Pica in Cattle

 Published on: Jun 5, 2021

In April and May this year up and down the country there have been reports of cows eating stones, drinking urine, chewing on wooden fences, licking loose cement on walls, and eating plastic. These cows aren’t just being inquisitive, if you watch them they are determined to eat the abnormal item.

The term for cows eating abnormal things is Pica. The severity and impact of it will vary farm on farm and may just be a drop in milk yield. There was a report of a 200 cow herd in Wales that had two cows die from complications from stone impactions and needed emergency surgery on two other cows. I have watched a video of the surgery and you can see the large volume of stone being emptied out. Stones can pass through a cow uneventfully in some situations and whilst pregnancy diagnosing cattle I have often found gravel and grit on my glove .
Pica is a relatively poorly understood condition and the reasons behind the occurrence can vary. It is usually associated with grazing herds, it can be in all age groups but most commonly found in lactating cows. It is typically associated with phosphorus deficiency but there are many other complicating factors including sodium, fibre intake and parasite burdens. It is important to blood sample any cows showing abnormal signs to work out the cause.

Outside of early lactation, phosphorus deficiency tends to be chronic in nature. Usually deficiency occurs in areas with low Phosphorus content in the soil, but other factors also may affect phosphorus availability to plants, including excessive calcium, aluminium and iron. Other factors discussed include fertiliser regimes and potentially feeding forages which may be lower in phosphorus.
Similar conditions we see much more regularly are Hypomagnesemia (Staggers) and Nervous Ketosis. We do not  commonly see Pica with these conditions but cows can be more aggressive and with Nervous ketosis will commonly lick items such as metal gates.