Just how big is big?

Craig Bennett always knew that bigger is better when it came to dairy heifers. But when he began weighing them regularly he realised just how much his heifers varied in size, and he discovered a powerful management tool.

Mr Bennett dairies with his wife Sophie near Simpson in Victoria’s Western District. They milk 250 cows with 75% calving in the spring and the rest in autumn, and plan to expand the herd to 270 next season.

The importance of having well-grown heifers hit home in their first season on the property when they milked a batch of 55 heifers that were below target weight, due to the previous season, the 2006 drought. Only about half these got back in calf in their first lactation.

A dairy heifer that doesn’t get back in calf to make it into her second lactation costs you money. The milk she produces in her first lactation won’t cover her breeding and rearing costs.

“We set ourselves a goal of meeting the heifer growth targets outlined in The InCalf Book. Our aim is to give heifers the best chance to get back in calf, compete with mature cows in the paddock and to last in the herd for many lactations,” he said.

In July 2008, the Bennetts started weighing their heifers regularly, using a service provided by Hicco, a local herd improvement organisation.

“It’s much easier than we expected and the cost is trivial. We drench the heifers at the same time so we’ve combined two jobs into one,” said Mr Bennett.

Having individual weights of heifers gives Sophie and Craig Bennett the ability to split them into groups which can be managed differently, to ensure they all reach target weights by joining.

He deferred joining a small group of late-born calves that were significantly below target weight. These will be mated to calve at 30 months with the autumn batch.

The group that is at, or above, target weight receives good quality pasture only. The group that are slightly below target weight receive good quality pasture plus silage.

“The heifers get the best pasture available, and on occasions take priority ahead of the milkers. Well-grown heifers will produce more milk year after year. That’s a much bigger return than giving the milkers the best pasture to get more milk in the vat tomorrow,” he said.

However Mr Bennett recognises he may need to feed the heifers a quality supplement during the months of limited pasture availability.

“We’ve had plenty of lush pasture this spring but we’ll probably feed the heifers silage and grain over the autumn and winter months,” he said.

The results from the November weighing showed Mr Bennett’s management changes had made a difference.

When the heifers were weighed in July, it was clear the Bennetts had a big challenge to achieve InCalf’s target weights at calving.

But the results from the November weighing show the Bennetts have boosted their heifers’ daily weight gains to an average of 1.3kg/day and are just about on track to achieve InCalf’s targets.

“We are absolutely delighted with the results after such a short time. While our initial focus was on the rising two year olds, we are now weighing the calves so that we can monitor growth from weaning.”

Mr Bennett’s experience has convinced him there’s no substitute for weighing heifers.

“No matter how well you think you can assess their condition, the scales always identify some surprises. Eyeballing just isn’t accurate enough. There’s no way we could manage without weighing now. The information is so valuable and there’s too much at stake,” he said.