Here's some figures of expected production for a Holstein cow. This can help you figure out if your herd is over or under performing.
Average daily milk production per Holstein cow with decent nutrition would be minimum of 60 pounds of 4% fat corrected milk.
If the herd has excellent nutrition and management, it could go up to 70 or 80 pounds of 4% fat corrected milk.
Average peak milk production for first calf heifers is normally around 7 - 14 pounds over average daily production for the lactation.
As for second lactation, older animals usually produce 15 - 30 pounds over average daily milk production.
Generally, mature cows and heifers will peak within 5 - 10 weeks after calving.
After animals reach peak milk production, the average decline in milk per month is generally 10 - 15% for most of the lactation.
If the herd has good nutrition, the decline may be slower.
In late lactation, cows may experience 12 - 20% decline.
A normal lactation length for cows is 290 to 310 days. Anything below 270 days is considered short.