The number of cows in Canterbury has increased more than 100% in the past eight years.
The Canterbury region dairy report for the 2012-13 season shows the total number of cows in the region is 769,417.
This is an increase of 107% over 2005 figures.
The number of dairy farms in Canterbury has increased 58% over the same period, while the average and median herd sizes have both increased 31%. The average size of a herd is now 771 cows, while the median herd size is 710 cows.
The biggest percentage rise in the number of larger herds came in herds of between 1001 and 2000 cows. In the 2004-05 year there were just 56 herds in this size range but in the past year the number of larger herds has risen to 208 - an increase of 271%.
The other big rise came in the number of herds with 601-1000 cows, which rose 133%.
There was a drop in the number of smaller herds - those up to 300 cows - from 141 herds in 2004-05 to just 79 herds. The report, produced by Environment Canterbury, shows that dairy effluent consent compliance rates in Canterbury have risen in the latest season, continuing the improving trend of the past four years.
The latest information shows that 72% of the region's 997 monitored dairy farms were fully compliant, an increase of two percentage points on the 2011-12 season. An analysis of compliance by the Canterbury water management strategy zone showed the majority of Canterbury's dairy farms (53.9%) are in either the Ashburton or Selwyn-Waihora zones.
The Ashburton zone has 349 herds, with 86 of them being between 1001 and 2000 cows and 164 herds of between 6001 and 1000 cows.
The Selwyn-Waihora zone has 188 herds. Forty-three of them are in the 1001-2000 bracket and 83 between 6001 and 1000 cows.
The Orari-Opihi-Pareora and Ashburton zones had the highest level of full compliance at 87% and 84.2% respectively. The highest level of non-compliance (in zones with more than five farms) was found in the Waimakariri (52%), Selwyn-Waihora (56.2%) and Kaikoura (56.5%) zones.
Nationally, the number of dairy cows has risen from just over 2 million in 1981-82 to 4.6 million in the 2001-12 year. The average herd size has risen from 130 to 393 cows in that period with the average number of cows per hectare rising from two to 2.83.