Cows that can produce high yields of good-quality milk from both their winter diet and grazed grass is the key breeding aim on the dairy unit at Blakiston Houston (BH) Estates.

Ian McAteer from BH Estates gave the NI Institute of Agricultural Science (NIIAS) an overview of the herd during a recent visit to the farm located at Dundonald, Co Down.

“We are looking for cows that produce high butterfat and protein content milk from forage when they are in the cubicle house and outside at grass. We are trying to breed a happy medium cow and make the best use of what we can grow in this country,” he said.

There are 320 cows in the herd at present, with an average yield of 9,486l at 4.41% butterfat and 3.33% protein. Concentrates fed per cow stand at 2,786kg, which equates to 2,713l from forage.

It was pointed out that the concentrates figure includes soya hulls, which are used to stretch winter feed supplies. This is because there is significant demand for silage from the dairy herd and a 500kW anaerobic digester (AD). If soya hulls were excluded, meal fed per cow would be closer to two tonnes.

Autumn calving

The autumn-calving herd calved down to the Holstein sires Heart, Rager Red and Network over the 2023/2024 season. Calving starts in September, around 250 cows are calved by Christmas and it finishes completely in February.

With sexed semen used for breeding replacements, the tight calving block means all replacement heifers are born early and make a uniform group throughout the rearing process.

“We keep around 90 heifer calves for replacements each year. There is scope to have less heifers in the system, but we like to have a few extra in case of something like a TB breakdown,” Ian said.

Cow comfort and hygiene is a big focus over the winter period. The cubicle house has brushes for cows to scratch and two robotic scrapers to keep slats clean. All cows wear collars for heat detection and to monitor mobility.

Ian said there is a strong focus on hoof health and cows are foot bathed after most milkings, either with formaldehyde or copper sulphate. Cows that show signs of lameness are treated quickly before symptoms worsen and all cows are routinely hoof-pared at drying off.

Grazing and feeding

During the grazing season, cows are allocated grass in 24-hour paddocks.

The aim is to have cows out during the day from mid-April and out night and day from mid-May.

“We try to keep grazing until mid-October if we can. Although they were housed a lot of nights last year because of the wet weather throughout the summer,” Ian said.

The farm is made up of 630 acres of grassland, 40 acres of winter rye, 40 acres of spring wheat, plus another 40 acres of trees and shrubs.

Around 400 acres are set aside for first-cut silage each year and this is kept solely for the milking herd.

Smaller areas are used for second and third cuts and this silage goes to young stock and the AD plant.

The current diet for the milkers includes 12kg of maize. Homegrown wholecrop is usually included in the diet, but a lighter crop last year led to it being used up early so bought-in maize is being used instead.

Renewable technologies and wastewater treatment

Jack Blakiston Houston told NIIAS members 83% of energy used on the dairy unit is supplied from renewable sources, mainly a 223kW wind turbine. The turbine is “de-rated” as its potential output is 900kW, but a restriction has been applied on it due to a limited grid connection.

“It produces 1 million kWh a year. If we took the choke off, it could produce 2.3 million kWh. All we need is the line capacity to take the power,” Jack said.

There is also a small source of renewable energy from 12kW of solar panels on the shed roof. “The only reason why the shed is not covered in solar panels is because there isn’t enough line capacity,” Jack said.

All lights in the cow shed have been recently changed to LED lux. These lights are more energy efficient than conventional halogens and are predicted to give a 30% return on investment.

There are constructed wetlands near the farmyard which are used for wastewater treatment. All parlour washings and run off from the yard flow into these reed beds.

A key measure of wastewater treatment is the change in biological oxygen demand, known as BOD. The water flowing into the wetlands at BH Estates has a value of 1,300 mg/litre, whereas the water flowing out scores 3 mg/litre.

The dairy herd at BH Estates has an average yield of 9,486l, at 4.41% butterfat and 3.33% protein.