Feeding diets with fodder beet decreased methane emissions from dry and lactating dairy cows in grazing systems

Abstract

Fodder beet (Beta vulgaris L.) has a very high readily fermentable carbohydrate concentration, which could affect rumen fermentation and reduce enteric methane (CH4) emissions. The objective of the current study was to estimate CH4 emissions from dry dairy cows grazing either fodder beet supplemented with perennial ryegrass (Lolium perenne L.)-dominated pasture silage (6 kg DM/cow/day; FB+Sil) or forage kale (Brassica oleracea L.) supplemented with barley (Hordeum vulgare L.) straw (3 kg DM/cow/day; kale+Str; dry cows, Experiment 1), and from dairy cows in early lactation grazing perennial ryegrass-dominated pasture alone (pasture) or supplemented with fodder beet bulbs (3 kg DM/cow/day; past+FB; lactating cows; Experiment 2). Methane measurements were performed using GreenFeed units (C-Lock Inc., Rapid City, SD, USA) for 40 days in August–September 2015 (Experiment 1) and for 22 days in November–December 2015 (Experiment 2), from 45 and 31 Holstein–Friesian × Jersey dairy cows in Experiments 1 and 2, respectively. Dry cows grazing FB+Sil in Experiment 1 produced 18% less CH4 (g/day) and had 28% lower CH4 yield (g/kg DM intake; P < 0.001) than did cows grazing kale+Str. Lactating cows grazing past+FB in Experiment 2 produced 18% less CH4 and had 16% lower CH4 intensity (g/kg fat and protein-corrected milk production; P < 0.01) than did cows grazing pasture alone, while milk production and composition were similar for the two groups. In conclusion, feeding fodder beet at ~50% and 20% of the diet of dry and lactating dairy cows in pastoral systems can mitigate CH4 emissions.