Lamb bloat is one of the most common and heart-breaking killers of pet lambs, especially those over 2-weeks-old.

Abomasal bloat is caused by milk going into the abomasum, or fourth stomach.
The milk might be too hot, creating the conditions for the growth of harmful bacteria.

These bacteria create a gas and the distinctive bloat. It can strike within 30 minutes of a feed.

Vet Services Hawke's Bay vet Georgina Campbell said the bloated abomasum puts pressure on other organs causing pain and suffering to the lamb.

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Lambs on their mothers in the paddock don't get it because their mothers simply don't stand still long enough for their lambs to overfeed and the milk is always the right temperature.

Pet lambs are fed less often and at greater volume and because they tend to guzzle their feed their risk of bloat is greater.

There are a number of ways to prevent bloat.

The first and most obvious is not to overfeed lambs. If using a multi-feeder with compartments, don't overfill them either. Harder teats with smaller holes make it harder for the lamb to feed too fast.

Consider using whey-based milk powder. It moves faster through the abomasum so there is less chance for bloat to develop.

Another innovation is yoghurt in the milk. Ordinary plain yoghurt stirred into the milk as it is prepared. A good spoonful is enough. It works because it has probiotics or good bacteria which compete with the bad bacteria to prevent problems.

Yoghurt also contains prebiotics which stimulate the growth of good bacteria. It also builds up the immunity of the lamb.

If a lamb does develop bloat fast action is needed. If you always have pet lambs ask your vet for a supply of antibiotics at the beginning of the season and have a hollow needle on hand.

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To treat a lamb, tip it on to its back. This will need two people to hold it still and stretch it slightly. At a point between the navel and the bottom of the ribcage insert the sterile needle to release the gas. Follow that up with about 5ml of antibiotic syringed straight into the mouth so the lamb swallows it.

When the lamb recovers take it back about a week in its feeding schedule. If it was on three feeds a day put it back on four times and build it up slowly because the bloat can recur once the lamb has had it.

Campbell said consistency was the best way to avoid bloat.

"Keep the milk the same temperature and the same consistency and feed them at regular times."

Although it is sensible to follow the feeding directions on the milk powder it also pays to take into account the size of the lambs.

A newborn triplet would always need less feed than a 3kg single newborn, she said.