Dear Bibek,
Vent pecking or cloacae cannibalism is most often found in layers birds and also seen in broilers flocks. There are many causes for this behavioral problem. As we all are aware that it may be caused by dietary insufficiency such as salt, vitamins, or amino acids (protein components). Other factors include stresses such as feed deprivation, over-crowding, over-heating, inadequate ventilation and bright lighting.
Most of the preventive measures you have already followed & all other learned forum members have also suggested their opinion. However, one major probability for this behavioral problem in deep litter system would be due to litter pest known as Darkling beetles/Lesser Mealworm (Alphitobius diaperinus) and the Hide Beetle (Dermestes maculates). Some cases have been found contributing to vent pecking due to these pests as they are nocturnal in nature and may bite birds & damage skin of birds which may attract birds towards vent pecking behavior.
Often it is only a few hens, which are doing most of the damage. However, it is difficult to break birds of the habit and it is best to cull those that begin pecking & injured one. To distract the culprit one you may spread some red coloured paper ½” to 1” squire pieces in litter.
How to find the cull?
Observe your hens and try to identify such hens.
The presence of blood spot or reddish skin on the vent often helps in identifying them.
Treat your deep litter with a little conditioner to reduce litter pests. Do correction of dietary ration & management improvement if necessary so that you could raise your layers flock without this problem.
Best wishes !
G.K.Dahal
