Johnstown Castle Winter Milk Herd

The Progressive Genetics team recently visited the Johnstown Castle Winter Milk unit in County Wexford. Farm Manager Aiden Lawless and Winter Milk Specialist James Dunne provided insights into the herd’s performance and breeding strategy. The farm’s success is rooted in genetics that deliver high combined fat and protein kg, high-component milk while maximizing the use of grazed pasture and conserved forages. Consistently, the farm has utilized high-EBI bulls with strong rankings in the milk sub-index, combined fat and protein, and health sub-index. The herd’s breeding objectives are as follows:

• The same genetic profile for the autumn and spring calving herds which is well balanced for fertility and milk traits
• Ensure long lasting fertile cows (Fertility Sub-Index)
  • Herd calving interval <375 days
  • Six week calving rates >80%
  • No recycling between calving blocks
  • High rates of survivability, with cows lasting 5+ lactations
• Strong emphasis on high solids milk production (Production Sub-index)
  • 85% of total liveweight delivered as kg of milk solids
  • Over 4,500 kg of high-component milk from forage
  • Protein percentage above 3.75%
  • Fat percentage above 4.45%
• Ability to maintain optimal body condition score with ease
• A functional, well-rounded cow

Fertility plays a vital role in establishing a mature herd and is a key factor in achieving high production and feed efficiency. On this farm, 70% of the herd calves during the confined autumn block. Breeding begins on December 12th and is strictly limited to 10 weeks. Last year, the farm achieved an impressive 21-day submission rate of 81% and a six-week calving rate of 78%, with the herd’s average calving interval standing at 370 days.

Over the past five years, the herd has achieved an average production of 7,392 kg of milk per cow, with 4.53% fat and 3.66% protein, equating to 605 kg of milk solids. On average, the herd is supplemented with 1.63 tonnes of concentrates annually, along with some maize silage.

The herd’s current EBI (Economic Breeding Index) stands at €237, with a milk sub-index of €79. This includes 22 kg of combined milk solids, comprising +108 kg of milk, +0.15% fat, and +0.12% protein.

The 2023-born heifers have an EBI of €277 and a milk sub-index of €91, delivering 26 kg of fat and protein from +85 kg of milk, with +0.18% fat and +0.15% protein.

The 2024-born youngstock have an impressive EBI of €293 and a milk sub-index of €94. Their combined fat and protein figure stands at 28 kg driven by +77 kg of milk, +0.23% fat, and +0.15% protein.

Bull Team Average

The team has selected a bull team that excels in fertility, production output, and high component percentages. The average EBI is €344, with a milk sub-index of €120, fertility at €141, maintenance at €8, and health at €23. In terms of production, the bull team boasts a milk sub-index of €120, delivering 37 kg of combined milk solids, consisting of +129 kg of milk, 23 kg of fat, and 14 kg of protein, with +0.30% fat and +0.17% protein.

Current Performance

During our visit, the cows were producing 2.19 kg of milk solids per day, yielding 27 Kg of milk at 4.45% butterfat and 3.67% protein while on a full-time grass diet supplemented with 6 kg of concentrates.

Now, on a fully indoor diet, they are producing 2.28 kg of milk solids daily, consisting of 28.5 Kg of milk at 4.40% fat and 3.60% protein. Their current diet, on a dry matter basis, includes approximately 7 kg of concentrates, 7 kg of grass silage, and 7 kg of maize silage. The herd continues to perform strongly under these conditions.

Key Message

The herd is part of the National Genotyping Program, and Aiden utilizes the genomic EBI data from the female youngstock to guide management decisions. This information helps determine which calves to breed for dairy replacements or sell. There is no difference in cow type on the farm, regardless of whether the female will be part of the winter or spring calving system, the same bull selection criteria is used for both herds

A big thank you to Aiden, James, and the team at Johnstown Castle Estate for taking the time to share their knowledge and giving us a great look into the breeding success of their Winter Milk research facility. A big thank you to South Wexford breeding advisor Eugene Kehoe for his outstanding service and support to the farm.