Effects of Storage Duration on the Quality and DNA Integrity of Nili-Ravi
Bull Spermatozoa Frozen and Stored in Liquid Nitrogen
Muhammad Shoaib, Nazir
Ahmad*, Maqbool Ahmad, Ijaz Ahmad, Sajid Iqbal1 and
Shamim Akhter2
Department of
Theriogenology, University of Agriculture, Faisalabad, Pakistan;1Semen Production Unit, Qadirabad, Sahiwal,
Pakistan; 2Department of Zoology, Pir Mehr Ali Shah Arid
Agricultural University, Rawalpindi, Pakistan; *Corresponding
author:
profnazir53@hotmail.com
Abstract
In the present study, effects of storage duration
on the quality and DNA integrity of Nili-Ravi
buffalo bull spermatozoa frozen and stored in liquid nitrogen for up to three
years were investigated. According to duration of storage, the semen
samples were categorized into 10 groups, viz. i) 0 day, ii) one day, iii) two
weeks, iv) one month, v) three months, vi) six months, vii) nine months, viii)
one year, ix) two years and x) three years. A total of 50 straws, with 5 straws
for each of the 10 groups were used. After thawing for 30 seconds at 37°C, these
samples were evaluated for sperm motility, livability, livability index, plasma
membrane integrity, acrosome damage and DNA damage. At 0 day, mean values for
sperm motility (%), livability (hrs), livability index, plasma membrane
integrity (%), acrosome damage (%) and DNA damage (%) were 53±1.22, 6.0±0.0,
130±5.2, 45.4±1.6, 3.8±0.6 and 2.2±0.4. After 3 years of storage, the
corresponding values were 39±3.32, 4.4±0.2, 78.5±5.7, 28.2±2.2, 12.0±0.7 and
5.8±0.6. Sperm motility and livability remained unaffected up to 3 months of
storage, followed by a decrease at 6th month, while absolute index of
livability and membrane integrity started decreasing at 1 month (P<0.05). Sperm
with damaged acrosome increased at 6th month (P<0.05). Similarly,
sperm with damaged DNA increased after one year of storage (P<0.05). Thus,
post-thaw motility, livability and acrosome integrity of spermatozoa of Nili-Ravi
bulls started decreasing at 6th month of storage, while sperm DNA
integrity remained unaffected for one year of storage in liquid nitrogen.