The body condition score (BCS) of suckler cows in the lead up to calving should be closely monitored and in-calf cows should be fed accordingly to their body condition scores (BCS).
While it is often best practice to have BCS on target in advance of housing and maintain an appropriate BCS on cows for the duration of gestation, changes can be made where cows are under fat or overfat in the lead up to calving.
Approximately 80% of the calf birth weight is grown in the last three months of the pregnancy, according to Teagasc and where herd BCS is not consistent, cows should be grouped by BCS at housing and fed as appropriate to achieve a BCS of 3.0 before calving or maintain BCS if at 3.0.
The graph below details the target BCS for suckler cows at different stages of the year:
Where a cow has a BCS of 3.25-3.5 at housing, 65-68% dry matter digestibility (DMD) grass silage fed ad-lib during the dry period is sufficient to allow for some mobilising of body reserves and aim for calving at BCS of 3.0.
If cows are in good BCS (3.0+) and only better-quality silage (>70% DMD) is available, farmers should restrict access to silage or incorporate straw into the silage to dilute the quality of the offered feed.
The effects of a low BCS at calving are only partially reversed by placing cows on a high plane of nutrition after calving and extra feeding post calving will not fully compensate for poor BCS at calving, according to Teagasc.
A suckler cow with a BCS of 1.75 will not cycle until at least 71 days after calving, according to Teagasc whereas cows with a BCS of 3.0 will be cycling by day 55. An extended post-partum interval increases the overall calving interval.