Duration is important in the effect of pasture allowance restriction on subsequent milk

In pasture-based dairy systems, feed supply can be limited in early spring due to inadequate pasture growth. The objective of this experiment was to investigate if different pasture allowances offered to early lactation grazing dairy cows, for different durations, influenced milk production. Cows were offered one of four pasture allowances (60, 80, 100 or 120% of intake capacity) for either 2 or 6 weeks. Once the 2- and 6-week time durations had elapsed, the cows in all treatments were offered 100% of intake capacity. At the end of the first 2 weeks of the experiment, milk yield was significantly different between all four allowances (18.5, 19.8, 21.4 and 23.1 kg cow‑1 day‑1 for 60, 80, 100 and 120% treatments, respectively). During weeks 7-10 there were no differences in milk yield between the 2-week treatments (23.5 kg cow‑1 day‑1). Milk yield of the 60×6 treatment was lower than the 100×6 and 120×6 treatments, but was similar to the 80×6 treatment. The 80×6 treatment was similar to the 100×6 treatment, but different to the 120×6 treatment. The 100×6 and 120×6 treatments were similar to each other. This indicates that differences in pasture allowance imposed for a 6-week period affected subsequent production and the data suggest that in early lactation the effect of pasture allowance on milk yield depends on the amplitude and the duration of the treatment application