Optimizing semen cryopreservation in Calomys laucha: a step forward in rodent reproductive research.

BACKGROUND: Examining semen cryopreservation in Calomys laucha offers valuable insights for reproductive research and species conservation. OBJECTIVE: To determine the most effective sugar for the cryopreservation of C. laucha semen. MATERIALS AND METHODS: Using 36 epididymides from C. laucha, semen samples were diluted in a 3% skimmed milk medium supplemented with one of four sugars (glucose, fructose, lactose, or sucrose) at a concentration of 0.3 M. These mixtures underwent a conditioning phase at 37 degree C for 10 min, cooled to -80 degree C for another 10 min, and were subsequently stored in liquid nitrogen. RESULTS: Upon thawing, samples treated with lactose and glucose solutions show superior sperm motility, achieving 8.2% and 10.0% respectively, in contrast to the fructose (2.0%) and sucrose (4.1%) mixtures. Furthermore, samples preserved in glucose registered the highest sperm penetration rates, reaching 44.9%. CONCLUSION: Our findings suggest that a cryopreservation medium containing 0.3 M glucose can contribute to the safeguarding C. laucha rodent semen. https://doi.org/10.54680/fr24210110612.

Endometrial responsiveness to interferon-tau and its association with subsequent reproductive performance in dairy heifers.

Our objectives were to evaluate the endometrial responsiveness of dairy heifers to an intrauterine infusion of recombinant bovine interferon-tau (rbIFN-τ) and to associate endometrial responses to rbIFN-τ with subsequent reproductive performance. In Experiments 1 and 2, cyclic heifers were enrolled in a 5-d CIDR Cosynch program for estrous synchronization, and blood sampling and ultrasonography examinations were performed on d 0, 4, 7, 11, and 14 of the estrous cycle. In Experiment 1, heifers were randomly assigned to receive an intrauterine infusion containing 2 µg of rbIFN-τ (rbIFN-τ = 19) or saline (CTRL = 19) into the uterine horn ipsilateral to the corpus luteum (CL) on d 14 of the estrous cycle. Six hours after the infusion, the infused uterine horn was flushed for sampling of the uterine luminal fluid (ULF) for analyses of composition, and the endometrium was biopsied for transcriptomics. In Experiment 2, 100 heifers received an intrauterine infusion of rbIFN-τ, and the same procedures for uterine sample collection described in Experiment 1 were performed. After the intrauterine test, heifers were enrolled in a breeding program and classified as highly fertile (HF; pregnant at first AI) or subfertile (SF; not pregnant at first AI). Statistical analyses were performed using linear regression models, which included the effects of treatment (Experiment 1: CTRL vs. rbIFN-τ) or fertility group (Experiment 2: HF vs. SF) and block of samples. Intrauterine infusion of rbIFN-τ increased the expression of classical interferon-stimulated genes in the endometrium (e.g., ISG15, MX1, OAS2, IRF9, and USP18), and an antiviral response was predicted to be the main downstream effect of the transcriptome changes. In addition, rbIFN-τ increased the abundance of cholesterol, glycerol, and the overall concentration of oxylipins in the ULF. Analysis of endometrial transcriptome between HF and SF heifers revealed important differences in the expression of proteins associated with cell signaling, metabolism, attachment, and migration, with a large representation of genes encoding extracellular matrix proteins. In general, differently expressed genes were expected to be downregulated by IFN-τ but seemed to fail to be downregulated in SF heifers, resulting in higher expression in SF compared with HF heifers. Subfertile heifers had lower concentrations of glycerol and an altered profile of oxylipins in the ULF, with lower abundance of oxylipins derived from arachidonic acid and dihomo-γ-linolenic acid, and greater abundance of oxylipins derived from linoleic acid. Measurements of ovarian function did not differ between groups and, therefore, did not influence the observed results in uterine biology. In conclusion, the endometrial responsiveness to IFN-τ is variable among individuals and associated with subsequent fertility of heifers, indicating that communication between conceptus and endometrium is critical for the uterine receptivity and survival of pregnancy.

