Morphologic characteristics of oviducts from hens producing eggs of different Haugh units caused by genetics and by...

Magnum and isthmus morphologic characteristics (surface epithelium height, fold height and diameter, and periodic acid-Schiff-positive area and surface epithelium cells) of stained 6-micron tissue sections were measured by light microscopy, with data acquisition using a digitizing tablet interfaced to a microscope and to a personal computer with morphometric-dimensional software. Tissues were obtained from Leghorn layers in two separate experiments in which production of eggs with low and high Haugh unit (HU) values was induced by either genetic selection or by feeding V. Eggs produced by these hens had HU differences between the high and low groups of 11 to 14 units (both experiments, P = .0001) and had a greater volume of thick albumen fraction in high-HU groups (both experiments, P = .0001). The computer software-integrated digitizing system enabled rapid measurements of multiple characteristics. In the genetic lines, higher magnum fold height and magnum and isthmus surface epithelium height were detected at moderate significance (all at P < .05) in the tissues of the layers producing high-HU eggs than in tissues from the low-HU line. Other morphologic variables were not different between genetic lines. In response to feeding V, none of the morphological characteristics were affected, although magnum fold height approached difference at P < .07. Based on the observations in these two experiments, magnum fold height may be a further important factor related to egg albumen condition, in addition to surface epithelium height. It appears, however, that layers producing eggs of considerably different HU values, due in these experiments to genetics or V feeding, can have magnum or isthmus morphological characteristics that are indistinguishable, or only moderately different, as detected by integrated digitizing technology.