Extend your grazing season by building autumn grass reserves

Although it is only early September, thoughts are turning to autumn and potentially housing cows. Michael Donoghue, B&T Dairy Advisor, Teagasc Galway/Clare, highlights three things that will determine when cows will be housed on your farm. These are: (1) weather; (2) soil type; and (3) grass supply.

The first one cannot be influenced. Soil type - in the longer term - can be managed at least to some extent through a combination of drainage, good access (roads and multiple access points) and in the short term by on/off grazing etc. Grass supply, however, is very much within a farmer’s control. Putting the correct amount of grass on the farm before October is critical to your housing date and that grass has to be mainly grown now.

The table below sets out targets to successfully build up enough autumn grass for a farmer stocked at 2.5 LU/ha (one cow/acre). Different stocking rates will require different targets, but the rotation length will be the same, contact your local advisor for details.

Table 1: Autumn grass targets at 2.5LU/ha (demand of 43kg DM/ha/day)

The key to achieving these targets is extending the rotation up to 35-40 days by the beginning of October, which is the start of the last rotation. Ways to extend the rotation include:

• Reduce stocking rate, so only milking cows are on the milking platform;
• Sell/move milking cows that can be dried/culled i.e. high SCC, bad feet, not in calf;
• Apply fertiliser or slurry to maintain grass growth (roughly 20 units of N/ac);
• Graze swards clean and don’t damage them;
• Feed extra ration or high-quality bale silage (this will reduce demand).

Occasionally, we can get very strong growth in September and grass can run ahead of target, especially on lighter stocked farms. If this happens action will be required, as very strong grass can lead to poor utilisation and severe sward damage if the weather turns. This in turn affects spring performance. Options here will include:

• Reducing meals, be careful of grass tetany if going below 2-3kg;
• Increasing stocking rate for a short time;
• Cutting bales - the earlier this is done the better, as regrowth will be slow.

Once we get to the first week of October, the main priority is spring 2024 grass supply. Grass that will be graze in February and early March needs to be grown in October. So minimise damage, graze swards as clean as possible and don’t re-graze from the 5^th of October. This date will vary a few days either way depending on growth and soil type.

A couple of last important points that need to be considered as we head into the autumn:

• 14^thSeptember is the last day for spreading chemical nitrogen and phosphorous;
• All slurry has to be spread by end of September;
• N statements from the Department of Agriculture, Food and the Marine should be available shortly, check yours as banding may have significantly changed your Kg of N/ha figure.
• Get your tax accounts done asap as some farmers have significant tax bills after last year’s high milk price, but that bill will have to be paid with a poor milk price this autumn.

Also read: Managing costs and cashflow

Also read: Irish grass-fed cows produce more nutritious milk