Why a close eye must be kept on BCS in early lactation
Rapid body condition score (BCS) loss post-calving can cause health implications or failure to go back in-calf in the future.
BCS loss is due to cows entering a negative energy balance post-calving; as a cow’s dry matter intake fails to meet her energy requirements. In prolonged cases, a cow will use up her bodily fat reserves to compensate for this energy deficit, or ‘milk off her own back’.
Thin cows (BCS < 3) at calving or cows carrying twins are high-risk animals when it comes to BCS loss post-calving.
Steps in maintaining BCS post-calving:
1. Monitor BCS closely
BCS should be monitored closely in early lactation to maintain an average herd BCS of 2.9.
This will help ensure all cows are submitted for breeding at the correct BCS (>2.75 and <3.25); to give them the best possible chance of going back in-calf for the following year.
Thin cows should not be ignored and should be acted on quickly to ensure they reach a target BCS of 2.75 at breeding.
Submitting cows at the correct BCS will result in higher overall conception rates at breeding time.
2. Maximise dry matter intakes
To maximise intakes, it is critical that cows are allocated a sufficient amount of high-quality feed daily.
If feed is of high quality, it will be more palatable encouraging intakes. It will also be higher in energy than if it was of poor quality.
According to Teagasc, a freshly-calved cow will eat a total of 8-10kg of dry matter (DM) per day. As the weeks progress, this will gradually increase by 0.75-1kg of DM per week until a peak intake of 16-18kg of DM at week 10-12 of lactation.
For example, a 100-cow herd – with a demand of 10kg of DM/cow (including 2kg of meal) – has a total grass requirement of 800kg of DM/day.
If the opening cover on the paddock is 1,100kg DM/ha – minus 300kg DM/ha left behind post-grazing – this equates to 1ha of area to be allocated per day. This can be divided in half if grazing in 12-hour blocks.
Although early spring grass is important, using supplementation – such as in periods of wet weather or when grass DM is low – is necessary to avoid a negative energy balance and inevitable BCS loss.
3. Pay attention to changes in milk production data
The easiest way to monitor the current nutritional status of your herd is through analysing your milk production data.
A sudden drop in milk yield or milk protein percentage is a clear indicator of reduced DM intake post-calving. This can typically occur after a period of wet weather, as the DM content of grass falls.
An examination of the fat and protein ratio is another useful indicator of the herd’s nutritional status.
Additionally, if a herd is producing a high volume of milk solids, this is indicative of a high energy and protein demand on the cow; the herd needs to be sufficiently fed to deal with this energy drain.