By Debbie James

Turning cows out onto shorter grass covers in spring is providing good quality grass for the second grazing rotation at a Denbigh dairy farm.

Cows must be trained to graze swards to a 3.5-4cm residual, or 1500kgDM/ha, and that means feeding the shorter covers at turnout, says grazing specialist Andre van Barneveld.

“The temptation is to turn cows into the longest covers but this is a key principle that farmers get wrong because the cows won’t graze it to the residual and the residual is what drives grass growth and quality,’’ says Mr van Barneveld, of Graise Consultancy.

He shared his key grazing principles during an open day at Bodysgaw, an AHDB strategic dairy farm near Denbigh.

The host farm runs an autumn calving system and produces almost half its milk from grazed pasture and forage.

Milk from forage is key to higher profitability for the Owen family – Arthur and Marian Owen, their sons, Guto and Gwion, and Marian’s father, Clwyd.

Cows are turned out in the first week of February and graze until the last week in November; to inform the grazing plan, grass measurements are taken weekly with a rising plate meter.

Milk yield per cow in the herd of 375 Friesians and crossbreds averages 6,788 litres; maximising grazing and producing good quality silage allows 3,072 litres of this yield to be produced from forage.

The business now aims to increase milk production from forage further, targeting 4,000 litres.

“You see other farmers who are achieving 4,000 litres so it is there for everyone, it is just down to management,’’ says Mr Owen.

How grass is managed will dictate that.

At spring turnout, Mr van Barneveld advises measuring grass and aiming to graze covers at 2,300-2,400kg DM/ha first; turn cows out with an appetite to graze.

“You need to almost under allocate on pasture that’s not very long and that is green to the base, the cows will willingly graze down to a lower residual,’’ he says.

“You can bring those cows off after three hours in the first three or four days. Turn them onto the grass, under allocate so they are grazing down to the right residual, then bring them back in to some feed to make sure they are looked after nutritionally.

“Once they are used to grazing down to the right residual you can then maybe transition to some of the slightly longer covers.’’

He recommends grazing the long covers, those over 3000kgDM/ha, at the beginning of March.

To avoid covers of 3000kg DM/ha or higher at spring turnout, Mr van Barneveld suggests a quick grazing rotation between October 10 and November 25, to provide a good quantity of high quality grass in the spring.

“If you graze after then you are making compromises for the spring when the grass is more valuable,’’ he says.

Grazed grass is as valuable in an autumn calving system as it is in spring-calving herds but there are differences in the key considerations at turnout as an autumn herd will be at peak feed demand at this point.

“If you are running at a reasonable stocking rate you can’t possibly have enough grass on the farm on February 1st to supply an autumn herd with three quarters of its diet from grass,’’ says Mr van Barneveld.

To work out what proportion of the herd diet can be provided by grazed grass he advised using a spring rotation planner, a key tool for allocating grass and managing pasture quality at a time of the year when grass growth is increasing.

“In a spring calving system you might set the rotation length at 100 days initially (1/100th of the farm grazed per day) but offering that to 370 autumn calving cows just wouldn’t work,’’ Mr van Barneveld warns.

He suggests allocating a bigger proportion of the grazing platform, or restricting turnout to only part of the herd.

“Perhaps offer 1/40th of the grazing platform to the whole herd, to provide 5-6kg a head of grazed grass, and house at night, or split the herd and fully turn out the lower producers to 10-12kg of pasture.’’