Here are some tips to help you get the most from your grassland
 | Better grazing management can increase farm profitability by €250 – 350/ha. |
A 10% increase in the proportion of grazed grass in a dairy cow’s diet reduces costs of production by 2.5 cent/litre. Grass budgeting is essential to ensure pasture based systems of production are profitable and efficiently convert grazed grass into milk.
The main ways to increase the proportion of grass in the animal diet is:
- Extend the grazing season into early spring and late autumn. This can be achieved by implementing grazing management
practices such as timely closing of paddocks in autumn for early spring grazing, where weather allows. - Where possible match the herd calving pattern to the grass growing season. Begin calving when grass starts growing – this results in most cows calving between 10th February and 1st March. Target an opening farm cover of 600 – 700 kg DM/ha.
- Match stocking rate to the grass growth potential of the farm. e.g. A cow consumes 5t grass DM. If farm is growing 14 t DM/ha it can be stocked at 2.8 cows/ha (14 ÷ 5 = 2.8).
- Ensure soil fertility is optimised (see soil fertility section).
- Implement a timely re-seeding programme to maximise sward productivity.
- Carry out regular farm grass cover measurement and grass budgeting.
- Ensure that farm infrastructure is sufficient to fully utilise grass grown, especially during periods of wet weather.
- Supplement with concentrate or high quality baled silage when grass is in short supply.
- Use on-off grazing during periods of wet weather to keep grass in the cows diet, provided soil conditions allow.
Maximise grass production and profitability throughout the year.
Spring
Simple Rule:1
- Turnout in mid-February
- 30% of farm grazed by 1st March
- 60% of farm grazed by 17th March
- 100% of farm grazed by first week in April
 | Graze paddocks to 3.5 cm during the first rotation |
| Each extra day at grass in spring is worth €2.70/cow/day. |
Mid-season
During mid-season the farm should be walked at least once per week and the farm cover (amount of grass on the farm) assessed.
Target pre-grazing yield is 1300 – 1600 kg DM/ha. Target postgrazing height during the main grazing season is 4 – 4.5 cm.
- If there is a surplus of grass on the farm, remove the paddock from the grazing system and cut for winter fodder.
- If there is not enough grass on the farm, the animals may need supplementation with silage or concentrate.
- Rotation length should be 18 – 21 days.
- Keep topping to a minimum as it delays re-growth of pasture. One round of topping to <4.5cm should be enough and should be completed from mid-May to late June.
| Maintaining the correct pre-grazing yield and post-grazing height during the main grazing season generates an extra €150/ha in milk receipts. |
Autumn
A 60:40 autumn rotation plan helps extend the grazing season into late autumn. Autumn closing management has the largest effect on spring grass supply. Start increasing rotation length by 1 day per week from 1st August. Rotation length should be >35 days from mid-September.
Simple Rule:
- Start closing 10th October.
- 60% of the farm should be closed by 1st week November.
- Remaining 40% should be closed by 1st December.
* These dates should be a week to two weeks earlier on heavier soil types or slow grass growing farms.
Once a paddock is closed it should not be re-grazed as this will reduce spring grass supply.
* Each day delay in closing from 1st October to 11th December can reduce spring grass availability by up to 15 kg DM/ha/day.
Close some drier paddocks earlier to facilitate early spring grazing. Graze paddocks to 3.5 – 4 cm during the final grazing rotation to encourage winter tillering. Closing cover target is 550 kg DM/ha for farms stocked at 2.5 cows/ha in late November.
During Wet Weather
Where soil conditions allow – use on-off grazing.
- Allow cows two three hour grazing periods after each milking.
- After each three hour period move cows from the paddock to a stand off area (e.g. a shed).
- Silage supplementation is not necessary.
- Ensure full allowance of grass is offered during these periods as cows adjust their grazing behaviour to achieve full intake.
Be flexible – graze lower grass covers (shorter grass) in wet weather. Ensure a good network of roadways to maximise pasture access and minimise poaching damage. Back fence areas that have been grazed to avoid poaching damage. Poaching paddocks can reduce grass growth throughout the year, particularly on heavy farms.
Reseeding
Achieving high levels of grass production and animal performance from swards which do not have a high proportion of perennial ryegrass is very difficult.
High perennial ryegrass swards can produce 3 DM/ha more than swards with low levels of perennial ryegrass. Swards with low levels of perennial ryegrass are not as responsive to nitrogen. Greater spring growth is achieved with high perennial ryegrass swards. Pastures with <65% perennial ryegrass should be reseeded.
Spring is the best time to reseed
- A spring reseed produces as much grass in its year of establishment as an old permanent pasture.
- It is easier to establish clover in spring reseeds as soil temperature are more stable then.
- Greater chance of more suitable weather and soil conditions.
Guidelines when choosing a seed mixture:
- Choose a grass mix that has good spring and autumn production, as most mixes have similar mid-season productivities.
- Choose varieties with a narrow range in heading dates (7-10 days).
- Choose a grass mix that provides adequate ground cover.
Choosing the right varieties:
The majority of pre-mixed grass seeds available from your local co-op are well balanced mixtures with varieties from the Irish recommended list.
Grazing
- Choose mainly late heading diploids but also have a proportion of tetraploid varieties.
- Tetraploid varieties have the highest DM yields and large leaf area, even though their tiller density is lower than diploids.
- Dry matter yields of tetraploids are generally on average 1 t DM/ha higher yield than diploids.
- Tetraploids should be combined with high ground cover, highly digestible diploids.
- 40% tetraploid is sufficient in a seed mix, higher levels of tetraploid can be used, but sward management should be adjusted to protect it from damage during the shoulder grazing periods.
- It is better use grass varieties that have similar heading dates, (e.g. 7-10 days), a wider range in heading dates will be reflected in a longer heading period.
Silage
- Intermediate heading varieties should be included in the seed mixes for intensive silage swards.
- Tetraploid varieties should make up about one third of silage mixes.
- For swards cut once a year and then grazed, the amount of intermediate can be reduced, and late heading cultivars can be used.
- Low yielding late diploids should be avoided on the land targeted for continuous silage harvests.
- Whatever the varieties in intensive silage systems, persistency will become an issue if high silage yields are harvested to low cutting heights.
Clover
- In grazing swards small and medium leaf clover varieties are recommended in combination with late heading perennial ryegrass varieties as they are more persistent than large leaf varieties.
- Care must be taken with the larger leafed clovers as their aggressive growth habit dominates swards over time. Varieties with high yield potential and good grazing persistence at both high and low nitrogen levels should be used.
Management of swards after reseeding
- Best time to control docks and other weeds is after reseeding.
- Apply post-emergence spray 6 weeks after establishment.
- Graze swards as soon as the new grass plants roots are strong enough to withstand grazing (i.e. can not be pulled out of sward).
- Aim to graze reseeded pastures 60 days after reseeding.
- Frequent grazing of light covers (<1400 kg DM/ha) during first year after establishment will help the sward to tiller and reduce opportunity for weed establishment.
- Check reseeds for slug/leatherjacket attack.
- If possible avoid cutting silage on the reseed during the first year.
Footnotes
- These dates should be a week later on heavier soil types or slow grass growing farms.