Evaluating Fertility Characteristics Belong to Isfahan Native Cocks.

This study was based on two experiments. The first experiment was carried out using 92 cocks, which were selected randomly from two hatches. Effect of age of the cocks on semen characteristics were evaluated for common characteristics of their sperms. Four groups of native cocks at 38, 48, 58 and 68 weeks of age were selected. Twice a week, the cocks were given practice to be accustomed for artificial insemination. The native hens of 33 to 65 weeks of age were randomly devoted to each cock. The collection of the fertilized eggs began from the second week and continued until the end of the third week (14 days). Then, the collected eggs incubated and after hatching, the non-hatched eggs were broken and examined to determine the fertile and infertile eggs. The experiment also included lab examinations to reveal the characteristics of the semen for colour, volume, motility (percentage of living sperms), rate of forward movement, percentage of normal and abnormal sperms, variety of abnormal ones, and pH of the semen and the concentration of the sperms per volume unit. Data was analysed by GLM procedure in SAS software. The results showed that the age of the cock had significant effect on semen volume, fertility and hatchability (P0.01) and percentage of normal sperms (P0.05). However, the age of the birds showed no significant effect on other factors including colour, motility, and rate of forward movement and the concentration of sperms in volume unit. The mean values of evaluated characteristics in different ages showed that the fertility increased with age of the cocks which showed highest fertility at 68 weeks of age (P0.05). Also, the hatchability of fertile eggs was more on 58 and 68 weeks of age (P0.05). There was no important variety in percentage of normal sperms from 38 to 58 weeks of age yet, it started to decrease at 68 weeks of age (P0.05). In addition, sperm concentration has significant effect on colour of semen (P0.01). The effect of motility was also significant on fertility and sperm's forward movement (P0.01) but it wasn't significant on percentage of normal sperms, concentration of sperms and the pH of the semen. In the other hand, sperm's forward movement showed significant effect on fertility (P0.01) and on sperm concentration (P0.05) but not on percentage of normal sperms. Also, hatchability was significant on fertility (P0.01). Laying rate showed inverse effect on fertility (P0.05) and hatchability (P0.01). There wasn't any significant effect between percentage of normal sperms and fertility, concentration of sperms and fertility, semen volume and concentration of sperms, colour and fertility. In general, the results showed that in most of the time suitable characteristics of semen weren't significant during early ages compared to late ages. Even, these kinds of characteristics mostly were at highest amount in late ages. In addition, because of the better fertility and fertility characteristics at 58 and 68 agecock- groups in comparison to others, it is recommended to use them in order to achieve the most economical benefit in parental flocks.