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"HEART OF AFRICA"
Burundi Goat Rehabilitation Project

Alliance Burundaise pour la Coopération et le Développement &
Austrian Help Program

burundigoats@yahoo.com
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BREEDING FOR GENETIC RESISTANCE

    By D. de Treville.  An earlier version was published in: JOURNAL OF THE NORTH CAROLINA DAIRY GOAT ASSOCIATION.  Spring, 2004;  the original version appeared in Artisan Cheese.

Although our project is in the center of Africa, there is a major problem that we share with goat producers in the Southern part of the United States: HUMID TROPICAL WEATHER CONDITIONS – that favor year-round procreation of parasites and other diseases. 

How do goats that evolved to flourish in temperate climates fare, when brought to humid, tropical environments?  It is true that animals taken to a different place [as well as people] can adapt – or become acclimated – to many environmental changes: blood thins or thickens – as does hair/fur, the gut gets used to a different diet, etc.  But this takes time.  For example, with our own imported Boers from South Africa and Alpine dairy goats from Germany,  we've found that it takes these exotic stock about 12 months to adapt to our humid tropical conditions. 

Doe that escaped the Rebels - in Coffee Field

An outstanding Central African Goat [CAG] doe, saved from rebels by being hidden here, in the farmer's small coffee garden. As the majority of tropical goats, she has been raised with no  medical input, and no supplements to her brush-based diet.  Here, she stands in alert pose, ready to sprint off if necessary, protecting her infant who is in the background

Carved Gazelle in Alert Pose

This locally-carved statue of a gazelle correctly portrays the alert stance shown in the above photo; muscles tensed and ready to flee.  The lean hardiness of wild browsers – similar to that of the indigenous goat shown above – is well depicted.

 

Nevertheless, as a breed, they will never perform as well – health-wise - as the indigenous, Central African Goat [CAG] breed.  They will always need 'more' of something - drenching, protection from ticks, enhanced nutrition, etc..  As well, our Alpines are far more susceptible to ticks and soremouth while Boers are more susceptible to CL and respiratory problems.  These are breed-specific 'weaknesses' in handling local, tropical conditions - and they can't be overcome by ongoing medication.   That is because over the thousands of years that goats and other ruminants and livestock have lived in the tropics, they have gradually evolved to develop genetic resistance to a wide variety of vector-based diseases, especially trypanosomosis, which is fly-borne, and various tick-borne diseases.  As well, research is showing that many of these breeds have genetically-based resistance to some internal parasites and other tropical diseases.  And while weight gain or size may not equal those of exotic breeds, they are far more capable of handling heat stress, poor fodder, water shortages, and wet conditions.

In order to combine the high survival traits of the local goats with the high production traits of exotics, we crossbreed our imported Alpine and Boer to the local Central African Goat (CAG).  In this way, we bring into the crossbreds certain genetically-based resistances to local pathogens that are found in CAGs - and by the 2nd generation of crosses our CAG-Meat and CAG-Dairy strains are just about as hardy as CAGs - but far more productive than the CAGs and far more resistant to problem pathogens than the exotics.  During this process, we cull those animals that are highly susceptible to local diseases.  In other words, we are selecting for disease resistance and thriftiness under tropical conditions of the CAGs that can be passed on through crossbreeding with Boer and Alpine imported stock.

It is also possible to develop a strain of [more] resistant goats within a breed, because genetically based variations of diseases can fluctuate as much within a breed as across breeds.  This is the breeding strategy being used in Australia and New Zealand with increasing numbers of commercial Merino sheep farms and also some commercial meat goat operations in relation to parasite resistance, and in the European Union in relation to scrapie resistance.

By identifying the most worm-resistant bucks within a herd - a genetic trait that has 20-25% heritability - breeding only with these bucks and systematically culling bucks with 'naturally' high worm burdens, it is possible over a 5-10 year period to gradually cut back on annual drenchings.  These are current results of  goat and sheep farms in Australia.  In 12-15+ years of systematic breeding it may be possible to forego drenching completely.

You or your veterinarian can help you identify most/least resistant goats by testing for worms [prior to drenching] all bucklings between 6-12 months of age, using McMaster slides and doing a fecal egg count [FEC], and then comparing in order to identify bucklings with most and least worms.

SO the moral is:  don't breed just for growth, size, good looks; lots of meat; lots of milk; good hair follicles; etc. - also prioritize and then factor in traits that you consider important, such as parasite resistance, hoofrot, soremouth – all of which can be genetically linked.  And, if your purebreds are giving too many problems in these or other areas, consider crossbreeding with a breed that performs well in your particular environment.  Cull those that require exceptionally high inputs, because chemical interventions are limited and eventually will no longer work effectively. Many small ruminant farms in Africa, Australia,  New Zealand, and S.E. Asia are already facing this tragic reality, because drenches from the three main drench families are no longer working effectively on their farms, where worms have become resistant to them.  Your pocketbook with thank you – as well as your animals. 

To Summarize our Strategy: 

The Central African Goat [CAG] that is indigenous to our area in central Africa exhibits varying levels of resistance as well as resilience to a variety of diseases, including pneumonia, certain tick-borne illnesses,  foot rot, orf, CL, and parasites – all of which more seriously affect the Project's imported German Alpine and Boer.  To help address this problem, the Project is crossbreeding CAGs with Boer and Alpine, thereby introducing local genetic materials into the imported breeds.

The following pictures show Central African Goat - German Alpine or Boer 1st through 4th generation crosses, some of the stock that is being bred by the Project for improved resistance or resilience to these diseases.

CAG Doe & 1st Alpine Cross

A CAG doe and ½ Alpine doeling – one of the first in the Project and one that has well-tolerated tropical conditions.

3rd & 4th Generation Alpine-CAG Crosses

Third & fourth generation Alpine-CAG crosses; good milkers while also retaining some genetic resistance to several tropical diseases – traits of the local CAGs who have lived hundreds of years in these areas

Frick & Frack - Young Buck Crosses

50% Alpine – CAG bucks, about a year old.  These brothers have never suffered from theileriosis, a debilitating tick-borne disease to which Alpines are particularly susceptible to a much greater extent than CAGs.  One has already  gone to a farmer goat association, and the other is being used as a breeding buck by the Project

1st Generation Boer-CAG Cross

50% Boer – CAG cross doe: a hardy and heavy meat goat that  is now into her 3rd year of providing does and bucks that are exceptionally large and hardy.

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