A regular question that we get asked at meetings across the country is, “At what age should you consider culling”? It is a difficult one to answer as there are many circumstances that can drive the discussion but often one argument for not culling too quickly is the cost of replacing the cow.

So, this is the starting point for the discussion. Firstly, if we take an average cow at 675kg and an average cull cow price over the course of 2018 of £1.30/kg, we have an animal worth £878. To replace her, there are several options from a home-bred heifer through to a cow with calf at foot.

For the purposes of this exercise, we will assume that the farmer is paying £1,350 for a purchased breeding heifer.

This gives a total depreciation/replacement cost of £472 over her life in the herd.

Table 1 below explores the cost per year in the herd from 10 years down to four. As can be seen, each year less in the herd increases the cost of the replacement by £5.25 to £23.80 per cow per year.

The question then becomes what does increasing the replacement rate do for the herd and what potential gains are available. At a liveweight price of £2.20 per kg of beef, each increase in the replacement rate only needs to add between 2kg and 11kg per cow of weaning weight to cover the additional cost.

The other advantage to a slightly higher replacement rate is that you are maximising the cull value of cows in the herd.

Table 2 offers an alternative perspective on this as with an average Scottish weaning rate of 86%, the calving interval is 424 days.

This means that with five years in the herd, the average cow will only produce 4.3 calves, eight years 6.9 calves, and 10 years 8.6 calves.

If we now price the depreciation per calf rather than per year, we get a much higher cost. A 20% replacement rate means a cost of nearly £110 per calf produced, 14% means £78 and 10% nearly £55.

Looking at the bigger picture, you need to be looking for seven to eight years of production from a cow to get six to seven calves to dilute the cost per calf of replacement.

This means that a home-bred replacement, calving at two, will leave the herd somewhere around nine to 10 years old.

Taking another two years out of her will get another two calves but by how much will the £14 extra per calf be lost in a reduction in cull value?

Most of the focus farms treated cattle for external skin parasites of lice and mites pre-Christmas. In most cases, this was done in the form of a pour-on product.

However, in a number of instances where a single treatment has been sufficient in previous years, farmers are reporting the need to go back in with a second treatment.

Speaking to farmers across the country, this seems to be quite a common complaint this year.

One reason for this could be the milder conditions experienced up until recently which aid external parasites to survive and thrive.

If the colder spell of weather is to continue, this could help reduce lice and mite burdens.

It is very important to get on top of any itching or scratching in your sheds as soon as possible.

Cattle simply will not thrive as well as expected if they are burning energy scratching or in discomfort.

Even where cattle are to be sold in the coming weeks, it is still worth treating.

An increase in daily liveweight gain of even 0.1kg/day will be worth over £15/head by the end of March.

Signs to look for: Stand in the shed an hour after feeding and observe cattle for a few minutes.

If you can see numerous animals licking, scratching off feed barriers or water troughs, then you need to treat.

Also look for bare patches of skin where cattle have rubbed off the hair or lick marks on the sides of cattle.

Treatment

Where cattle are in need of a second treatment, the focus farms are going in with a different product to the one used previously. What we must be aware of is that the products we use will not cover all types of lice.

There are two types – sucking and licking. Injectable treatments such as Ivermectin will only cover sucking lice.

Therefore, by going in with a different active ingredient we are more likely to cover all bases.

Where a pour-on product is being used, clipping the cattle’s back will mean direct contact of the product with the skin.

If you have been using the same product year on year, resistance can be an issue and a change of product, and more importantly active ingredient can have a positive effect.