How to produce milk that's similar to blood?

Question

How could a mammal produce milk which resembles blood?

The blood milk should keep as many properties of milk as possible, curding for example, while resembling blood as much as possible. The mammal does not have to exist or eat earth food, but if it doesn't what would that food be like?

By the properties of mean I mostly mean:

• The ability to feed babies (lactose)
• Curding (Cheese)
• Liquid at room temperature
• Preferably not poison to human-like species

By the properties of blood I mostly mean:

• Red
• (Very) slightly thicker

Answer 1

The creature in question eats foods rich in natural red dyes

Most of these plants require boiling to get the dye, but the acid bath of digestion is enough to get to that point. The problem, of course, is that the mammal would need to eat this stuff almost exclusively (or at least a whole lot of it). But methinks it would create the color you're looking for.

• Autumn red leaves (seasonal)
• Bamboo
• Bedstraw Root
• Beet Root
• Brazilwood
• Canadian Hemlock
• Choke Cherries
• Crabapple Bark
• Elderberries¹
• Hibiscus Flowers
• Madder Root
• Portulaca
• Rose Hips
• St. John's Wort (a bit harder, requires mixing with isopropyl alcohol)
• Sumac Fruit
• Sycamore Bark

(Found from this source)

But what about the thicker fluid?

I believe you'll need to live without this. Mammary glands are designed to create and pass a relatively specific fluid thickness (not unlike the kidneys or liver). If you try to force something substantially thicker through the glands, they get all clogged up (not unlike the kidneys or liver). Getting something the thickness of blood that didn't hurt the lady would require a physiological change to the glands.

You could thicken the fluid somewhat by consuming high-starch foods, but I believe that's the best you'd get.

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_{¹ "It is by my will alone that I set my mind in motion...." Sorry, I had to include a gratuitous "Dune" reference. Eating enough elderberries to turn milk red might turn the whole blooming cow red.}

Answer 2

There is blood in the milk.

https://www.researchgate.net/publication/283120356_Causes_Diagnosis_and_Treatment_of_Blood_in_Milk_Hemolactia_in_Cows_and_Buffaloes

Milk comes from glands. Glands have blood vessels. There are various reasons a blood vessel might burst and bleed more or less blood into the milk.

https://www.researchgate.net/publication/283120356_Causes_Diagnosis_and_Treatment_of_Blood_in_Milk_Hemolactia_in_Cows_and_Buffaloes

Dairy farmers frequently approach practicing veterinarians for the treatment of cows or buffaloes producing milk which is reddish or pinkish due to the presence of blood. Farmers suffer from the economic loss because bloody milk is often rejected by the consumers. The condition is usually sporadic in occurrence but rarely several lactating animals may be affected at a time...

The main reason is that the animals are being milked a lot, but I took away that some animals idiosyncratically are more likely to have this happen.

Evolution could totally work on this. Suppose an animal were born with a genetic variation that led to more vessels in the milk glands and they were prone to bleed. The nursing young get benefit from this and are more likely to grow to adulthood - maybe they get more iron, or more antibodies from the added blood. The genetic variation has improved reproductive fitness and it spreads through the population. Generations later, all the mammals of this sort have blood in the milk.

Answer 3

Blood is red from the protein, hemoglobin. Hemoglobin has a molecule called a "heme" which has the metal iron in it. When the iron is oxygenated, it becomes red. When the iron is deoxygenated, it becomes darker red.

Source

I would say the animal would probably eat food very high in iron, be it red meat, or spinach (a lot of leafy greens have high iron content).

Add some sort of clotting agent when it comes out. For example, Lipids which gets thicker when it cools. I could be wrong here, but I believe that if you increased the fat content in the milk this could cause this... Also, I would say that milk straight from a goat (the only example I have seen in person) is a similar thickness to un-clotted blood. Although (from the same source) you could add a gum thickener, which has the added benift of making it slightly sticky.