Tza'ar ba'alei chayim (literally means: "the suffering of living creatures") is a Jewish commandment which bans causing animals unnecessary suffering. This concept is not clearly enunciated in the written Torah, but was accepted by the Talmud as being a Biblical mandate. It is linked in the Talmud from the Biblical law requiring people to assist in unloading burdens from animals (Exodus 23:5).
In traditional Jewish law, kosher animals may be eaten if they're killed using the slaughter method known as shechitah, where the animal is killed by having its throat cut swiftly using an extremely sharp and specially designed knife. Many Rabbis assert that these regulations were put in place to reduce tza'ar ba'alei chayim and to ensure that the animal has the easiest possible death. The design of the kosher knives as well as regulation relating to how the cut is made have been seen to greatly reduce or completely eliminate reaction from the kosher cut. Even modern day scientists that are critical of shechita agree that it greatly improved welfare at slaughter in historical periods. Though, there is disagreement as to shechita's effectivity when compared to modern day slaughter methods, with some scientific experts in favor of the humanness of shechita and others opposed.
In 2000, the Rabbinical Assembly of Conservative Judaism's Committee on Jewish Law and Standards banned the common slaughter method of "shackling and hoisting" (pulling a conscious animal into the air with a chain before slaughter). Rabbis Joel Roth and Elliot Dorff wrote a responsum on this topic which concluded that shackling and hoisting "unquestionably constitutes a violation of Jewish laws that forbid us to cause undue pain to animals."
Enforcing a commitment to tza'ar ba'alei chayim in food production has been part of the effort of Conservative Judaism's Magen Tzedek commission, formerly known as Hekshher Tzedek. The Magen Tzedek commission sees compliance with the Humane Farm Animal Care Standards (HFAC) as sufficiently preventing unnecessary suffering to animals. Amid disputed claims of Orthodox opposition the Magen Tzedek commission has not been successful in recruiting any food producers into its certification program.