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Burundi Goat Rehabilitation Project

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Goats Thrive in Arid and Savannah Climates Because That's Where They Evolved

 

D. de Treville.  An earlier version was published in: THE GOAT RANCHER MAGAZINE, Sarah, Mississippi, November 2003; the original version appeared in ChevonTalk.

I was thinking about the very negative impacts on your goats that a lot of you experienced in humid areas of North America, during Summer 2003, due to high temperatures/heavy rain - climates that are technically associated with subhumid and humid ecosystems.  Maybe that's not the kind of climate that you normally experience in your area - but it is clearly seems to have been the ecosystem construct for many of you over the last year.

This has had major implications for parasite population explosions: coccidiosis, stomach worms, flukes, etc. - affecting goats to a far greater extent than cattle and horses, and other livestock.  As well, pasture grasses in wet climates will be less nutritious because they will be water-logged and minerals will have been leached out of them.

 

Water Point, Goats & Donkeys in the Sahel
- Zootechnie des régions chaudes

As well, heat stress, lowered libido / oestrose, pneumonia, hoof-rot, and increased vulnerability to other diseases are often found in goats experiencing these climatic conditions – when either by breed or by conditioning, they are not able to efficiently cope with these conditions.

Why do most goats suffer so much in these conditions?!  Simple.  For tens of thousands of years they evolved in, and developed optimal survival strategies for living in arid and semiarid ecosystems where extensive pastoral, rather than intensive sedentary farming systems, are the norm. 

For a bird's-eye view of how close the species-breed-ecosystem link is, here's how goat (and sheep) populations stack up in Africa - where over 30% (160 million) of the world's goat population is found:

 

% Goats By Ecosystem
On The African Continent:

Zone

Goats

Sheep

Arid             

39%

36%

Semiarid         

27%

22%

Subhumid         

16%

14%

Humid             

9%

8%

[Note - %'s do not add up to 100% due to irregularities and/orambiguities of some of the data associated with this survey

Why are there only 9% of Africa's 160 million goats in humid zones, while 39% are in arid and 27% in semiarid areas - the latter two representing a whopping 66% of the goat population?  Because that's the kind of climate in which they evolved and therefore thrive: able to travel long distances in search of forage that is often coarse and of high tannin content and so unsuitable for other stock, and able to go long periods without water - 5 days for some breeds.

Map of goat distribution in Africa; 1 point = 100,00 heads of goats
- Zootechnie des régions chaudes

 

By nature goats are not heavy water drinkers as they have a highly efficient digestive process whereby liquid is efficiently extracted from ingested food.  Compare, for example, goat berries with cow dung and you'll se how much more liquid the goat's digestive tract removes than is the case with cow dung.  As well, goats HATE rain!  They evolved largely in ecozones where there is little rainfall – and when rain does fall in arid and semiarid regions, it is generally a brief cloudburst.  Hence, goat coats in many breeds do not have the oily, protective 'anti-rain/snow' features of cattle, horses, dogs and other breeds that evolved in wetter climates.  As well, many goat breeds  are easily susceptible to hoof-rot in these wet conditions.

Due to extensive browsing patterns by which goats in their natural habitat travel many hundreds of square miles annually in search of food, as well as due to the pattern of browsing whereby goats do not generally eat close to the ground, it was not necessary for the original breeds to develop high levels of resilience or genetic resistance to parasites.  Therefore, many of today's breeds coming from arid and semi-arid regions simply cannot naturally (efficiently) cope with high worm burdens and some diseases that are met in more humid areas – without substantial inputs by way of wormers and more intensive management practices.  In such humid or wet areas, goats may have to graze close to the ground rather than browse, thus increasing parasite intake from pasture and forbs.  As well, the goat-to-land ratio may be so high as to result in dangerously high parasite populations in pastures

Goats do exist in humid areas, but without increased inputs and more systematic management practices, a high price is paid as regards productivity: prolificacy can be much lower and pre/post-weaning mortality much higher.  As well, heat/humidity stress, virulent tick-borne diseases, lower nutritive value of fodder, hoof problems, etc, are common.

West African Dwarf- of Guinea origin  browsing Ficus leaves and twigs
  - Zootechnie des régions chaudes

Some of the breeds in Africa that have been many generations in humid and subhumid ecozones have, through natural selection, developed a certain varying degrees of genetic resistance to certain parasites.  Examples include  West African Dwarf breeds, the Small East African Goats, and our own Central African Goats.   These breeds have adapted to a wide variety of brush and grasses that are closer to the ground and generally more dense.  Hence, travelling long distances and 'reaching high' are not necessary adaptive strategies.  Shorter, more compact body types and greater resilience or genetic resistance to parasites have apparently been the adaptive strategies for goats that have been in these areas over the last several millennia. 

 

As well, lower twinning rates, reduced oestrose cycles, greater heat/humidity tolerance, tolerance to some tick-borne diseases, resistance to pneumonia and foot-rot, etc, are adaptive strategies that have helped indigenous goat breeds to survive - and thrive - in these more humid areas.  However as mentioned, the price paid is lower productivity - with the exception of the Boer, whose origin in the South African veldt fairly closely replicates the semiarid regions in which goats originally evolved.

Dwarf breeds in tropical areas of West Africa have over generations evolved to deal effectively with high parasite burdens. 
- International Livestock Research Institute

So, it's a risky strategy to think that – in subtropical areas of North America where meat goat production is increasing goat-to-land rations and where goats are being grazed rather than browsed - that wormers and medical inputs alone are going to solve the problems.  When exotic goat breeds – such as the Boer, which originated in a semi-arid environment – are introduced into theses areas they simply aren't genetically equipped to deal with the problem in ways that can sustainably lead to high production levels and therefore high economic returns.   In areas typified by cold weather part of the year, the parasite and disease cycles will be cut or at least modified.

Improved management and breeding for genetic resistance seem, now, to offer the best, non-chemical methods to begin to deal with the problem of increasing sustainable, intensive production of goats in subtropical and tropical ecosystems - both in Africa and in North America.  Improved management can be accomplished in the short term, particularly management that works to strategically incorporate browse and agroforestry species into the farming system and to manage pastures in ways that minimize parasite loads. 

As for breeding for genetic resistance, this is a long-term and sometimes costly process – possibly more easily sustained in Africa, Australia and New Zealand than in the Northern Hemisphere for reasons of cost and prior experience in resistance breeding.  But with lessons-learned that are wholly applicable to North American and elsewhere.

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