Methane production from dairy cows fed red clover- or corn silage-based diets supplemented with linseed oil

Abstract Text: The objective of this study was to examine the effect of linseed oil (LO) supplementation on enteric CH₄ emissions from dairy cow fed red clover-(RC) or corn silage (CS)-based diets. Twelve lactating, multiparous Holstein cows (DIM = 91 ± 25; milk yield = 45.2 ± 4.7 kg) were used in a replicated 4 × 4 Latin square (35-d period; 14-d adaptation) with a 2 × 2 factorial arrangement of treatments. Cows were fed (ad libitum; 5% orts on an as-fed basis) a TMR (60:40, forage:concentrate ratio) not supplemented or supplemented with 4% LO (DM basis) and with the forage portion of the TMR consisting of either RC or CS. Production of CH₄ was determined (3 consecutive days) using respiration chambers, while milk performance was determined over 6 consecutive days. Main effects of forage source, LO supplementation and interactions (LO × forage source) were determined using the MIXED Procedure of SAS and significance was declared at P ≤ 0.05. Significant interactions between LO and forage source were observed for DM intake, and yield of fat-corrected milk, which were not changed by adding LO to RC-based diets but decreased when LO was added in CS-based diets. Similarly, CH₄ production (g/d or as a proportion of gross energy intake) was unaffected by supplementing LO to RC-based diets, but declined by 25% when LO was included in CS-based diets (LO × forage source interaction; P < 0.01). When expressed on FCM yield basis, CH₄ production decreased with LO addition regardless the source of forage used (12.7 vs. 14.4 g CH₄/kg FCM). Results of this study show that 4% LO had no effect on CH₄ production when supplemented to RC-based diets, but decreased daily CH₄ emissions and CH₄ energy losses if supplemented to CS-based diets.

Keywords: dairy cow, methane, corn silage, red clover silage, linseed oil