Calving slows, now, when to take the bulls out?

Over the past week, only half a dozen cows have calved. The next decision will be when to take the bulls out of the herd.

Traditionally, our herd begins to calve in mid-July but we’re in transition towards a new start date. Because the winters seem to be warmer and the springs shorter here, we began to mate the cows last July for an April 20 start to calving (like people, cows have a nine-month gestation period).

This is designed to match the cows’ peak production of milk with the peak growth of grass and reduce the need to maintain high energy levels over summer, which is a tough time to keep fodder up to the cows on a rain-fed rather than an irrigated farm.

So, when to stop? Some farmers arrange mating dates to have a couple of batches of calves throughout the year, relatively few calve all year round and most aim for seasonal calving over a period of eight to 12 weeks. These days, it’s becoming increasingly hard to get all the cows in calf each year and not all cows need to be pregnant annually to produce well. Extended lactation, as it’s called, is now very common for a portion of dairy herds and, according to the gurus like Greg O’Brien at the Department of Primary Industries, could be quite viable.

Since I want to shift our start date and rapidly shorten the calving season from our current transitory (and excruciating) six months, I’m inclined to be reassured by Greg’s advice and pull the bulls out earlier rather than later. Last year, it was New Year’s Day, this year, I’m considering mid-November. It’ll be mostly the late calvers who miss out under this regime and because we’ll be mating again in July, extended lactation is even less of an issue – it’s not a two-year lactation, anyhow.

In the next couple of weeks, we’ll arrange a pregnancy test for the cows who either calved early this year or didn’t calve at all. The vets are confident of due dates when pregnancies are at least eight weeks.

Wish me luck!

The art of caring for new mums

New mums deserve TLC courtesy of our researchers

There’s a real art and a science to looking after cows in the lead-up to, and just after, calving. As you can imagine, cows need an incredible amount of calcium to both grow their calves and to produce milk.

You’d think that adding extra calcium in their diets would be a good idea, wouldn’t you? Well, actually vets tell us that adding calcium is one of the worst things you can do to a cow that’s about to calve. It makes her much more likely to suffer from a life-threatening disorder called “milk fever”, where the body cannot produce enough calcium to power her muscles (including the heart).

Instead, we must choose feeds that encourage the cow’s body to draw calcium from her bones and that will help her adjust to the diet she’ll receive as a member of the milking herd. If we don’t get the feeding regime right during the two to three weeks before calving, cows are more likely to have trouble calving, develop lameness, lose weight, produce less milk and get sick with mastitis.

Ironically, too much grass at this time also spells big trouble. It generally has a high dietary cation anion difference (DCAD), which doesn’t help get precious calcium into the bloodstream. That’s why cows in our calving paddock have access to short but clean grass, anion salts in their drinking water, cereal hay and half the ration of grain they’ll get in the dairy. They’re too precious to treat with any less TLC.