Prioritise grass quality in peak milk season

Farmers with more pasture than usual closed up for late silage this face a scarcity for grazing unless we get very good summer growth.

If there is to be a compromise between grazing and silage, grazing should always get priority.

Grassland management for the remainder of the year means providing as much high quality grass as possible for mid-season grazing, when most of the milk is produced.

Milk yields per cow and the milk protein percentage usually take a hit in mid-summer, indicating deterioration in grass quality from late May onwards.

Mid-season grassland management requires very careful monitoring in order to maintain high yields of quality milk well into the autumn.

Milk yields should not drop by more than 10% per month.

Rotations will normally have to be maintained between 18 and 21 days.

Some paddocks may have to be taken out in order to maintain grass quality.

Most farmers had the opportunity to graze out pastures well in late May and in June. As a result, pastures generally contain good quality grass, especially where bales were taken off to maintain quality.

Pastures that were not adequately grazed should be topped to 4cm. Otherwise there will be high, fibrous stubble facing into mid-summer, which will not produce high quality grazing.

Some farmers are inclined to build grass covers in May and June to ensure sufficient supply during lower growth periods or drought. However, despite the cost, the correct management is to take out surplus paddocks for baled silage, which can be fed back if necessary in times of scarcity.

Adequate fertiliser has to be applied, and this depends on what has been spread already.

High-N compounds containing NPK and sulphur will be required on most farms.

Adequate N, based on stocking rates, will be required sooner rather than later to avail of good growing conditions.

Many farmers are unnecessarily overstocked for their type of land and also for the amount of grass they grow on their farms. At least, they are now being correctly advised to have a buffer of 20% extra winter feed and adequate concentrates to meet the requirements of cows and appropriate stocking rates for the future.

How Good is your Grass?

Milk protein should keep rising from May but co-op deliveries often show the opposite is the reality.

Average milk protein generally drops to about 3.25% in June and to almost 3.2% in July.

From July the protein rises to 3.3% in August, 3.45% in September and to almost 3.6% in October, when it flattens out for the remainder of the year. This is a strong indication that mid season grass quality is not as good as it should be on a lot of farms.

Many of the top farmers have milk protein levels in excess of 3.5% throughout the year, mainly due to high quality grass.

This increase in milk protein would be worth over €2,000 to the average dairy farmer.

Grass quality is measured mainly by its dry matter digestibility (DMD).

Good quality grass will have a DMD of over 80, while poor grass will be under 70.

Good quality grass will support yields of 6.5 gallons and increase milk protein by around 0.25%.

Poor quality grass supports yields of only four gallons, and depresses milk protein.

Not only can cows eat more of the good grass; each kilo of this grass contains a lot more energy (The same applies to high and low DMD silage).

The limitations of poor pasture are also likely to be a significant factor causing infertility in cows.

Too many farmers give priority to the quantity of mid-season grass rather than quality.

Of course, poor grazing conditions such as cold, wet weather will also reduce cow intakes of grass.

Most dairy herds are capable of milking in excess of six gallons (27 litres) per cow per day in mid season.

Yet the majority of dairy herds fall short of five gallons.

This indicates that either grass quality is mostly below standard, or that cows are forced to graze too tightly and are under-fed.

Most farmers should feed a few kg of concentrates containing high quality minerals and magnesium.

Despite the low price for milk, the results from even a sub-clinical level of magnesium or other minerals would make the economical situation far worse.

Research in Moorepark has given excellent guidelines for mid season grassland management.

Cows should not be going into low grass covers of around 1,000 kg.

Apart from growing less grass, low pre-grazing covers and short rotations are difficult to manage and are prone to deficits of grass, especially in poor growing conditions.

Heavy covers over 2,000 kg are also difficult to manage, and grass can easily get ahead of cows, so a lot of bales have to be taken off to control quality.

A pre-grazing cover of 1,300 to 1,400 kg of DM/ha seems ideal from the point of view of grass growth, milk production and ease of management.

Rotations should be 18 to 21 days.

Short rotations reduce grass production while long rotations can result in stemmy pastures.

Short rotations, especially with fairly high N applications, could cause problems with non-protein nitrogen.


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