Effect of time at pasture combined with restricted indoor feeding on production and behaviour in dairy cows

Extremely high nutrient loads have been reported in grazed grassland regimes compared with cutting regimes in some dairy systems that include the use of supplemental feeding. The aim of this study was, therefore, to investigate the effects on productivity and behaviour of high-yielding dairy cows with limited access to indoor feed and restriction in the time at pasture in a continuous stocking system. During a 6-week period from the start of the grazing season 2005, an experiment was conducted with the aim of investigating the effect of restrictive indoor feeding combined with limiting the time at pasture on the productivity and behaviour of high-yielding dairy cows (31.0 ± 5.4 kg energy-corrected milk) in a system based on continuous stocking. The herd was split into three groups allocated to three treatments consisting of 4, 6.5 and 9 h at pasture, respectively. Each group of cows grazed in separate paddocks with three replicates and was separately housed in a cubicle system with slatted floor during the rest of the day. All cows were fed the same amount of supplement, adjusted daily to meet the ad libitum indoor intake of the cows at pasture for nine hours. The herbage allowance was 1650 kg dry matter (DM) per ha, and the intake of supplemental feed was 9.1 kg DM per cow daily. The limitation of the time at pasture to 4 h in combination with restrictive indoor feeding reduced the daily milk, fat and protein yield and live weight compared with 9 h of access to pasture. The proportion of time during which the cows were grazing while at pasture increased from 0.64 to 0.86 and the estimated herbage intake per h at pasture decreased from 2547 g DM to1398 g DM, when time at pasture changed from 4 to 9 h. It can be concluded, that in systems with a high herbage allowance, the cow was able to compensate for 0.8 of the reduction in time at pasture by increasing the proportion of time spent grazing and presumably also both the bite rate and mass, although the latter two have not been directly confirmed in the present study.