Brain Alterations in Crested Versus Non-Crested Breeds of Domestic Ducks (Anas platyrhynchos f.d.)

Abstract

A comparison of brain size and brain composition was made between two uncrested duck breeds and Crested Ducks (CR) and between CR individuals that do possess crests and those that do not have the crest. Domestic ducks of the breed CR have allometrically larger brains than uncrested duck breeds. The crest inserts on a cushion of fat and connective tissue that is partly nourished by brain vessels via small holes in the skull. Through these holes, fat tissue may invade the brain cavity. Because the fat accumulations are sometimes hidden deep between the telencephalon, tectum, and cerebellum, they may be invisible macroscopically and, thus, give the impression of a large brain. The size of the crest, however, is not strictly correlated with fat accumulations in the brain, because 2 among 10 specimens of CR showed no fat body at all, and the investigation of 10 uncrested CR (ducks from the same genetic stock, but without the crests) also revealed fat accumulations in 6 specimens. After subtraction of the volume of the fat body, the brain volume of CR (crested and uncrested) was of equal size to that of "Hochbrutflugenten" and Pommeranian ducks, as was the volumes of most brain structures measured. Significantly smaller in CR were the olfactory bulbs, the prepiriform area, and the cerebellum, which was always situated in close proximity to the fat body in CR.

Discontinuous Variability of Brain Composition among Domestic Chicken Breeds

“…This suggests inflexibility. We examined brains in pigeons, chickens, ducks and rabbits and our data could not support the point of view that brain composition is the same across breeds [Rehkämper et al, 1988[Rehkämper et al, , 1999Frahm and Rehkämper, 1998;Frahm et al, 2001]. In homing pigeons for example, the olfactory bulb and hippocampus are allometrically larger than in nonhoming pigeon breeds.…”

Evidence of the crested form of domestic hen (Gallus gallus f. domestica) from three post-medieval sites in Hungary

“…In this species, the crest grows on a cushion of fat nourished by brain vessels via the small holes of the skull. By this connection, the fat tissue may invade the brain cavity and give the impression of the enlarged brain, especially between the telencephalon and cerebellum (Frahm et al, 2001). Cnotka (2006, p. 96-97 in Teegen 2008) stated, that fatty depots can cause the reduction of the cerebellum and tegmentum, which are important for motor capabilities.…”

Variations in the morphology, distribution, and arrangement of feathers in domesticated birds

“…Comparable linkages between intracranial and subcutaneous lipomas have also been reported in human beings (Sari et al,'98). Frahm et al (2001) mentioned that some brain structures of crested ducks, such as the olfactory bulb and the cerebellum, were significantly reduced in size. They hypothesized that these size reductions resulted from space constraints during fat accumulation in the brain cavity.…”