Benítez Mora, Maria Paz (2024) Innovative strategies to improve sustainability of dairy livestock. [Tesi di dottorato]

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Abstract

The buffalo is an important source of food production worldwide (Zicarelli et al., 2007) and Italy is the European country with the largest number of buffaloes, the Mozzarella di Bufala Campana D.O.P. (protected designation of origin) cheese is the reason for the success of the breeding farms, as it is a product in great demand worldwide (Di Francesco et al., 2010). Reproductive biotechnologies on buffalo seeks to disseminate selected genetics, increase reproductive rates, reduce generational intervals, and accelerate genetic improvement (Campanile et al., 2010; Gasparrini et al., 2013). Buffaloe´s reproduction is confronted with challenges and concerns as being generally less efficient to reproduce compared with cattle (Baruselli et al., 2018; 2020). Among biological functions, reproduction is a typically energy-demanding activity that incurs an elevated metabolic rate, which is predicted to result in greater ROS generation (Pintus et al., 2021). It is known that Oxidative Stress is associated with reproductive disorders and low fertility in livestock, directly and indirectly affects health (Miller et al.,1993; Harrison et al.,1984). The aim of this thesis was to evaluate the effects of natural antioxidants on both female and male fertility. In particular, the research focused on the use of extracts of green tea (Camelia sinensis), pomegranate (Punica granatum) and olive fruit (Olea europaea). In female the novelty of the study was to evaluate for the first time the effect of dietary supplementation with green tea on oocyte developmental competence in livestock. This may open the way for the inclusion in the diet of natural polyphenols as a more physiological approach to modulating ovarian function in high-yielding dairy buffaloes. The hypothesis tested was that dietary supplementation with green tea extracts (GTE) would increase oocyte quality and developmental competence during the non-breeding season in buffaloes, by improving antioxidant status and liver function. A preliminary study was carried out to evaluate the effect of different GTE concentrations during in vitro maturation (IVM) of buffalo oocytes on oocyte maturation, as well as cleavage and blastocyst rate after in vitro fertilization (IVF). Another objective was to assess the effects of GTE on liver function, by using an in vitro model, i.e. cultured hepatic cells exposed to a chemical insult. Finally, based on the results of the in-vitro trials the antioxidant status and the developmental competence of oocytes recovered by ovum pick-up (OPU) in Italian Mediterranean buffaloes supplemented with GTE for 90 days were evaluated. beneficial effect of dietary supplementation with GTE on the ovarian function of buffaloes undergoing OPU during the non-breeding season. The GTE supplement increased the number of total follicles, large follicles, and good-quality COCs and improved oocyte developmental competence, as indicated by the higher embryo yields. The beneficial effect of GTE on buffalo oocyte competence was likely due to its antioxidant activity, as demonstrated by the improved oxidative status of both plasma and follicular environments in treated animals. Similarly, the inclusion of GTE during in vitro maturation positive affected nuclear maturation rate and blastocyst yield. Furthermore, an in vitro model was used to evaluate the effect of GTE on liver function. The preserved viability, morphology, and antioxidant ability of methanol-exposed hepatic cells in the presence of GTE demonstrated its protective effect. The antioxidants play an important role in maintaining sperm quality and preserving DNA integrity challenged by increased ROS levels (Hughes et al., 1998). As the results of GTE in the female were beneficial, this compound was the first choice to start testing in the male. To the best of our knowledge, this is the first report that investigated the effect of GTE, PE and OFE on buffalo frozen-thawed sperm. First were planned to assess the effects of natural antioxidants on frozen-thawed buffalo sperm, to select the most efficient one to further assess its influence on semen cryotolerance. On results, the addition of GTE was not positive, showing detrimental effects on sperm viability. Pomegranate extract showed improvement in some post-thawed semen characteristics. OFE obtained the most profitable results. For this reason, OFE was used to test adding the natural antioxidant to the pre-frozen diluent, testing 3 concentrations. On the semen thawed evaluation the D50 OFE group increased (P<0.01) the post-thawing total and progressive motility compared to the control and the other treated groups (P<0.05). The higher concentration tested reduced total and progressive motility compared to the other treated groups (P<0.01) and the control (P<0.05).

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