The Effect of Diffrent Factors on X- and Y Bearing Sperm in Bull Semen

Newborn gender ratio is one of the most important factors in livestock industry. This ratio has affected on economic condition and controls sex-linked genetically transferred diseases. Offspring sex ratio is affected by such various factors. One of these factors is the Y to X bearing sperm ratio in normal semen that is called primary sex ratio, season and individual differences are important factors that can have an effect on primary sex ratio.

The objective of this study was to investigate two main effective factors, Individual difference and season, on proportion of sperms containing Y-chromosomes to sperms containing X-chromosomes in bull semen.

Semens were collected from 16 bulls during summer (Jul-Aug) and winter (Dec. to Jun). After sperm analysis, DNAs were extracted and Real-time PCR performed using three sets of primers to study SRY (Y-chromosome specific sequence), PLP (X-chromosome specific sequence) and PAR (Housekeeping) genes.

The results showed that the sex ratio of sperms in normal ejaculation was not equal in different bulls. Moreover, season can affect primary sex ratio. Y-bearing sperm increase in summer.

We concluded that the primary sex ratio is affected by individual differences and season. We also suggested using Northern blotting on PCR products to confirm results