Correct supplementation will maintain production during poor grass growth

By Mark Moloney, InTouch Feeding Specialist

Rainfall levels in Ireland for April and May have been the lowest since records began, which has left a soil moisture deficit (SMD) of between 30mm and 80mm around the country.

This has resulted in a current growth rate of around 50kg of dry matter (DM)/day – much lower than the five-year average of over 80kg DM/day. As this only represents farms that measure grass, growth rates are a lot less in other areas.

Grass quality and peak milk yield

Maintaining high milk production during this time is not only important from a monetary perspective. Falling milk yield or solids represent a deficiency of intake.

This can have a knock-on effect on fertility as well and be represented in that ‘lull’ in calving that we get in early March.

Not alone has a soil moisture deficit caused a slowdown in grass growth, but this lack of water and excessive heat will also cause the plant to reproduce at lower covers.

Some farms have reported that even at the ideal covers of 1,200–1,400kg DM, grass is producing seed heads, with most having to graze lighter covers to maintain quality.

Those who have continued to graze those reproductive paddocks have seen a noticeable decline in milk volume and solids percentage. In a spring-calving system, cows are not far past their peak and the maximum drop in production, if any, should be 2% per week.

If the milk drop is small, then this could be caused by quality or quantity of grass. But if large, it is more than likely caused by a lack of dry matter intake (DMI). Too often we see, for example, a cow dropping from 28L peak to 24L over a month.

These cows should not be much lower than 26L, based on a 2% drop, which is a loss of almost €1,500 for a 100-cow herd.

Managing grass

Grass allocation now needs to be accurate and utilisation is paramount. Regularly walk your farm. This is the only way to ensure you are not over or under-feeding your cows.

The aim is to get the grass demand per day the same or below (depending on soil type) the growth rate per day and to maintain your rotation length somewhere in the region of 25 days.

Aim to keep around 10 days grass ahead at any time, so when conditions improve and a surge of growth comes, you are in a position to take full advantage quickly.

Supplementation and dry matter intake

It is crucial to get a handle on what your cows are eating. A typical Holstein Friesian herd doing 6,500L and 500kg of milk solids in the year could eat 18–20kg DM/day.

A simplified way to do this is to get the peak yield and divide by 1.5 or 3–3.5% of body weight. In the conditions we are experiencing at the moment, getting the DMI correct will get you 90% of the way there; the extra 10% will be the quality of the feed.

Having the right size paddocks for your cows is something that is often overlooked on many farms. For example, a herd of 100 cows consuming 16kg of DM/day and going into a 1,300kg cover would need 1.2ha (3ac) for 24 hours.

Second, calibrating parlour feeders is also important; knowing what a ‘pull’ of meal is equal to. This could be the difference in a 1kg of dry matter on some farms.

What you currently need to do is slow down the rotation. While feeding in the parlour might be less work, it is important to stick to the concentrate feeding template (Table 1).

By following this, the addition of a conserved forage will be more cost-effective, make-up DMI deficits better and the rumen of the animal will be healthier.

Table 1: Concentrate feeding levels guide based on grass intake of the cow

Tables 2 and 3 outline the benefit of 40 c/cow/day of introducing a conserved forage beyond a certain level of concentrate in the diet to make up for a lack of DMI.

Table 2: A typical milk cow diet based on grazed grass and concentrate in the parlour
Table 3: A typical milk cow diet based on grazed grass, concentrate in the parlour and silage, straw and concentrate available as part of a buffer

Feed budgeting

When using conserved forage out of season, one eye must be kept on whether you are eating into the winter stock of feed.

We should try and avoid, where possible, using first-cut silage on farms just yet. As cows are producing close to peak, we should be using high-quality surplus bales that have been taken from the platform earlier in the season.

If these are not available and you are currently eating into winter feed, then you need to complete a feed budget for your farm. A rough guide on this would be 1.6t of forage per cow per month and 1t of forage for youngstock.

More information

For more information on buffer feeding ideas, ways of stretching grass and feed budgeting advice, please contact InTouch at: 059 910 1320