Marijan Cergolj

Effects of bovine spermatozoa preparation on embryonic development in vitro

The aim of our research was to examine the ability of density gradient preparation BoviPure® and swim up method on bull sperm separation and in vitro embryo production (IVP) systems. Frozen/thawed semen from six Simmental bulls was pooled and treated using both methods. The sperm motility, concentration, membrane activity, membrane integrity and acrosomal status were evaluated and compared before and after sperm processing using BoviPure® and swim up methods. We also evaluated and compared cleavage rates, embryo yield and quality between the methods. There were significant differences (P < 0.05) between the sperm characteristics before and after BoviPure®, but not after swim up method. However, there were significant differences for sperm results among those two mentioned methods. A total of 641 oocytes were matured and fertilized in vitro and cultured in SOFaaBSA. The percentage of cleavage (Day 2) and the percentage of hatched embryos (Day 9) were similar for both methods. However, embryo production rate (Day 7) was significantly higher using BoviPure® method (P < 0.05). Also, total cell number and embryo differential staining (inner cell mass and trophectoderm cells) of Day 7 morulas and blastocysts showed that BoviPure® treated sperm displayed higher quality embryos compared to swim up method (P < 0.05). Our results indicate that BoviPure® method has an enhanced capacity in sperm selection for in vitro embryo production when compared with swim up method. So, we concluded that BoviPure® could be considered as a better alternative to swim up method for separating bull spermatozoa from frozen/thawed semen for IVP of bovine embryos.

Prevalence and aetiology of subclinical mastitis in goats

Abstract The study was conducted in 2006 on 20 French alpine goat farms in Croatia. Milk samples were taken from each udder half, for the mastitis test and the bacteriological test, 2120 samples in total. Subclinical mastitis was diagnosed in 211 out of 1060 goats, or in 20% of the studied population. Mastitis of one udder half was diagnosed in 84% of the affected population, while mastitis of both udder halves was diagnosed in 16% of the affected goats. A positive mastitis test reaction was identified in 605 samples (28%), and the pathogenic bacterium was isolated from 244 of these samples (36%). From 22 samples (1.5%) which were negative to mastitis test, pathogenic bacteria, namely S. aureus (21 samples) and Streptococcus D (1 sample), were isolated. Staphylococcus aureus was isolated from 72% mastitis test positive samples, coagulase-negative staphylococci in 16%, other bacteria were isolated from a smaller number of samples: Streptococcus D (6%), Bacillus spp. (2%), and E. coli (2%). The results of the study lead to the conclusion that the subclinical mastitis in goats has a prevalence of 20% on average which increases with higher lactation number. Staphylococcus aureus is the primary causative agent of the inflammations.