Hi John, Thirdly, you say that the more an animal eats the more methane it produces. This may be true but the presupposition here is that domestic ruminants producing methane is actually a problem in terms of Global warming. But methane from livestock is short lived (as you admit) and, more significantly, such methane is part of the existing natural cycle of Carbon. If it weren't cattle's enteric microbes producing methane from the anaerobic metabolism of grasses it would be similar methanogenic microbes living in sediments or the guts of termites producing similar quantities as they breakd down the same grasses. And surely the volume of methane produced by domestic ruminants now would be no different (and, given the estimates of the size of prehistoric herds of buffalo in North America and wild ruminants in Africa, probably far less) to that produces in wild ruminants which consumed the grasses in vast grassland biomes before human agriculture existed (and, surely, this is incontestable since grasses and ruminants evolved along side each other - they coevolved - along with their enteric methanogens). As far as I understand it, the real (and effectively the only) issue with global warming is GHGs produced from the burning of fossil fuels (along with the potential release of gases from other long-termed sequestered carbon reserves like methane trapped in permafrost or deep oceanic sediments as a concomitant result of rising temperatures caused by burning fossil fuels), and not carbon already present in short-term natural cycles (which includes methane released from livestock), and the only reason we have thought methane from livestock is part of the problem is because the fossil fuel industry's propaganda machine is telling us this as they try to deflect attention from the true source of the problem - them. And, for some reason, no one has woken up to this lie. We have just swallowed it with out questioning it. If i'm right, cattle and sheep aren't the problem; oil, coal and gas are. In fact, properly managed cattle are the most effective solution to the problem of global warming since correctly managed cattle grazing will sequester far more carbon in the soil than cattle release as CH4 ( which degrades quickly to CO2). I have heard it said that if environmentally adapted cattle raised on all presently used agricultural marginal land (which is not suitable for cropping) could result in the increase in the percentage of organic matter by only a few percent and, as a result of this, all the CO2 released from the burning of fossil fuel since the start of the Industrial Revolution would be removed from the atmosphere

Hi John, thanks for doing these videos. I am very interested in this topic because I think it will inevitably determine the future of beef cattle. It has become an issue of "social license" and therefore the survival of cattle as a human food source. I am still learning so please be patient with me. May I first please ask about some presuppositions. Firstly, you say there is nothing which correlates with feed efficiency which is going to cause any production loss. But l have heard lots of people say that selecting for feed efficiency selects against fat deposition which, because the ability to lay down fat correlates with fertility, selects against fertility. They say this is self evident since, they say, it takes far more energy (food) to lay down fat than muscle so animals which are laying down less fat are going to gain weight (in the form of mostly muscle) far better than animals using energy (food) to lay down both fat and muscle so animals with the best feed efficiency will be the least fat and so also the least fertile. You talk about there being 120 genes associated with the physiology of food metabolism but surely this still does not change the basics of the amount of energy required to lay down fat versus muscle? Secondly, you say that measuring feed efficiency using pellets in your bunkers is a good approximation of the efficiency of cattle feeding on grass. But this ignores the fact that "efficiency" can mean different things. An animal which can take in a large amount of poor quality forage and successfully convert it into meat may not be "efficient" in the sense that you define it (i.e. kg of body mass produced per kg of food eaten) but couldn't it be said that such an animal is still very "efficient" in terms of converting low quality food, (which is all that is available in large areas of Australia), into meat? concomitantevolution could be removed from the atmosphere and stored as organis matter in the soil, which constitutes a long term carbon sink.

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