Methane emissions from two breeds of beef cows offered diets containing barley straw with either grass silage or brewers’ grains

• Published in: Animal (Cambridge, England) England), 2015-10, Vol.9 (10), p.1680-1687
• Main Authors: Duthie, C-A., Rooke, J. A., Hyslop, J. J., Waterhouse, A.
• Format: Article
• Language: English
• Subjects: acetates; Animals; barley; barley straw; beef cows; body condition; breeds; brewers’ grains; butyrates; cattle; Cattle - physiology; crossbreds; Diet - veterinary; dietary fat; Dietary Fats - metabolism; dry matter intake; energy intake; Female; grass silage; greenhouse gas; greenhouse gas emissions; Hordeum - chemistry; methane; Methane - metabolism; Nutrition; Poaceae - chemistry; Pregnancy; propionic acid; purebreds; Research Article; Rumen - metabolism; rumen fluids; sampling; Silage - analysis
• ISSN: 1751-7311; 1751-732X; 1751-732X
• DOI: 10.1017/S1751731115001251

Increasing the concentration of dietary lipid is a promising strategy for reducing methane (CH4) emissions from ruminants. This study investigated the effect of replacing grass silage with brewers’ grains on CH4 emissions of pregnant, non-lactating beef cows of two breeds. The experiment was a two×two factorial design comprising two breeds (LIMx, crossbred Limousin; and LUI, purebred Luing) and two diets consisting of (g/kg diet dry matter (DM)) barley straw (687) and grass silage (301, GS), or barley straw (763) and brewers’ grains (226, BG), which were offered ad libitum. Replacing GS with BG increased the acid-hydrolysed ether extract concentration from 21 to 37 g/kg diet DM. Cows (n=48) were group-housed in equal numbers of each breed across two pens and each diet was allocated to one pen. Before measurements of CH4, individual dry matter intake (DMI), weekly BW and weekly body condition score were measured for a minimum of 3 weeks, following a 4-week period to acclimatise to the diets. CH4 emissions were subsequently measured on one occasion from each cow using individual respiration chambers. Due to occasional equipment failures, CH4 measurements were run over 9 weeks giving 10 observations for each breed×treatment combination (total n=40). There were no differences between diets for daily DMI measured in the chambers (9.92 v. 9.86 kg/day for BG and GS, respectively; P>0.05). Cows offered the BG diet produced less daily CH4 than GS-fed cows (131 v. 156 g/day: P