In dairy cattle breeding, herd reproductive management is the primary focus, affecting a large part of the general costs. A negative association was observed between the level of milk production and fertility. Some studies have shown that a significant percentage of reproductive failure is attributable to semen quality; therefore, if reproduction management is based on artificial insemination, then it is important to assess the fertility level of the sires. In this study, proteomic analysis was used to compare the protein expression profiles from sperm of high-and low-fertility bulls. Comparative proteomic analysis showed that expression of several proteins [nine different two-dimensional electrophoresis (2-DE) spots] is related to fertility level (p≤0.05). These proteins are involved in sperm-egg interactions and cell cycle regulation. Differences in protein expression levels might explain reductions in fertility due to mistakes in sperm-oocyte communication or in cell cycle regulation. Proteomics of sperm can be a valuable tool to identify protein expression changes related to fertility; in particular, 2-DE-based proteome analysis is very useful for the characterization of spermatozoa protein expression related to high-and low-fertility rates. Furthermore, analysis of expression profiles could be critical to the identification of protein biomarkers of bull fertility.
The present paper explores the diversity of mycobiota inhabiting raw milk sampled at different altitudes (1400 m, 1800 m, 2200 m) from cows grazing Alpine pastures of Valle d’Aosta (North-Western Italian Alps). To this aim, multilocus sequencing was performed at barcodes commonly used for fungal identification (ITS1, D1/D2 domains of the 26S rRNA gene, and part of the β-tubulin gene). A total of 31 species were detected, most of them yeasts, followed by moulds and by 2 sequences of macroscopic fungi. Several yeasts and moulds were well-characterized inhabitants of the dairy environment, known to positively contribute to cheesemaking. Among these, Candida was the most represented genus with a tendency to cluster at the highest altitudes (6 over 8 observations at ≥ 1800 m), and Kluyveromyces marxianus the most abundant single species, retrieved at all altitudes. The environmental ascomycetous Atrotorquata lineata, never put in relation with food nor described outside North-America, was another species among those most frequently retrieved and was detected in 6 milks at 1400 and 1800 m. The remaining fungi, in general never reported in milk, were mostly environmental. Many of them resulted associated with plants as pathogens or symbionts. Finally, the highest sampled altitude yielded a significant fungal diversity (17 species). This work enlarges the knowledge of fungal consortia inhabiting raw milk and introduces microbial ecology among the altitude-dependent factors, in the composition of Alpine pastures, with the potential of shaping the properties of milks and cheeses, together with the already described physical, chemical and botanical variables.
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