SummaryThe cryopreservation of epididymal sperm is an important technique that allows genetic material to be preserved, even post mortem. However, cryopreservation leads to increased oxidative stress and impaired sperm viability. Polyunsaturated fatty acid (PUFA) supplementation may improve certain sperm characteristics, but it also makes sperm more susceptible to oxidative stress, therefore adding antioxidants that counteract oxidative stress has become an option. In this context, this study aimed to evaluate the effect of the interaction between docosahexaenoic acid (DHA) and antioxidants on the quality after the cryopreservation of epididymal bull sperm. Twenty epididymides were collected after slaughter, and epididymal sperm was cryopreserved with bovine extender supplemented with docosahexaenoic acid (DHA), glutathione peroxidase (GPx) and superoxide dismutase (SOD). We verified an improvement in motility in the group that was treated only with DHA 5 µM and a concentration-dependent effect on susceptibility to lipid peroxidation that was associated with DHA concentration (1 µM, 5 µM or 10 µM). Moreover, treatment with DHA (5 µM) and SOD (20 IU/ml) resulted in higher sperm motility. Thus, the association between DHA (5 µM) and SOD (20 IU/ml) appears to be an option for increased epididymal sperm features in bulls.

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Sperm samples used on fertilization strongly influence the in vitro production (IVP) rates. However, sperm traits behind this effect are not stated consistently until now. This study aimed to evaluate the isolated and combined effect of some sperm traits (MB: total motility before Percoll® gradient, MA: total motility after Percoll® gradient, AI: acrosome integrity, MI: membrane integrity, MP: mitochondrial membrane potential, and CR: chromatin resistance) on IVP rates. This is the first study focusing on the isolated effect of distinct traits. For this purpose, the experiment was divided in three steps. In first step, to study behavior of traits sperm samples (n = 63 batches) were analyzed and ranked based on each trait. In second step, samples ranked were selected from target ranks regions and allocated in groups of four to five batches, creating Higher and Lower groups, according to two different approaches. One aimed to form groups that differed to all sperm traits simultaneously (effect of combined traits). The other aimed to form groups that differed only to a single sperm trait while no differences were observed for the remaining traits (effect of each isolated trait). In third step, for each group successfully formed in step 2, sperm samples were individually and prospectively used for IVP. Cleavage, embryo development and blastocyst rates were recorded and compared between Higher and Lower of respective trait groups. Surprisingly, evaluation of isolated effects revealed that lower levels of MB, AI and MP resulted in higher embryo development and blastocyst rates (p<0.05), which was not observed on cleavage rate. We conclude that sperm traits strongly influence embryo development after in vitro fertilization (IVF), affecting the zygote competence to achieve blastocyst stage. Individually, levels of MB, AI or MP could be some of the key traits that may define IVP efficiency on current systems of embryo production.

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The aim of this study was to evaluate the response of prepubertal ewe lambs to exogenous administration of either medroxyprogesterone acetate (MAP) or long-acting progesterone (LAP) together with biostimulation. Two Pool Dorset adult males and 75 mixed-breed prepubertal ewe lambs (average of 179 days-old and 30.0kg) were used. The females were randomly assigned to three different groups. In the first group the females were submitted to the insertion of intravaginal sponges containing MAP (60 mg) for 12 days and were then biostimulated for eight weeks. In the second group the females were submitted to a single injection of LAP (225 mg) and then to biostimulation for eight weeks. In the last group, the females were only submitted to biostimulation for eight weeks. Animals were considered cyclic when plasma progesterone (P4) concentration exceeded 1.0 ng/mL in at least one of two consecutive blood samples taken within a 7-day interval in three distinct experimental moments. After treatments 93.3% of the females disregarding their group started their cyclicity and most of them (92.0%), continued to be cyclic after 63 days of either MAP or LAP together with biostimulation under both male and female effect. We conclude that prepubertal ewe lambs when submitted to protocols of either MAP or LAP followed by biostimulation result in puberty at the 7 month of age. It can be deducted that some ewe lambs submitted to the administration of either MAP or LAP together with biostimulation promoted a multiplier effect upon the other young females that were then stimulated to start cyclicity

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Escherichia coli is the most common contaminant of the bovine uterus in the first few weeks postpartum, and one of the most important pathogens involved in uterine infections. This bacterium is characterised by diverse virulence factors (VF); however, the profile of E. coli VF in physiologic postpartum uterine contamination is not well established. Therefore, the present study aimed to investigate the prevalence of intrauterine bacteria, a set of virulence factors and phylogroups of E. coli isolates, leukogram and uterine cytology in 75 Holstein cows at 24 h (Sampling time 1) and 14 days (Sampling time 2) postpartum. Escherichia coli, α-haemolytic Streptococcus, Trueperella pyogenes, and Pasteurella multocida were the most common microorganisms isolated in pure culture, whereas E. coli and Clostridium perfringens Type A, E. coli and α-haemolytic Streptococcus, and E. coli and Proteus mirabilis were the most frequent microorganisms in mixed colonies at both studied sampling times. In the 59 E. coli isolates after 24 h (n = 35) and 14 days (n = 24) postpartum, the genes detected for VF were fimH, iucD/aer, kps, hlyA, usp, vt1 and vt2. Most E. coli strains detected in both moments of study belonged to Commensal phylogenetic groups A and B1, whereas Pathogenic groups D and B2 were identified at 24 h and 14 days postpartum respectively. All cows presented suitable immune response against the presence of bacteria in uterine lumen, observed by leukocytosis, neutrophilia, lymphocytosis and monocytosis at leukogram and a high number of polymorphonuclear leukocytes in uterine cytology, in both studied moments. Thus, a complex diversity of aerobic and anaerobic bacteria is involved in uterine contamination in the early postpartum of cows, besides the predominance of E. coli. Moreover, the genes fimH, iucD/aer, hlyA, kps, usp, vt1 and vt2 play a key role in the virulence of E. coli in this period.