The supply is called a staff because some people need a staff to walk and do their work, and people need bread to live. Bread represents all kinds of food. Alternate translation: "the supply of food" (See: [[rc://en/ta/man/translate/figs-metaphor]] and [[rc://en/ta/man/translate/figs-synecdoche]])
You may need to make explicit why they will ration the bread. "they will carefully divide their bread because they fear that there will not be enough" (See: [[rc://en/ta/man/translate/figs-explicit]])
The word "shaking" is a metaphor for being afraid and "trembling" represents fear. Alternate translation: "rationing it while shaking" or "rationing it in fear" (See: [[rc://en/ta/man/translate/figs-metonymy]])