Cow fertility

Proactive Management
August 22, 2019
Just Milk finalist in the 2019 Santam Agriculture National Silage Competition
September 18, 2019

A Just Milk Sharefarmer, Gavin Beaumont, recently attended a cow fertility session with a knowledgeable Vet, Dr Willem Schultheiss, from Ceva and Jean Louw.  Below are some of the important points taken from the session.

Mature weight target percentages:

Age of Heifer

Weight target (% of mature target weight)

6 months old  


15 months old


22 months old


As a Just Milk group, our target weight is 440kgs.

This means:

  1. We easily reach 132kg at 6 month due to our complete feeding
  2. We don’t always reach 264kg at 15 months due to various reasons
  3. We do reach 396kg normally on home grown heifers at 22 months

Some top tips:

  • It is important to note that synchronization programmes do not improve fertility in cows, but manipulates the timing.
  • Birth mass heritability on heifers is not very high.  
  • PG (progesterone) such as estrumate only works at 6 to 17 days after a heat.
  • Reasons to synchronize are profit based decisions.  A skipped cycle costs the farm R1200 per cow, that is R57 per day.
  • A 21 day IC (in calf rate) rate is often under underestimated and we should watch this figure.
  • Nutrition has a massive effect on hormones in a cow.  A well fed cow will supply adequate LH (luteinizing hormone) to fully express a follicle on an ovary.  Nutrition and fertility are linked and is often forgotten.
  • An under condition cow deposits fat in her liver that will take a long time to process out.  This affects the future functioning of the liver.
  • Heat stress delays ovulation and can reduce final conception by 5 to 8 %.
  • Synchronization programs involve a lot of timed procedures, are management sensitive and make or break a result.  Stick to the agreed program.
  • We often see cows and heifers riding each other at device removal.  These are often the riding cows about to ovulate and not the cow being ridden.  Standing heat occurs on these cows shortly after.
  • Semen needs time to mature after insemination (called capacitation).  We must remember that ovulation continues after standing heat or the rubbed estrotect.  Therefore there is a lot that happens in a cow after insemination and it is a very important time.

Lastly, an interesting statement:

Negative energy balance and hypocalcaemia (metabolic calcium too low) are the two biggest causes of low immunity and therefore disease.  We can prevent most cow disease with a balanced nutrition plan.