Managing negative energy balance (NEB) in cows is vital to ensuring that they go on to have a successful lactation.
Up to two weeks before calving, dairy cows enter a NEB, with this status potentially lasting for a number of weeks after calving. This is due to dry matter (DM) intakes being reduced post-calving.
NEB mean that the energy requirements for maintenance, gestation and production are not met by energy intake.
Prolonged periods of NEB or severe cases can result in cows developing metabolic disorders such as ketosis.
So monitoring freshly calved autumn-calving cows is vital to ensure that issues with cows do not occur.
Negative energy balance
The effects of NEB in cows are seen when condition is lost post-calving. Although some level of loss is to be expected at this time, excessive loss could be a sign of an issue.
Almost all cows will have some degree of NEB in early lactation, but excessive or prolonged NEB can lead to conditions such as ketosis, fatty liver and displaced abomasum.
According to Teagasc, indicators of an NEB issue in the herd are:
- Less than 15% of early lactation cows with milk protein <3.05%;
- Less than 15% of cows with a milk fat: protein ratio >1.4;
- Less than 25% of cows with >0.5 units of body condition score (BCS) loss in early lactation.
In severe cases, cows may have a lethargic look. These cows will most likely be off their feed and lose excessive body condition score (BCS) in a short amount of time.
This is due to them mobilising body fat to make up for the NEB; a cow losing a full condition score within the first 30 days after calving is unacceptable.
Dry cow
The risk of many issues post-calving can be greatly reduced through good management practices during the dry period.
Cows should enter the dry period in the correct BCS, with their score not increasing over 3.0 during the period.
Overfat cows are susceptible to issues at calving and metabolic issues post-calving – which is why the monitoring of BCS is so important ahead of, and during the dry period.
It is difficult to correct BCS during the dry period so ensuring that cows enter and leave the dry period in the correct BCS is important.
Cows should be slowly introduced to the milk-cow diet. And cows should be fed a high-energy diet ahead of calving to help partially compensate for lower dry matter intakes.