Getting to the bottom of sex-related first week mortality

Getting to the bottom of sex-related first week mortality

Written by Lenise Inacio de Souza, Incubation specialist, Pas Reform do Brasil

"Why are so many chicks dying in their first week?" I could hear the worry in his voice when I received a call from the manager of a single-stage broiler hatchery in southern Brazil. It was a cold winter (yes, even in this tropical country temperatures can go below 10°C) and he was getting reports of 3-5% of chicks dying in their first week, and in some cases even 10%.

Wanting to get to the bottom of this alarmingly high first-week mortality, I went to visit the plant, where I learned there was no relationship between setter/hatcher room or breeder flock/line. Stranger still: either males or females were dying, but not both sexes from the same hatch day. Naturally, my first reaction was that something might be going wrong after the chicks had been sexed. Or perhaps transport was the problem? But the manager said they'd looked at these too and could find no correlation.

After tracking & tracing all chick handling procedures after sexing, we realised that the worst cases were when chicks hatched on the Friday but were not delivered until Saturday - so they had stayed overnight at the hatchery. But the records from the chick delivery room showed nothing unusual: temperature and humidity were fine.

It was time to take a look inside the chick delivery room. Once again, the record sheet showed normal environment data. But ... when I stood close to the wall where air was entering the room, I could feel the cold on my bare arms. The chicks on that side were huddled together in their boxes. Measuring their rectal temperature (it was 101-102°F) confirmed that they were suffering from hypothermia. The temperature around these boxes, which contained male chicks, was only 19°C.

The female chicks from the same breeder flock had been place in the centre of the room. Their...

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