Evaluation of chromatin integrity of fowl spermatozoa (Gallus gallus, Linnaeus, 1758) from meat chicken in two ages

Abstract

In poultry breeding, male fertility has extreme importance to assure a better production of fertile eggs. Evaluation techniques for fertility of fowls are not well explored and in most cases, the evaluation is done through sampling considering only morphophysiological factors directly related with the spermatozoon. It's known that in other species, besides morphophysiological factors, there are intrinsic problems to the spermatozoon such as less chromatin condensation that can lead to fertility problems that in most cases are not diagnosised. The purpose of this work was the adaptation of techniques of chromatin evaluation for chicken (Gallus Gallus, Linnaeus, 1758) which have already been described in other species, correlating the chromatin alterations with the morphological alterations and the fertility. Fowl semen samples with different levels of fertility were used for test different methods to identify chromatin alterations using toluidine blue and acridine orange die. Evaluations have shown that smears of fresh semen with posterior fixation generate artfacts that change the head shape and the chromatin integrity not being indicated in methods of fertility evaluation. Although all the tested methods have presented methodology imperfections and some certain degree of subjectivity, the method that has generated best results was the mixture of one semen drop conserved in buffered phormol and a drop of acridine orange on microscopy slide with posterior staining and observation in fluorescence microscopy with blue excitation filter. Through this method it was verified that alterations in the chromatin condensation of fowl spermatozoa are generally not followed by morphological alterations and that generally the morphologic alterations of fowl spermatozoa are generally followed by alterations in chromatin condensation. This is an important factor in the determination of the fowl fertility.