IGNITING GENETIC IMPROVEMENT
IN BRITISH SIMMENTAL
20 years of breeding – where have we come from, and what does the future hold?
Breeding lies at the foundation of any beef production system. Whilst herd breeding decisions are just one element of cattle management, selecting superior parents for breeding will lead to cumulative and permanent gains in herd productivity, profitability and efficiency.
Suckler farmers across the UK have a variety of systems, resources and end markets, each of which has its own requirements in terms of both male and female performance. Identifying what you yourself, and your customers require from your cattle, is an essential first step to choosing a bull to breed your cows with.
Good genetics are the basic building blocks of animal production, no amount of extra feed and good management
can truly overcome the influence of poor genetics. The benefits of genetic improvement are both cumulative and permanent, so good breeding decisions will continue to pay dividends in the herd over many years, and the use of estimated breeding values (EBVs) across the agricultural industry has led to huge gains in productivity and profitability in the past 50 years. As the industry has gained more knowledge on the use of these tools, we are now able to continue that improvement in productivity while maintaining health and welfare traits.
In this article we take a closer look at Simmental genetic improvement since 2000, to discover how the breed has improved over time, and how more effective use of EBVs could speed up progress and add value within the breed.
Genetic index trends
Looking at the trend in index values for the Simmental breed since 2000 (Figure 1), we can see that the breed has made progress in terms of both the Terminal Index, and the Self Replacing Index. The breed averages (Mean EBV) for the Terminal and Self Replacing index have each increased by over 50%. For each index, animals that were within the top 10% of the breed in 2000, would find themselves in the bottom 20% of the breed by today’s standards.
In figure 2, we can see that over the past 20 years, the traits where we see the biggest improvements have been terminal traits such as weaning weight, yearling weight, and finishing weight, where genetic gains have increased by approximately 40% between 2000 and 2018. On the maternal side, milkiness remains a strength of the Simmental breed, where the breed average EBV has increased by 50% since 2000.
In figure 3 we can see the genetic trend lines for the 4 traits relating to calving: birth weight, calving ease direct, calving ease daughters, and gestation length. Here we see an increase in genetic gain for birth weight, calving ease daughters, and gestation length, and a decrease in genetic gain for direct calving ease. Where there has to be care is in the trends that can be seen for birth weight and for calving ease direct, and particularly in a breed where value is placed on maternal characteristics.
The Simmental has a recognised reputation for being an easy calving breed, and this may become an increasing challenge to take sight of and maintain if the current genetic trends for birth weight and direct calving ease continue.
Both the calf and the dam have an effect on overall calving ease, the calf through its size and shape (the ‘direct’ component), and the dam through her pelvic size and shape (the ‘maternal’ component). The calving ease daughters EBV is made up of the maternal genetic component, plus ½ of the direct genetic component for calving ease. The increase we see in calving ease daughters over time will be driven by the maternal genetic component of this EBV.
The other potential challenge is the EBV for mature cow size, where we see the breed average EBV increasing by over 1kg per year. Despite larger cows generally producing progeny with higher carcase weights, these gains are outweighed by higher cow maintenance costs, and decreased fertility. The question of “how heavy is too heavy” is discussed in more detail on page 80.
How can maternal traits be an issue if the self-replacing index is improving?
The Self Replacing Index is designed to rank bulls by their genetic potential for the production of female replacements while producing prime steers and excess heifers for beef production. It therefore takes into account both terminal and maternal traits. It is quite likely that the improvements in the self-replacing index are being driven by the terminal component of this index. It’s therefore important to look at individual EBVs for maternal traits, as well as the self-replacing index when selecting maternal bulls for breeding.
Where do we go now?
|Trait (units)||Current Change Per Year||Intensity Of Selection (2019 Benchmark)|
|Mature cow weight (kg)||1.09||45%|
|Carcase weight (kg)||0.90||45%|
|Eye Muscle Area (cm2)||0.08||45%|
|Gestation length (days)||-0.02||50%|
|Calving ease direct (%)||-0.03||50%|
|Calving ease daughters (%)||0.01||50%|
|Weaning weight (kg)||0.54||50%|
|Yearling weight (kg)||1.16||50%|
|Finishing weight (kg)||1.14||50%|
|Scrotal size (cm)||0.02||50%|
|Fat depth (mm)||-0.01||50%|
|Retail beef yield (%)||0.04||50%|
|Intramuscular fat (%)||-0.01||50%|
Table 1: the current rate of change per year for each recorded trait in Simmental cattle, based on animals born in 2000-2020, alongside intensity of selection that this is equivalent to.
Data since 2000 shows that the general strategy employed in breeding Simmental cattle is to select animals whose genetics reflect the breed average or better (Table 1). The breed has therefore taken the important first step towards good genetic progress, by not breeding from animals whose genetics are below average.
Although it’s a great first step, using the breed average as your selection threshold for breeding will set an upper limit to the amount of progress over time. If the breed continues to use “above average” as their selection threshold, while other breeds push towards breeding only animals from (for example) the top 20% of the breed, there is a high risk of the breed being left behind in terms of performance.
To really ignite genetic progress in the breed, and ensure that the Simmental retains and kicks on it’s place in the UK beef market, then there is a challenge to hold your breeding cattle to higher standards of performance, and target only the top 25% of animals for use in breeding.
At the moment it may not be as easy as you would like to identify these higher performing animals. As with so many things in life, “If you can’t measure it, you can’t manage it”. The best way to identify the best genetics within the Simmental population is to encourage widespread performance recording among pedigree breeders.
Take home messages:
- Aim high, not average (select within top 25% of breed)
- Performance record wherever possible “If you can’t measure it, you can’t manage it”)
- Keep an eye on maternal performance
- Know your market, and breed animals that will excel for yourself and your customers
*The British Simmental Cattle Society uses the Breedplan system which is one of the most widely used beef recording systems in the world. Breeders submit weight and performance data to the Society which is in turn sent to ABRI, the providers of Breedplan, who generate the EBVs across a range of maternal and terminal traits. EBVs are calculated and updated on a monthly basis and fed back to members. Herd costs to performance record starts at £120 per annum. If you are a BSCS member and wish to begin performance recording your herd, please email email@example.com and request a Breedplan membership pack.