Milk

Milk is a high-calcium beverage that slightly replenishes Link's health. In both Ocarina of Time and The Minish Cap, it comes from Lon Lon Ranch. In Majora's Mask, it comes from Romani Ranch.

Types of Milk
There are three types of Milk: Lon Lon Milk, Romani Milk, and Chateau Romani. Each bottle of milk has two servings. While it's not as powerful or as energizing as the Red Potion, it does the job of recovering Link's health with great taste. Milk can be obtained directly from the cows found inside some Secret Grottos or in the two ranches. After playing Epona's Song to a cow, it will reward Link with a free serving of Milk. Chateau Romani can only be obtained by buying it in the Milk Bar of Clock Town.

In The Minish Cap, after finding the key to Talon's house, Malon goes to Hyrule Town to sell the Lon Lon milk. The bottles are carried on Epona and are 100 Rupees each.

Milk is served in the Milk Bar of Clock Town in Majora's Mask and on Mercay Island in Phantom Hourglass; however, it cannot be purchased in Phantom Hourglass.

Milk returns in Twilight Princess. In this game, it is goat milk. One serving restores three hearts, and a bottle holds two servings. Link gets his first bottle with Milk from Sera after helping her, but it's only half full.

In the Super Smash Bros. Series
In Super Smash Bros. Melee, Young Link drinks Lon Lon Milk as his taunt. It appears as a trophy in Melee and as a sticker in Super Smash Bros. Brawl.

Trivia

 * The café on Windfall Island in The Wind Waker apparently serves Lon Lon Milk, as a chalkboard written in Hylian advertises it along with "Deku Seed Cake" and "Zora Coffee". There are also a few empty bottles in the Nintendo Gallery with "Lon Lon Milk" text.