Grasstec: Important grazing decisions

COMMENT: As I write this the weather extended weather forecast suggests clear blue skies and frosty conditions by night -in most cases this is ideal at the end of the grazing year, allowing the final few heavy covers to be grazed out down to circa 4cms and less chance of poaching.

This final weeks of grazing still requires some important grazing decisions, most important is achieving the target closing average farm cover and what is the highest paddock cover on the farm at closing – should it be grazed or not before closing this year?

To answer the first question – What is the target closing average farm cover? This can only be answered properly by completing a Spring grass budget which identifies what the opening farm cover should be in February. When this figure is known we can back calculate the closing cover in November also taking into account the expected growth through December and January. For most farms this opening farm cover target is between 580-650kgs DM/ha and assuming over Winter growth of 2-3kgDM/ha/day then closing cover can be 450-500kgDM/ha. There is off course significant regional variation in over Winter growth with frost prone parts of the Midlands and North West often only achieving 1-2kgDM/ha/day and coastal regions of the South and South East achieving 5-6kgDM/ha/day. The bottom line is that all farms are different and it is seldom that one rule fits all – do it for yourself.

To answer the second question – What is the highest individual paddock cover that should be carried through the Winter. This answer is a function of your Autumn rotation planner and target closing farm cover. A general rule is that if the paddock cover is >1200kgDM/ha then you should consider re-grazing it – but bear the following in mind:

  • If you had >65% of the farm grazed in the first 30 days of closing paddocks since early October, then you can re-graze one or two paddock covers that are over 1200kgDM/ha
  • If, when deciding to graze them again, your average farm cover will still be above your target closing average farm cover then it is ok to graze them.

Carrying high covers through the Winter leads to more Winter kill in those individual paddocks – i.e they do not accumulate cover through the Winter compared to lowers paddock. However, grazing them late in November may reduce the amount of grass available to graze in February. It is worth more to you to have it available in the Spring compared to grazing it now.

On a separate note, you assessment of cow body condition is critical at this time of year. Beauty is in the eye of the beholder and there is a big variation in farmers perception of ideal body condition score at calving and more importantly now, the body condition score at drying off. Ideal calving BCS is somewhere between 3 and 3.25 however with calving spread out over the months of February, March with some late one in April it is often guess work as to the proper drying off date for the individual cows. The simplest technique that I use is to categorise each animal into those who require 8 weeks, 10 weeks or 12+ weeks dry period then work back from their expected calving date as to when they should be dried off. Do this every 7-10 days from now until all the herd is dry. It is critical to continuously evaluate BCS of the whole herd through the dry period and be prepared to batch and re-batch groups according to BCS and feeding regime.

Final note – did you do your soil testing? If so have you acted on the results for pH? If lime is required then this cold snap may provide an ideal opportunity to get it applied with little as ground dries out. It is advised not to apply lime within two months of expected Urea application in the new year – so now is the time to do it.

By Noel Gowen, consultant with Grasstec Dairy Solutions who provide a dairy consultancy, farm infrastructure design and livestock sourcing service in Ireland and UK

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