburgh, United Kingdom
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Bell M.J.,SAC Sustainable Livestock Systems Group | Wall E.,SAC Sustainable Livestock Systems Group | Russell G.,University of Edinburgh | Morgan C.,SAC Sustainable Livestock Systems Group | Simm G.,SAC Sustainable Livestock Systems Group
Animal Production Science | Year: 2010

Enteric methane production from livestock is an important source of anthropogenic greenhouse gas emissions. The aim of the present study was to (1) assess the effect of long-term breeding for kilograms of milk fat plus protein production and (2) investigate the influence of parity, genetic line and diet on predicted enteric methane emissions of Holstein Friesian dairy cows. Analyses were based on 17 years of experimental data for lactating and dry cows, housed and at pasture. Restricted maximum likelihood (REML) was used to assess the effects of parity, genetic line and diet on the predicted enteric methane output of lactating and dry cows. A non-linear equation based on metabolisable energy intake (MEI) was used to predict daily enteric methane output. The present study found that selection for kilograms of milk fat plus protein production, zero-grazing low-forage diets and maintaining persistently high-yielding older cows can reduce a cow's enteric methane emissions per kilogram milk by up to 12%, on average. Comparing the first 5 years to the most recent 5 years of the study period showed that large savings of 19% and 23% in enteric methane per kilogram milk were made in cows selected for milk fat plus protein or selected to remain close to the average genetic merit for milk fat plus protein production for all animals evaluated in the UK, respectively. Additionally, management to minimise the length of the drying-off period can help reduce enteric methane emissions during a cow's lactation period. © 2010 CSIRO.


Bell M.J.,SAC Sustainable Livestock Systems Group | Wall E.,SAC Sustainable Livestock Systems Group | Simm G.,SAC Sustainable Livestock Systems Group | Russell G.,University of Edinburgh
Animal Feed Science and Technology | Year: 2011

Improving the efficiency of livestock production is a promising way to reduce CH 4 emissions from farming systems. The aims of this study were to: (1) assess effects of lactation number, genetic line and feeding system on estimated enteric and manure CH 4 emissions from dairy cows prior to entering the milking herd and over a lactation period (i.e., whilst lactating and not lactating) per kg of energy corrected milk (ECM) (2) identify the main factors influencing a dairy cow's total lifetime CH 4 emissions/kg ECM, and (3) suggest how animal and system effects could contribute to effective CH 4 emission mitigations. This study utilized production data to predict enteric and manure CH 4 emissions from the Langhill Holstein-Friesian dairy herd, which is part of a long term experiment to evaluate genetic line×feeding system interactions. Data were from January 1990 to 2002 at Farm 1 and 2003 to June 2008 at Farm 2. Total CH 4 emissions (i.e., enteric and manure) were estimated for 824 cows, for a total of 1639 lactations. Cows were either on a low forage with grazing at Farm 1 or non-grazing at Farm 2, or high forage with grazing at both Farm 1 and 2, feeding system. Within each feeding system, cows belonged to genetic lines selected for increased milk fat plus crude protein (CP) yield (Select) or selected to remain close to the average genetic merit for milk fat plus CP yield (Control) for Holstein-Friesians evaluated in the UK annually. Total CH 4 emissions from non-milking cows and manure CH 4 emissions from lactating cows were predicted using Intergovernmental Panel on Climate Change Tier II methodology (1997), whilst enteric CH 4 emissions for lactating cows were estimated using a non-linear equation (Mills et al., 2003) based on metabolizable energy intake. Residual Maximum Likelihood was used to assess effects of lactation number, genetic line, feeding system, as well as the main factors influencing dairy system CH 4 emissions. Results show that cows maintained on the low forage feeding system produced ∼8% less enteric CH 4 emissions/kg ECM versus the high forage system. At Farm 2, there was no difference in total CH 4 emissions between a non-grazing low forage feeding system and a high forage system because lower enteric CH 4 emissions were compensated for by higher manure CH 4 emissions associated with slurry production. Cows selected for increased milk fat plus CP yield (Select) had lower total CH 4 emissions/kg ECM up to their third lactation but, over a lifetime, there appears to be no meaningful reduction compared to Control cows. Higher dry matter intake and a longer lactation period, which were positively correlated with average ECM yield, were associated with lower total lifetime CH 4 emissions/kg ECM. This article is part of the special issue entitled: Greenhouse Gases in Animal Agriculture-Finding a Balance between Food and Emissions, Guest Edited by T.A. McAllister, Section Guest Editors; K.A. Beauchemin, X. Hao, S. McGinn and Editor for Animal Feed Science and Technology, P.H. Robinson. © 2011 Elsevier B.V.

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