Monica
No you are wrong, both systems produce meat that is safe for us to eat it’s the freedom that other countries have to dictate welfare standards that differ, stocking rates, slaughter supervision, veterinary supervision, management supervision and traceability. Add to that environmental regulation which in many countries does not exist and economy of scale, if consumers want a free for all, fine but realize what you are buying.
Scrapie in sheep has nothing to do with what animals eat it is a rare sporadic condition just like CJD in humans and BSE was in cattle. The BSE epidemic was caused because an official lowering of temperature processing animal protein There had been no problem for many decades until then, nobody foresaw the effect.
On most Beef production systems Cows are kept at pasture (or range} calves are born and live with their mothers for 6 or 8 months then weaned and either finished in yards or on pasture. Age at finishing varies from 12 months up to 24 months depending on buyers requirement, a typical beef animal would need 3 or 4 months on a cereal diet to reach prime condition, very different to your assertion that it’s whole life is cereal fed.
Some beef cattle are dairy bred reared in groups on milk substitute (baby milk) then then fed a mixed diet or grazed depending on season to enable them to grow, reaching prime condition at 18 months or so.
Most beef (and sheep} systems are based on grass or other forage and all would be given some cereal supplement in the final months to give an acceptable finish. So most beef cattle are fed a mixed diet of forage and cereals and that would vary a great deal according to climate, season, age and breed of cattle.
Much of the land grass or other forage crops are grown is totally unsuitable for vegetable growing, too dry, too wet, too steep, shallow soil, so the area left for vegetable growing would be much less than many vegetable advocates say. In addition because no organic fertilizer from animals is available much more chemical fertilizer would be needed, vegetable crops also need weed and pest control whereas grass needs very little, so that not especially sustainable is it. All plants need a certain quantity of nutrients to grow and produce crop, it does not matter if it is organic or chemical or a combination, no nutrients no crop.
On this basis I submit that converting the world to vegetarian diets will not feed a population of 8 billion today let alone future population growth, despite the assertion of some so called experts every government agrees that a mixed diet is the way to feed the population.