Winter dairying

Focus on cow condition scores to boost fertility

MANAGING body condition score in the pre- and post-calving period will help ensure better reproductive performance this winter.

That is according to NWF Agriculture technical specialist Rachel Lander, who says the variable quality and quantity of forages seen on many farms means fertility will be a big drain on dairy cow profits this winter.

“Fertility is a multi-factorial problem, but the immediate pre- and post-calving period is particularly important, especially the management of cow condition.

“Body condition score (BCS) has a huge impact of performance and fertility. Managing BCS around calving is the most important single thing you can do to improve overall dairy cow health.”

Ms Lander says to improve fertility, it is vital to manage BCS closely at drying off and calving down, as it has a big impact on the cow’s ability to move from being dry to lactating.

She says cows need to dry off and calve down at the target score of 3.0, aiming to lose no more than 0.75 units in the first 90 days.

While many farmers are aware of the problems associated with cows which are too thin, Ms Lander says cows which are too fat are also a problem.

Monitoring

“Cows at a low BCS at calving will have poorer fertility. Cows with a BCS of 2.5 or less are much less likely to get in-calf.

“Cows which are over-conditioned at calving are four times more likely to suffer from milk fever and tend to lose more condition post-calving.

“The rate of change in condition score is just as important as the actual condition score.

“Where BCS at calving is 3.25, 30 per cent of cows will lose at least 0.5 units of BCS in early lactation, but where BCS at calving is 3.5, 47 per cent of cows lose at least 0.5 units of BCS in the same time. Cows which lose more condition tend to be harder to get in calf.”

Ms Lander believes BCS monitoring is not a difficult skill to learn and is one which improves with practice, so she urges farmers to learn how to do it and then to condition score cows regularly and track scores on a tool such as the NWF BCS monitor.

“Excess BCS change in early lactation is directly related to the management of negative energy balance (NEB) at and around calving,” she says.

Dry cows can suffer a period of low dry matter and energy intakes in the two weeks pre-calving. This is followed by a period of NEB post-calving, when body fat is mobilised to meet the energy deficit, which can lead to retained placenta, fatty liver, displaced abomasums and immune suppression. All these will reduce fertility.

“Cows with a high BCS are particularly prone to negative energy balance. For cows in correct condition, the aim must be to do all you can to encourage high intakes of a diet high in glucogenic energy sources.” (see panel)

Once cows are calved, she stresses the importance of building energy and dry matter intakes.

“Research shows herds with significantly higher mean intakes of DM and ME during the first 100 days of lactation achieved higher conception rates to first insemination.

“Paying attention to BCS and negative energy balance at and around calving will be one way to improve fertility this winter,” says Ms Lander.

Tips for high intakes

  • Rachel Lander’s tips to encourage high intakes:
  • Make sure cows have at least 60cm trough space per cow
  • Check the feed barrier design is not restricting intakes
  • Neck lesions are a sure sign the neck rail needs adjusting
  • Reduce the stocking rate of dry cows to reduce the risk of bullying.

 

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