Impact of pugging by dairy cows on pastures and indicators of pugging damage to pasture soil in south-western Victoria

Pugging damage by cows in wet winters is an important limitation for dairyi ng in Victoria and Tasmania. A grazing trial was conducted to identify the effects of pugging by dairy cows on pasture yield and utilisation in south- western Victoria, Australia. A series of pugging severity treatments (no pu gging, light, medium, and heavy pugging) were imposed by varying stocking d ensity at different soil moisture levels. Medium-heavy pugging in winter re duced pasture yield in the following spring by 40-42%, pasture utilisation by 34-40%, and perennial ryegrass (Lolium perenne L.) tiller density by 39- 54%. Light pugging had no effect on pasture yield, utilisation, and perenni al ryegrass tiller density. Pasture growth rate showed a similar pattern be tween treatments; however, the impact was greater in the first 9 weeks afte r pugging than later (9-14 weeks). With heavy stocking density, there could be a potential risk of pugging damage when soil strength is <700 kPa. Indi cators of pugging severity (pugging score, depth, and soil surface roughnes s) were highly correlated. The relationship between pugging severity and pa sture yield, utilisation, and ryegrass tiller density was best described by a negative linear regression when pugging scores were 0-2.