Effects of source of supplementary trace minerals in pre- and postpartum diets on reproductive biology and performance in dairy cows.

Our objectives were to evaluate the effects of complete replacement of inorganic salts of trace minerals (STM) with organic trace minerals (OTM) in both pre- and postpartum diets on ovarian dynamics, estrous behavior measured by sensors, preimplantation conceptus development, and reproductive performance in dairy cows. Pregnant cows and heifers (n = 273) were blocked by parity and body condition score and randomly assigned to either STM or OTM diets at 45 ± 3 d before their expected calving. Pre- and postpartum diets were formulated to meet 100% of recommended levels of each trace mineral in both treatments, taking into consideration both basal and supplemental levels. The final target concentrations of Co, Cu, Mn, Se, and Zn were, respectively, 0.25, 13.7, 40.0, 0.3, and 40.0 mg/kg in the prepartum diet, and 0.25, 15.7, 40.0, 0.3, and 63.0 mg/kg in the postpartum diet. The STM group was supplemented with Co, Cu, Mn, and Zn sulfates and sodium selenite, while the OTM group was supplemented with Co, Cu, Mn, and Zn proteinates and selenized yeast. Treatments continued until 156 d in milk (DIM) and were assigned to individual cows using automatic feeding gates. Starting at 21 DIM, ultrasonography examinations of the ovaries were performed weekly to determine the presence of a corpus luteum and postpartum resumption of ovarian cyclicity. Cows were presynchronized with 2 injections of PGF2α at 42 and 56 DIM. Estrous behavior was monitored using electronic activity tags that indirectly measured walking activity. Cows detected in estrus after the second PGF2α were inseminated, and those not detected in estrus by 67 DIM were enrolled in a synchronization program. Cows that returned to estrus after artificial insemination (AI) were reinseminated. Pregnancy diagnosis was performed 33 d after AI, and nonpregnant cows were resynchronized. Transcript expression of interferon-stimulated genes in peripheral blood leukocytes was performed in a subgroup of cows (STM, n = 67; OTM, n = 73) on d 19 after AI. A different subgroup of cows (28 STM, 29 OTM) received uterine flushing 15 d after AI for recovery of conceptuses and uterine fluid for analyses of transcriptomics and metabolomics, respectively. In addition, dominant follicle diameter, luteal size and blood flow, and concentration of progesterone in plasma were measured on d 0, 7, and 15 relative to AI. After flushing, PGF2α was given and the dominant follicle was aspirated 2 d later to measure the concentration of trace minerals by mass spectrometry. Estrous behavior, size of the dominant follicle and corpus luteum, concentration of progesterone, time to pregnancy, and proportion of cows pregnant by 100 d of the breeding period did not differ between treatments. A greater proportion of cows supplemented with OTM had a corpus luteum detected before presynchronization (64.3 vs. 75.2%), and primiparous cows supplemented with OTM tended to resume cyclicity earlier than their STM counterparts. Cows supplemented with OTM had a greater concentration of Cu in follicular fluid than cows supplemented with STM (0.89 vs. 0.77 µg/mL, respectively). In pregnant multiparous cows, expression of receptor transporter protein 4 in peripheral blood leukocytes was 42% greater in the OTM group. Conceptuses of the 2 treatments had 589 differentially expressed transcripts, with many indicating advanced conceptus elongation and greater transcript expression of selenoproteins in the OTM group. In pregnant cows, 24 metabolites were more abundant in the uterine fluid of OTM, including spermidine, sucrose, and cholesterol. In conclusion, replacing STM with OTM caused modest improvements to resumption of ovarian cyclicity and important changes in preimplantation conceptus development, but it did not alter conception risk and pregnancy rate.

Effects of replacing inorganic salts of trace minerals with organic trace minerals in the diet of prepartum cows on quality of colostrum and immunity of newborn calves.

