TAGS

Getting up to calving weight

It is more efficient to put weight on cows when they are milking than when they are dry, and it’s easier to put it on with higher quality feed. So now is a great time to set them up to be in good condition for calving. 

When on leafy summer pasture with 10 megajoules metabolisable energy per kilogram of dry matter (MJME/kgDM), on top of daily requirements for digesting food, walking, producing milk and maintaining a pregnancy:

  • A lactating cow would need to eat 4kgDM to gain 1kg.  

  • A dry cow would require 5.4kgDM (of the same grass) to gain 1kg.

If palm kernel with 12 MJME/kgDM was used: 

  • A lactating cow would need to eat 3.6kgDM to gain 1kg.  

  • A dry cow would require 4.3kgDM to gain 1kg.
     

A 500kg cow needs 33kg liveweight gain for 1 body condition score (BCS) gain. So, for a 500kg cow to gain 1 BCS using the leafy summer pasture at 10 MJME/kgDM (on top of the feed needed for her lactation and daily maintenance): 

  • A lactating cow would need to eat a total of 128kgDM.

  • A dry cow would require a total of 178kgDM. 
     

Of course, there also needs to be enough protein in the diet for efficient growth – but late summer is the main time in a dairy cow’s yearly diet that this may not happen. If the grass has gone dry and stalky (e.g. 140g crude protein (CP) per kgDM) and it is being supplemented with only maize silage (80g CP/kgDM), the protein levels can be low enough in the diet that it will limit efficient digestion. Which in turn can limit both weight gain and milk production.

Autumn and spring grass is much higher in protein (300g CP/kg DM and 250g CP/kgDM respectively) and feeding a low protein supplement like maize silage is very unlikely to cause a protein deficiency in the diet at these times. Choice of feed is very important in summer, particularly if aiming to put weight on cows.

Why do my cows need to have a certain body condition for calving? 

Cows that calve at BCS 5-5.5 will have improved outcomes after calving, including better repro rates.

Cows with BCS lower than 5 at calving will produce less milk and take longer to start cycling and get pregnant again.  

Body condition scores higher than 5.5 can reduce the appetite of cows, resulting in a greater drop in condition after calving. These fatter cows can have more problems with ketosis and milk fever in spring and can also take longer to get back in calf.

Why do cows lose weight after calving?

Going from pregnant and not milking (dry) to calved and milking doubles a cow’s energy requirements within a very short period of time. Cows take longer to adjust their feed intakes to match these new energy requirements than milk production allows, so weight can easily be lost. 

While there are theories as to why a cow does not voluntarily eat enough to prevent her losing weight in the first weeks of lactation, it is not completely known why. Usually, after about seven weeks post-calving, a dairy cow being offered enough high quality food will stop losing weight and come back into a positive energy balance.

Because of this, most cows tend to lose 1 BCS after calving. If problems arise due to insufficient or poor diet, or other illnesses after calving, more than 1 BCS may be lost, and it may take longer to reach the point where the cow has a positive energy balance.

This impacts the milk production and fertility of the cow, even if she started at a good BCS of 5. Hence everyone knows how vital feeding your herd right over the milking period is.

How does pregnancy affect cows putting on weight?

The energy required to grow a fetus is relatively low in early pregnancy compared to a cow’s lactating or daily maintenance requirements, but it does increase in late pregnancy due to the rapid growth of the calf.

However, the cow does not increase her feed intake relative to this increase in requirement over late autumn and winter. This could be because of how much room the calf is taking up in the abdomen, shrinking the available space in the rumen, but it may also be related to discomfort and hormonal changes.

Gaining weight in late pregnancy also tends to increase the weight the calf is born at, causing more assisted calvings. 

Weight gain is often more achievable and appropriate in summer. 

Are my cows a good weight?

Body condition scoring is used to see whether cows are in the right condition.

Key body condition scoring times throughout the season are:  

  • Just before planned start of calving, 

  • Two weeks before planned start of mating,

  • After the end of mating, but before pasture quality drops in summer, 

  • Late lactation. 

If you would like help to score your herd to help identify what actions you need to take now ahead of calving next season, please get in touch. 



 

This product has been added to your cart

CHECKOUT