Early egg production in genetically blind (rc/rc) chickens in comparison with sighted (Rc+/rc) controls

The impact of blindness on egg production was investigated by utilizing genetically blind chickens in a factorial experiment involving two genotypes (blind vs. sighted), two densities (1000 cm2 per bird vs. 2000 cm2 per bird), two flock sizes (1 male, 4 female female vs. 4 male male, 16 female female), and two replications (floor pens). Traits measured were number of eggs collected, egg weight, amount of feed taken from the feed troughs, body weight gain, fertility of eggs, feather pecking and comb damage scores, leukocyte count, plasma corticosterone level, and adrenal gland weight. During the 2-month experimental period, blind hens produced 12.7% more eggs (hen-day production) while requiring 44.1 g less feed per bird day compared to sighted hens. There was no significant difference in body weight gained between the two genotypes. Significant genotype X flock size and genotype X density interactions also indicated that the performance of the blind chickens was less affected by differences in density and flock size compared with sighted chickens. Other traits measured provided evidence that the blind chickens were less active, had better feather coverage, and were perhaps under less stress than sighted ones.