SPERM DNA FRAGMENTATION AND SIRE CONCEPTION RATE IN HOLSTEIN FRIESIAN BULLS
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Date
2022
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KARNATAKA VETERINARY, ANIMAL AND FISHERIES SCIENCES UNIVERSITY, BIDAR
Abstract
The present study was undertaken to know the association of sire conception rate
with bull age, sperm phenotypic characters, sperm DNA fragmentation (SDF), protamine
polymorphism and PRM1:PRM2 expression ratio in selected HF bulls maintained at
State Semen Collection Center, Bengaluru, Karnataka. The overall mean sire conception
rate in the study was 50.61 ± 1.17%. Group G-I (Bulls aged < 3 years) had significantly
lower sire conception rate (45.0 ± 0.01%), than G-II (3-5.5 years) and G-III (> 5.5 years)
with sire conception rates of 50.61 ± 1.17% and 53.0 ± 0.017% respectively. The Single
Nucleotide Polymorphism (SNP) analysis of Protamine1 gene revealed presence of six
different SNPs in the 5’ promoter region and no SNPs in the exonic and intronic region of
Protamine 1 gene. The SNP in TATA box TT > TG (TATATAA), 30 bp upstream from
exon 1 was found to be related to the low expression of Protamine1 and hence a lower
sire conception rate. No differences in semen and sperm phenotypic traits were observed
among bulls of different age group. The average PRM1 to PRM2 ratio and DNA
Fragmentation Index% (DFI) observed in present study were 1:0.06 and 8.88 ± 0.22%
respectively. Significant lower expression levels of PRM1 was observed in younger (GI)
bulls. DFI% was higher in younger aged bulls (9.2 ± 0.39) than aged bulls (8.6 ± 0.36)
but not significantly different. DFI% was negatively correlated with PRM1 (r = -0.660)
and PRM2 (r = -0.518) expression levels. Sire conception rate was negatively correlated
with DFI% also and positively correlated with PRM1 expression (0.564) and Protamine
ratio (0.581). However, PRM2 was found to be not significantly correlated with sire
conception rate. Present study revealed that lower protamination is a probable reason for
lower sire conception rate in younger bulls.