Genetic variation & cattle

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The New York Times Magazine has a long piece about replacement of Uganda’s native Ankole breed with Holsteins:

“You know, in Uganda, we have to look for survival of the fittest,” Mugira said once he finished sorting out the confusion. “These ones, they are the fittest,” he went on to say, gesturing toward his Holsteins. In physical terms, there was really no contest between the tough Ankoles and the fussy foreign cattle, which were always hungry and often sick. But the foreigners possessed arguably the single most important adaptive trait for livestock: they made money. Holsteins are lactating behemoths. In an African setting, a good one can produce 20 or 30 times as much milk as an Ankole.

Who could complain about over an order of magnitude increase in productivity? Well:

If the Ankole cattle are able to mount a comeback, it will be because circumstances have endowed them with a unique set of defenses, both evolutionary and political. Members of President Museveni’s ethnic group populate the upper ranks of Uganda’s government. Some prominent Bahima have started an organization devoted to preserving Ankoles, under the patronage of a one-eyed army general who spends his free time painting rapturous portraits of cows. One afternoon, at a pricey restaurant in Kampala, I had lunch with the organization’s chairman, Samuel Mugasi. Dressed in a dapper gray suit and a French-cuffed pale blue shirt, he told me he was a civil servant and part-time rancher.

“They have tasted the money,” Mugasi said of the farmers who switched to Holsteins. “They are excited about having these big earnings, and they are forgetting the cultural aspect.

A lot of people talk as if white tourists in Third World countries are special in the way that they bemoan the passing of quaint “traditions” which they had enjoyed “experiencing,” but which the “natives” were happy to get rid of. But this sort of patronizing and instrumental attitude toward the unwashed is universal, it seems to be an attitude correlated with leisured status. Indian Americans and Irish Americans who visit their ancestral “homelands” over the years complain about the destruction of the cultural traditions, i.e, poverty, which made their earlier experiences more “authentic: (luckily for Indian Americans who want to get in touch with their “roots” most of India is still living in authentic squalor and deprivation!).

But there’s a serious case to be made for preservation of extant genetic variation. The question I have is this: how many individuals of various breeds do you really need to keep around so that diversity is preserved for future utilization? In other words, I understand the logic of adaptive acceleration where large Ne is critical to the production of rare positive mutations; but don’t we get to a point of diminishing returns for populations where we’re more interested in modal alleles which might be disjoint across breeds? That is, the genetic traits from breed A you want to preserve in case they come in handy are common in breed A, so you don’t need that many of breed A around to serve as a reservoir. I just don’t see why we need maximal diversity, it seems the sort of variation which is encapsulated by species richness is more important here than proportionally weighted diversity indexes.

In any case, as alluded to in the article, maintaining relict populations of dying breeds like this seems like a public good which any prudent government can provide. But another issue with the article is that it doesn’t seem like the author is a science writer, so he engages in the fallacy of blending genetics. For example:

…And something else is being obliterated: genes. Each time a farmer crossbreeds his Ankoles, a little of the country’s stockpile of adaptive traits disappears. It isn’t easy to measure genetic “dilution.” What is evident, however, is that the Ankoles possess much worth saving. For instance, their horns, often seen as ornaments, actually disperse excess body heat.

I guess it’s nice that he put quotes around dilution, but the rest of the article suggests to me that the author hasn’t internalized that genetics is discrete, and that information isn’t destroyed through cross-breeding. Rather, it seems that a good program of cross-breeding could result in a superior breeds of Holstein optimally suited to the local climate. That’s what happened with indigenous African lineages as they hybridized with introduced South Asian ones 2,000 years ago to produce the Ankole according to the article! This sort of piece in a widely circulated publication such as The New York Times Magazine could have been a serious examination of agricultural and quantitative genetics, and just how much we depend on these unsexy sciences to feed the world. As it is, there’s a lot of hand-waving scare-mongering….

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10 Comments

  1. Are either the Bahima or Bairu people lactose intolerant? From the descriptions it seemed the Bahima were Tutsi and the Bairu Bantu, but I’m not sure. 
     
