Extending Days in Milk

February 2017

Days in milk are gold for the dairy business, as it’s bloody difficult to make money from dry cows…

The national average days in milk (DIM) reported for the 2012/13 season was 258 days. (254 days for the North Island.) This means that, on average, we have cows with 100 unproductive days each season. There’s an area of opportunity for dairy businesses here, as cows really only require a 60-day dry period.

What issues need to be addressed to allow more cows to achieve 305-day lactations?

There are two main drivers of short lactation, calving spread and lack of feed on farm.

Calving spread

Reproductive performance is a complex topic that we will address specifically in another newsletter, however, batch drying-off strategies can be manipulated. There’s not a lot of point drying off all of your cows mid-May when some of them aren’t due to calve until September… Drying cows off in batches specific to calving date can drive efficiency. You can utilise your pregnancy scanning data to make these decisions.

Feed requirements

Then we need to focus on feeding. A 500kg cow in her eighth month of lactation, producing 1.6kg MS and gaining 0.2kg liveweight daily, will require the following feed inputs:

 Kg DMI
(Dry matter intake)
ME Supply
(Metabolisable energy)
MP Supply
(Metabolisable protein)
Autumn pasture 10.5kg 110 MJ 1.34kg
Silage 3kg 30 MJ 0.34kg
Crop 3kg 33 MJ 0.17kg
Complete 11 2.7kg 33 MJ 0.20kg
Totals19.2kg DMI206 MJ2.05kg
Requirements 19.5kg DMI 207 MJ 1.84kg MP

We can see from the table above that in this case, metabolisable protein (MP) is not limiting production. Energy will be the first constraint to increased production. However, a cow producing 1.6kg MS daily is still viable for twice a day milking.

(assuming pellets contribute $1.83 and maize silage is $0.95 per cow per day)

More than enough reason to keep feeding and milking these cows on to reach a 305 day lactation.

Ensuring that we do have feed on hand to get us through summer and autumn feed deficits will be pivotal to achieving 305 DIM. It’s not enough to hope it will rain!

The revenue equation

There is still a lot of revenue to be collected throughout May and June for a herd calving in July/August.

If we are bold enough to milk into June and move our average DIM from 258 days to even 288 days, the extra 30 days in milk at 1.5kg MS per cow daily means an additional 45kg milk solids!

At a $6.00/kg MS payout, that is an additional $270 revenue per cow.
Multiply that by the average 300 cow herd and you’re talking about $81,000 additional revenue for the season.

For more specific assistance in understanding the feed requirements of your herd to extend lactation, contact your local Dairy Nutrition Specialist.


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