More first cut silage samples are testing higher in energy than protein – raising concern that dairy rations may become imbalanced this winter.
Challenges with low silage protein levels were first flagged in early first cut silage analysis results. But later first cuts suggest the picture is becoming more extreme – translating into even lower average crude protein levels.
Average crude proteins are now 13%, according to an analysis of 163 silage samples, including later May-June cuts, by Mole Valley Feed Solutions. This is down from around 14.5% for early first cuts. The range runs from 8.2% to 21.6% crude protein.
Mole Valley senior nutritionist Robin Hawkey says the fermentable energy and protein balance (NFEPB) is of particular concern. “Left unaddressed, this could negatively impact on milk output,” he explains.
Normally, crude protein levels to be higher than metabolisable energy at about 14-16% crude protein and 11MJ/kg DM. But this season NFEPB has been reversed with some silages analysing at 10% crude protein and 11MJ/kg DM.
Dr Hawkey, says such a pattern is unusual. “I think that’s linked to the very cold, dry spring. It suggests that applied fertiliser wasn’t taken up, so the plant didn’t produce as much protein.”
Farmers that cut very early appear to have been impacted less. Those most affected appear to be farmers who planned to cut in the second or third week of May and then had to delay due to the weather and cut in late May-early June.
The issue is not just with crude protein, but how that protein is made up. Rumen fermentable protein (RFP) and total fermentable protein (TFP) levels are both particularly low, says Dr Hawkey.
This “raises flags over rumen function,” he adds. RFP and TFP are needed to promote rumen function, maximise nitrogen efficiencies and optimise production of microbial protein.
To address the protein and energy imbalance and protect milk production, Dr Hawkey advises feeding rumen fermentable protein sources such as rapeseed.
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