How Much Fat To Feed?
Fat requirements for dairy cows have been wide researched throughout the years. While the exact amount of fat required isn't known, general rules of thumb have been developed to determine the approximate amount of fat in rations for particular levels of production. However, there isn't much of a definite guide as to what is the optimal level of fat to include in a ration for most of the other species.
It is well established that the optimal level of fat in a ration in order to have very efficient milk production occurs when 15 - 20% of the ME in the cow's diet comes from fat. This would roughly be 6 - 8% of ration DM for high producing cows.
The next step to find out the fat required is to determine the balance between fat consumed in feed versus the fat output in milk per day. A good estimate for cows in energy balance (not gaining or losing body condition) is to feed as much fat as is secreted in milk. This is shown in the table below.
The fat released from the body stores during periods of negative energy balance could also affect the requirements of fats of the cow. This usually happens to high producing cows since a lot of energy is required during milk production but the diet provides inadequate energy. Therefore, in such situations, the cow's energy requirements can be met by feeding additional bypass fats, taking into account the contribution from mobilised body fat.
Table: Guideline fat requirements for dairy cows in energy balance.