Dairy NZ

If the actual APC is below the target line then the quickest way to get back on track is to hold the rotation length until APC is back on target.

Figure 2 (Dairy Research Corporation, No. 2 Dairy in the 1980's) shows that with a fast spring rotation, it takes a lot longer to recover than taking the hit early with a slow rotation. When APC is back on target, the area allocated daily can follow the Spring Rotation Planner from that date onwards.

[Insert Figure 2. Effect of speed of rotation on pasture cover (kg DM/ha)]

If the farm is on a fast rotation and plants are grazed before the third leaf emerges (ryegrass), resulting in average pasture cover (APC) dropping below 1800kg DM/ha, pasture growth rates will be reduced. This was demonstrated by a trial at DRC in the early 1990's (Figure 3). Grazing the paddock down to 1000kg DM/ha does not reduce growth rates providing the paddock is not grazed again before the third leaf emerges - i.e. frequency of grazing reduces pasture growth, not intensity of grazing or APC itself. 

[Insert Figure 3. Average farm cover in spring and the effect on pasture growth]

Therefore, a slow rotation that keeps APC above 1800kg DM/ha is important to maximise pasture growth in the spring.