FEEDING FOCUS May 2016 • Issue 15
Heifers at grass Getting heifers of the right weight and stature for 24 month calving requires an average weight gain of 0.80kg/day throughout the rearing period. Calving down at the right weight for age is critical for future performance. For every extra kg of bodyweight at calving, heifers will see an average increase of 14.5kg of milk in their first lactation. An additional 70kg of bodyweight equates to an extra 1,000kg of milk in the first lactation - see Figure 1. Figure 1 - Average increase of milk yield per kg BW.
Achieving this performance at grass can be a challenge, but it is entirely possible to obtain the desired weight gain whilst maximising use of grazed grass with the correct feeding and management systems in place. Dry Matter Intakes A heifer’s dry matter intake (kg/day) is relative to her body weight. For a heifer to achieve her required dry matter intake from grazed grass alone it makes sense that the required quantity of grass must be available. Measuring grass cover will highlight the amount of concentrate or forage required to buffer any shortfall.
Milk yield in first 300 DIM (kg)
Monitor energy intakes Depending on the age, weight and rearing environment of a heifer, she will require a daily intake of approximately 70MJ of energy in order to achieve a 0.8kg daily growth rate. There will be times during the grazing season when even the best quality grass will not provide the energy levels required to maintain desired daily growth rate targets. It is essential to assess the amount of energy heifers are obtaining from grass and buffer feed with concentrates when shortfalls in energy supplies are suspected. Bodyweight at calving (kg)