Selecting bulls for a better block

Strategic dairy farmer David Cotton and breeding adviser Keith Gue explore the factors involved in selecting the right bulls to improve herd fertility.

Bridge Farm is located near Glastonbury in Somerset and owned and operated by David and Lene Cotton.

Their herd manager, Steve Crowther, has worked with David for nine years. Keith Gue, their breeding consultant, has been helping David and Steve develop a more autumn-block-calving-friendly herd since they made the transition from all-year-round calving back in 2016.

Choosing breeding priorities that suit your system

With the new system in place, they have focused their breeding decisions on strong fertility traits – a key factor in autumn block-calving systems.

Prior to switching systems, they calved between September and April and, in David’s words, “we were drifting, with no real priorities in calving or breeding.”

When Keith started working with David, there had been a focus on stature as the cows had started to get too tall and narrow. He shared: “There was some focus on legs and feet and the Cheswick bulls had made a big impact on body size. The decisions made were probably a little narrow and they had probably let fertility and life span focus drop. Since then, we have been focusing on healthy cows that you don’t notice and are no trouble.”

Exploring the detailed information they obtained from the herd genetic reports, empowered through milk recording data, they set themselves the priorities of improving fertility performance while focusing on smaller, stronger cows that eat less, maintain production and are more suited to their new system.

Defining the key breeding factors at Bridge Farm

David, Steve and Keith always take time to sit down once a year to examine the performance statistics and assess considerations for the next season. This is a time for detail and complete honesty. Together, they look at all elements, including fertility, calving, yields, illness, body condition, life span and, importantly, why most cows leave the farm.

This year, they completed these discussions in early September and established that cows mainly left the herd after failing to conceive within the 12-week calving block.

So, fertility and smaller, ‘hardier’ cows that had more longevity were decided on as key factors. But, as David explained, there are other considerations that are non-negotiable in the annual shortlist for key traits.

“One thing that we have always been keen on is high fat and protein percentages. Throughout the farm’s history, we have always supplied cheesemakers. From the very beginning, the farm supplied the village cheesemaker, through to the present day with Arla. So, we are looking at heifers that are delivering 6,500 litres with 4.6% fat and 3.5% protein.”

Over the next five years, David would like to maintain his favoured Holstein reds within the herd and hopes that his average milk yield will progress from 8,000 litres with 50% forage through to 8,500 litres. David is looking for cows that can go on and stay in the herd and cited how one cow who is fifteen years old is still going strong.

How Bridge Farm approach servicing the herd

Steve is central to improving the genetic merit of the herd, how well the breeding is performing, and he carefully marks up and helps serve most of the cows. He uses tail paint as markers for Johne’s, TBIR and for cows he decides are barren, have had health issues or previous history.

David and Steve believe that sexed semen has improved a lot over the last two years. They are using more sexed semen on the maiden heifers and making sure they do this early. They have also started to use more beef semen earlier too. Once they achieve 80–90 replacement heifers, everything else is served Angus. They are likely to attempt sexed on cows next year to help reduce the number of bull calves.

How Bridge Farm use data to choose the right bull

Breeding expert Keith Gue uses a custom index based to narrow down the identified options, which means they do not always need to choose the top 5–10% traits when selecting bulls, which reduces expense. They also look at over-indexes for autumn block-calving (ACI) herds to see how they are progressing against others.

David and Keith explained that they had reduced focus on choosing high-yielding milk traits in their selection process as they had not seen an uplift when they had trialled this previously. “While yield is always a consideration, it is definitely not the main driver for our selections. Double-digit fertility, life span and a reduction in body weight now means we get healthier, more fertile cows that eat less while maintaining production. In turn, that helps the farm be more sustainable.”

The SCI and ACI  indexes for block-calving herds, and PLI for all-year-round, offer a good way of benchmarking and monitoring the progress of your herd.

Keith and David explained that in the process of narrowing they look at the averages, measure these against their key goals and rank the bulls from our custom index. It is then a case of ‘nitpicking’. They also align the gestation period of the breeds. Recently, they moved from a Hereford bull to an Aberdeen Angus as the gestation matched the herd’s black and whites and made an additional £300 a head when sold.

The analysis of the bull choices they made marked those in the top 10% in key traits of life span fertility, life span and maintenance in yellow, which helped them single out the ones they wanted to use. It is then a case of repeating the process every year and tailoring your choices based on the information and experiences you have. David, Keith and Steve all agreed there is always something to learn and amend year-on-year, but that this level of focus is something they would recommend.  

Improving the herd’s genetic merit is yielding great results at Bridge Farm

The genetic merit of a herd is one of the Optimal Dairy Systems’ key performance indicators. A focus on the careful management of this over the last two years has resulted in David and his team’s herd ranking in the top 5%. Their older cows rank in the top 20% and their youngstock is reaching the pinnacle of the top 1%.