Objective: Survey on the effect of different egg yolk preparation methods on yolk HI titre.
Design: Experimental study.
Procedure: One hundred eggs and 50 sera were procured from a breeder farm. The eggs were divided into two groups of 50 eggs each and processed with two different methods. In group I, the yolks were individually weighted, mixed with an equal amount of phosphate butfered sal ine (PBS) and extracted with
chloroform. In group 2, the Samples of 0.3 ml were taken from the yolks centers and processed for chloroform extraction. In both groups, before adding chloroform, a part of each sample was Just mixed with PHS
Statistical analysis: Analysis of variance (ANOY A) and Fisher's exact test.
Results: Mean HI titre of complete yolks, extracted with chloroform, were significantly lower than those of other yolk groups, but there was no significant difference between the titres of serum and yolk groups.
Conclusion: Based on the results of this study, egg yolk is a
. good substitution for serum in HI test for Newcastle disease and
I either of egg yolk preparation methods, described in this study,
could be used. Since the formation of yolk is as concentric layers in which the titre of antibody could be different, the use of complete yolk is recommended. Moreover, regarding to costs, PHS diluting of yolk is preferred to chloroform extraction.
! J. Fae. Vet. Med. Un;v. Tehran. 57.4: 1-3, 2002.