IntroductionThe purpose of the current study was to evaluate the blood glutathione peroxidase (GSH-Px) and malondialdehyde (MDA) levels under seasonal variations in dairy cows during transition period, and to assess the relationship between chosen reproductive parameters, GSH-Px, and MDA.Material and MethodsHolstein cows calving in January were assigned into winter group (n = 42), while cows calving in August were assigned into summer group (n = 42). Blood samples were collected from the jugular vein 21, 14, and 7 days before calving, at calving (0 day), and 7, 14, and 21 days after calving. Reproductive parameters obtained from farm records were evaluated.ResultsIn both groups of cows, GSH-Px activity decreased from 21 days before calving to day 0, and it gradually continued to increase until 21 days after calving. GSH-Px activity was higher in winter group compared to summer group during the transition period (P < 0.05). MDA levels in both groups increased over time starting from 21 days before calving to 0 day, but it gradually decreased thereafter. MDA levels were higher in summer group compared to winter group during the transition periods (P < 0.05). Summer group of cows showed higher intervals of calving-to-oestrus, calving-to-conception, and higher insemination index (P < 0.01). Negative correlation was recorded between GSH-Px and MDA during all examination days (P < 0.01). MDA levels correlated with calving to conception interval on day 21 before calving and day 0 (P < 0.01) and insemination index on day 0 and 21 days after calving (P < 0.01). GSH-Px activity was negatively correlated with calving to conception interval on day 21 before calving, day 0, and 21 days (P < 0.01) after calving. Negative correlation on day 21 before calving and day 0 was also determined between GSH-Px and insemination index (P < 0.01).ConclusionThis study showed that blood oxidant and antioxidant levels have affected the fertility parameters in cows under seasonal variations.

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ABSTRACT:This study was designed to determine the prevalence of Neospora caninum, the effect of infection on abortion and fertility parameters and the efficacy and outcomes with combination treatment in a dairy farm with high abortion rates and low fertility parameters. Four hundred and eighty-six cows were tested using the immunofluorescence antibody test (IFAT). The seroprevalence of N. caninum was 19%. Sulphadiazine-trimethoprim and toltrazuril were administered to the seropositive animals. The risk of abortion increased 19-fold in animals infected with N. caninum (P < 0.05), and N. caninum-induced abortions occurred more often between the fourth and the sixth months of gestation. N. caninum infection also had an adverse influence on the number of inseminations to conception (P < 0.05) and calving to conception interval (P < 0.05). The treatment protocol improved the fertility parameters. Although, it is not a radical approach, this combination therapy may be recommended as the primary treatment in neosporosis.

The aim of the current study was to investigate the relationship between prepartum body condition score (BCS), blood metabolites (Glucose, beta-hydroxybutyrate; BHB), oxidative stress (Malondialdehyde; MDA, Glutathione peroxidase; GSH-Px) in transition period and some reproductive parameters in Holstein dairy cows. Fifty cows were divided into two groups [low-BCS = 2.75-3.0 (n=25); adequate-BCS = 3.25-3.75 (n=25)] according to BCS on the 21st day before expected calving. BCS was also recorded at 0 and +21 days after calving. Blood samples collected at -21, 0 and +21 days from calving for MDA and GSH-Px analysis as well as at -21, +14 and +21 days of postpartum for glucose and BHB. Data on reproductive parameters obtained from farm records were also collected. MDA concentrations were higher in group of low-BCS compared to group of adequate-BCS at -21 and 0 d related to calving (p<0.05). GSH-Px activity was lower in group of low-BCS than adequate one during the transition period (p<0.05). Low-BCS group also showed higher concentrations of BHB at +14 and +21 days after calving. During the transition period, low-BCS group had lower glucose concentrations compared to adequate one (p<0.05). Adequate-BCS group of cows showed shorter intervals of calving to first estrus (p<0.01) and calving to conception (p<0.01). In conclusion, cows with lower BCS at the prepartum period had worse metabolic and oxidative balance during the transition period. This situation also was associated with worse reproductive performance in cows.

This study details the relationship between maternal plasma oxidant-antioxidant enzymes with colostrum quality, serum gamma glutamyl transferase (GGT), immunoglobulin G (IgG) and IgM concentrations of calves in the different calving seasons. Holstein breed cows between two and eight lactations and their calves were enrolled in the study. Holstein cows calving in winter (n=45) and their calves (n=45) were assigned to the winter group, while cows calving in summer (n=45) and their calves (n=45) were assigned to the summer group. Samples for malondialdehyde (MDA) and glutathione peroxidase (GSH-Px) were collected on day -21±3 before expected calving and also on calving day (Day 0). IgG and the specific gravity of the colostrum were determined after calving. Serum GGT and IgG and IgM were measured before the feeding, with colostrum, of calves (0 hours) and also in the 24 th hour following the feeding of colostrum. Plasma MDA levels at -21±3 and 0 days in the summer cows were determined to be higher. GSH-Px activity was higher in the winter cows. IgG levels and the specific gravity of the colostrum were also higher in the winter cows. Calf IgG levels at the 24 th hour of life were higher in the winter cows. In the winter group, IgM levels at 0 and 24 hours were also higher. While MDA was negatively correlated with IgG, IgM, GGT, IgG and the specific gravity of colostrum, GSH-Px activity had a positive correlation with IgG, IgM, GGT, IgG and the specific gravity of colostrum. The observed differences in plasma MDA, GSH-Px, calf serum IgG and IgM levels, and colostrum quality between both groups suggest a possible seasonal effect. The relationship between maternal oxidant-antioxidant enzymes, colostrum quality, and passive calf immunity revealed that these enzymes could be used as indicators in the evaluation of calf health and colostrum quality.