Drying off: Let the cows decide!

Monday, February 3, 2014

The more cows yield, the harder it is to get them dry, so every few years scientists examine the possibilities of milking through into the next lactation. The results of the latest trial of this option are just out and give some cause for optimism

by NORMAN DUNN

We all look at simple solutions in farming with more than a little suspicion. Just look at how long it's taking for no-till, or even minimum till, to catch on. And what about automatic milking? I remember reporting the first developments in this area 30 years ago. Only now is the system being seriously considered for every new barn that goes up in Europe.

Maybe we're taking the same tortuous route with drying off? Let's just think back and recall the problems with those cows that simply won't stop milking. You can cut their feed down to barley straw and fresh air – and they'll still be producing 20 kilograms daily with calving just three weeks away.

Now and again, the job proves impossible and milkers calve and slide into the next lactation without a hiccup. The subsequent yield suffers, of course.  But I'm certain I'm not the only one to reflect that also missed is the expense of antibiotic treatment at drying off and vet visits for retained placentas, or cases of milk fever and ketosis.

It's doubtless the resultant 20 per cent drop in peak yield that has put a stop to any large-scale consideration of milking through – at least with some cows. Scientists, though, don't have the bank manager to think about. That's probably why trials comparing conventional drying off and milking through crop up continually.

About 10 years back, the Danish Cattle Association and other interested bodies in Denmark financed a comparison with Holstein milkers, 14 of them prepared for their next lactation with a seven-week dry period and the same number milked through. These were cows producing at least 50 kilograms per day at peak lactation and still pumping out around 20 kilograms daily at conventional drying off time.

In fact, only the very highest yielders in the milking-through group actually continued in-milk. Three cows naturally ran dry as calving approached. Another four dropped below five-kilograms-a-day production and were conventionally dried off. The Danish scientists found that average peak yield was 22 per cent higher with the conventionally dried off group.

But metabolic imbalance during subsequent early lactation was higher with these cows, too. Little wonder: after all, these cows go from producing over 20 kilograms of milk to nil and then back to full production within seven or eight weeks. Interestingly, body condition based on scoring was the same after calving for both groups.

Still, the Danish team was sufficiently impressed by the yield penalty to refrain from approving any commercial development of milking through, even for some cows in the herd.

But now we have the results of the next test along these lines, conducted by the University of Munich in Germany over the last year in a number of commercial Fleckvieh dairy herds with automatic milking systems.

This time, there's open approval of the effects that milking through can have. The cows without a dry period came into heat after calving about a week earlier than the dried off cows. A higher percentage of the former group held to their first service, too. The body condition and health status of these cows was such that the researchers from Munich estimated the equivalent of C$148 per cow was saved in veterinary material and treatments.

The expected flattening out of peak yield was there too, of course, and taking Bavarian milk prices it was reckoned the loss here for the cows that weren't dried off averaged $84 a head. The researchers found there was therefore an advantage of around $18 per head in allowing cows still producing well to milk on. They added that the effect could be even more profitable with higher-yielding Holsteins.  

As shown in both trials, there are plenty of cows that dry off naturally as their calving time draws near – or that give so little milk at that time that drying off is the simpler solution. Such herd members should be able to produce enough colostrum for all calves.

None of these tests was continued through to a subsequent calving, so knock-on effects are not known so far. However, there are now dairy farmers in Europe who are at least considering the milking-through option with a lot more optimism. BF

Norman Dunn writes about European agriculture from Germany.