Unipd Research: exploring cognitive differences in two hybrid broiler chicken strains

30.10.2023

In the world of poultry farming, the most widely used hybrid broiler strains are the Ross308 and the Hybro. While seemingly indistinguishable, it turns out that one chicken strain is less "intelligent" than the other. Selected to guarantee a greater meat yield, the Ross308 strain proves to hold poorer results in cognitive testing.

Published in Poultry Science, the study entitled Hybro chicks outperform Ross308 in a numerical-ordinal task. Cognitive and behavioral comparisons between 2 broiler strains of newborn domestic chicks, is the result of work conducted by the Department of General Psychology at the University of Padua. 

Raised for their meat, both male and female domestic chicken broiler strains have undergone some of the most intensive selection processes in the animal farming industry in recent decades. With the primary objective to obtain higher energy use efficiency and faster growth rates at minimize production costs, particularly feed expenses, such intense selection could have repercussions on the behavior and cognitive abilities of the animals. As of now, no evidence on broiler breeds is available.

The UniPd research explores the intensive selection process for meat production about the cognitive abilities of two hybrid broilers domestic chicks: the Hybro and the Ross308, by assessing their ordinal-numerical abilities.

Researchers trained 5-day-old chicks to find a food reward inside the fourth container in a series of ten identical containers. To locate the container that granted access to the food, the chicks then had to use a numerical clue and "count" to four. The chicks underwent two tests, a sagittal test, and a frontal-parallel test. In the sagittal test, the arrangement of the 10 containers was identical to that experienced during training. In the frontal-parallel test, researchers rotated each of the 10 containers by 90°, thus left-to-right oriented, thus assessing the capability of transferring the learned rule with a novel spatial orientation. In both tests, all chicks selected the fourth container above chance. However, the Hybro chicks performed significantly better than the Ross308 chicks.

First author of the study, Rosa Rugani explains, “These results open a window on a subject we know little about. By exploring how intensive selection can influence behavior and cognition, our study represents a step closer to better understanding the world of livestock. Studying their cognitive abilities allows us to appreciate their needs and promotes their well-being, even in breeding contexts."

The continuation of the study involves the identification of cognitive and behavioral differences between varieties of domestic chicken, including the native Padovana chicken and other hybrids selected for industrial production.