How much fat to feed

For most other species there are no definitive guidelines as to the most beneficial level of fat to include in a ration.

However, fat requirements for dairy cows have been widely researched and general ‘rules of thumb’ developed to determine the adequacy of fat in rations for particular levels of production.

It is well-established that the optimal level of fat in a ration for maximum efficiency of milk production occurs when 15 to 20 % of the ME in the diet comes from fat. For high-producing cows, this could be equivalent to around 6 to 8 % of ration dry matter.

A further approach is to work out the balance between fat consumed in feed and fat output in milk per day (Palmquist and Eastridge, 1991). A good approximation for cows in energy balance (not gaining or losing body condition) is to feed as much fat as is secreted in milk - see example in Table 1.

Table 1      Guideline fat requirement for dairy cows in energy balance

DM intake                                   20 kg/d
Diet fat                                3.5% DM
Fat consumed                                   700 g/d
Milk yield                                   30 kg/d
Milk fat                                     4.0%
Fat output in milk                                1,200 g/d
Fat balance                                 -500 g/d

Recommendation: supplement the diet with 500 g of rumen-protected fat to make up the shortfall. 

Click HERE to calculate the daily fat requirements of dairy cows at different levels of production