As the weather improves full time grazing has become a regular routine on farm and with the calving slowing down, we need to look forward towards breeding. The success of your breeding season will be determined by how you manage the energy balance in cows from now on. It’s too late to look at this at the end of April into May, we need to get it right now. Grass is a great feed for cows, but it’s all about making sure the dry matter and energy intake, as well as their dietary requirements are met daily. Of the various nutrients cows require, metabolisable energy (ME) is the first consideration in rationing. Performance and well-being also depend on achieving enough levels of protein, minerals and vitamins in the right balance.  Energy is however almost always the primary performance limiting factor and is directly linked to DMI.

One of the most important performance drivers in a spring block calving herd is a cows feed intake. A cow will reach her highest daily milk yield 6 to 8 weeks post calving but only reaches her maximum dry matter intake 4 to 6 weeks later. The cow then resorts to “milking off her back “ to make up this deficit. She achieves this by mobilising energy from body fat via the liver. When this happens, she is in danger of losing too much body condition and this is referred to as a negative energy balance. The goal is to keep BCS loss at less than 0.5 to 0.75BCS. When excessive BCS loss occurs, first ovulation after calving is delayed, conception rates decline, and days open increase.


Dry matter intake will increase by 0.75 -1.0 kg per week until peak intake capacity of 16-20kg DM is reached. The moisture content of grass varies significantly during spring, especially true this year, as most herds have been unable to turn out as early as normal. This can have a major impact on dry matter intake and it is important not to overestimate the DMI a cow can get from pasture or else fertility and performance can be compromised. For example, a cow estimated to consume 12kg of at 15% DM will require an intake of 80kg of fresh grass, this is a large volume of grass for any cow to eat. Buffer feeding and or extra concentrate feeding should be considered especially during wet periods when required grass DMI cannot be maintained due to the low dry matter of the grass.


Meeting a cow’s energy needs at this time of the year will drive solids production as well as the success of your upcoming breeding season. Cows require a certain amount of metabolisable energy each day to support their basic body functions, this is before she has produced a litre of milk or maintained a pregnancy.


Cows require 10% of their body weight plus 10 MJ of ME each day for maintenance.

This means a 550kg Holstein/ Friesian cow requires (550 X 10/100) + 10 = 65 MJ of ME/ Day for maintenance.

A typical Holstein / Friesian cow producing milk at 3.8% fat and 3.2% protein require around 5.2 MJ of ME for every litre of milk produced.

This means a cow giving 30 litres requires (30 x 5.2) =156 MJ of ME/day for production. These requirements increase as the solid percentages increase so will be higher for cross breeds and Jersey cows.


The cows body fat reserves provide a balancing mechanism between the amount of ME a cow needs and the amount available in their daily diet. Whenever insufficient DMI occurs such as at the beginning of their lactation to support production, energy is mobolised from body fat via the liver. This allows cows to continue milking off their backs whilst losing body condition (NEGATIVE ENERGY BALANCE). If this goes on unchecked the cow will become ketotic. The fat broken down forms ketone bodies which in turn depresses the appetite causing further BCS loss and liver damage. For farmers that see their cows everyday there are several factors to take note of in this early lactation period, which, if they are observed should be addressed as soon as possible by calling your nutritionist.

  • Rapid loss of BCS post calving, anything above 0.5 to 0.7 BCS is a concern
  • Depressed post calving DMI (look at rumen fill)
  • Watch your milk tank results for any milk fat -protein ratio inversion

Ketosis or even sub clinical ketosis (far more prevalent) is another biometrical expression of negative energy balance. It not only affects milk production, BCS and the ability of a cow to conceive but has other far reaching effects which will impact on every farmers bottom line. Lameness is another consequence of ketosis as it leads to a weakened claw structure as well being linked to reductions in the fat pad of the digital cushion in the claws. This leaves the cow more susceptible to sole ulcers and white line disease. Metritis, inflammation of the uterus, can be caused by a suppressed immune system, meaning the cow is unable to fight infection and this in turn can be linked to nutrition (as well as environment and general management) and therefore secondary ketosis is often a result of diseases which reduce the appetite like metritis and a displaced abomasum.

All this takes place prior to breeding and no farmer needs to be told that dirty cows, lame cows and very thin cows do not conceive or take longer to conceive.

Prophylactic treatments once the ketosis has been diagnosed, in the form of propylene glycol normally get the cow through this crisis but once it has been observed, liver damage has already occurred, and milk production inhibited for that and subsequent lactations.


It is better to be safe than sorry and the dairy cow’s journey to this point starts at drying off. (I will cover this further in another article). The most effective tool in managing ketosis is encouraging greater DMI and managing those days where poor weather and rain reduce DMI by supplementing with feed either in the parlour or in the bunker. There are various feed additives that can be included in your dairy rations to reduce the incidence of sub and clinical ketosis. These feed additives are used to increase the DMI and therefore the energy the fresh premating cow requires. There are also liver supplements which assist the liver to flush out fats and reduce liver damage and numerous yeast supplements which increase the buffering ability of the rumen as well as the degradation of feeds. As rumen PH is critical this action stabilizes the rumen PH and micro bacteria, which in turn encourage greater mobility and more time eating. One cannot simply increase energy density of the ration as this is usually at the expense of effective fibre in exchange for higher soluble carbohydrates or fats content leading to a greater risk of rumen upsets and in turn a diminished DMI.

It is difficult in these times of isolation and uncertainty when faced with problems on your farm, however should you just need some information on a product or just to talk through some issue then please feel free to contact us at Jameson’s and we will try our best to help find you a solution.

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