In temperate climates, grazed grass is the cheapest source of nutrients for the dairy cow (Finneran et al. 2010), therefore its utilisation should be optimised throughout the grazing season to increase enterprise profitability (Shalloo et al. 2004). Within spring-calving systems, energy requirements increase for the post-parturient dairy cow during the spring period. On the other hand, spring grass supply can be limited given low over-winter grass growth rates. The imposition of a lower post-grazing sward height (PGH) during this critical time may be a viable solution to increase grass availability. As the season progresses, PGH may be increased or decreased to adjust the allowance of grass in the dairy cow’s diet depending on farm grass supply. Quantifying the variation in animal production with changes in PGH will inform such decisions. Currently, there is no information available on the milk production response to changes in PGH over a short period of the lactation. Therefore, the aim of this experiment was to determine the short-term variation in milk yield (MY) and yields of protein, fat and lactose in response to changes in PGH around the tenth week of lactation of the spring calving dairy cow
