Abstract
This study evaluated the effect of breed on the survivability and motility rate of cryopreserved cock semen. Semen from three cock breeds; White Leghorn (WL), Ovambo (OV) and Potchefstroom Koekoek (PK) was collected by means of the abdominal massage technique. Following semen collection, sperm were analyzed for motility and survivability with the use of contrast light BHTU microscope (20 x magnification). The semen was diluted (1 : 2 v/v) with egg yolk citrate (EYC) (extender A) and thereafter with extender B (EYC + 5% DMSO). The equilibration after each dilution was 2 h at 5 °C. The diluted samples were evaluated for sperm concentration, motility, survivability and pH. The samples were then loaded into straws and cooled in programmable freezer from 5 °C to -20 °C at the rate of 1 °C/minute. Semen straws were then exposed to liquid nitrogen vapour (-80 °C) for five minutes, plunged directly into liquid nitrogen (-196 °C) and stored for a week or more. Frozen straws were thawed at 5 °C and evaluated at 0, 30, 60 and 90 min post-thaw. From the results there was no significant effect of breed on the survival and motility of fresh-diluted and frozen-thawed semen at 30 and 90 min post-thaw in all breeds. The sperm survivability of the PK breed was significantly higher than that of the WL breed. However, there was no sperm survivability difference between PK and OV breed immediately after thawing. The cryopreservation and thawing processes affected the survivability and motility of sperm of all poultry breeds negatively.
Highlights
Cryopreservation can be defined as the freezing of tissues or cells to preserve them indefinitely for future use
The objective of this study was to determine the effect of cryopreservation on the survivability and motility rate of sperm obtained from the indigenous Ovambo, Potchefstroom Koekoek and White Leghorn breeds
This is the first study in South Africa to be done on freezing of semen of indigenous southern African chicken breeds
Summary
Cryopreservation can be defined as the freezing of tissues or cells to preserve them indefinitely for future use. Cryopreservation of cock sperm remains a challenging obstacle due to low survival and motility rate of frozen-thawed cock semen. Blanco et al (2000) reported that artificial insemination (AI) with frozen-thawed avian sperm produces fewer fertile eggs than do inseminations with fresh semen. Chickens have a short generation interval when compared to most farm animals (Jennen et al, 2005). Genetic improvement could be attained at a faster rate. Successful cryopreservation of cock sperm will play an important role in preserving and transferring valuable genes to future generations, and it will assist in the conservation of the male gametes of endangered indigenous poultry breeds
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