Anna Szymanowska

EFFECT OF PRNP GENE POLYMORPHISM ON REPRODUCTIVE PERFORMANCE OF MOTHER SHEEP AND THEIR OFFSPRING GROWTH

Abstract The polymorphism of prion protein (PrP) amino acids in codons 136 (A/V), 154 (R/H); and 171 (Q/R/H) was established. Reproductive performance of mother sheep was evaluated analysing the fertility coefficient and litter size, i.e. the number of born and reared lambs. The studies included mothers of synthetic lines BCP - 111 sheep and SCP - 104 sheep born in 2001-2007. In the examined ovine PRNP gene, the following four alleles were identified: ARR, AHQ, ARQ, and VRQ, with the absence of the ARH allele. The highest frequency was determined for the ARR (49.8%) and ARQ (45.8%) alleles. In the studied sheep population, the occurrence of seven different genotypes was reported. It was found that 71.6% of the animals had the genotypes ARR/ARR, ARR/ARQ, and ARR/AHQ, which are regarded as the most resistant to scrapie, while 7.9% of the population had ARR/VRQ-bearing genotypes (low resistance) or ARQ/VRQ ones (high susceptibility to scrapie). The analysis of the obtained results indicates that the PRNP genotype does not affect reproduction efficiency of mothers, or their offspring growth. It was concluded that flock elimination of ewes of genotypes with high and very high susceptibility to scrapie will not reduce the reproduction parameters of ewes or growth of their lambs.

The utility of nanowater for ram semen cryopreservation

Nanowater (NW; water declusterized in the low-temperature plasma reactor) has specific physicochemical properties that could increase semen viability after freezing and hence fertility after artificial insemination (AI) procedures. The main goal of this study was to evaluate ram semen quality after freezing in the media containing NW. Ejaculates from 10 rams were divided into two equal parts, diluted in a commercially available semen extender (Triladyl®; MiniTüb GmbH, Tiefenbach, Germany) prepared with deionized water (DW) or NW, and then frozen in liquid nitrogen. Semen samples were examined for sperm motility and morphology using the sperm class analyzer system and light microscopy. Cryo-scanning electron microscopy (cryo-SEM) was employed to determine the size of extracellular water crystals in frozen semen samples. Survival time at room temperature, aspartate aminotransferase (AspAT) and alkaline phosphatase (ALP) concentrations post-thawing as well as conception/lambing rates after laparoscopic intrauterine AI of 120 ewes were also determined. There were no significant differences between DW and NW groups in sperm progressive motility (26.4 ± 12.2 and 30.8 ± 12.4%) or survival time (266.6 ± 61.3 and 270.9 ± 76.7 min) after thawing and no differences in the percentages of spermatozoa with various morphological defects before or after freezing. There were, however, differences (P < 0.05) in AspAT (DW: 187.1 ± 160.4 vs. NW: 152.7 ± 118.3 U/l) and ALP concentrations (DW: 2198.3 ± 1810.5 vs. NW: 1612.1 ± 1144.8 U/l) in semen samples post-thawing. Extracellular water crystals were larger (P < 0.05) in ejaculates frozen in NW-containing media. Ultrasonographic examinations on day 40 post-AI revealed higher (P < 0.05) conception rates in ewes inseminated with NW (78.3%) compared with DW semen (58.3%), and the percentages of ewes that carried lambs to term were 73.3% and 45.0% in NW and DW groups, respectively (P < 0.01). In summary, the use of a semen extender prepared with NW was associated with a substantial improvement in the fertilizing ability of frozen-thawed ram semen and lamb productivity of inseminated ewes.