Why enough space to eat is vital for heifer health and growth

Paying attention to feed and water access for replacement heifers is the key to ensuring coccidiosis prevention works – and that youngstock can achieve their growth targets.

Adding medicine such as coccidiostats to feed only works when youngstock can eat sufficient feed to gain the correct dose, points out US vet Dr Matt Dodd from animal health company Diamond V.

He says preventing coccidiosis is essential because treatment will not fix the damage it causes in a young calf.

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“If you are seeing signs [of coccidiosis], you are three weeks behind – there is lots of damage you haven’t been able to see by the time [there are] physical symptoms.

“Preventing it is best, but you need the right feed intake for that,” he says.

On heifer rearing units in the US, Matt says the ration is often blamed for giving digestive upsets to post-weaned animals, yet he finds it is often caused by a lack of physical access to feed.

Access to feed

Overcrowded pens or not enough trough space lead to poor or inconsistent intakes.

And the at-risk calves in a pen struggle most because they cannot eat enough medicated feed, he says.

Weaned heifers with a functioning rumen should have manure that is firming up, according to Matt.

Groups of youngstock with dung ranging from loose to very firm, however, indicate that some animals are overeating concentrates, while others get only forage.

Rather than requiring a ration reformulation, the issue is to address feeding practice.

“Heifers are herd animals and want to eat together, but we don’t let them because of overcrowding.

“You need enough bunk space for every calf,” he says.

Can calves reach?

While the first calves might be able to reach feed because the trough is full, by the time a marginal calf gets up to eat, leftover food is out of reach, or it is too small or weak to stretch to it.

“We see bunks that just don’t work. We need to give [calves] all the same opportunity to eat the ration, otherwise we don’t get the growth rates we want,” says Matt.

He adds that wooden blocks can be used to raise the back of a trough.

In the absence of research on bunk design for heifers, he says US vets typically work on a minimum measurement of 80cm for a 205kg calf.

This comes from adding together the trough height (or depth), the length of the trough lip, plus the distance a calf has to reach to the back of a trough.

© MAG/Shirley Macmillan

Farm management also compounds the feed space issue.

“How many times are your weaned calves without feed?

“We are trying to drive intake and create a stable rumen, so four hours with nothing to eat and the bunk licked clean – they are hungry.”

Similarly, whereas milking cows are given a transition period of three weeks to help rumen bugs adjust, calves are expected to cope with feed changes from one day to the next.

Farms can then get huge respiratory disease outbreaks from stress, says Matt.

Adjust heights

In the UK, vet and researcher Prof Ginny Sherwin of the University of Nottingham says feeding regime and farm facilities dictate space requirements – which need adjusting as calves grow.

“We say, post weaning, at least 40cm of trough space a calf and at least 50cm by the time they are nine to 12 months,” she says.

“Adjust neck rail height as calves grow to avoid neck rubs.

“You can weld adjustable brackets onto the side to raise and lower it, or use lorry straps, which flex with the calves.”  

Where concentrates are fed truly ad lib – with always enough left for latecomers – it is possible to have a bit less trough space.

© MAG/Shirley Macmillan

Feeding times

For farms feeding the standard rate of 2kg, this is ideally best done twice a day as smaller meals avoid acidosis.

It also gives the youngstock rearer two chances to inspect animals, says Ginny.

“With timed feeding of 2kg a head, it’s like the free-for-all buffet, and you need space for all heifers to eat at once. They are really social animals,” she stresses.

“Chopped straw plus concentrates is the easiest way to control growth rates to six months as the rumen is not yet adapted to silage.

“It’s also good feed conversion efficiency, as 50% of skeletal, lean growth is in the first six months.”

Feeding straw, however, requires the same minimum feeding space as for concentrates. It must be offered ad lib – calves should not have to make up intakes from their bedding.

“It’s one way to pass on faecal pathogens, and if straw is mucky, they won’t want to eat it,” she points out.

Raised troughs or racks are essential to keep straw off the floor so it stays clean and palatable, with racks positioned so that dusty straw does not drop into eyes.

Group drinking

Access to fresh water is a given for livestock, yet calves are routinely expected to drink dirty water, or from supplies they cannot reach.

Modern, shallow bowls with bungs may be easy to reach and clean, says Ginny, but do not allow for group drinking.

© MAG/Shirley Macmillan

“It is important to make sure there is enough space – at least 5cm a calf – and for a minimum 10% of heifers to be able to drink together,” she adds.

“Each farm will be different in terms of pen size and setup, but the cost of an extra trough and some blue piping is not massive and needs to be compared with the difference it can make to daily liveweight gains.”

Dr Matt Dodd was speaking at the Dairy Calf and Heifer Association’s annual conference in Colorado, US.