Genetic improve one way of increasing production

1. International Center for Agricultural Research in the Dry Areas
icarda.org cgiar.org
A CGIAR Research Center
Tesfaye Getachew and Aynalem Haile
Addis Ababa, Ethiopia
Skill Training on breeding goal, objectives and
selection criteria

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Setting up a breeding program starts with the definition of a breeding goal and is followed by the design of
a scheme that is able to deliver genetic progress in line with this goal. A breeding goal with the relevant
traits, collection of performance data, analysis of the data for the identification of superior animals, and
the use of superior animals to produce the next generation, are the main components of structured
breeding programs.
Definitions
A breeding goal is the specification of the traits to be improved including the emphasis given to each trait.
It gives the direction in which we want to improve the population.
A Breeding program is a program aiming at defined breeding objectives for the production of a next
generation of animals. It is the combination of recording selected traits, the estimation of breeding values,
the selection of potential parents and a mating programme for the selected parents including appropriate
(artificial) reproduction methods. See scheme at the beginning of this chapter.
A remark: traits with an optimum value
For most of the traits, the objective is a continuous improvement, but for some of the traits the goal is to
reach intermediate values. Examples of such traits are egg weight where a market exists for table eggs
between 55 and 70 grams. Mature body size is positively related to returns at slaughter but negatively
with feed efficiency. The production aim is a high carcass value in combination with low feed cost. Thus in
many meat production systems mature body weight of the animals has an optimum.
The breeding goal

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• A breeding objective describes animals you would like to breed that are appropriate for
your production system and market and selection is the method by which the producer
identifies that animal
• All breeding enterprises should establish breeding objectives and goals and implement
selection processes to meet those objectives as part of the overall business planning
process
• Breeding objectives
• A breeding objective describes characteristics that affect profit the most, as well as how
important each trait is to profit
• can best defied with the concept of economic theory (it represent by the demand
at least one stakeholder associated with livestock industry for a technical change in
each individual genetic trait of interest and is commonly quantified as a set of
economic values expressed in currency unit per unit of change in each trait)
• Supply side of genetic improvement (depends on factors such as heritability of
recorded traits, cost of recording and relationship of recorded traits with traits
defined in the breeding objectives)
Breeding objective and selection

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When developing breeding objectives consider:
• A breeding objective should be specific, measurable and attainable
• A breeding objective is generally specific to a particular market, therefore it is important
to understand customer and market requirements
• Depending on the target market, some traits or characteristics have greater economic
importance than others eg growth rate as an influencer of live weight at sale
• Monitoring the current herd or flock performance against customer or market
requirements and considering how this performance and the requirements might change
over time.
• Some traits are highly heritable or readily passed on from one generation to another.
Greater progress towards breeding objectives can be achieved by targeting traits that are
highly heritable
• Focus on traits of economic importance rather than traits that have more to do with
'tradition' or 'personal preference'

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Your breeding objective should target characteristics (traits) that:
• can continue to be improved within the limitations of your environment and
production system;
• contributes the most to your profit;
• are heritable and have sufficient genetic variation to enable progress to be
made.
• Also note that the more traits that you include, the progress for each will be
slower, however the progress against the objective can still be high
• Breeding objectives generally include the characteristics of importance, the
level they should achieve and the time frame in which this will be achieved

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• Before defining the breeding goal many questions on the
production system have to be answered.
• For what reason the animals are kept? In which way the products
and animals are marketed? What are important aspects of feeding
and management? Are the breeders organized? Is there already a
breeding program in place? What traits can be recorded? Is
artificial reproduction applicable? Hence, these aspects of
production systems determine the possibilities for breeding
programs and for the selection of breeding goal traits.

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• The choice of the most appropriate breed to use in a given environment or
production system should be the first step when initiating a breeding
program
• Numerous examples exist of animals of high productive breeds (e.g. Holstein
Friesian dairy cow) imported in tropical countries without any success.
• The animals are not adapted to the high temperature, they hardly reproduce and
heat stress impedes high production levels. In addition many tropical diseases lead
to a high mortality.
• When adaptation ignored, the fitness of the animals will be reduced.
Adaptive fitness is characterized by survival, health and reproduction related
traits
• Locally adapted autochthonous breeds display a far greater level of
resistance and adaptation due to their evolutionary roots as compared to
imported breeds

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• The breeding goal for food production aims, irrespectively of the
species, at: improving gross efficiency (amount of product
divided by the amount of feed consumed) and reducing cost
price by:
• improving productivity (higher yield and financial returns,
• improving feed conversion (less feed per kg of product and
less costs) and
• improving reproduction, health and survival (less
replacement animals needed and less costs).
• Increasing attention to improve welfare and to reduce
environmental impact might be additional breeding goal traits.