Our objectives were to evaluate the impact of supplementary trace mineral (TM) form-inorganic salts (STM; Co, Cu, Mn, Zn sulfates, and Na selenite) or organic (OTM; Co, Cu, Mn, Zn proteinates, and selenized yeast)-in the prepartum diet on quantity and quality of colostrum, passive immunity, antioxidant biomarkers, cytokine responses to lipopolysaccharide (LPS), health, and growth of newborn calves. Pregnant heifers (n = 100) and cows (n = 173) were enrolled at 45 d before calving, blocked by parity and body condition score, and allocated randomly to STM (50 heifers; 86 cows) or OTM (50 heifers; 87 cows) supplementation. Cows in both treatments were fed the same diet, except for the source of supplementary TM. Within 2 h of calving, dams and calves were separated, colostrum was harvested, the yield was measured, and a sample was saved for posterior analyses of colostrum quality. A subgroup of calves (n = 68) had a blood sample collected before colostrum feeding. After colostrum feeding, all samples and data collection were limited to 163 calves (STM = 82; OTM = 81) fed 3 L of good quality (Brix% >22) maternal colostrum via nipple bottle minutes after harvesting. Concentration of IgG in colostrum and serum was determined 24 h after colostrum feeding using radial immunodiffusion. Concentration of TM in colostrum and serum were performed by inductively coupled plasma mass spectrometry. Activity of glutathione peroxidase, ferric reducing ability of plasma, and concentration of superoxide dismutase were evaluated in plasma by colorimetric assays. Ex vivo whole blood stimulation with LPS was performed on d 7 of life to evaluate cytokine responses in a subgroup of 66 calves. Health events were recorded from birth to weaning, and body weight was recorded at birth (all calves) and on d 30 and 60 (heifers only). Continuous variables were analyzed by ANOVA and binary responses were analyzed by logistic regression. Complete replacement of STM by OTM in prepartum diet resulted in greater concentration of Se (461 vs. 543 ± 7 µg/g; ± SEM) but did not alter the concentration or total mass of other TM and IgG in colostrum. Female calves of the OTM group had greater concentration of Se in serum at birth (0.23 vs. 0.37 ± 0.05 µg/mL), were lighter in weight at birth (40.9 vs. 38.8 ± 0.6 kg) and weaning (93.2 vs. 89.7 ± 1.6 kg) than those of the STM group. Maternal treatments did not affect passive immunity or antioxidant biomarkers. On d 7, basal concentrations (log10 of concentration in pg/mL) of IFNγ (0.70 vs. 0.95 ± 0.083) and LPS-stimulated concentrations of CC chemokine ligand 2 (CCL2; 2.45 vs. 2.54 ± 0.026), CC chemokine ligand 3 (CCL3; 2.63 vs. 2.76 ± 0.038), IL-1α (2.32 vs. 2.49 ± 0.054), and IL-1ß (3.62 vs. 3.86 ± 0.067) were greater in OTM than in STM. Supplementation with OTM in pregnant heifers, but not in pregnant cows, reduced the incidence of preweaning health problems in their calves (36.4 vs. 11.5%). Complete replacement of STM by OTM in the prepartum diet did not cause major changes in colostrum quality, passive immunity, and antioxidant capacity, but increased cytokine and chemokine responses to LPS on d 7 of life and benefited preweaning health of calves born to primiparous cows.

Neutrophil function and antibody production during the transition period: Effect of form of supplementary trace minerals and associations with postpartum clinical disease and blood metabolites.

