M. Kreuzer et al., VARIABILITY OF PROCESSING PROPERTIES OF A LBUMIN AND YOLK BETWEEN ANDWITHIN PURE LINES OF BROWN-EGG LAYERS, Archiv fur Geflugelkunde, 59(1), 1995, pp. 82-88
Eggs of three different pure Lines of a brown-egg breeding program wer
e used to evaluate the variation in processing properties as potential
selection criteria. In some 4200 eggs obtained in the 24th and in the
32th week of laying, height and width of albumen and yolk were obtain
ed. Out of the members of each line, 2 x 30 hens showing extremely low
or high albumen height were selected according to the result of the f
irst measurement. In four eggs of these hens obtained in intervals of
three weeks, albumen and yolk pH as well as foaming ability and the st
ability of foam and of yolk-oil-water emulsions mere determined. All e
ggs mere stored for a variable time before analyses, however the resul
ts were unbiased with respect to storage length due to the particular
design of the analysis. Within and between the breeding lines, a consi
derable variation was found in albumen proportions and in the stabilit
y of foam and emulsion. Variation was low in yolk proportions and in p
H values. Foam stability was 82.2%, 88.3% and 89.9% in the three lines
, the corresponding values for emulsion stability were 21.5%, 33.9% an
d 31.5% with mostly significant differences among means. Direct select
ion for foam or emulsion stability seems promising according to the fa
vourable repeatabilities of about 0.4 to 0.6, however the determinatio
n is quite time-consuming. Foaming ability had a poor repeatability an
d behaved contrary to foam stability. The possibilities to improve fun
ctional egg properties by indirect selection for albumen or yolk propo
rtions were calculated. A relatively close relation existed between al
bumen height and foam stability. The phenotypic correlation between bo
th criteria as obtained in different eggs of the same hens was 0.4, an
d hens with low or high albumen height significantly differed in the f
oaming properties. Yolk proportion had little predictive value for the
emulsifying properties.