The effects of supplementing grazing dairy cows with partial mixed ration on enteric methane emissions and milk production during mid to late lactation

Abstract

This study compared the enteric CH(4) emissions and milk production of cows offered various grass-based diets during mid to late lactation. Forty-eight spring-calving Holstein-Friesian dairy cows were randomly assigned to 1 of 3 nutritional treatments for 8 wk: (1) low grass allowance (LGA) + partial mixed ration (PMR), (2) high grass allowance (HGA), or (3) LGA. The PMR group received an allocation of 13.9 kg of grass dry matter (DM)/cow per day and in addition were offered 4.1 kg of PMR DM/cow per day. The HGA group received an allocation of 19.3 kg of grass DM/cow per day and the LGA group received an allocation of 14.4 kg of grass DM/cow per day. The PMR offered was composed of 450 g of maize silage/kg of DM, 450 g of concentrate blend/kg of DM, and 100g of barley straw/kg of DM. Daily CH(4) emissions were determined using the emissions from ruminants using a calibrated tracer technique, using sulfur hexafluoride, for 5 consecutive days during 2 periods. Simultaneously, grass DM intake (DMI) was estimated using the n-alkane technique and the PMR DMI was also recorded. Cows offered PMR had higher DMI than either the HGA or LGA cows (16.5 vs. 14.9 and 13.9 kg of DM/d). The higher DMI of PMR cows increased milk production relative to HGA and LGA cows: milk yield (17.0 vs. 14.6 and 13.1 kg) and fat and protein yield (1.29 vs. 1.14 and 1.04 kg). Daily CH(4) emissions were higher for the PMR group than for the HGA and LGA groups (406 vs. 384 and 349 g/cow per day). The enteric CH(4) emissions intensity per unit of DMI, milk yield, solids-corrected milk yield, and fat and protein yield did not differ between treatments. Effects observed in the PMR treatment were due to an increase in DMI rather than to any nutritional characteristic of the PMR.

Ryegrass pasture combined with partial total mixed ration reduces enteric methane emissions and maintains the performance of dairy cows during mid to late lactation

“…The higher daily production of methane in animals that were fed TMR compared with those that received the other treatments cannot be attributed to differences in the daily intake of DM because DMI was similar between treatments; this result differs from observations made in previous studies (O'Neill et al, 2011(O'Neill et al, , 2012Hassanat et al, 2013). Thus, in the present study, the higher emission of methane in animals that were fed the TMR compared with those that received the partial TMR treatments was correlated with the NDF content and ADF:NDF relationship.…”

“…The milk production of cows that received supplementation with a partial TMR in pasture-based systems was increased compared with that of cows that consumed solely a pasture diet (O'Neill et al, 2012;Miguel et al, 2014). Further per-cow advantages have also been found during periods of low pasture accumulation rate or in areas with low grazing availability (Wales et al, 2013).…”

“…Similarly, compared with cows that solely consumed a pasture diet, cows that grazed high-quality pastures during mid to late lactation did not have lower enteric methane emissions per unit of DMI when they received TMR supplementation (O'Neill et al, 2012). Additionally, the daily amount of time spent at pasture and in certain grazing sections (after a.m. or p.m. milking) affected the proportion of pasture in total DMI (Orr et al, 2001).…”

Effects of concentrate crude protein content on nutrient digestibility, energy utilization, and methane emissions in lactating dairy cows fed fresh-cut perennial grass

“…In the present study, GEI lost as CH 4 -E averaged 5.6%. This figure was very close to the simulated prediction (5.8%) by Bannink et al (2010) with lactating dairy cows on a similar DMI and fresh forage-to-concentrate ratio, and similar to that (average 5.7%) of grazing dairy cows with CH 4 emissions measured using the SF 6 technique (O'Neill et al, 2012;Jiao et al, 2014). However, these CH 4 /GEI data were all lower than that of 6.5% recommended by the IPCC (2006) to calculate enteric CH 4 emission inventory for a region where local CH 4 emission data are not available.…”

Reducing the carbon footprint of Australian milk production by mitigation of enteric methane emissions

“…Unlike the calorimetric chamber method, the SF 6 tracer technique can be used on large numbers of animals simultaneously (e.g. McNaughton et al 2005;O'Neill et al 2012) and, importantly, for Australian dairy research, can be used to determine the methane emissions from grazing or non-grazing dairy cows (e.g. Grainger et al 2007Grainger et al , 2008a.…”