Natural Remedies – #3 Rennet



Uses: For ruminant animals of a young age being fed milk. Assists in coagulation of milk, helpful for situations when a young animal is scouring and their own digestive system is malfunctioning. For humans, it’s used for dessert & cheese. Yummm! 🙂

Dosage: Refer to package. Match the amount of rennet to approximately the amount of milk you will be feeding the young animal.

  • To make your own dosage, base the amount off of these conversions:
    • The cheesemaking equivalent is approximately 1/4 tsp (1.2cc) of liquid rennet per gallon of milk.
    • In cheesemaking, the 1/4 tsp rennet is diluted in 1/4 cup of water before being added to the milk.

Fresh rennet or double strength rennet – use a smaller dose. Old rennet (2-3 years + old, if kept stable) or single strength – use a bit larger dose.

  • A small lamb being fed a few ounces of milk would only require a few drops of rennet. The dosage is not a big deal, as long as the milk does not coagulate before the animal can drink the milk. Therefore, a smaller dose is preferable. If the milk coagulates before the animal has consumed it, try again with fresh milk and a much lower dose of rennet. Animals can sometimes suck coagulated milk out of a bottle, but it’s awkward and better to avoid if the animal is already stressed or weak.
  • Small ruminants such as lambs or kids – use 1/4 to 1/2 ml liquid rennet in 10 ml water.
  • Large ruminants such as older calves – use 1/2 to 1 ml liquid rennet in 10 ml water.
  • Non-ruminants – I have not used rennet for other types of sick animals, although the possibility exists. For example, a soft pudding made from milk and rennet could be a healthy snack for a struggling chicken or piglet.

Administration: Use a syringe (10cc in size, give or take, without needle). Draw up rennet, then draw up water into syringe. Shake a bit to disperse. Squirt in the back of the mouth of the animal, just before feeding milk. Rinse the syringe for future (non-sterile) use such as the next feeding.

Alternate option: Add liquid rennet to the milk feeding, shake a few times, then feed immediately. If you wait too long to feed the renneted milk, the milk will coagulate (become solid) and not come out the bottle. In cheesemaking, rennet is stirred 15 seconds to 1 minute and coagulation occurs in as little as 10 minutes or less.

Frequency: Can be used on a regular basis, but is more practical being used for sick animals only. Symptoms may resolve within a day or two. For very sick animals, continue using the rennet until the animal is on the mend.

Other info: Ruminant babies naturally secrete rennet enzymes from their fourth stomach to coagulate the milk they drink. Normal, healthy ruminant babies do not need supplemental rennet, if they are fed a proper diet.

  • Visual of how rennet was harvested in the past: Animal Rennet Making at Home.
  • The other stomach chambers are still developing in a mammal of this age and when a young calf feeds the act of stretching its neck positions its digestive tract in such a way that the milk flow directly to this fourth stomach bypassing the others.  When the milk reaches the fourth stomach it comes in contact with the chymosin (rennet) and curdles.”

Case Study:

We’ve had calves and lambs scour for various reasons. Rennet has been a great supplement to add to the milk of sick animals as it helps moderate digestion of the milk, reducing dehydration and increasing absorption of nutrients.


  • Buy:
    • Some places, such as RencoNZ or BioStart NZ, sell rennet specifically as a calf supplement. I wasn’t able to find much for US suppliers of animal rennet for animal use.
    • I keep calf rennet in stock for cheesemaking and use that for any sick animals, as I already have it on hand. My favorite suppliers include Glengarry Cheesemaking (Ships to US customers from NY) & Dairy Connection/GetCulture. If you have microbial rennet, etc. on hand, those are suitable substitutes. Follow package dosage for what you would use to make a 1/2 or 1 gal. batch of cheese.
  • Your local store may carry Junket rennet – found on the baking aisle near jello, etc. This is a quick, easy way to obtain rennet. Junket source


Up next…Apple Cider Vinegar


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