    If so, it is possible the Bahima may be overly attached to their status as lactose-tolerant Tutsis amongst lactose-intolerant Bantu populations and the ankole cattle that have conferred this nutritional advantage. The rise of dairy cattle as an export industry allows the potentially lactose-intolerant Bairu to profit off Holstein dairy cattle in a way that threatens the previous genetic-driven division of labor between the two populations.  
     
    I thought this article as especially interesting if viewed through a human genetics lens of lactose tolerance. How genetic variability between Bahima and Bairu produced the Ugandan social structure, and perhaps how the differing traits have slowly evinced themselves in marriage patterns and their creation myths: 
     
    http://www.ugandatravelguide.com/ankole-culture.html 
     
    The NYT article fails to talk about the cheapest method of saving the ankole. Allow a small feral population to breed like the Texas longhorns or the feral Dromedaries of Australia. Both populations have become valuable gene banks for the American cattle industry and Middle Eastern camel trade at practically no cost.

  2. Are either the Bahima or Bairu people lactose intolerant? From the descriptions it seemed the Bahima were Tutsi and the Bairu Bantu, but I’m not sure. 
     
    i think you’re assessment is right. wikipedia calls the ankole ‘watusi’ cattle. as for lactase persistence (the PC-genetic term we prefer! ;-) it seems like it varies the way you assume. there is an allusion to this possibility in the text, but as you said, they didn’t push it very far.

  3. Here’s the link.

  4. If we have access to the original strains, we can later choose to make whatever crosses and hybridizations we please. 
     
    Once we’ve made the crosses, if we didn’t preserve the parents, there’s really no way to retrieve the originals without genetic engineering far beyond our current technology and a lot of guesswork. 
     
    Genes are discrete, but phenotypes are composed of the interaction of so many discrete elements that they often look and act continuous. 
     
    (sigh) This is so much simpler with potato breeding…

  5. Check out the Nazi yaks

  6. genetics is discrete, and that information isn’t destroyed through cross-breeding.  
     
    Hmmm? Cross breeding of the sort described in the article will drive the frequency of local alleles down and of foreign alleles up. Many infrequent local alleles will quickly be driven to a frequency of zero, because of the strong artificial selection pressure against their propagation. The most common alleles will stick around for sometime, but it’s not true that “information isn’t destroyed”.

  7. right, but it’s not the cross-breeding per se that’s the problem. it’s the reduction in effective size and/or selection of the F1…Fn….

  8. I think if a very large # of Holsteins is suddenly introduced to a smaller population of Ankole, or the Holsteins are selectively bred more aggressively than the Ankole that there are three risks: 
     
    In a fairly short period of time nobody will remember what the good characterstics of the Ankole were – even if the genetics are still hidden in Holstein looking cows, nobody will look for them. 
     
    It’s possible for the potentially positive Ankole characteristics to be the result of a group of genes working in concert – which would be broken apart by crossbreeding 
     
    It’s possible that the beneficial genes get so widely dispersed among a large # of Holstein genes that they cannot reasonably be found even if people start to look for them later on.

  9. I read the whole article, and came away with a different conclusion that some of you. 
     
    Ankole had been kept for both meat and milk production, making them neither great at either. Holsteins are specialist milk producers, so compared to the Ankole, they will always beat them. Ankole however supposedly produce a rather good tasting steak. So with a little more selective Ankole breeding, they may be turned into a meat producing breed to possibly rival Aberdeen Angus, for prime quality. 
     
    Obviously it would be useful if the Holsteins could pick up some drought and tropical disease resistance alleles from the Ankole. But once these have been located, they can be transferred to the Holsteins later… 
     
    So there you have it, a best of breed solution.

  10. I also thought along the lines of pconroy. If the Ankole are good beef cattle they should be improved following those lines. I live in South Louisiana and the most popular beef cattle breed here is the Brangus – a cross between Angus (tasty) and Brahma (good resistance to heat and tropical diseases) Perhaps the Ankole is another candidate for introducing heat and tropical disease resistance to standard beef cattle.  
     
    The real problem in Uganda isn’t that there is cross breeding occuring, but that most of it is being done helter skelter rather than with any particular objectives in mind. It’s likely that it will produce no positive results, or at least not the positive results that could be produced by a directed breeding program.

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