The autumn calving herd at the Teagasc winter milk research farm at Johnstown Castle in Co Wexford is proving that good performance can be achieved by using moderate levels of input.

The herd has produced an average of 620kg to 630kg MS/cow over the last four to five years from 1.6t of meal per cow.

The six-week calving rate is 78% and the calving interval is 370 days. The conception rate to first service is 57%, and the empty rate after 10 weeks of breeding is 13%. No cows are recycled between spring and autumn calving.

Farm manager Aidan Lawless said that there is no distinction in the breeding policy between cows in the autumn herd and cows in the spring herd:

“We use the same criteria when picking bulls for the autumn herd, as we do for the spring herd. We want to use bulls with at least €100 for fertility sub-index in EBI, and we want bulls with at least 35kg for solids and plus 0.2% for fat, and plus 0.15% for protein.

“We haven’t used any Jersey bulls, but we did have some Norwegian Red cows back in the 2000s, and some of their genetics are still in the herd.

“The cows are doing 7,500kg of milk annually, and we only ever use bulls that are no more than plus 100kg to plus 200kg in milk volume, so we get plenty of milk without having to use extremely high milk bulls,” Aidan says.

Economic Breeding Index

The EBI of the herd is €206, with €78 for milk sub-index and €87 for fertility sub-index. This year’s maiden heifers have an EBI of €267, and Aidan is hoping that they will be at 360kg to 370kg at breeding, but he says he will be bulling them all then anyway, whether they are at target weight or not.

Calving starts in mid-September and is finished by the end of November, before breeding starts on 12 December. The mean calving date is 9 October.

Grassland management

Teagasc adviser Vincent Treacy spoke about the importance of grassland management, in terms of achieving good animal performance and reducing feed costs.

Vincent said that there is approximately 1t of meal fed over a four-month period when cows are indoors and at peak production.

He said that the target on the research farm is to have one-third of the farm grazed by 1 March, but he said they would be happy to exceed that figure if the weather was good and push it up to 40% to 45% grazed by 1 March.

With all the cows calved, there is no shortage of demand, so it’s relatively easy to get through area in spring.

Vincent said that some silage is in the diet throughout the entire first rotation, and that the secret to having sufficient grass in the second rotation in April and May is to ensure that there is enough of the farm grazed early, because this land has a long time to recover before being grazed again.

Grazing target

The target is to have two-thirds of the farm grazed by 15 March and to start the second rotation in early April.

During wet weather, cows will be out for short grazing bouts of two to three hours at a time, and Vincent said that it’s normally just one grazing bout per day, but this can vary depending on weather and grass supply.

Silage and meal feeding rates will be adjusted accordingly and the objective is to reduce feed as quickly as possible.

Since a high proportion of milk is produced over the winter, silage quality is critical and the target is to have first cut taken by 14 May. Aidan says that if the conditions are good enough, he will cut on 10 May.

He says one of the key things that needs to happen to achieve this is to ensure that fertiliser is spread in time. Silage quality is generally between 74% and 75% DMD, as there is no room for any poor-quality silage on 100% winter milk herds.


Managing grass in autumn can often be tricky on winter milk farms, because cows are dry and the demand for grass decreases. At the open day on 6 September, all the cows were dry and were out grazing.

Prior to calving, cows are moved to a stemmy paddock of grass 10 to 15 days before calving, where they get access to hay and straw in a feeder and calve outdoors, weather depending.

Aidan says 80% of the cows will calve outdoors, where they also get free access to dry cow minerals in tubs. The field that the cows calve down on never gets slurry, so the potash levels in the sward are low, which helps to prevent milk fever.

Prior to calving and when some of the cows are dry and others are still milking, the milkers will graze ahead of the dry cows.

Key aspect

One of the key aspects of grassland management identified by Aidan and Vincent is around ensuring that covers don’t get too strong in the autumn for freshly calved cows.

Vincent says that freshly calved cows should be grazing covers of around 1,400kg and not covers of 2,000kg or more that spring calving cows can tolerate.

The peak grass cover in autumn is never more than 950kg/ha, with silage typically fed from 1 November and a target closing cover of 650kg/ha by 10 to 15 November.

In 2022, the farm grew a total of 12.9t DM/ha from 198kg N/ha of chemical nitrogen with reduced nitrogen on high clover swards. Of the 12.9t DM/ha grown, 10.6t was grazed and 2.3t DM/ha was produced as silage.

“We try to get 65% to 70% of the farm grazed in October and we don’t like feeding silage until November if we can, because what we find is that if we buffer with silage in autumn, they will leave grass behind them.

"It’s the opposite in spring; if we buffer with silage, then they will eat the grass and leave the silage,” Aidan says.

Freshly calved cows start at 2kg of meal per day and build up to 5kg over the space of a week or so. The most amount of meal fed is 8kg per cow during the peak period.

Aidan says that one of the biggest costs with an autumn calving system is that good grass in August, September and October is being fed to dry cows, as opposed to milking cows.


A new calf shed was built in Johnstown Castle and newborn calves are brought there after calving. They are fed colostrum and transition milk for five days after calving, and then are fed milk replacer for the rest of the rearing period.

Calves are weaned off milk at 95kg to 100kg liveweight, and then turned out to grass on 1 February.

Aidan says younger stock get prioritised when it comes to grass quality.