Backyard hens nibble on lead

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People who have backyard chickens should check them for lead, a local veterinarian says.
Chickens could dig up old lead that ‘‘persists in the soil’’, doctor of veterinary medicine Liz Cowie, of Albert Town, said.
‘‘Backyard chickens fall into an interesting category between pets and food-producing animals — and many owners are unaware that their hens may be ingesting lead in their day-to-day foraging.’’
While working in Auckland, Dr Cowie conducted research on lead exposure in backyard chickens.
Her study showed over three­quarters of the hens sampled had detectable levels of lead in the bloodstream.
While her research focused on Auckland, it was likely that chickens in other regions could also be affected.
‘‘I do know that other chickens have had positive lead testing in other areas.’’
Of particular concern were chickens grazing by houses built before the 1940s.
‘‘I would be concerned that there could be lead issues in chickens where we have our older historic homes or historic land use.’’
Houses were painted with lead paint before 1945 and lead paint was phased out in the late 1970s.
Older buildings could also have lead in roofs and nails, Dr Cowie said.
Lead ‘‘persists for tens if not hundreds of years in the soil, so what we did as humans a long, long time ago — often the lead will stick around.’’
Chickens ate a lot of soil as part of their foraging —‘‘part of the soil and stones are good for their gizzard. They keep stones in their gizzard for digestion’’.
Chickens required calcium for egg laying, and calcium and lead shared properties.
‘‘Which means that lead is absorbed through the chicken’s gut in much the same way calcium is.’’
Ingesting lead was not good for anyone, especially young children or those starting a family, Dr Cowie said.
‘‘Lead can have quite detrimental effects on neurological development and lead to other health issues later in life.’’
For her study, blood lead concentrations in 30 Auckland hens were sampled, and over three-quarters had detectable levels of lead in the bloodstream.
Veterinarians could conduct blood test on hens for lead, Dr Cowie said.
Egg testing could also be done via laboratories, which could cost about $75 per egg.