Layered Plan Needed To Fight BVD
Bovine Viral Diarrhoea (BVD) is sometimes viewed as a dairy industry issue, but the reality is that the disease can have serious consequences for beef breeding herds as well.
The Results of a Poorly Managed Transition
A poorly managed transition often begins with cows losing body condition before they calve, placing massive strain on the liver and triggering a landslide of post-calving weight loss. Cows that lose too much condition often suffer from clinical metabolic diseases such as milk fever and ketosis, but the hidden costs can be even greater.
Pre-calving condition loss commonly coincides with poor appetite. You may notice cows standing off feed in the days before calving, reducing intake and leaving them low on energy at calving, increasing the risk of calving difficulties.
Beyond immediate calving and appetite problems, a poor transition weakens the immune system, leading to higher rates of retained membranes, metritis, 'dirty cows', and mastitis. From a production point of view, these cows eat less, reach a lower peak milk yield, and take longer to cycle, all of which can negatively affect your six-week in-calf rates.
Tuning The 'Engine' and The Rumen
Think of the liver as the engine of the cow and the rumen as the fuel tank. During transition, the liver's workload doubles as it prepares to produce the glucose needed for milk. If the cow is over-conditioned, her liver can get 'choked' with mobilised fat, which kills her appetite just when she needs it most.
To get the rumen 'match-fit' for calving, we need to focus on fibre. Feeding plenty of quality fibre (like pasture hay) stretches the rumen wall, which physically increases the cow's appetite capacity after she calves. It also keeps her full, and because hunger is the biggest stressor for a cow, a full cow is a happy, more resilient cow.
The Nutrition Balance
Managing the transition diet is about getting the right balance:
Energy
Aim to feed about 90-110% of maintenance energy. It's all about gene expression, meaning overfeeding energy can accidentally switch on genes that upset insulin, fat mobilisation and appetite. Underfeeding energy causes her to start mobilising fat too early, so she's short on energy at calving.
Protein
Cows need at least 14% crude protein minimum, but over-conditioned cows actually need more (16-18%) in order to help their livers process energy efficiently from increased fat mobilisation.
Minerals
We use DCAD management to shift the cow's internal chemistry, making her more responsive to the hormones that unlock calcium and phosphorus from her bones when she needs them for milk. Alongside DCAD and rumen buffering keep magnesium and phosphorus balanced, and don't forget the trace minerals.
Key Management Steps
To ensure your cows hit the ground running and recover within two to three days of calving, follow these essential steps:
- Monitor your cows closely to ensure they don't lose condition pre-calving. They should not drop a single bit of fat or muscle until they are within hours of calving.
- Target the right condition by aiming for a tight herd range between 4.8 and 5.2 at calving. Over-conditioned cows (>5.5) are the hardest to manage and need extra liver support.
- Ad-lib fibre is key. Always provide access to quality hay to keep the rumen stretched, working hard, and full.
- A full 21-day transition is the "gold-standard" in helping the rumen and liver to adapt fully, maximising cow potential for the coming lactation.
- Keep total dietary phosphorus above 0.3% and below 0.4%. Going too low hurts appetite, milk production, and increases the risk of a crawler cow around calving or during early lactation, while going too high can interfere with calcium metabolism.
- Use a rumen buffer through transition and early lactation to increase rumen performance and reduce stress
- Reduce social stress by giving cows plenty of space (one metre of feed-face per cow) and avoid shifting them into new groups during the final three weeks to keep stress low.
- Ensure consistent supplementation by feeding your most important minerals and silages in the morning when cows are hungriest to ensure every cow gets her fair share.
- Balance the DCAD. This can be measured by herbage testing your springer feed. Having the total DCAD of the diet (including your DCAD supplement) between 40 and 100 is ideal.
- Ensure your mangnesium, calcium, and phosphorus level are in the right balance. Make sure copper, zinc, cobalt, selenium, iodine, boron, and chromium are all at optimum levels in the diet, as these are critical for liver function and cow health.
- For over-conditioned herds that are often problematic around calving, liver support supplements like choline betaine, B-group vitamins and methionine can be added options.
Get the transition right, and you've set the season up to win. Get it wrong, and you'll be fighting problems all year. By following this plan, you'll cut disease, lift peak milk and protect your six-week in-calf rate.
