Smart steps to maximise fertility and cut costs

Planning is key as breeding season looms and nutrition is first factor to consider

The nutritional status of dairy cows pre-calving plays a huge role in subsequent fertility
The nutritional status of dairy cows pre-calving plays a huge role in subsequent fertility

Dr Finbar Mulligan

The impending breeding season brings many challenges for the modern dairy farmer. Tight margins and scarce labour have focused minds on how to combine simplicity with reliability when it comes to optimising breeding programmes.

No farmer needs to be reminded of the massive hidden costs that are associated with poor fertility in the herd. Whether it is lost productivity through later calving or increased workloads because of long calving seasons, the aim is clear -- to maximise fertility and minimise costs.

According to ICBF, the costs for a calving interval of more than 365 days in a seasonal situation are €10-12 a day. In this feature, experts from UCD's School of Agriculture, Food Science and Veterinary Medicine analyse the key roles that genetics, nutritional status, health status, infectious diseases and management all play in succeeding in getting cows back in calf.

When you need to get your cows back in calf early in the lactation, their nutritional status during the first few months in milk, and even before they calve, plays an important role in the success of the breeding season. The nutritional status of dairy cows pre-calving plays a huge role in subsequent fertility outcomes through its influence on their health and metabolic status around calving and in the very early weeks of lactation. The key nutritional issues pre-calving are:

  • Body condition: Ensure that cows have a body condition score (BCS) of 3.0 or 3.25 at calving. Having this right reduces the risk of many metabolic problems (fatty liver, ketosis, milk fever) and reduces the risk that cows will lose excess BCS in early lactation.
  • Energy levels: Ensure that cows do not have a negative energy status pre-calving. Not all cows have a negative energy status pre-calving but those that do will have an immune system that does not function optimally, which increases the risk of retained placenta and prolonged uterine infection. To avoid the problem, pay close attention to simple things such as stock numbers in dry cow pens, bullying in dry cow pens and the quality of silage offered to dry cows.
  • Calcium: Make sure the cow has a good calcium status through the calving and early lactation period. This is essential as cows don't have to go down with milk fever for low calcium status to cause problems with issues such as rumen function and immune system function. The best way to ensure this is to feed all dry cows approximately 20g/day of magnesium, ensure calving BCS is optimal and avoid the use of high potassium and high nitrogen fodders such as silage that received a lot of slurry.
  • Minerals and vitamins: Ensure cows have an adequate trace element and antioxidant status. Some of the trace elements, especially selenium and copper, and antioxidants such as vitamin E, play an important role in maintaining immune system function around calving. Farmers should ensure that cows have good access to good-quality dry cow minerals and every effort is made to ensure they can be consumed effectively.

The following nutritional issues must be prioritised after calving:

  • Energy: Energy status must be maintained at a sufficient level to minimise BCS loss in early lactation. In many cases this is possible with good grassland management for the appropriate type of cow. However, in other cases farmers may have to feed extra concentrates to reduce BCS loss. If this is the case, the focus with the concentrate should be on energy, not protein.

While the cows will naturally milk more in response to the concentrate feed, they generally also have reduced BCS loss. This has been demonstrated in published research with Irish dairy cows. Farmers should pay attention to grass availability and consult with their nutritionist, Teagasc adviser or local vet to monitor energy status in early lactation cows. Where low energy status is suspected, introduce an energy supplement.

  • Weather: It may well be the case that short-term energy restriction around the time of breeding reduces conception rates. There is no research to back this up with dairy cows, however this effect has been proven for beef heifers in Ireland. These short-term energy restrictions may be caused by reduced grass dry matter content or reduced growth rates.

What we in the UCD Dairy Herd Health Group have noticed is that one-week periods of high rainfall are correlated with reduced conception rates on Irish dairy farms. It is possible that reduced dry matter intakes contribute to this effect.

  • Protein: Protein should only be fed to requirement. Some research suggests that excess protein feeding will reduce fertility, although this is not universally accepted. Farmers should ask their feed suppliers to justify the protein levels in the concentrate feeds being purchased by using the recently adopted PDI (protein digestible in the intestine) system and the latest relevant values for grasses available from Moorepark or the values from the farm's own grass silage analysis.
  • Trace elements: Ensure trace elements are fed until cows are back in calf. Irish dairy herds may be susceptible to copper, selenium and iodine deficiency if left unsupplemented. Farmers should ensure cows are supplemented with appropriate levels from one month pre-calving until cows are back in calf.

Dr Finbar Mulligan lectures on herd health and animal husbandry at the School of Agriculture Food Science and Veterinary Medicine in UCD

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