INDICES exist for different markets such as terminal index and self-replacing index.
Choosing the highest index animal will not necessarily result in a suite of traits that will suit your herd.
Compromise will likely be needed. It is still essential therefore, to look at the Estimated Breeding Value (EBV) for each trait and determine if they are appropriate to your needs and ultimately satisfy the previously identified desires.
Cattle producers should align their bull selection criteria to their herd goals. This starts with identifying their desired markets.
Many commercial operations sell calves at weaning, though some retain ownership in the feed yard. Other producers focus on raising replacement heifers. Some finish dressing cattle themselves and sell freezer beef. Each of these markets requires a different set of traits.
Knowing the desired market helps producers focus on bulls that excel in these areas.
Producers should know if bulls are classified as having terminal or maternal traits.
Traits are often classified as terminal or maternal. Terminal traits focus on carcass, marbling and yearling weight.
Maternal traits cater more towards birth weight, weaning weight, milk and mature cow size.
Financial values for performance measures are calculated for each breed’s production and market.
Using genetic theory, these financial values are used to calculate appropriate weightings for the EBVs currently available. A bull that excels in traits that benefit their operation is valuable as the animal could impact a herd for the next five to 20 years in some cases.
Some bulls look better on paper than they do in real life.
Producers should make sure the bull has the conformation traits necessary to do the job. First and foremost, a bull needs to function.
Its job is to breed as many cows as possible in a limited amount of time.
This requires the animal to be structurally sound, have adequate condition and a strong libido.
Producers have several genetic and scientific tools to help with bull selection.
The most common data measurement buyers use are expected progeny differences (EPDs). These numbers predict how a bull’s offspring will perform compared to its counterparts.
Producers should also pay attention to hoof health and shape, testicle size and leg movement. This will show if the bull is able to cover ground and breed the number of cows expected.
Docility is important, too, especially if labour or facilities are not readily available.
Methods of selection should be based on clear breeding goals, aimed at increased milk and/or beef, and improved productivity using the available resources in a sustainable manner.
Ideally, animal recording schemes (milk recording for dairy animals and performance recording for beef animals) should be in place.
This will allow for the selection of sires used in artificial insemination (AI) based on EBV of the sire’s parents or, in the case of beef breeds, his own EBVs for different traits.
The availability of EBVs in a population depends on an internationally approved pedigree registering and recording system.
Individual animals should be clearly identified by ear tag or other equally effective technique (collars, freeze brands, electronic subcutaneous devices).
Basic milk recording entails regular milk weights and analysis for percentage butter fat and percentage protein.
Bulls selected on the basis of their genetic merit should be subjected to a general clinical examination, an examination of the reproductive organs, semen examination and serving ability assessment.
This will be done routinely at the time of collection of progeny test doses of semen. The fertility performance of each bull should be recorded from conception rates based on pregnancy diagnosis.
Non-return rates (NRR) may be used in situations where pregnancy diagnosis is not available to farmers.
NRR are only reliable as an index of bull fertility in artificial insemination where heat detection efficiency is very high.
Selection of bulls with high efficiency of reproductive functions will improve the running of the AI centre and ensure improvement of male reproductive efficiency in the population.
It should be stressed that fulfillment of breeding goals and genetic improvement requires rigorous selection and culling.
Contract matings using semen from the best bulls inseminated into cows that are ranked high in the population on their production provide the source of bull calves.
A selection panel of people knowledgeable about cattle and the industry advises on contract matings and inspects the calves, selecting individuals on breed type, health and conformation for the progeny test team.
One thousand doses of each young bull’s semen is distributed randomly to farms participating in the progeny test scheme.
This must result in at least 25 herd recorded daughters in 15 herds for minimum reliability of the EBVs derived from the production of those daughters.
The basis for selection and ranking of bulls with respect to their genetic value for different attributes is the EBV.
The EBV for a characteristic such as milk production of daughters is heritability x phenotypic superiority.
The latter is the difference between the value for a bull and the mean value for the population in a country or specified area.
The cornerstones for genetic improvement are:
l Objective measurements of performance: In areas with small-holder farms, some deliberate selection of the better farms for contract matings is probably necessary to obtain accurate and regular results. Records on AI dates and calving dates are essential. Some form of approved milk recording or the use of a likeability score is necessary. An incentive scheme is usual for farmers participating in progeny test programmes. Herds accepting semen from bulls to be progeny-tested may have the cost of that semen discounted.
Normal conformation and functionality: Selection of bulls, semen or cows for genetic improvement under African conditions should be based on fertility and production performance within African environments. Animals should be able to reproduce and produce efficiently. The first requirement is that the AI sires should be born without assistance. Their daughters should have regular and normal calvings. Cows for contract matings should have a record of regular and normal calving.
l The progeny of a cow tells how good she really is. The cow has to produce a daughter that is better than she is (measured by kg of milk, likeability or other measure). Function in the herd is first based on production and freedom from disease, then on conformation and other traits. Inspection of animals and records of their reproduction and production is generally done by a panel including a veterinarian and a geneticist.
l Adaptability: This is the ability to sustain production under adverse conditions. Records of progeny of AI bulls and contract-mated cows will provide a measure of reproductive and productive adaptability. African environments are harsher than the European and North American environment. Selecting for sustained high production under different African conditions should be a priority.
Large frame size, very high milk production, high feed intake and ability to sustain production under housed conditions may not be the best genetic base for many African conditions. Ability to produce and reproduce under poor nutritional conditions, together with tolerance to heat, ticks and tick borne diseases are important attributes often found in indigenous breeds.
The length of time a cow remains in the herd and reasons for culling may form a useful basis for measuring sustainability. These cornerstones are the same for the improvement of indigenous breeds, exotic breeds, cross breeding and the formation of synthetic breeds.
Dr Tony Monda holds a PhD in Art Theory and Philosophy and a DBA (Doctorate in Business Administration) and post-colonial heritage studies. He is a writer, lecturer, musician, art critic, practicing artist and corporate image consultant. He is also a specialist art consultant, post-colonial scholar, Zimbabwean socio-economic analyst and researcher. E-mail: tonym.MONDA@gmail.com