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Recording breeding goal traits raises a lot of questions:
• What can be measured?
• How often can or should the trait be measured?
• Who or what is measuring the trait?
• What animals can or should be involved?
• At what age?
• How detailed?
• What is the accuracy of the measurement?
Measurements of breeding goal traits

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• Breeding goal traits might be quantitative. Milk, meat or egg production, body
measurements or performance expressions are examples of quantitative traits. They are
measured in units: in kg or simply in numbers: kg of milk, grams of growth and number
of eggs.
• Breeding goals might be qualitative e.g. the quality of a product or an important trait in
the breed standard. Product traits, scores for body traits, disease incidences or
performance impressions are examples of qualitative traits. They are measured in
classes: e.g. a 1 (good), 2 (moderate) or 3 (bad) for meat quality or simply 0 (not present
in the animal) or 1 (present).
• Some breeding goals traits cannot be measured at the time when it is relevant. E.g. in
meat production, meat quality is an important breeding goal trait. However, you cannot
measure carcass composition of a young calf, piglet or lamb at the moment you
consider to use the animal for breeding. It can be measured only after slaughter and
then breeding with that animal is impossible. Indicator traits, obtained by scanning live
animals for body composition before you take breeding decisions may help to predict
carcass composition.
Which traits should be recorded

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• Breeding goals can be simple or complex. In case of commercial breeding programs many traits are
recorded and have an influence on the profit of animals produced by these commercial breeding
programs.
• In extensive production conditions or in case of hobby breeding only a few important traits are
recorded and simple breeding goals consisting of a few traits are used.
• In order to rank the individual selection candidates for the breeding goal traits it is necessary to
comprise the values for the respective traits into one single selection criterion.
• The value of this criterion can be obtained by summing up the breeding value for each trait multiplied
by a weighing factor based on the relevance of that trait in the breeding goal.
• The relevance might be based on the relative economic value of the trait.
Index

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Farmers trait preference
Survey, flock ranking, choice experiments
• Simple
• Helps to identify true breeding objectives of farmers
• Considering economic selection index might be difficult

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Selection
• Once producers understand the requirements of the target market and have
developed breeding objectives that are aligned to these requirements, they can begin
selecting livestock that meet the breeding objectives
• Selection describes the process of choosing animals that meet the requirements of the
breeding objective and will, in a breeding enterprise, pass particular traits onto their
progeny.
• Selection should consider both subjectively measured traits (visual assessment) and
objectively measured traits (genetic assessment).
Subjective, visual assessment
• Visual assessment is an assessment of an animal based on what can be physically seen.
• While the requirements will vary depending on the enterprise's breeding objectives,
traits to look for when visually assessing livestock include:
• The conformation or shape of the animal eg muscling.

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Objective, genetic assessment
• Objective assessment uses actual measurements to assess the relative
worth of an animal to an enterprise.
• One form of objective assessment is genetic evaluation which provides an
insight into the genetic makeup of animals.
• This is particularly useful when sires are being acquired to improve a herd
or flock according to the enterprises breeding objectives.
• The difficult task of selecting breeding stock based on genetic assessment
has been made easier and more precise through estimated breeding values
(EBVs)
• Breeding values are calculated using information from each animal's own
performance and from the performance of its relatives.
• This information can help select and breed livestock that will achieve
performance targets and improve profitability.

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Breeding, classing and culling
• Classing and culling play an important role in improving the average
genetic merit of a herd or flock.
• Producers can class livestock and cull where necessary to achieve market
specifications and the enterprises breeding objectives.
• This may occur prior to selling and be based on factors such as condition
score, or prior to breeding and consider more fundamental
conformational or genetic traits.
• Regardless of when classing occurs, target market specifications should
play a major role in the process.