That’d still be quite high in emissions. Land deforestation and the massive amounts of feed are large portions of emissions for meat and dairy products. It takes far more feed than it does to eat crops directly due to the energy loss from creatures using that energy to move around, on their body functions, etc.
The practices somewhat similar to what’s suggested there work out too well in practice. Manure lagoons, where waste is stored in huge pools to break down, have several environmental problems
Rates of asthma in children living near a CAFO are consistently elevated.[4] The process of anaerobic digestion has been shown to release over 400 volatile compounds from lagoons.[13] The most prevalent of these are: ammonia, hydrogen sulfide, methane, and carbon dioxide
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Contaminants that are water-soluble can escape from anaerobic lagoons and enter the environment through leakage from badly constructed or poorly maintained manure lagoons as well as during excess rain or high winds, resulting in an overflow of lagoons.[2] These leaks and overflows can contaminate surrounding surface and ground water with some hazardous materials which are contained in the lagoon.[2] The most serious of these contaminants are pathogens, antibiotics, heavy metals and hormones. For example, runoff from farms in Maryland and North Carolina are a leading candidate for Pfiesteria piscicida. This contaminant has the ability to kill fish, and it can also cause skin irritation and short term memory loss in humans[20]
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Antibiotics are fed to livestock to prevent disease and to increase weight and development, so that there is a shortened time from birth to slaughter. However, because these antibiotics are administered at sub-therapeutic levels, bacterial colonies can build up resistance to the drugs through the natural selection of bacteria resistant to these antibiotics. These antibiotic-resistant bacteria are then excreted and transferred to the lagoons, where they can infect humans and other animals.[13]
Each year, 24.6 million pounds of antimicrobials are administered to livestock for non-therapeutic purposes.[23] Seventy percent of all antibiotics and related drugs are given to animals as feed additives.[4] Nearly half of the antibiotics used are nearly identical to ones given to humans. There is strong evidence that the use of antibiotics in animal feed is contributing to an increase in antibiotic-resistant microbes and causing antibiotics to be less effective for humans.[4] Due to concerns over antibiotic-resistant bacteria, the American Medical Association passed a resolution stating its opposition to the use of sub-therapeutic levels of antimicrobials in livestock.[13]