Effects of Herbage Allowance on Dry Matter Intake, Efficiency of Grazing,Milk Yield and Grazing Behaviour of Crossbred Holstein-Jersey Dairy Cows Grazing Alfalfa Pastures

Abstract

The objectives of this study were to research the effects of herbage allowance (HA) on dry matter (DM) intake, milk yield, grazing efficiency and grazing behaviour of dairy cows grazing alfalfa (Medicago sativa L.) pastures, and to compare the estimates of herbage DM intake using either an external intake marker developed from a purified enriched lignin (LIPE®) or the animal performance method, the latter based on calculations of energy requirements.Twenty six spring calving crossbred Holstein-Jersey dairy cows (84 days in milk) were balanced and assigned to either the low HA (Lo-HA; 10.0 kg DM/cow/day) or the high HA treatment (Hi-HA; 14.5 kg DM/cow/day). Cows were offered alfalfa (Medicago sativa L.) pastures at grazing, Sorghum (Sorghum bicolor) silage (3.7 kg DM/cow/day) and concentrates (5.6 kg DM/cow/day). Herbage DM intake was estimated using the sward cutting method, the animal performance method and an indigestible intake marker (LIPE®). Decreasing herbage allowance (HA) decreased herbage DM intake by 1.1 kg cow/day (P <0.05), increased the efficiency of grazing by 210 g/kg (P <0.01), increased silage DM intake by 0.3 kg cow/day (P <0.05), decreased total metabolisable energy intake by 12 MJ ME cow/day (P <0.05), but did not affect total DM intake (P >0.05). The cows on the Lo-HA treatment produced less milk (-4.1 kg cow/day (P <0.05) and grazed 26 min/day longer (P <0.05) than cows at the Hi-HA. Herbage DM intake measured with LIPE® was positively correlated with estimates of herbage DM intake from the animal performance method (R=0.65, P<0.01).This study showed that cows at the Hi-HA treatment had greater herbage DM intake and milk yield, but had an efficiency of grazing 210 g/kg lower than cows at the Lo-HA in early lactation.

The effects of organic grass and grass-birdsfoot trefoil pastures on Jersey heifer development: Herbage characteristics affecting intake

“…Estimates of apparent herbage intake were based upon herbage disappearance between the pre-grazing and postgrazing herbage mass estimates for each pad-dock (Macoon et al, 2003), with adjustments made for daily herbage accumulation and grazing efficiency. Grazing efficiency (the proportion of herbage consumed by livestock compared with the total that disappears due to all other activities) increases as grazing pressure increases (Allison et al, 1982;Smart et al, 2010;Baudracco et al, 2013). Estimates of grazing efficiency (on a paddock basis) were calculated by regressing modified herbage allowance data from this study (modified as kg of herbage/kg of BW per day) using an equation developed from the Allison et al (1982) comparisons of herbage allowance and grazing efficiency (i.e., grazing efficiency = 105.11 − 463.30 × modified herbage allowance; R 2 = 0.93).…”

“…Herbage Allowance, Height, and Fructan (PC3). The importance of herbage allowance on herbage intake has been well documented in the literature (Vazquez and Smith, 2000;Sollenberger et al, 2005;Baudracco et al, 2010;Sollenberger and Vanzant, 2011;Baudracco et al, 2013). In general, at low herbage allowance, nonnutritional factors such as herbage mass largely drive herbage intake; as such, intake by cattle increases as herbage allowance increases (Baudracco et al, 2010;Sollenberger and Vanzant, 2011).…”