Our objectives were to evaluate the effect of the form of supplementary trace minerals-inorganic salts (STM: Co, Cu, Mn, and Zn sulfates and Na selenite) or organic (OTM: Co, Cu, Mn, Zn proteinates, and selenized yeast)-fed at 100% of recommended levels in both pre- and postpartum diets on in vitro phagocytic activity of neutrophils, and in vivo IgG responses to an ovalbumin challenge during the transition period. In addition, we investigated the associations of these immunological responses with incidence of postpartum clinical diseases and the dynamic changes of metabolic markers during the transition period. Pregnant heifers and cows (n = 273) were enrolled at 45 ± 3 d before expected calving, blocked by parity and body condition score, and allocated randomly to STM or OTM supplementation. Cows in both treatments were fed the same diet, except for the form of supplementary trace minerals. Automatic feeding gates were used to assign treatments to individual cows. Blood was collected on d -7 ± 3 and 7 ± 3 relative to calving in a subgroup of cows (n = 131 and 133, respectively) to measure phagocytic activity of neutrophils in vitro using flow cytometry. Subcutaneous immunization with 0.5 mg of chicken egg ovalbumin was performed in a subgroup of cows (n = 181) on d -45, -21, and 3 relative to calving. Concentration of anti-ovalbumin IgG in serum was measured by ELISA on d -45, -21, 3, 7, and 21. Trace mineral concentrations in blood were measured by inductively coupled plasma mass spectrometry on d -45, -21, -7, 0, 7, and 21 relative to calving. Selected metabolites were measured on d -21, -10, -3, 0, 3, 7, 10, 14, and 21 relative to calving. Treatment did not affect the percentage of neutrophils performing phagocytosis on d -7 or 7 but the median fluorescence intensity of phagocytosis on d 7 was greater for OTM than STM. We found no differences between treatments in the level of anti-ovalbumin IgG in serum on any of the sampling days. Changes in neutrophil function from prepartum to postpartum were associated with incidence of postpartum clinical disease, postpartum feed intake and milk production, concentrations of Ca, K, Se, Mn, Co, and total protein in serum. Immunoglobulin G responses to ovalbumin injections were not associated with incidence of postpartum clinical disease but were associated with body weight, feed intake, energy balance, and concentrations of nonesterified fatty acids, aspartate aminotransferase, gamma-glutamyl transpeptidase, albumin, Na, P, and Cu in serum. In conclusion, replacement of STM by OTM improved one measure of phagocytic capacity of neutrophils in vitro, which was also greater in cows that did not develop postpartum clinical disease. The associations of innate and acquired immune responses with feed intake, energy balance, and circulating concentrations of key macro and micronutrients reinforce the importance of nutritional management for the health of dairy cows during the transition period.

Effects of replacing inorganic salts of trace minerals with organic trace minerals in pre- and postpartum diets on feeding behavior, rumen fermentation, and performance of dairy cows.

