Autumn closing: Disciplined approach to housing date needed
Hitting grazing targets has been a challenge throughout 2024, and it appears that the end of the grazing year is going to be no different. Dairy Specialist at Teagasc, Stuart Childs provides a timely reminder on autumn grassland management to facilitate a supply of grass next spring.
The objective now is to set up the farm for grazing in the spring. Grass grown from closing in early October is the grass that will facilitate grazing in the spring of 2025. It is important to remember the value of this spring grass is €4/cow/day. This occurs as spring grass has a high energy feed value relative to silage. When spring grass replaces silage in the diet, it delivers higher energy, resulting in better milk solids production, a higher value litre as well as more litres being sold.
Closing targets
In order to have grass in the spring time, there is a need for discipline in the autumn to leave enough grass behind. The key target figure here is 700-750kg DM/ha. It is important to note that this figure is required on or about the 1st of December. This means that cover can go lower than this before this date, but it can only go as low as growth will allow.
Predicted growth rate from PastureBase Ireland for the weeks starting the 18th and 25th of November is 20kg DM/ha and 15kg DM/ha per day, respectively. This indicates that if you stop grazing on the 17th of November with an average farm cover of 500kg DM/ha, there will be sufficient growth over the last two weeks of the month (Table 1) to hit the target closing cover on the 1st of December.
However, if the farm is only closed on December 1st and the cover is 500kg DM/ha on this date, on a 40ha farm, there is 9.8t less grass on the farm at closing. This will carry through to the spring. Yes, there will be a cost associated with feeding the cows if housed two weeks earlier in the autumn, but it is far easier to meet cow requirements with silage and meal at this stage of lactation.
Table 1: Impact of housing date on grass availability in the spring
| Date of housing | November 17th | December 1st |
|---|---|---|
| Average farm cover at housing | 500kg DM/ha | 500kg DM/ha |
| Expected growth week of 18th November (kg DM/ha) | 20kg DM/ha/day x 7 = 140 | N/A |
| Expected growth week of 25th November (kg DM/ha) | 15kg DM/ha/day x 7 = 105 | N/A |
| Closing average farm cover (kg DM/ha on December 1st 2024) | 745 | 500 |
| Over winter growth (kg DM/day) | 4kg DM/ha/day x 62 = 244 | 4kg DM/ha/day x 61 = 244 |
| Opening average farm cover (kg DM/ha on February 1st 2025) | 944 | 744 |
There will be growth over the months of December and January. Even if the farm is closed with the target 750kg DM/ha, an average growth of 4kg DM/ha/day is required to hit the opening cover target of 1,000kg DM/ha on the 1st of February.
Consequently, it should be clear that in order to have grass on the farm in the spring of 2025, farmers will need to start closing paddocks from now on. If we are fortunate to get growth throughout the month of October, then one or two of this paddocks closed early may be eligible for grazing one more time before housing fulltime.
The key thing is to have the discipline to house at the right time to protect the farm cover for next spring and avoid the temptation to continue grazing. As farms are well behind the target cover they should have for this time of year normally, it is essential that grass is allocated carefully for the next month or six weeks to keep grass in the diet but not bare the farm. This will require continuous supplementary feeding in the form of concentrates and/or silage depending on grass availability. For further advice on how to manage this situation on your farm contact you advisor.