Don’t underestimate your grass

There have been a number of useful articles published in the farming press over the past couple of months aimed at helping dairy farmers make better use of grass this spring (whenever that may be). However, I notice more and more seem to be erring on the side of caution when it comes to how much milk you can expect from grazing. Of course, right now, we might not want to get too ambitious about how much we can depend on grass when growth rates remain in single figures and what grass we have looks more purple than green.

The cows on our farm have been out for over a week now and I am really pleased with how they are performing off what is essentially winter cover. Despite the 50 shades of green and purple that form our pasture right now, intakes are good and milk yields have gone up. I think this winter grass has provided an ideal dietary transition from the winter ration our cows have been eating over the last six months. With grazed grass dry matter recently at between 25 and 30%, we have avoided cows making an overnight switch from a dry, fibrous winter diet to wet, leafy spring grass and I reckon the rumen bugs are grateful for this.

We currently have 177 cows in milk – 92 high yielders still housed at night and 85 low yielders now out night and day. Just to illustrate that turning cows out in less than ideal conditions can delivere some real savings, rather than simply an act to promote Free Range Dairy, here are some figures from our herd to show the economics of challenging our cows and making the most of the grass we have over the past week.

Increase in milk yield per day 400 litres
     Value per day @ 30p / litre £120
Silage saved per day   3,500kg
     Value per day @ £20 / tonne -£70
Concentrates saved per day      300kg
     Value per day @ £260 / tonne -£78

This has effectively improved our margin by £268 a day. Okay, so I haven’t yet allowed any cost for the grazed grass that has replaced silage and concentrates. We have removed 3,500kg of silage from the diets (1 tonne of DM) and 300kg of concentrates (270kg of DM), so I could put in cost of say £15 for the 1.27 tonnes of grazed grass that has replaced these. However, this is more than offset by the cost of bedding and labour associated with housing all the cows night and day.

I am determined to start the grazing season with some ambition this year and try learn more about what our grass can deliver. I think too many are constrained by advice that says high yielding cows need to be buffer fed and we shouldn’t expect more than 15 litres of milk a day from grass. If you have a cow with an appetite for 22kg of dry matter a day, it’s unlikely she will be able to eat enough grass to satisfy her hunger (110kg a day at 20% DM). However, start by trying to maximise grass intakes rather than filling cows up with silage and expensive feed and leaving them to ‘top up’ off grass.

If you target your cows to eat 15kg grass DM a day there is potential to achieve 20 litres of milk from grass, calculated as follows:

Daily grass intake   15kg DM
Energy consumed @ 12MJ ME / kg DM 180MJ ME
Maintenance requirement   70MJ ME
Milk production @ 5.5MJ ME / litre   20 litres

This might seem a bit simplistic and the doubters will say that grazing conditions will be less than ideal most days, etc, etc. BUT, start from here – challenge your cows and your grass. If you don’t leave room for them to eat grass, how will you ever produce more milk from it? Fresh calved cows won’t die if you graze them. They can produce milk from grass and, what’s more, they’ll have more fun doing it!

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