The revised figures added an extra 332m litres of milk to the total UK production volume between January and October last year, an increase of 2.7% on what was originally published.
Cumulative production for the current season between April and November 2017 is now 9,860m litres, 2.8% higher than initially thought.
The revision had a marginal positive impact on UK farmgate milk prices, with the only major change coming with the October 2017 average increasing by 0.18p/litre to 31.79p/litre.
A Defra spokesman said the changes were made after the reanalysis of data submitted quarterly by some dairy processors.
“We think it is vital government acts on making regular milk price data reporting from the big processors mandatory,” said NFU chief dairy adviser, Sian Davies.
“Up-to-date information would allow farmers to make better decisions especially when looking at volatility tools and locking in fixed prices.”
Ms Davies said providing a fortnightly national average from which dairy farmers could make more informed decisions and lobby for the best prices would not require the big processors to publish business sensitive information.
“The EU Commission already receive data on [skim milk powder] and cheddar prices from the UK so it wouldn’t be too difficult for Defra to audit that information for publication here.
“There’s no reason we couldn’t have a situation similar to the United States Department of Agriculture which has a great system where production data is collected daily.”
AHDB Dairy added they believe Defra production figures for May to December 2017 were about 20m litres/month below what they should be.