22 May 1998

Stones: Lambs at risk

WARMER weather means lambs will drink less, increasing risk of urinary calculi in wether lambs.

That warning comes from MLC sheep scientist Jenny Anderson, who says that in warm weather, lambs are likely to lie in the shade, drinking less and becoming lethargic.

Urinary calculi occurs mainly in lambs fed on concentrates or where they have had access to magnesium or phosphorus – perhaps through high magnesium ewe licks.

"The calculi – or stones – are caused by crystals of magnesium ammonium phosphate forming in the urine and blocking the tube from the bladder to the penis – the urethra. This can cause the bladder to fill up and rupture, causing death. Wether lambs are more at risk than entires because their urethra is narrower since the penis will not mature fully."

To reduce risks, fresh water must be freely available. This means ensuring troughs are low enough for lambs to reach and high enough so that the water in them does not become stale. Reduce concentrate levels and increase calcium intake by providing licks, while feeding roughage such as hay can help increase water intake, salivation and rumination, again cutting concerns, says Dr Anderson.

Symptoms include lambs being off-colour, restless, straining or kicking their bellies. The abdomen swells as the bladder becomes increasingly full, and drops of blood many be passed or the penis may become blackened.