Seasonal Effect on Feed Intake and Methane Emissions of Cow–Calf Systems on Native Grassland with Variable Herbage Allowance

Abstract

The aim of this study was to measure methane emissions (CH4) and herbage intake, and, on the basis of these results, obtain the methane yield (MY, methane yield as g CH4/kg dry matter intake (DMI) and Ym, methane yield as a percentage of Gross Energy intake), from beef cows grazing on native grasslands. We used forty pregnant heifers, with two treatments of herbage allowance (HA) adjusted seasonally (8 and 5 kg dry matter (DM)/kg cattle live weight (LW), on average), during autumn, winter and spring. Methane emissions (207 g CH4/d), organic matter intake (OMI, 7.7 kg organic matter (OM)/d), MY (23.6 g CH4/kg DMI) and Ym (7.4%), were similar between treatments. On the other hand, all variables had a marked increase in spring (10.8 kg OM/d and 312 g CH4/d), except for Ym. The methane emission factor from Intergovernmental Panel on Climate Change (IPCC) Tier 2 estimated with these results was 78 kg CH4/head/year. The results show that methane emissions and intake were influenced by the season, but not by the HA analyzed in this study. This information for cow–calf systems in native grasslands in Uruguay can be used in National greenhouse gases (GHG) inventories, representing a relevant contribution to global GHG inventories.

Relationship between Chemical Composition and In Vitro Methane Production of High Andean Grasses

“…In recent years, studies have been conducted in Peru to measure enteric CH 4 emissions with camelids or cattle [ 21 , 23 , 32 , 33 ] and although their results vary, all authors agree on the relationship between CH 4 emissions and nutritional compounds such as fiber, which can be significantly affected in the dry season [ 34 ]. These in vivo results are not different from those obtained in this experiment conducted under controlled conditions, where 7 of the 8 species evaluated showed higher CH 4 production during the dry season.…”

Volatile fatty acids, proxies for methane production in ruminant animals

“…Animals in P2 generally produced lower MY irrespective of season while those in other parities had higher values in wet and cold seasons compared to the dry season. Interestingly animals in P3 had the highest MY values, this is in contradiction to the fact that heavier animals would produce more CH 4 (Demarchi et al, 2016;Negussie et al, 2017;Washaya et al, 2018;Orcasberro, 2021). Hence a controlled study to evaluate and prove this fact is recommended for future studies.…”

Supplement feed efficiency of growing beef cattle grazing native Campos grasslands during winter: a collated analysis

“… Poppi et al (2018) suggest that supplementation response is based on achieving the best combinations to increase metabolizable protein and ME supply when animals are grazing low CP concentration forage. The protein concentration of herbage in native Campos grasslands during winter varies, but 8.4% is commonly observed ( Cazzuli et al, 2019 ; Fedrigo et al, 2021 ; Orcasberro et al, 2021 ), above what McLennan et al (2017) consider “low CP forages” (<7% CP). This CP concentration is about one-third that of sown temperate pastures in winter (20% ± 6%, Mieres et al, 2004 ), but not as low as values reported for tropical grasslands during the dry season (e.g., less than 3% in Australian rangelands, Bowen et al, 2017 ).…”

“…However, the nutrients they provide are not always sufficient to meet the desired animal performance goals. This is often the case for growing ruminants during winter or the dry season, when available herbage is either insufficient or of limited nutritive value ( Hall et al, 1998 ; Williams et al, 2018 ; Orcasberro et al, 2021 ).…”