Milking on Shabbat is a very fascinating subject, and it has generated a broad range of innovative halachic-technical solutions. The greatest rabbis from all sectors of Judaism have joined together to enable religious farmers to raise cows in a modern dairy barn.
"One who milks an animal on Shabbat is guilty of desecrating the Shabbat." Most of the early commentators explain that the basis for this prohibition is dash – threshing – which includes the process of extraction (such as squeezing juice from a lemon). In the same way as a farmer separates the wheat from the skin that covers it, so a person separates the juice from the fruit. Similarly, the farmer separates milk from the udder.
In principle, it is permitted to "milk" a substance that is not needed. That is, just as in threshing the grain is separated from the stalk in order to keep the grain, milking is prohibited only if the person needs the substance that is removed (in this case, the milk). Milking in such a way that the milk will be discarded is not prohibited. Since not milking the cow will also cause it discomfort, this process is permitted if the milk will not be kept.
However, in a modern dairy farm it is not possible to actually throw away the milk. A farmer who discards 15% of all the milk (taking into account Shabbat and holidays throughout the year) will very quickly find himself out of business. The great rabbis of the previous generation (Rabbi Isaac Halevy Herzog and the Chazon Ish) found a way to keep the milk while from a halachic point of view it is being "discarded." The principle is that at the start of the process, the milk is indeed sent to a tank with material that spoils it (such as soap or kerosene). Once the milk has started flowing, the farmer changes the direction of flow of
the milk, sending it into a clean tank.
Implementing this solution (in addition to other halachic limitations that the rabbis insisted on) leads to various technical problems. For example: How can we be sure that the farmer will not forget to return the equipment to the status of "spoiling" before starting to milk the next cow? How can we make sure that no contamination will contaminate the pipes that lead to the "spoiled" milk container and ruin the entire system? Is there a way to simplify the act of changing the milk flow so that the farmer will not have to be involved with the inconvenience of valves, which may stick?
The Zomet Institute uses pneumatic and vacuum systems for this purpose. Such systems are standard equipment in modern dairies, and their use makes it possible for all the work in a dairy to be carried out by Jews on Shabbat without any halachic problems.
Aside from the questions involved in the milking itself, there are a number of problems involving electronics and electrical systems in the modern dairy farm, and innovative solutions have also been found for these problems.
To arrange a meeting to discuss further details, contact The Zomet Institute.