Management of cows body condition in early lactation, by Centenary Agri’s Animal Nutritionist, Howard Stanley.

Spring is upon us, and many farms are at the latter end of calving at this stage. As this is a stressful period for both the farmer and the cows, it is easy to take your eye off the ball when it comes to balancing the herd’s diet in early lactation. Early lactation is a key time in a cows productive cycle, the farmer is trying to maximise milk production from the cows whilst aiming to have a successful breeding season.

In the first few weeks after calving, cows will physically struggle to eat enough to match their energy requirements and therefore they won’t be consuming enough energy to support maintenance and production, This is known as negative energy balance (NEB). A cow going into negative energy will happen naturally but with good management the effect of being in negative energy is greatly reduced, it is important not to lose excessive body condition, as doing so has been shown to be linked to negative fertility performance in the herd

The extra energy required to match the cow’s milk output will come from her body reserves, and she will start to mobilise body condition and use it to fill the energy deficit as a result. Farmers will often refer to this as “cows milking off their back”. The graph below provides a visual explanation of what is going on with a cow in terms of negative energy balance. Area highlighted in yellow shows that the energy demands of a cow increases at a rapid pace prior to calving. Peak milk production will happen 40-60 days after calving cows and therefore energy demand is at its peak. The area highlighted in blue shows the increase in the dry matter intake of a cow. This curve rises gradually in comparison to the energy demand of cows. The grey area of the graph highlights the time a cows spends in negative energy balance and this is therefore the time a cow will spend loosing body condition. The dotted line indicated the decline in body condition of a cow, you will notice a steep decline in body condition but when the cow has reached maximum intake, and as milk yield start to reduce her body condition start to increase again.

As a farmer it is important to understand that we will not stop a cow entering negative energy balance as this is to a certain degree a natural process, however, with proper management we can make the “grey area” between feed intake and energy demand a lot less and negate the effect negative energy on cows.

The amount of condition the cow will lose in early lactation will have a significant impact on her milk yield performance and an impact on her fertility for the year ahead. For example, it’s no coincidence that a lame cow or a problem cow doesn’t go in calf during the breeding season. Ideally, we do not want to lose more than 0.5 BCS in the first six weeks after calving; this would equate to a loss of around 25kg in your typical 600kg Friesian cow, or 4% of her mature body weight.

According to Teagasc, indicators of an NEB issue in the herd are:

• Less than 15% of early lactation cows with milk protein <3.05%; Milk protein results are influenced by energy intake. If your milk protein test results are low, there is a very high chance that your dietary energy is low.
• Less than 15% of cows with a milk fat: protein ratio >1.4; (this can be done by milk fat divided by milk protein. Or in other words if your milk test results show that butter fat is very high say 4.75% and milk protein is low at 3.15% this is a sign that there is not enough energy in the diet. The ideal ratio is 1.18.
  Less than 25% of cows with >0.5 units of body condition score (BCS) loss in early lactation.
• Monitoring body condition of cows and monitoring there cows overall appearance is very important. If cows look like they are under pressure with poor, dry looking hair they will need more energy in the diet. The important thing to note is that every farm is different, but the same principle can be applied to your farm’s individual requirements depending on the cow breed, size, peak milk yield and quality of the forages, etc.

When you break down what the indicators of Negative Energy Balance are it will make it easier to come up with a plan to prevent it.

Energy requirement of a cow in early lactation
As a rule of thumb a cow require 6 ufl for daily maintenance only. She also requires energy for milk production – for every litre of milk a cow produces she has an energy requirement of 0.45 ufl. Choosing a feed with energy ingredients such as maize, barley, wheat, beet pulp, to name a few is a step in the right direction.

Take an example of a herd producing 28 litres in early lactation. The herd will have an energy requirement of 12.5ufl for milk production plus maintenance of 6 ufl – making a total energy requirement of 18.5 ufl. The three most common scenarios that you would see on a spring calving herd are:

• 1. Scenario One we see in spring where grazing is limited due to wet weather or grass is wet and dry matter intakes are poor. The diet will consist
  of Average silage +5kg of concentrates. This diet will only deliver 13-14 ufl and therefore a shortfall in energy is created instantly. These cows require supplementation, and additional concentrates should be giving along with forage at the feed barrier or cows will start losing body condition which leads to poor fertility, trouble getting back in calf etc.
• 2. Scenario Two is cows are out grazing dry grass full time being fed approx. 4kg of feed in the parlour. Fresh dry grass + 4kg of feed in the parlour will provide 18-19 ufl. The key thing to remember is DRY GRASS and if weather conditions change and grass becomes wet it has a great impact on dry matter intake. Wet weather has a negative impact on grass utilisation, and DMI will drop 0.4kg for every 1% drop in grass DM under 18%. Feed in the parlour maybe have to be increased and or added at the feed barrier. It is very important to react to weather conditions to ensure cows are constantly eating enough to support maintenance and production.
• 3. Scenario Three is where cows are out grazing by day, grazing for a few hours in the evening but are indoors by night. Fresh dry grass + 6kg of feed + silage in the parlour will provide 16-18 ufl (measuring grass intake and grass dry matter is important so that you as a farmer are aware of how dry matter is coming from grass). Silage quality will have a big influence on energy intake. If the silage is good it will only complement energy intake but if silage is of poorer quality further supplementation will be required.

In Summary
Be aware of the effects of negative energy balance in cows. Although cows losing body condition in early lactation is a natural occurrence, if you are feeding the cows enough energy you won’t have any negative effects and you will have a successful breeding season followed by a successful year of milk production. Talk to your sales reps about the best feed available to your herd and I wish every farmer a prosperous year.