Grazing Management of the Future Herd

This article is one of a series prepared jointly by CAFRE and John Thompson & Sons, focusing on the key grassland management issues facing dairy farmers during the 2008 grazing season.  The articles draw on experiences from the management of the Future Herd at Greenmount Campus, CAFRE managed in partnership with Thompsons, and data from Thompson’s Milk Manager, taken from customers’ dairy herds across Northern Ireland.

The spring of 2008 will be remembered as being very late, but when it did arrive grass growth suddenly took off making it a very difficult season to manage grass effectively.  At Greenmount, cows in the Future Herd are normally put out to graze during the day in mid-late March.  This year cows were first turned out on 15 April, around three weeks later than usual.

Results from GrassCheck from six sites around Northern Ireland show below average grass growth in 2008 up until 12 May when the growth rates exceeded the seasonal average for the first time.  Growth rates at Greenmount have exceeded 100 KG DM/ha/day over the last few weeks leading to a rapid increase in the average grass cover across the paddocks.  This article outlines some of the management practices being adopted at Greenmount to maintain grass quality into the early summer and make the most of the cheapest feed available.

Michael Graham, the farm manager and Jim Fulton, the dairy stockman walk the grazing paddocks on a weekly basis to assess grass cover in each paddock and estimate the total cover available.  Walking the paddocks and using grass growth predictions from GrassCheck helps Michael and Jim predict periods of grass surplus or deficit.  This enables them to budget grass supply 12-14 days ahead - an exercise which has been particularly important this year.

In spring before first cut silage, the 140 cow Future Herd normally graze around 26 hectares divided up into 1 hectare paddocks.  In May, cows are ideally turned into swards with a pre-grazing cover of 12-14 cm (up to 3,200 kg DM/ha), leaving a residual cover of around 6-7 cm (1,800 KG DM/ha).  This gives an available grass cover of around 1,400 KG DM/ha.  Across the whole grazing area, Michael tries to maintain a cover of around 2,700 KG DM/ha (11 cm on average).  Given an average grass cover of 2,800 KG DM/ha at the end of April, five paddocks (4.8 hectares) with covers of over 3,000 KG DM/ha were identified.  With grass growth estimates at that time of around 80 KG DM/day, these paddocks were cut along with the first cut silage on 6 May.  A further five paddocks (5.8 hectares) were cut for silage on 13 May.  As well as the potential for making high D-value and ME silage there are a number of benefits.  Firstly, the maximum value was made of grass with no wastage and quality silage was made for next winter.  Even more importantly, by taking the paddocks out early, the swards recovered quickly and more paddocks were able to rejoin the grazing rotation with minimal disruption to grazing management.

The fertiliser policy at Greenmount Campus is to make the most of the nutrients available in slurry.  This involves the use of trailing shoe slurry spreading on the silage ground to maximising the amount of available nitrogen.  However, on the grazing paddocks fertiliser nitrogen is applied to optimise grass growth as the trailing shoe would not provide sufficient growth for a three week grazing rotation.  Since the paddocks have a P and K soil index of 3 or above, 27.5 percent N fertiliser is used.  Around one third of paddocks are fertilised on a weekly basis.  In the first two applications, 55 KG N/ha (45 units/acre) were applied each time with a further 41 KG N/ha (33 units/acre) to be applied every three weeks for the rest of the season.   

Grazing paddocks at Greenmount don’t generally get topped until after the second or third round of grazing from mid May onwards.  Residual covers of over 1,800 KG DM/ha (7cm) are topped to 5-6 cm (2-2.5 inches), cutting the grass below the first node to remove the stem and delay subsequent development of the seed head.  This encourages the re-growth of fresh leafy grass increasing quality, palatability and intake.  This maximises milk from forage and reduces the costs of production.

Given the substantial increase in the cost of feed and fertiliser, it is important to make the most from grass and maximise the production of milk from forage.  To do this while still meeting the nutritional requirements of cows yielding over 40 litres, cows have been grazed in two batches.

The low yielding group comprising around 80 autumn/early winter calving cows and first lactation heifers, all confirmed pregnant were turned out on 15 April.  Since 21 April they have been grazing night and day on high quality grass swards, supplemented in the parlour with 1.2 KG concentrate and are currently yielding around 22 litres per day.  To maximise the intake of grass, estimated at 17 KG DM/cow/day, cows are turned into paddocks with a pre-grazing cover of 3,000-3,200 KG DM/ha (12-14cm) leaving a residual cover of around 1,600 to 1,800 KG DM/ha (5-6cm).

The other group is a high yielding group of around 60 cows, comprised of cows yielding over 35 litres per day and cows not confirmed pregnant.  This group was first turned out on 21 April.  They graze during the day and are housed at night where they are supplemented with a grass/wholecrop silage and concentrate blend.  The cows are eating 14 KG silage, 5 KG wholecrop DM and 3 KG concentrate (fresh weight) per day in the TMR and an average of 4.3 KG concentrate through the parlour.  This limits the grass intake to 40 KG fresh weight with cows allocated 0.3 ha per day of grazing with grass covers of over 3,000 KG DM/ha.

Michael Graham finds it much easier to meet the nutritional requirements of individual cows when they can be batched according to yield.  Given today’s feed costs, this means that the low yielding group can be fed for around £1.20 per day while feed costs for the higher yielding group housed at night is around £2.80 per cow per day.  With a predicted base milk price of around 22 pence per litre in the next few months, milk production from a 22 litre cow is worth about £4.80 per day - and there is no sense in throwing this hard earned money away by overfeeding lower yielding cows an expensive diet that costs more than £1/cow/day more.

David Mackey, Jim Fulton and Michael Graham assessing grass covers of the grazing paddocks.