Our objectives were to evaluate the effects of complete replacement of supplementary inorganic salts of trace minerals (STM) by organic trace minerals (OTM) in both pre- and postpartum diets on feeding behavior, ruminal fermentation, rumination activity, energy metabolism, and lactation performance in dairy cows. Pregnant cows and heifers (n = 273) were blocked by parity and body condition score and randomly assigned to either STM or OTM diets at 45 ± 3 d before their expected calving date. Both groups received the same diet, except for the source of trace minerals (TM). The STM group was supplemented with Co, Cu, Mn, and Zn sulfates and Na selenite, whereas the OTM group was supplemented with Co, Cu, Mn, and Zn proteinates and selenized yeast. Treatments continued until 156 days in milk and pre- and postpartum diets were formulated to meet 100% of recommended levels of each TM in both treatments, taking into consideration both basal and supplemental levels. Automatic feed bins were used to assign treatments to individual cows and to measure feed intake and feeding behavior. Rumination activity was monitored by sensors attached to a collar from wk -3 to 3 relative to calving. Blood metabolites were evaluated on d -21, -10, -3, 0, 3, 7, 10, 14, 23, and 65 relative to calving. Ruminal fluid samples were collected using an ororuminal sampling device on d -21, 23, and 65 relative to calving, for measurement of ruminal pH and concentration of volatile fatty acids. Cows were milked twice a day and milk components were measured monthly. Cows supplemented with OTM tended to have longer daily feeding time (188 vs. 197 min/d), and greater dry matter intake (DMI; 12.9 vs. 13.3 kg), and had a more positive energy balance (3.6 vs. 4.2 Mcal/d) and shorter rumination time per kg of dry matter (DM; 40.1 vs. 37.5 min/kg of DM) than cows supplemented with STM during the prepartum period. In the postpartum period, OTM increased DMI in multiparous cows (24.1 vs. 24.7 kg/d) but not in primiparous cows (19.1 vs. 18.7 kg/d). The difference in DMI of multiparous cows was more evident in the first 5 wk of lactation, when it averaged 1 kg/d. Milk yield was not affected by treatment in multiparous cows (44.1 vs. 44.2 kg/d); however, primiparous cows supplemented with OTM had lesser yields than primiparous cows supplemented with STM (31.9 vs. 29.8 kg/d). Cows supplemented with OTM had a greater percentage of protein in milk (3.11 vs. 3.17%), reduced concentration of nonesterified fatty acids in serum (0.45 vs. 0.40 mmol/L), and rumination activity (30.1 vs. 27.8 min/kg of DM) than cows supplemented with STM. At the end of the transition period, cows supplemented with OTM had reduced molar proportion of acetate, reduced pH, and tended to have a greater concentration of total volatile fatty acids in ruminal fluid. In conclusion, complete replacement of STM by OTM caused modest changes in rumen fermentation, feeding behavior, energy metabolism, and performance of dairy cows, improving postpartum DMI in multiparous cows and reducing circulating levels of nonesterified fatty acids. The pre-absorptive effects of TM source and the parity specific responses on performance warrant further research.

Effects of parity, blood progesterone, and non-steroidal anti-inflammatory treatment on the dynamics of the uterine microbiota of healthy postpartum dairy cows.

This study evaluated the effects of treatment with meloxicam (a non-steroidal anti-inflammatory drug), parity, and blood progesterone concentration on the dynamics of the uterine microbiota of 16 clinically healthy postpartum dairy cows. Seven primiparous and 9 multiparous postpartum Holstein cows either received meloxicam (0.5 mg/kg SC, n = 7 cows) once daily for 4 days (10 to 13 days in milk (DIM)) or were untreated (n = 9 cows). Endometrial cytology samples were collected by cytobrush at 10, 21, and 35 DIM, from which the microbiota analysis was conducted using 16S rRNA gene sequence analysis. A radioimmunoassay was used to measure progesterone concentration in blood serum samples at 35 DIM and cows were classified as ˃ 1 ng/mL (n = 10) or ≤ 1 ng/mL (n = 6). Alpha diversity for bacterial genera (Chao1, Shannon-Weiner, and Camargo's evenness indices) were not affected by DIM, meloxicam treatment, parity, or progesterone category. For beta diversity (genera level), principal coordinate analysis (Bray-Curtis) showed differences in microbiota between parity groups. At the phylum level, the relative abundance of Actinobacteria was greater in primiparous than multiparous cows. At the genus level, there was lesser relative abundance of Bifidobacterium, Lactobacillus, Neisseriaceae, Paracoccus, Staphylococcus, and Streptococcus and greater relative abundance of Bacillus and Fusobacterium in primiparous than multiparous cows. Bray-Curtis dissimilarity did not differ by DIM at sampling, meloxicam treatment, or progesterone category at 35 DIM. In conclusion, uterine bacterial composition was not different at 10, 21, or 35 DIM, and meloxicam treatment or progesterone category did not affect the uterine microbiota in clinically healthy postpartum dairy cows. Primiparous cows presented a different composition of uterine bacteria than multiparous cows. The differences in microbiota associated with parity might be attributable to changes that occur consequent to the first calving, but this hypothesis should be investigated further.

Dynamics of lipid droplets in the endometrium and fatty acids and oxylipins in the uterine lumen, blood, and milk of lactating cows during diestrus.

