Investigating the impact of treading damage on the plantain (Plantago lanceolata L.) content and performance of a plantain/ perennial ryegrass (Lolium perenne L.) pasture over two years.

There is industry concern over the difficulty of maintaining a satisfactory plantain (Plantago lanceolata L.) content within plantain/ perennial ryegrass (Lolium perenne L.) dairy pastures. One cause of the sharp decline in plantain content may be treading damage from grazing dairy cows during early spring. In an experiment at Massey University, Palmerston North, the impact of cow treading damage on the plantain content of a plantain/perennial ryegrass pasture was investigated over two production years. Measurements of pasture yield, canopy development, botanical composition and growing point density captured the response of the pasture, to the treading damage. Pasture growth was reduced by 50% and 75% following cow treading damage during the early spring periods of year one (2022) and two (2023), respectively (P<0.05). Plantain content and shoot density tended to be lower in damaged plots during early spring, before recovering throughout summer, although this effect was more pronounced during year one. These results re-iterate the importance of avoiding treading damage to ensure optimal plantain content and pasture production throughout spring. The reduction in plantain content in all plots during the second year of the experiment reflected industry observations, suggesting that treading damage likely provides only a part of the explanation for declines in plantain content observed on-farm. Alternative causes, and potential mitigations of the decline in plantain content within perennial ryegrass-based dairy pastures, are discussed.