The competitiveness of export based dairy production systems (e.g., Uruguay, New Zealand) is supported by an intensive use of pasture on the diets. The aim of this work was to evaluate which factors linked to feeding and grazing management in commercial dairy farms, determine herbage DMI. Biweekly visits to commercial dairies were carried out between June 2016 and May 2017 to record individual milk production, quantity and type of supplemented on offer, access time to the grazing plots and sward characteristics like sward height, herbage mass and allowance. Herbage DMI (kgDM/cow/d) was determined according to Baudracco et al. (New Zeal. J. Agr. Res., 2010) considering herbage allowance, and by energy balance according to NRC (2001). The dairy farms were categorized in 2 groups according to the differences in DMI between the 2 estimation methods (overall mean ± 15%). Farms that had low differences between both DMI estimation methods were considered farms with high pasture harvesting efficiency (HE, 4.12 ± 1.85 kgMS/cow/d) and farms with large differences were considered farms with low pasture harvesting efficiency (LE, 7.18 ± 0.75 kgMS/cow/d). The 2 groups were compared with the MIXED procedure and considered different when P ≤ 0.10. No differences were detected between groups in access time to grazing pasture (11.7 ± 4.8 h), sward height (32.1 ± 17.7 cm), herbage mass (2600 ± 1491 kgDM/ha) and herbage allowance (39.7 ± 29.7 kgDM/cow/d). However, HE dairy systems had high pasture and less supplement DMI (kgDM/cow/d) than LE dairy systems (Table 1). Despite a lower individual milk production in the HE dairy systems, the margin over feeding cost (U$S/cow/d) was not different between groups. Table 1. Intake, milk production, and margin over feeding cost in dairy systems with high (HE) or low (LE) pasture efficiency use

Item	HE	LE	P-value
Herbage intake (kgDM/cow/d)1	8.4 ± 0.72	6.5 ± 0.84	0.10
Supplement intake (kgDM/cow/d)	9.2 ± 0.64	14.0 ± 1.10	≤0.01
Milk production (L/cow/d)	20.3 ± 1.02	25.3 ± 1.21	≤0.01
Margin over feeding cost (U$S/cow/d)	4.1 ± 0.30	3.9 ± 0.26	0.60

¹Estimated by energy balance difference.