Our objective was to investigate the lipid content of uterus, blood plasma, and milk at early, mid, and late diestrus. Lactating cows (n = 30) had the estrous cycle and ovulation synchronized by administration of exogenous hormones. Cows were blocked by parity and assigned randomly to receive transcervical uterine flushing and biopsy on d 5 (early diestrus), 10 (mid diestrus) or 15 (late diestrus) of the estrous cycle. Flushing and endometrial biopsy were performed in the uterine horn ipsilateral to the corpus luteum. The recovered flushing was used for analyses of lipid composition by liquid chromatography-tandem mass spectrometry and the biopsy was used for investigation of lipid droplet abundance in endometrial cryosections using a neutral lipid fluorescent dye. In addition, blood and milk samples were collected from all cows on d 5, 10, and 15. All blood samples were used to measure the concentration of progesterone in plasma, and all milk samples were used to determine milk composition. Subsamples of blood plasma and milk were also used to evaluate the composition of fatty acids and oxylipins using the same methodology used for uterine flushing samples. The abundance of lipid droplets in the endometrium increased 1.9-fold from d 5 to 10, and 2-fold from d 10 to 15. Concentration of long-chain fatty acids and oxylipins in uterine flushing were, on average, 2.2 and 2.5 times greater in samples collected on d 15 compared with those collected on d 5 and 10. These differences were not observed in blood and milk, suggesting that accumulation of fatty acids and oxylipins in the uterus is regulated locally. In addition to concentration, the profile of individual fatty acids and oxylipins in uterine lumen changed substantially during diestrus. The main categories with increased abundance at late diestrus were mono- and polyunsaturated fatty acids, and oxylipins derived from arachidonic acid, dihomo-γ-linolenic acid, and docosahexaenoic acid. In conclusion, fatty acids and oxylipins accumulate in the uterine lumen during diestrus and might work as a mechanism to supply these lipids to the developing conceptus at late diestrus, when the onset of elongation occurs and substantial synthesis of biomass and cell signaling by lipid mediators are required.

Association of metabolic markers with neutrophil function in healthy postpartum dairy cows.

The objective of this study was to evaluate the associations of serum markers for systemic inflammation, liver, mineral, and energy status, and blood neutrophil counts with the function of circulating neutrophils in postpartum dairy cows. Blood samples were collected from 21 healthy Holstein cows at 5, 10, 14, and 21 d postpartum. Serum samples were used to measure concentrations of total calcium, phosphorus, magnesium, total protein, albumin, globulin, cholesterol, urea, glucose, gamma-glutamyl transferase, aspartate aminotransferase, glutamate dehydrogenase, haptoglobin (Hp), ß-hydroxybutyrate, non-esterified fatty acids (NEFA), and insulin-like growth factor-1. The shift of percentage of activated neutrophils for phagocytosis (PPC) and oxidative burst (POB) and the median fluorescence intensity (MFI) for PC (MFIPC), OB (MFIOB), and endocytic and proteolytic degradation measured via DQ-ovalbumin (MFIDQ) were evaluated using flow cytometry. Mixed linear regression models were used to assess the associations of serum concentrations of metabolites and blood neutrophil counts with each neutrophil function assay outcome accounting for d postpartum, parity, and body condition score. Pearson correlation tests (r) were used to describe the relationships of metabolites and neutrophil counts with neutrophil function assays that were significant in the regression models. Greater serum concentrations of Hp were associated with lesser OB function (POB and MFIOB; r = -0.2 for both), but greater PPC and MFIDQ (r = 0.3 for both). Greater serum NEFA and cholesterol were associated with lesser (r = -0.3) and greater (r = 0.2) POB function, respectively. Blood neutrophil counts were associated with PPC (r = -0.2) and MFIDQ (r = -0.3). At 5 d postpartum, greater serum total protein was associated with greater OB function (POB and MFIOB; r = 0.4 for both). Other markers were not associated with neutrophil function. Some metabolic and inflammatory markers in healthy postpartum dairy cows were associated with circulating neutrophil function. However, these associations only explained a small proportion of the variance in neutrophil function. Serum Hp concentration was most associated with neutrophil function changes but had opposite directions of association with OB- and PC-related functions. Future studies should focus on understanding the mechanisms by which Hp and other metabolic indicators affect neutrophil function in healthy and diseased postpartum dairy cows.

