Intake, Energy Expenditure and Methane Emissions of Grazing Dairy Cows at Two Pre-Grazing Herbage Masses

Abstract

A grazing experiment was undertaken to assess the effects of two levels of herbage mass (HM) on herbage DM intake (DMI), fat and protein corrected milk yield (FPCM), grazing behaviour, energy expenditure (HP), and methane emissions (CH 4 ) of grazing dairy cows in spring. Treatments were a low HM (1447 kg DM/ha; LHM) or a high HM (1859 kg DM/ha; HHM). Pasture was composed mainly of cocksfoot (Dactylis glomerata) and lucerne (Medicago sativa), offered at a daily herbage allowance of 30 kg DM/cow, above 5 cm. Eight multiparous Holstein cows were used in a 2 × 2 Latin Square design in two 10-day periods. Despite the differences in pre-grazing HM between treatments, OM digestibility was not different (P = 0.28). Herbage mass did not affect DMI or FPCM. Grazing time was not different between treatments, but cows had a greater bite rate when grazing on LHM swards. However, HP did not differ between treatments. Daily methane emission (per cow), methane emission intensity (per kg FPCM) and methane yield (as percentage of gross energy intake) were not different. The lack of effect of the amount of pre-grazing HM on energy intake, confirms that the difference between HM treatments was beyond the limits that impose extra energy expenditure during grazing.

Beef Steers and Enteric Methane: Reducing Emissions by Managing Forage Diet Fiber Content

“…For example, in Uruguay, Dini et al [ 61 ] and Oscarberro et al [ 78 ] reported grazing average emission values of 109–177 g CH 4 /day and 140–329 g CH 4 /day for heifers, respectively. For grazing lactating cows, Loza et al [ 79 ] reported values between 353 and 374 g CH 4 /day, while in Argentina, for the same animal category and grazing system, Gere et al [ 76 ] reported values from 157 to 203 g CH 4 /day. Studies in Brazil, for example, those by Maciel et al [ 5 ], Oliveira et al [ 4 ], and Hoffman et al [ 80 ], which measured heifers and steers with forage diets, showed results with a wider range of 80–184 g CH 4 /day.…”

Performance of Dairy Cows During Different Seasons With Daily Herbage Allowance: A Review

“…The influence of performance and milk content is shown in table 1. Loza et al (2021) found no differences in total enteric CH4 emissions (363 g/d on average) or CH4 emission intensity (18.4 g/kg FPCM on average), and the findings are consistent with previous international Munoz et al (2016); Westberg et al (2001); Zubieta et al (2020). Furthermore, Loza et al (2021) reported an average CH4 emission per unit of the estimated feed intake at 21 g/kg DMI and CH4 emission as a percentage of gross energy intake, which is consistent with previous findings of Dini et al (2021) and Cottle et al (2018), which performed metaanalysis for grazing dairy cows on temperate pastures.…”