Effects of plane of nutrition on oxidative stress in goats during the peripartum period

Changes of vitamins A, E, and C and lipid peroxidation status of breeding and pregnant sheep during dry seasons on medium-to-low quality forages

This study assessed the changes of plasma vitamin A, E, and C and the lipid peroxidation status of sheep during breeding and pregnancy under drought conditions. The study was conducted on 105 cross-bred fat tailed ewes, 3-5 years old with body condition scores (BCS) of 2.5 to 3.5. The ewes were grazing on medium-to-low quality forages during summer and low quality forages within the succeeding months and had ad libitum access to a mixture of alfalfa hay (40%) and wheat straw (60%) in the afternoons. From 3 weeks before breeding till 1 month after the introduction of rams, 300 g of barley grain/head/day was offered to the ewes and then the supplemental grain was reduced to 100 g/head/day. For better synchronization of estrus cycles in ewes, they were isolated from the rams for at least 2 months and then kept in close proximity of the rams for 1 week before the introduction of the rams to the ewe flock. Then, whole blood samples were collected on days 1, 7, 21, and 120 after ram introduction. Vitamins A, E, and C were measured in plasma. Malondialdehyde (MDA) was measured in the hemolysate as a biomarker of lipid peroxidation. Plasma progesterone (P4) was measured in the samples of day 120 for assessing pregnancy status of the ewes. Vitamins A and C showed continuous and significant declines (P < 0.05) through days 1 to 120. Vitamin E declined only during the first 21 days of the study and remained almost constant till day 120. MDA concentration increased significantly at day 21. An elevated concentration of MDA was also detected at day 120. The difference between days 21 and 120 was not significant (P > 0.05). A positive correlation between vitamins E and C was detected at day 120 (r = 0.349, P < 0.01). Age and BCS did not affect the patterns of changes. Assuming that the ewes with P4 concentrations ≥2.5 ng/ml were pregnant, 95 out of 105 ewes (90.5%) were pregnant at day 120 of the study. Under the conditions of the present study with medium-to-low quality pastures as the main sources of feed, ewes of various ages and body conditions may suffer from oxidative stress during breeding and pregnancy.

Antioxidant enzymes in erythrocytes from goats seropositive to the sheep nose bot fly (Oestrus ovis L., Diptera: Oestridae) infection

Oestrus ovis (Diptera: Oestridae) causes an important cosmopolitan parasitosis of the nasal and sinusal cavities of sheep and goats called oestrosis. Our objective was to analyze the participation of erythrocytes in the antioxidant system in goats seropositive to O. ovis infection under field conditions. Fifty female goats naturally exposed to O. ovis infection from Baja California Sur, México, were blood-sampled. Erythrocytic intracellular content was obtained from blood plasma. Oestrosis serodiagnosis was determined by ELISA. Protein, hemoglobin (Hb), superoxide dismutase (SOD), mieloperoxidase (MPO), catalase (CAT), glutathione-S-transferase (GST), and lipid peroxidation in erythrocytes were determined in both seropositive and seronegative goats. Overall seroprevalence of O. ovis infection in goats was 56%. Positive significant (P<0.05) associations were observed among systemic IgG level and protein (0.34), hemoglobin (0.43), SOD (0.32), and MPO (0.41) in erythrocytes. Protein and hemoglobin concentrations, as well as SOD and MPO activities in erythrocytes were found significantly higher (P<0.05) in seropositive than in seronegative goats. By contrast, enzymatic activities of CAT and GST and lipid peroxidation values were similar in seropositive and seronegative groups. In conclusion, there was a systemic stimulation of Reactive Oxygen Species which was efficiently scavenged by erythrocytic antioxidant enzymes in goats seropositive to O. ovis infection.

Effect of dietary energy intake on erythrocytic antioxidant defence in growing lambs fed a wheat straw-based diet

Twenty-four Muzaffarnagari lambs (~8 months, 26.56 ± 2.04 kg), consisting 12 each of male and female, were used for ascertaining the effect of dietary energy restriction on the erythrocytic antioxidant defence including lipid peroxidation. The lambs, allotted randomly into three equal groups, were fed on wheat straw-based diets to provide 100, 80 and 70% of calculated metabolisable energy (ME) requirements. Bodyweight gain and feed intake were recorded. Blood samples were collected at the start and thereafter at 60-day intervals during 180 days of experimental duration and analysed for malonyl dialdehyde (MDA), reduced glutathione (GSH) and total thiol groups in addition to catalase, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glutathione S-transferase. Dietary treatments imparted significant (P < 0.001) effects on feed intake and average daily gain. The haemoglobin and haematocrit contents in blood reduced significantly (P < 0.001) on reduction in dietary energy levels. The dietary alterations elicited no change in the activities of SOD, catalase and glutathione S-transferase, but reduced activities of GSH-Px (P < 0.001) and GSH (P = 0.133) were evident on feeding the diet with 70% ME. Concentrations of total thiols decreased (P < 0.001) with reduced energy level. Both the energy-restricted groups exhibited a significant (P < 0.001) increase in MDA, indicative of increased lipid peroxidation. It was concluded that long-term energy malnutrition on a wheat straw-based diet reduces the erythrocytic antioxidant defence in growing lambs.

