Effects of low-density lipoprotein extracted from egg yolk on preservation of chilled canine semen (4oC)

Low-density lipoprotein (LDL) derived from hen egg yolk has been considered an important component in the storage of canine semen; however, in Vietnam, there have not been many studies regarding this topic. Therefore, this study aimed to evaluate the effectiveness of LDL in the preservation of canine chilled semen in Vietnam. The assessment of semen samples was based on four criteria: storage time, motility, absolute viability, and integrity of acrosomal membrane at motility rate 0.9; 0.5 and 0.3. The semen samples collected were divided into three equal parts, each was then diluted with three different extenders and stored at 4oC. The extenders were LDL + basic extender (LDL), egg yolk + basic extender (EY), and basic extender (C). The storage time of canine semen was recorded from the beginning of monitoring until the motility decreased to 0.3. The storage time of the three extenders was in the order of EY > LDL > C, with 108 h, 60 h, and 48 h, respectively. The absolute viability of fertilizable sperm (Sa5) in the extender was EY (768), LDL (423) and C (280), which was significant (P < 0.001). The percentage of viable sperm with intact acrosome membrane at motility time A = 0.9 in LDL was 59.31%, higher than that in EY (30.99%). In the storage period from A = 0.9 to A = 0.5, the acrosome loss percentage of both EY and LDL decreased equally (7.30% and 7.23%), but the storage time of EY (84 h) was longer than that of LDL (48 h). In conclusion, the EY gave a longer storage time, higher absolute viability and longer maintain percentage of viable sperms and intact acrosome membrane compared to the LDL. However, within the first hours of storage, the percentage of viable sperm and intact acrosome membrane in the EY was lower than that in the LDL. Therefore, to preserve canine semen for a short time (less than 48 h), the LDL extender should be used for better effectiveness.