Protein

Milk Protein and Cheese Yield

Milk protein, more than any other milk solid, determines how much cheese can be made from a given amount of milk. The cheese yield is strongly correlated to both milk fat and milk protein, however, the correlation between protein and cheese yield is higher than the correlation between milk fat and cheese yield (see Chart below). This higher correlation indicates that protein is more important for the cheese yield than fat.

Protein Requirements of a Dairy Goat

The protein content of feedstuff is usually expressed in percentage of crude protein (CP). For dairy goats, a CP of approximately 18% seems optimal.

A goat cannot digest all the CP it eats. Digestibility varies from feed to feed, but is around 70% on average. Hence, about 0.7 g of every gram of CP is digestible protein (DP).

The protein demand of a fully grown dairy goat during lactation, some time after kidding, consists of the base demand, which varies from about 100 to 150 g CP daily, depending on the size of the goat, and the additional protein demand for milk production. The latter is approximately 1.45 g DP, or 2.07 g CP, respectively, for the production of one gram of milk protein (US National Research Council 2007). Hence, the production of 4 liters of milk with a protein content of 3.1%, for example, requires additional 257 g of crude protein.

The maximum possible milk protein production is limited by the amount of feed a goat can physically eat. Depending on the size of the goat, it is around 250 - 400 g per day (full article).