Beware the Impact of Wet Grass on Cow Performance says Duncan Rose, Chief Technical Officer for Carrs Billington Agriculture.
Duncan Rose,Chief Technical Officer
for Carrs Billington Agriculture
The first point to make about the milk from grass figures (provided by Frank Wright/ Trouw Nutrition International) is that the averages are taken from samples taken across the whole of the UK.
In Wales, the North of England and Scotland the weather has been awful and the Dry Matter content of many grass samples have been down below 10%. This is lower than the Dry Matter content of milk!
It reduces the potential milk yield from grazing to nearer M+5 litres rather than M+15 litres, which is more typical for June.
Cows will struggle to eat 100kg grass so if it is only 10% dry this is only 10kg Dry Matter, enough to support just 7 litres of milk. The immediate consequence seen on dairy farms has been a drop in milk yield but we are also seeing milk proteins suffer because cows are low in energy. Do not let this energy gap go on for too long otherwise it will have a long term effect on milk yield, milk quality, health and fertility.
Don’t forget that youngstock will also suffer and need extra supplementary feeding during this very wet spell to maintain health and growth rates.
Another point to note is the variable milk ureas being reported, often much lower than one would expect for this time of year-some down to 150 instead of 250 or above. What is different this year?
1) Lower fertiliser applications
2) More leaching of fertiliser by heavy rain
3) More silage buffer feeding (lower in protein than grass)
It is not unhealthy to have low milk ureas but it may be an indication that cows need to be fed more protein.
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