If cows are too fat or too thin, farmers face difficulties at or after calving. It is key to have cows calving down in the right condition.
With cows at grass, getting autumn-calving cows in the correct body condition score (BCS) can be especially tricky for farmers.
At the Johnstown Castle winter milk open day, Vincent Treacy from Teagasc outlined how the herd approaches cow condition.
The Johnstown Castle autumn herd is due to start calving down from September 25.
"Let's say the dry period is about 60 days - for the first 42 days of this, the dry cows follow the milking herd in terms of grazing," said Mr Treacy (pictured left).
"They go into paddocks after the milkers are out. It is about bringing down that body condition score in that 42 days. You want the cow calving at a score of 3.25 ideally - not too thin or too fat, but in that area."
After this period, the cows are then let into a paddock that has been growing for 50 to 60 days and they are given a small area of just 2m per day. The cover in this paddock is around 3,000kg dry matter per hectare.
The logic behind this heavy cover, according to Mr Treacy, is that this stronger grass is lower in potassium (K), which will help reduce the risk of milk fever. This heavy paddock has received no K fertiliser since the spring.
"The cows are also fed haylage or hay too as well as a half a kilo of rolled barely too with 100g of magnesium. The barley is just a carrier for the cows to go eat the magnesium," he said.
Mr Treacy added that 40pc of the autumn herd will be calved in September and 80pc calved by the end of October.
Assuming ground conditions hold up, just 20pc of the herd will calved indoors.