Increasing Survival and Meat Content of Broiler Chickens

Supported by the BARD Fund, a US and Israeli team of researchers are developing a method for improving the survival rates of broiler chickens. Their method may help farmers increase the efficiency, cost-effectiveness, and profitability of growing broiler chicken.

Chicks in incubatorCenturies of selective breeding by farmers of the chickens with the highest growth rate has led to a highly productive broiler-chicken industry. Yet, improved chicken growth rates have been found to negatively impact on their survival rate. This is mainly due to the chicken’s diminished ability to cope with the hot environment typical of broiler-growing regions in the world. Global warming is expected to magnify this problem.

A group of BARD-funded scientists from Israel and the United States have found a way of improving the survival rate of chickens raised in hot climates. Their research reveals that raising the temperature in the incubator to 39.5°C for twelve hours per day from day seven to sixteen of embryogenesis improves the hatched chicken’s ability to successfully deal with heat stress. It is during this embryonic period that the thyroid – the organ responsible for thermoregulatory control – and the adrenal gland – the organ responsible for stress responses – develop. This observed improved outcome was due to a decrease in the chicken’s body temperature set point, leading to a lowering of its metabolic rate, stress levels, and increasing heat loss due to convection and radiation.

Surprisingly, the treatment also increased the amount of breast muscle by almost 1% and, furthermore, reduced abdominal fat – both being desirable broiler-chicken quality traits. Equally important, the altered incubation conditions did not adversely affect hatchability rates.

When the scientists exposed chicken embryos to a similar (yet shorter) intermittent thermal regime from day sixteen to eighteen of incubation, they observed a marked increase in muscle cell (i.e., myoblasts) proliferation. Their results further revealed that the myoblasts exhibited an immediate stimulatory effect, which lasted for up to two weeks after the chickens hatched, translating into an increase in the size of the chicken muscle at marketing age.

The Core Group of Scientists:

  • Shlomo Yahav, Institute of Animal Science, The Volcani Center, Israel
  • John Brake, Department of Poultry Science, North Carolina State University
  • Orna Halevy, Department of Animal Sciences, Hebrew University of Jerusalem, Israel