Sperm morphology in progeny-tested Swedish AI dairy bull sires

Use of bull semen with high levels of sperm abnormalities, reflecting genital dysfunction, is not recommendable to use for AI since it most likely leads to subfertility. If sperm morphology deteriorates with age, it becomes a source of concern when using ageing progeny-tested AI-bull sires. However, whether a relationship between sperm morphology and fertility after AI in progeny-tested bull sires is present remains to be proven and constituted the reason for a retrospective study of progeny-tested bull sires of the Swedish Red and White (SRB) and Swedish Holstein (SLB) breeds performed with data of 8 SRB and 4 SLB sires analysed in an University specialized andrological laboratory. Particular attention was paid to the influence of age and breed as well as the variation between- and within-bull for presence and level of sperm abnormalities. Sperm morphology differed between sires, ejaculates and breed, with 6/12 sires having ejaculates with more than 10% of morphologically deviating sperm heads, an used threshold for young AI bulls. However, with the exception of pear-shaped or narrow at the base anomalies, individual defect mean values were always within what is expected for a bull sire, and considered within acceptable limits. Breed and bull within breed age affected some semen (ejaculate volume) and most sperm morphology variables, while age significantly affected only few sperm morphology variables (nuclear pouches and sperm head contour). Estimated breeding values for male fertility output differed significantly among bulls and, when all ejaculates were accounted for, the percentage of morphologically normal spermatozoa was positively related to fertility. Few individual sperm abnormalities in all ejaculates correlated significantly to fertility, as pear-shaped sperm heads. When separated by breed, these correlations were restricted, in SRB bulls, to the normal spermatozoa in wet smears, or lost in SLB bulls, probably owing to the reduced sire material examined. In conclusion, the presence of some relationships between sperm morphology and fertility after AI calls for routine, frequently done assessments of sperm morphology in AI-stud bull sires during their entire active life

In vitro characterisation of fresh and frozen sex-sorted bull spermatozoa

peer-reviewedThis study sought to compare the in vitro characteristics of fresh and frozen non-sorted (NS) and sex-sorted (SS) bull spermatozoa. Experiment 1: Holstein–Friesian ejaculates (n = 10 bulls) were split across four treatments and processed: (1) NS fresh at 3 × 106 spermatozoa, (2) X-SS frozen at 2 × 106 spermatozoa, (3) X-SS fresh at 2 × 106 spermatozoa and (4) X-SS fresh at 1 × 106 spermatozoa. NS frozen controls of 20 × 106 spermatozoa per straw were sourced from previously frozen ejaculates (n = 3 bulls). Experiment 2: Aberdeen Angus ejaculates (n = 4 bulls) were split across four treatments and processed as: (1) NS fresh 3 × 106 spermatozoa, (2) Y-SS fresh at 1 × 106 spermatozoa, (3) Y-SS fresh at 2 × 106 spermatozoa and (4) X-SS fresh at 2 × 106 spermatozoa. Controls were sourced as per Experiment 1. In vitro assessments for progressive linear motility, acrosomal status and oxidative stress were carried out on Days 1, 2 and 3 after sorting (Day 0 = day of sorting. In both experiments SS fresh treatments had higher levels of agglutination in comparison to the NS fresh (P < 0.001), NS frozen treatments had the greatest PLM (P < 0.05) and NS spermatozoa exhibited higher levels of superoxide anion production compared with SS spermatozoa (P < 0.05). Experiment 1 found both fresh and frozen SS treatments had higher levels of viable acrosome-intact spermatozoa compared with the NS frozen treatments (P < 0.01).ACCEPTEDpeer-reviewe

Multiscale characterisation of Achilles tendons during mechanical loading

Although mechanical loading correlate to multi-hierarchical changes, the multiscale response during tendon damage remains not yet fully understood. Therefore, this thesis assessed the multiscale structure-function mechanisms in response to different levels and durations of strains in GAG and un/depleted Achilles tendons. At the nano/macroscales, increased levels and durations of strains resulted in increased changes in form and function. This thesis identifies a variety of multiscale properties that may contribute to the understanding of the mechanism of tendon pathology