Biomarkers of oxidative stress in ruminant medicine

The study of oxidative stress is a relatively young field of research in ruminant medicine. Oxidative stress results from increased exposure to or production of oxidants, or from decreased dietary intake, de novo synthesis or increased turnover of antioxidants. The understanding of the role of oxidants and antioxidants in physiological and pathological conditions is rapidly increasing. Oxidative stress is an active field of research in veterinary medicine and has been implicated in numerous disease processes including sepsis, mastitis, acidosis, ketosis, enteritis, pneumonia, respiratory, and joint diseases. Compared to human medicine, only a limited number of conditions have been investigated in regard to the effects of oxidative stress in ruminants. Studies in cattle have been sporadic and mainly with mastitis, pneumonia, and retained placenta. More recently, studies have been focused on metabolic diseases that affect dairy cows during the peripartum period. Numerous and rapidly evolving methodologies for evaluating oxidative stress are available to researchers and clinicians, each with their own distinct advantages and disadvantages. Differences in models and methodologies make it difficult to make meaningful comparisons, even for studies that seem quite similar superficially. With this in mind, it is the goal of this review to discuss the advantages and shortfalls of different methodologies commonly used to measure oxidative stress and damage in ruminants. Clarity of understanding of the pathophysiology of oxidative stress in ruminants will allow the design of specific antioxidant therapies. Future research should focus on the establishment of a reference panel of biomarker of oxidative stress to be used in ruminant medicine. To help accelerate practical applications, we propose the development of an oxidative stress index as an approach in ruminant and veterinary medicine.

Effects of Yerba Mate (Ilex paraguariensis) supplementation on the productive performance of dairy cows during mid-lactation

Yerba Mate (Ilex paraguariensis), a tea known for its high antioxidant content, was fed (250 g/cow.day) to 8 of 16 Holstein cows for 6 weeks to assess its effect on their performance. Cows were weighed and blood samples were taken on Weeks 0, 3 and 6. Blood samples were centrifuged and plasma was analysed for reactive oxygen metabolites, biological antioxidant potential, advanced oxidation protein products and non-esterified fatty acids. Cows were milked two times daily and milk yields were recorded daily for individual cows. On Weeks 0 and 6, individual milk samples were collected from two consecutive milkings, composited, and analysed for somatic cell counts, fat and true protein concentrations. Plasma concentrations of reactive oxygen metabolites, biological antioxidant potential and non-esterified fatty acids were not affected by Yerba Mate supplementation. Similarly, no effect of Yerba Mate supplementation was noted on milk fat and protein content and on somatic cell counts. This study indicates that supplementation of dairy cows’ diet with Yerba Mate during mid lactation seems to improve milk yield when cows are fed with maize silage; however, even if the effect on milk yield was significant it was quite small and needs to be validated with further studies. Cows’ oxidative status was not affected by Yerba Mate supplementation indicating that the effect of Yerba Mate on their productive performances is not mediated by changes in redox status.

Effects of Yerba Mate (Ilex paraguariensis) supplementation on the performance of dairy calves

Yerba Mate (Ilex paraguariensis), a tea known for its high antioxidant content, was supplemented to 24 of 48 Holstein calves to assess its effect on the calves’ performance. Calves were weighed and blood samples were taken each week. Serum was assayed for metabolic parameters (total protein, albumin, urea, non-esterified fatty acids, triglycerides and β-hydroxybutyric acid) and markers of oxidative status [advanced oxidation protein products, 8-isoprostane and total antioxidant capacity (TAC) concentration]. Supplemented calves had higher triglyceride levels (P < 0.05) suggesting that Yerba Mate induced fat mobilisation and usage. A significant effect of the interaction time of sampling × diet (P < 0.05) was noted for plasma TAC concentration with the Yerba mate calves presenting significantly lower levels of TAC on the last week of the trial. Yerba Mate supplemented calves had significantly lower levels of total protein (P < 0.05) and albumin (P < 0.05) compared with the non-supplemented calves. The net result was reduced liveweight in Yerba Mate supplemented calves (P < 0.001) and thus the hypothesis that Yerba Mate supplementation would increase dairy calves’ growth rates was rejected. This study demonstrated that supplementation of Yerba Mate to dairy calves had significant effects on their metabolic and oxidative status, which resulted in lower liveweight at the end of the trial.

Effect of diet, energy balance and milk production on oxidative stress in early-lactating dairy cows grazing pasture

The aim of this study was to determine the effect of diet, energy balance and milk production on oxidative stress in early-lactating, Holstein-Friesian dairy cows fed to produce either low or high levels of milk. Indicators of energy balance (non-esterified fatty acids, β-hydroxybutyrate, glucose and insulin-like growth factor-1) and indicators of oxidative stress (reactive oxygen metabolites and biological antioxidants) were measured in the first 5 weeks of lactation. Energy balance indicators showed that high producing animals had a lower degree of negative energy balance. Diet was found to have an indirect effect on the level of oxidative stress. Factors associated with a high level of oxidative stress were severe negative energy balance (mean -71 ± 6.85 27 MJ/cow/day, P < 0.05) and lower levels of milk production (mean 26.4 ± 0.07 28 L/cow/day, P < 0 .05). Further studies will be required to more precisely determine the specific effects of diet, energy balance and milk production on such stress in dairy cows and to establish normal ranges for these biomarkers.