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Are You Underutilizing Grazing?

17 February 2015

The nutritional content of your grass depends not just on quality, but how much each cow eats, writes a UK dairy adviser.

In a consideration of grazing and cow requirements, a technical extension officer from DairyCo looks at what a middle to high yielding herd may need. This is for the less than 30 litres, in calf cow. 

A 600Kg cow requires 70 MJ of ME for maintenance, writes Piers Badnell, DairyCo. She will require 5.3MJ ME per litre for a 4 per cent fat and 3.3 per cent protein litre of milk.

IMAGE NAME/DESCRIPTION
Training cows to "graze well" can result in eating 16 kg of DM/day

Energy Calculations

So, if this cow consumes 10Kg DM of 12 ME grass this will give her 120 MJ ME. Take off 70 MJ for maintenance and that leaves 50 MJ ME, writes Mr Badnell.

Divide this by 5.3 and this equals 9.43 litres of milk. If she consumes 16Kg DM, grazing at 12 ME, this gives her 192 MJ ME. Take her maintenance of 70 MJ from this and that leaves 122 MJ ME. Divide this by 5.3 and this equals 23 litres of milk. Source DairyCo Feeding+ manual chapter 7.

Can a Cow Eat 16Kg DM of grazing in a Day?

The answer is yes, some herds get to 17 or 18Kg DM a day. But she needs training to graze well. That means when grass supply is not limited, not filling her with buffer. It also means giving her plenty of time to do it, as she can only bite so many times per minute. If she is stood twice a day in a collecting yard for four hours then she won’t have the time.

In order to get these type of intakes we have to present the cow with a quality, and accurately allocated, area. She will also have to have an edge to her appetite when she goes out to graze. She is very unlikely to achieve these intakes if it is hammering down with rain, but if it is dry, and the DM of the grass is in the low to mid-twenties, and she does not to have to walk miles, and has the time to graze, the potential for high DM intake is there.

Some work done at SRUC in Dumfries, on dry matter intakes in wet and dry weather, showed that for late lactation 20 litre cows, on autumn grass intakes on dry days was 15Kg DM, whilst on wet days it had fallen to 8-10Kg DM.

Are We Underutilizing Our Grazing?

Mr Badnell reviewed a consultant's presentation looking at grazing based farmers in the UK, in New Zealand as an average and in Southland. 

The presentation was by LIC consultant Alicia Newport at the Pasture to Profit Conference last autumn. 

Mr Badnell adds: Alicia suggested that UK grazing farmers were best compared to Southland in New Zealand, as the climates were far more comparable. As such, if we compare the percentage imported feed are we under utilising our grazing?

The challenge is there. Make sure your paddocks are both performing well and being utilised fully. As the table above shows, farmers in New Zealand’s Southland are achieving higher solids on less imported feeds, can we do the same?

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