Choose an energy level that ensures unchanged body condition during the dry period.
During the dry period, energy needs and requirements for individual nutrients are relatively low and are almost always met. Therefore, feed allocation and ration composition are usually guided by a desire to steer the cow’s physiological status in a direction that provides optimal production and health in the subsequent lactation.
A cow’s feed intake capacity is far higher than her actual feed needs. Meeting the needs of the individual cow requires great care in feeding and ration composition.
Over the course of time, there have been different feeding strategies throughout the dry period. In order to divide dry cows into groups that are fed differently, it is common to divide the dry cows into two groups with different needs. A ration can be calculated using the table below, which can be used throughout the dry period by adjusting the requirements.
The common breakdown of the dry period:
1. The period from drying to three weeks before calving
2. The last three weeks before calving.
If no body condition change is desired during the dry period, the norm for energy and protein is calculated based on the need for maintenance and foetal growth.
Table: Energy Requirements for dry cows plus the recommended energy level of a ration throughout the dry period (fodder with a low energy level and high volume per MJ)
Physiological energy needs of dry cows Recommended energy level
Energy level, MJ NEL/day * First weeks of the dry period Last 2-3 weeks before calving Ration throughout the dry period
*MJ NEL/day: Mega joule Net Energy Content for lactation per day
NEL (Net Energy Content for Lactation) is the calculation of energy level of the ration using the following formula:
NEL = 0.60*[1+0.004*(q-57)] * ME
NEL = Net Energy Content for Lactation (MJ/kg dry matter)
q = energy concentration in the ration (ME/GE), where ME is Metabolic Energy, GE – Gross Energy.
Where the recommended energy level is slightly higher than the feed need with the same ration throughout the dry period, this is due to a desire to ensure that the cows do not lose weight during the dry period. The desired effect of a low energy ration is still assured.
Increase feeding level by up to 20% for cows with body condition <2.5
In groups of cows with lower body condition (<2.5), the feed strength should be increased if possible but by no more than 7-14 MJ NEL per day, as high energy feeding can have a negative effect on feed intake after calving because the metabolism of a cow, who builds up her energy during the dry period, responds as though she has a strong body condition (although she does not). This results in decreased feed intake at the start of lactation.