Managing Dairy Cow Lactation during dry spell

Managing Dairy Cow Lactation during dry spell


Some Glanbia milk suppliers have started to experience drought conditions and based on the current weather forecast the severity and scale will increase over the next week. This will have a big impact on milk output and the ability to build winter fodder supplies.

Grass growth rates have fallen significantly and quality has also been challenging. Across most of Leinster grass growth is currently between 40 & 50 Kgs DM/ha/day and has fallen below demand. The result has been a more rapid than normal decline in milk output. Normally milk output post peak should not fall by more than 2.5% per week.

In a 100 cow herd, currently yielding 26 litres/day (mean calving date March 15th), the difference between a decline of 3%/week and 2.5% per week would be a loss of >€8,000 between now and the end of lactation. If a dairy farmer could stem the decline to 2% per week, it would add circa €9,000 to farm output compared with normal.


It is essential to measure and budget grass to optimize profit. Cows will need 18 Kgs of Grass dry matter per day. If we haven’t got it we have to bridge the gap with feed/grazing 2nd cut silage ground and or buffer feeding. Ideally we require 180 kgs grass DM ahead of the cows (10 days grazing). Holding the rotation length at 20 days is essential.

  • Make sure 2nd cut silage ground/grazing ground is adequately fertilized
  • Measure and budget grass supply and hold rotation length at 20 days to ensure you are grazing the correct type of cover (and remember grass grows grass)
  • Fill any feed (dry matter intake gap) with up to 6 kgs of concentrate.
  • Where the gap is greater than 6kgs/head/day consider using some silage bales and or soya hulls/close substitutes.
  • It is more economically prudent to graze some second cut silage ground than to feed silage already made.
  • Target pre-grazing covers of 1400kgDMha.
  • Spread at least 1 unit N/day and sulphur to maximise growth rates and grass quality. Grass deficient in nitrogen will become stressed and lose quality as a result.
  • In dry warm weather ensure there is adequate water available for cows
  • When grass is tight or the grazing covers are low, provide access to some level of long fibre such as wilted baled silage. Do not feed silage within 3 weeks of ensiling it (due to the risk of nitrogen dioxide toxicity and fermentation stability