Cheever tells Danforth,
There be so many cows wanderin' the highroads, now their masters are in the jails, and much disagreement who they will belong to now. I know Mr. Parris be arguin' with farmers all yesterday—there is great contention, sir, about the cows.
In other words, there are so many people in the jails, accused or even convicted of witchcraft, that their livestock are wandering around Salem, miserable and in pain because they need to be milked. No one knows exactly who the cows will belong to anymore now that the people who care for them can no longer do so or have been convicted and will lose their property. Marshall Herrick had told Tituba earlier in the act that the noise she heard outside wasn't the Devil come for her but, rather, it was "a poor old cow with a hatful of milk." In other words, some cow was lowing outside the jail, in need of milking (her "hatful of milk" refers to her engorged udder).
In addition, Parris and Hale now fear that there will be rebellion in the town. Very few people turned out for John Proctor's excommunication and Parris thinks "That speak a discontent." In addition, Hale says to Danforth,
there are orphans wandering from house to house; abandoned cattle bellow on the highroads, the stink of rotting crops hangs everywhere, and no man knows when the harlots' cry will ed his life—and you wonder yet if rebellion's spoke?
In other words, then, living conditions are pretty terrible in Salem at this point. People are displeased with the trials and talking rebellion against the court, there is no one to tend to livestock or bring in the crops, and everyone fears that he will be the next person accused of witchery. Food is going to waste, innocents are being hanged, children are orphaned when their parents are executed. It is really, really bad.