Genetic diversity reduces the chances of disease ravaging livestock. Factory farming has already reduced diversity to an all time low, which is why you things like Mad Cow disease spreading so quickly.
Cloned meat will make this situation much, much worse, since you can have the possibility of an entire farm with the same genotype. Whatever vulnerabilities one cow has, all the others will have as well. This means that it's possible that virtually the entire meat supply in America could be contaminated in a very short period of time.
Animals are not toasters - they shouldn't produced on an assembly line just because there are meager short term cost savings.