This article was written by Amy Hughes, Senior KE Manager at AHDB Beef & Lamb after she had spoken to Arron Nerbas to get an insight into Nerbas Bros. Angus.

Epigenetics is a word that we are starting to hear more frequently in the world of livestock breeding, but what does it mean and how do we apply it, practically, to our businesses?

Nerbas Bros. Aberdeen Angus is a multigenerational business that runs across 3 families, Arron, his brother Shane and their respective families and their parents, Cynthia and Gene. The business is based on a regenerative and holistic model, with low inputs and cattle that thrive in a forage-based system. Spread over 5000 acres, Nerbas Bros. run 550 pure Aberdeen Angus on a 100% perennial forage-based operation which focusses on improving swards through grazing management, bale grazing and seed bank infusions.

In the mid-2000s, the family made the decision to place focus on a cow type that fit with a lower input, holistic model and that was able to thrive on forage only. After looking, unsuccessfully, for local bull suppliers that fit the bill, Arron decided to go down the route of AI, which they have used extensively in the herd since. “Our breeding goal is very singular. To make better cows that are the most efficient animal at harvesting our forage, with minimal intervention from us.” And minimal intervention they have, with the herd generally only being handled 4 times per year. The genetics that have been brought into the herd have focussed on a moderate frame, moderate mature weight (570kgs), a defined forage type. The family have also paid close attention to moderate weaning weight, yearling weight and milk EPDs and a high feed efficiency value. “There is nothing terminal about what we do. Every animal born has to be capable of replacing the animals before them. It is all about the cow.”

The herd is run as a commercial herd of 475 pure females and 75 pedigree, unrecorded, females. “Extreme growth and carcase EPDs do not favour the system that we’re running here. If we were to start focussing on those traits, the system would have to change” said Arron “We keep our nucleus of 75 registered animals, to keep a track of lineage and to see what effect we can have by introducing different traits of influence” The pedigree herd has always produced some of the bulls for in house usage, however, going forward all the bulls used within the herd will come from these 75 animals, as the family have taken the decision to become a fully closed herd, following the extensive use of AI over the past 20 years. Arron said, “This is a gamble in some ways, but we feel that our genetics are now in the right place for our business”.

The main market for the business is the sale of breeding stock, with 70, mainly unregistered, bulls being sold per year. A large proportion of which are sold to repeat customers. The rest of the bull calves are castrated and sold on the open market. “When we take our steers to auction, there is a difference in the way they look compared to other cattle that have been bred for growth and carcase traits. We don’t receive any less for them though” says Arron. The top 2/3 of the herds heifers are selected as quality replacement females, with the businesses own replacements being kept from these and the rest sold privately to buyers that run a similar system. The rest are sold on the open market and go to other, grass-based systems.  “Everything is selected by eye, and we have a keen focus on type. We need a forage capable animal that has capacity,” said Arron. Extremes are also avoided, with the largest and smallest being further cut from the initial selection of heifers. The pedigree replacements go through the same process, but pedigrees and gene pools are also considered to keep the herd balanced for future matings.

The family work on 95% of the land being in a recovery state at any one time, with the cattle being moved every 2-3 days. “On average, the whole farm will be grazed 1.5 times over the course of the year, but this varies. Some of our more productive land will get grazed 3 times” says Arron “Our mindset is very much that we don’t like to do anything that a cow could do herself. So, if any of the forage goes to seed, we’ll just stock that area at a higher rate for a couple of days to allow the cattle to trample the seeds in and improve the lay for next year” All cattle are outwintered and the business has never used any artificial fertiliser.

So how does a focus on Epigenetics fit into such a simple, low input system? “Epigenetics, to me, means anything that effects phenotype but that isn’t related to the genome itself” says Arron “We have applied continual management pressure across our whole herd for years. By not focussing on individuals and having a herd first approach, only the type we want stay in the herd and produce progeny to replace them.”

In terms of maternal performance, the herd excels. With only a 55 day breeding period allowed, 60% calving in the first 3 weeks and assisted calvings at less than 2%. “Barren cows are pulled out when we handle the cattle for the calves first vaccination. We usually pull 5-10%, some of which will have calved and lost them” “Having a short breeding period like this, keeps the selection pressure for fertility on constantly, it also keeps the calf crop uniform and the system simpler”.

At weaning, the cows are kept as one group and put on bale grazing for roughly 4 months until the next calving. “We don’t split our cattle according to body condition score, if they can’t hold their condition correctly, then they don’t suit our system. Most cows would wean at BCS 3 with around half a score put on whilst on bale grazing before calving”.

So, what about data? Nerbas Bros. Aberdeen Angus take a ‘herd first’ approach to management. However, they do recognise certain traits in cow families that they like or that particularly fit the system. “These are the cow families that we make a point of trying to reintroduce sires from as we move forward.” “We don’t weigh stock or work out what % of her body weight she’s weaned, I just don’t think in our system, it’s necessary. You can obviously see which ones have underperformed by eye, and as long as you cull those animals from the herd, you’ll make progress” The business also puts emphasis on heifers grazing with their mothers from birth to weaning, in what Arron calls ‘forage training’ “When others view our herd, one of the main comments we always hear is that our cows are always grazing. Heads down all the time,” said Arron.

The breeding goals of Nerbas Bros. Aberdeen Angus are extremely clear; By applying strict selection pressures that fit with the system and sticking with the overall goal for the business, Arron and his family have been able to produce a cow that works for them in a profitable way “I believe focussing on epigenetics has improved our whole herd over time” says Arron “You could evaluate individual animals and chase their performance, but then you would end up with a herd full of cows with different input requirements, which just doesn’t work for us”

“It’s really just letting the system take over the selection process, taking the human element out. The result is a consistent and predictable herd.”

During development, the DNA that makes up a gene accumulates chemical markers that determine how much that gene is expressed. The different environmental pressures put on that gene, rearrange those markers, meaning that genes are expressed in different ways.

Epigenetics = How the environment influences the expression of genes.

Photography Credit @Jenny Wood Photography