Effect of anti-inflammatory treatment on systemic inflammation, immune function, and endometrial health in postpartum dairy cows.

Systemic inflammation (SI) is increasingly studied in several species because it may be central in many metabolic disturbances and be a risk factor for clinical disease. This proof-of-concept study evaluated the effects of the anti-inflammatory drug meloxicam on markers of SI and energy metabolism, polymorphonuclear neutrophil (PMN) function, and endometritis in clinically healthy postpartum dairy cows. Cows received meloxicam (0.5 mg/kg of body weight; n = 20) once daily for 4 days (10-13 days postpartum) or were untreated (n = 22). Blood samples were collected -7, 1, 3, 5, 7, 10, 11, 12, 13, 14, 18, 21, 28, and 35 days relative to calving to measure serum concentrations of metabolic and inflammatory markers. Function of peripheral blood PMN were evaluated at 5, 10, 14, and 21, and proportion of PMN in endometrial cytology were performed at 5, 10, 14, 21, 28 and 35 days postpartum. Meloxicam decreased serum haptoglobin from the second until the last day of treatment, and improved indicators of energy metabolism (lesser ß-hydroxybutyrate and greater insulin-like growth factor-1 during treatment, and greater glucose at the end of treatment than control cows). This improved PMN function at 14 days postpartum, but the endometrial inflammatory status was not affected.

Antioxidant Effect of Xanthan Gum on Ram Sperm after Freezing and Thawing.

BACKGROUND: Xanthan gum is used as thickener in media to preserve food products, having cryoprotectant and antioxidant properties that may be relevant for sperm cryopreservation. OBJECTIVE: To evaluate the effects of adding xanthan gum to freezing extenders on post-thawing quality and oxidant activity of ram sperm. METHODS: Ejaculates from seven rams extended TRIS-egg yolk-glycerol were split in three treatments including xanthan gum (0.15%; 0.20%; and 0.25%) and a control with no xanthan gum. RESULTS: After thawing, motility and production of reactive oxygen species (ROS) with 0.20% and 0.25% xanthan gum were lower than for the control (P < 0.05), but mitochondrial functionality and integrity of membrane, acrosome and DNA did not differ (P > 0.05). Xanthan gum at 0.20% and 0.25% may be an efficient antioxidant for frozen-thawed ram sperm, due to the reduction in ROS production.

Exogenous paraoxonase-1 during oocyte maturation improves bovine embryo development in vitro.

Paraoxonase-1 (PON1) is an enzyme found in serum and follicular fluid that protects cell membrane and circulating lipids against oxidative damage. The aims of this study were to measure the direct effects of recombinant PON1 (rPON1) on bovine oocyte maturation at the molecular level (gene expression) and to measure the carry-over effects of PON1 on pre-implantation embryo development in vitro. COCs were submitted to IVM with the addition of 0.0, 0.02, 0.04 and 0.08 mg ml(-1) of rPON1, corresponding to an average PON1 arylesterase enzyme activity of 2.2 ± 0.4, 15.5 ± 1.5, 30.2 ± 3.0 and 57.9 ± 5.0 U ml(-1) , respectively. The results indicated that addition of rPON1 during IVM improved embryo development in a dose-dependent manner as D7 embryo development was 22.2%, 29.4%, 32.2% and 37.0% for the treatment groups, respectively (p = 0.02). In conclusion, addition of PON1 enzyme during IVM exerted dose-related positive effects on embryo development rates to blastocysts.