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Genetics

How it works

The Genetic Programme

Deer Improvement’s leadership in breeding high BV stags can be attributed to the scale of the operation and the application of science.

The programme is run to ensure that non-genetic factors are excluded so that genetic variation is apparent. This demands strict mob management so that animals can be compared with their contemporary group. It is vital that feeding and animal health are managed to ensure the observed differences between individuals are, as far as possible, based on genetic differences.

Genetic gain is driven by several key factors as listed in the following equation:

Rate of                                   Genetic Variation x Accuracy x Selection Intensity

Genetic Gain            =                                  Generation Interval

The larger the variation in genetic value between individuals, the greater the opportunity to apply selection pressure to make gains. The variation between growth rates of deer raised together is large and enables us to identify, select and breed from animals with much higher genetic value than the average.

Accuracy is increased through initiatives such as DNA parentage testing, multiple weighings, careful recording and use of electronic ID. In addition, the accuracy of individual animal BVs are increased by enlarging family size and for this reason a large embryo transfer programme is implemented. Such a programme demands a management regime with extreme focus on detail. Facilities must enable data collection to be efficient, reliable and repeatable. Data collection and interpretation is the essence of a soundly based breeding programme.

Selection intensity is driven by the numbers of animals involved, and this is why Deer Improvement’s Balfour farm was selected partly for its carrying capacity. In future we will have hundreds of elite stags born annually from which to select the new AI team. AI and ET are both tools enabling further selection intensity as they are used to multiply favourable genotypes. Because our AI team will be comprised of animals ranking in the top few percent, we have very strong selection intensity.

Generation Interval

Each generation provides an opportunity to make genetic gain, so the more quickly the generations can be turned over, the faster the rate of gain. This is why our embryo programme is based on use of spikers and yearling hinds. By the time an animal is 12 months old we have all of the information necessary to calculate a reliable BV, so any unnecessary delays in capturing their genetic potential would represent an opportunity cost.

Reproductive Technologies

Embryo Transfer is expensive but it is an important tool in driving genetic gain because it enables multiple offspring to be generated from the most desirable sire/dam combinations.

In a well run genetic programme the new generation always contains the animals of highest genetic merit, and because shortening the generation interval is so crucial to increasing the rate of gain, we concentrate our embryo programme on spikers and yearling hinds.

The Deer Improvement ET programme has proven to be hugely successful under the management of Dr Mike Bringans. Semen has been collected from virtually all spikers targeted, the number of embryos collected has exceeded 10 per hind, and the hold rate on implantation is close to 90%.

Cumulatively these factors have propelled the genetic programme well ahead of schedule and our nucleus herd of elite hinds is quickly growing to provide the scale and therefore the selection intensity needed to optimise genetic gain.

Breeding Values and their application

A Breeding Value is simply a tool to rank animals based on their genetic merit.

The calculation of the Breeding Value will incorporate various sources of information such as the animal’s own performance, that of its sire and dam, its offspring, and other related animals. It will make adjustments to ensure that environmental effects are stripped out to expose the impact of the genetics alone.

The computer calculation that generates the Breeding Value is complex, but utilising the Breeding Value is easy. On average the offspring of a sire and dam will inherit the average of the parents BVs but we can also predict the proportion of offspring whose genetic merit will exceed this average by a specific amount. This is because the variation around the average follows a normal distribution pattern.

A commercial herd can match the annual rate of genetic gain in the Deer Improvement AI stag team simply by mating proportion of the hinds each year.