Recognising PICA early can prevent serious secondary health problems in your herd. The signs are usually visible — once you know what you’re looking at.

The most common signs of PICA in cattle include:

• Licking or eating soil and clay
• Chewing stones, gravel or concrete
• Gnawing wood — fence posts, gates, feed barriers
• Consuming plastic, rope or other man-made materials
• Chewing or eating bones (a strong indicator of phosphorus deficiency specifically)
• Licking walls, metal surfaces or machinery
• Reduced appetite for normal feed and forage
• Loss of body condition despite adequate grass availability

In more advanced cases you may also notice:

• Poor coat condition and a dull, staring appearance
• Reduced milk yield
• Sluggish, depressed demeanour
• Signs of hardware disease — grunting, reluctance to move, drop in production — if foreign materials have been ingested

A note on secondary dangers

A cow displaying PICA is a cow at risk of more than a mineral deficiency. Ingested wire, nails, stones or plastic can cause hardware disease, rumen impaction and in severe cases death. If you are seeing PICA in your herd, treat it as an urgent signal — not a quirk to monitor.

Causes of PICA in Cattle

PICA is rarely a sign of a poorly managed herd. In fact, it commonly appears in herds that are otherwise thriving and healthy — which is why it catches so many farmers off guard.

Phosphorus Deficiency

The most well-established cause of PICA in cattle is phosphorus deficiency. When dietary phosphorus falls below the level required for normal metabolic function, cattle will instinctively seek it out through soil, bones, stones and other materials. Phosphorus deficiency is typically associated with drought conditions and soils with a low phosphorus index (P index 1 or below), where grass growth outpaces the soil’s ability to supply adequate phosphorus to grazing cattle.

Low Dietary Fibre

Rapidly growing grass during the breeding season — June and July in particular — is high in soluble nutrients but low in structural fibre. This imbalance in the diet can trigger PICA behaviour even in cows that appear to be in good condition and eating well. It is one of the reasons PICA appears in well-managed, productive herds and should not be dismissed as a management failure.

Seasonal and Weather Conditions

A cold or dry spell in April and May can significantly exacerbate PICA risk. When grass growth stalls or slows during a dry period, the nutritional profile of available forage changes and the gap between what the cow needs and what the pasture provides widens. These seasonal conditions are a key trigger point to watch for, particularly on farms with naturally lower soil phosphorus levels.

Problems from PICA in Cattle

Pica can lead to:

• Loose dung
• Reduced ‘cudding’ and therefore saliva production, which can result in ruminal acidosis due to the decreased buffering from saliva within the rumen
• Reduced milk fats due to a change in the balance of fatty acids being produced by a more acidic rumen
• Feed intake drops and therefore milk production suffers