Calculate dry off dates carefully

Dry cows gain very little, if any, BCS in the week after dry-off or in the last month before calving.

Failing to plan adequately may lead to disappointing results with cows' body condition scores as calving time approaches.

Developing and implementing a strategy is the key to achieving target body condition score at calving.

The saying "failing to plan is planning to fail" could not be truer when it comes to achieving those targets.

There are four main strategies to achieve body condition score (BCS) gain leading up to calving: increase feed allocation to lactating cows; once-a-day (OAD) milking; and dry off cows or increase the feed allocation to dry cows.

"Increasing feed allocation (pasture or supplement) for lactating dairy cows has only a small impact on BCS gain, as the energy is primarily partitioned towards milk production," says DairyNZ senior scientist Jane Kay. Data from a DairyNZ experiment also indicates that altering the type of supplement in a pasture-based system during late lactation alters milk production but does not affect BCS gain.

There was no difference in BCS gain when cows were fed a diet of two-thirds pasture and pasture silage and one-third of either a high-starch feed (maize grain) or a high fibre feed (palm kernel extract) for two months before drying off.

Milking cows once a day during mid/late lactation does increase BCS gain

"There is a relatively minor impact on total season milk production (a 4 per cent loss) and the greater BCS at dry-off results in less feed and time needed during the dry period to gain BCS," Kay says.

"However, the BCS gains due to OAD milking are still relatively small and this strategy takes time (at least one month) before any positive results occur."

The best strategy

Drying off cows with enough time and feed to achieve target BCS at calving is one of the most successful strategies.

"It's important to consider that when planning dry-off dates.

"Dry cows gain very little, if any, BCS in the week after dry-off or in the last month before calving.

"This time needs to be factored into calculating the time required to gain BCS while dry."

Type of feed an important factor

The type of feed offered to dry cows is also important as some are more efficient than others in increasing BCS.

"Research indicates that BCS gain is less efficient [on a metabolisable energy basis]

with autumn pasture compared with maize silage, spring pasture silage or PKE," Kay says.

"However, the whole farm system (infrastructure, available feed and cost of feeding) needs to be considered when deciding which feeds to use during the dry period."

Irrespective of the chosen strategy, implementing it in late summer/early autumn and with continued monitoring of BCS will help achieve target BCS at calving.