Effects of a perennial ryegrass diet or total mixed ration diet offered to spring-calving Holstein-Friesian dairy cows on methane emissions, dry matter intake, and milk production

Abstract

The objective of the present study was to compare the enteric methane (CH4) emissions and milk production of spring-calving Holstein-Friesian cows offered either a grazed perennial ryegrass diet or a total mixed ration (TMR) diet for 10 wk in early lactation. Forty-eight spring-calving Holstein-Friesian dairy cows were randomly assigned to 1 of 2 nutritional treatments for 10 wk: 1) grass or 2) TMR. The grass group received an allocation of 17 kg of dry matter (DM) of grass per cow per day with a pre-grazing herbage mass of 1,492 kg of DM/ha. The TMR offered per cow per day was composed of maize silage (7.5 kg of DM), concentrate blend (8.6 kg of DM), grass silage (3.5 kg of DM), molasses (0.7 kg of DM), and straw (0.5 kg of DM). Daily CH4 emissions were determined via the emissions from ruminants using a calibrated tracer technique for 5 consecutive days during wk 4 and 10 of the study. Simultaneously, herbage dry matter intake (DMI) for the grass group was estimated using the n-alkane technique, whereas DMI for the TMR group was recorded using the Griffith Elder feeding system. Cows offered TMR had higher milk yield (29.5 vs. 21.1 kg/d), solids-corrected milk yield (27.7 vs. 20.1 kg/d), fat and protein (FP) yield (2.09 vs. 1.54 kg/d), bodyweight change (0.54 kg of gain/d vs. 0.37 kg of loss/d), and body condition score change (0.36 unit gain vs. 0.33 unit loss) than did the grass group over the course of the 10-wk study. Methane emissions were higher for the TMR group than the grass group (397 vs. 251 g/cow per day). The TMR group also emitted more CH4 per kg of FP (200 vs. 174 g/kg of FP) than did the grass group. They also emitted more CH4 per kg of DMI (20.28 vs. 18.06 g/kg of DMI) than did the grass group. In this study, spring-calving cows, consuming a high quality perennial ryegrass diet in the spring, produced less enteric CH4 emissions per cow, per unit of intake, and per unit of FP than did cows offered a standard TMR diet.

Milk mid-infrared spectra enable prediction of lactation-stage-dependent methane emissions of dairy cattle within routine population-scale milk recording schemes

“…This decrease in predicted methane emissions could be explained by a decrease in feed intake when temperature increases during summer (Hammami et al 2015) and also because the majority of dairy cows in the Walloon Region of Belgium are outdoors grazing in the summer period. In general, dry matter intake of grass-fed cows is expected to be lower compared with cows fed with a total mixed ration (Robertson and Waghorn 2002) leading to a decrease of methane emissions (O'Neill et al 2011) because dry matter intake represents the main driver of methane production (Hegarty et al 2007). The majority of cows used in this study calved during autumn (36% of cows calved in September, October, or November).…”

Evaluation of the effect of accounting method, IPCC v. LCA, on grass-based and confinement dairy systems’ greenhouse gas emissions

“…Several studies have reported that feed intake is the principal determinant of enteric CH 4 emissions from cattle (Mills et al, 2003;Hegarty et al, 2007;O'Neill et al, 2011). In addition, feed intake is also a key variable required to quantify CH 4 and N 2 O emissions from manure (Basset-Mens et al, 2009).…”

The Carbon Navigator: a decision support tool to reduce greenhouse gas emissions from livestock production systems

“…Firstly, grass grazed in situ in the early and late grazing season is a higher-quality more digestible feed than the grass silage, which is the main feed, once animals are housed. The higher digestible feed leads to improvements in animal productivity as well as reductions in the proportion of dietary energy lost as methane and a reduction in methane per unit of output (O'Neill et al, 2011). The shorter housing season also leads to reduced slurry methane (CH 4 ) and nitrous oxide (N 2 O) emissions from storage, as quantities stored will be lower.…”