نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه علوم دامی، دانشکده کشاورزی، دانشگاه بوعلی سینا، همدان،همدان، ایران.
2 گروه علوم دامی،دانشکده کشاورزی، دانشگاه بوعلی سینا همدان، همدان، ایران.
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Introduction: Maternal stimuli, such as nutrition, result in developmental adaptations by the fetus which changes physiology and metabolism of offspring. In ewe energy level and source during gestation have been shown to impact lamb performance. Supplementation of fatty acids during gestation has been shown to affect offspring in dairy cattle and sheep. The omega-3 (n-3) fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are particularly bioactive and can alter physiology and metabolism by increasing the transcription of lipolytic genes and decreasing the transcription of lipogenic genes, potentially increasing the utilization of fatty acids for energy, which yields more energy than other metabolizable nutrients. The bioactive properties of EPA and DHA allow them to affect offspring development through changes in metabolism in non-ruminant species. Therefore, we hypothesized that supplementation of EPA and DHA will alter metabolism of pregnant ewes, which in turn will modulate growth and metabolism of the offspring.
Antioxidants protect the body against free radicals that are responsible for causing more than 100 diseases. Among the most important natural antioxidants are retinol (vitamin A), carotenoids, tocopherol (vitamin E), ascorbic acid, butyric acid, EPA and DHA. Long-chain unsaturated fatty acids have high antioxidant power, as it is reported that EPA and DHA have the same antioxidant capacity as vitamins. It has also been reported that supplementation of EPA, DHA in the diet of dairy cows has increased the concentration of antioxidants in milk.
Materials and Methods: 45 ewes were selected while were in the last two months of pregnancy and randomly assigned to three treatments, including control (first treatment) second treatment which received EPA and DHA supplement and third treatment received a basal diet with one percent calcium fat supplement. Plasma samples were collected to measure glucose, triglycerides, cholesterol, total protein, albumin, globulin, urea nitrogen, non-esterified fatty acids, beta-hydroxybutyrate and antioxidants. The amount of milk production and milk composition were also determined.
Results and Discussion: There was a significant difference in birth weight between different treatments. In a study conducted on dairy cows in the last weeks of gestation with long-chain unsaturated fatty acids, the birth weight of calves born on long-chain unsaturated fatty acid supplementation was significantly different compared to other treatments. In another study, the birth weight of lambs whose mothers received fat supplement was not significantly different from the control group. Plasma concentrations of glucose, non-esterified fatty acids and beta-hydroxybutyrate were significantly different between treatments. Supplementation of ewes in the last two months of pregnancy with eicosapentaenoic acid and docosahexaenoic acid fatty acids increased glucose and decreased non-esterified fatty acids and beta-hydroxybutyrate compared to other treatments, which releases fatty acids from the tissue to reduce energy balance to provide the energy needed for breastfeeding. In a study it was found that addition of trans fats to the diets of pregnant cows reduced glucose levels and increased NEFA, possibly due to increased circulating fat. There was no significant difference in the amount of blood metabolites such as triglycerides, cholesterol, total protein and urea between treatments.
Milk production in 3 hours showed a significant difference between treatments, as EPA and DHA supplemented group produced more milk than other groups, which can be attributed to the higher amount of blood glucose in this treatment. Experimental diets had no effect on the amount of protein, fat and total SNF of milk. It was also observed that consumption of 18 mg per kg metabolic body weight during pregnancy did not show any change in milk parameter.
The use of EPA and DHA supplements in the diet of pregnant ewes increased the total antioxidant capacity of milk and colostrum. Omega-3 fatty acids reduce the effect of free radicals. In this way, omega-3 fatty acids may increase the level of catalase in the peroxisomes and cytoplasm and, thus, improve the defense against free radicals.
Conclusion: The use of EPA and DHA supplementation in pregnant ewes caused significant changes in the birth weight of lambs, milk production and the amount of antioxidant production in milk and colostrum. It also altered glucose, non-esterified fatty acids and beta-hydroxybutyrate in the plasma metabolite on lambing in ewes.
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