Generally, most feeds used in livestock nutrition are deficient in some nutrients, and require nutritional supplements. Among the supplements, micro and macro minerals are particular importance. Selenium (Se) plays an important role in the reproductive function and immune system and is known as an antioxidant and catalyst for the production of thyroid hormone. It is believed that low selenium absorption in ruminants is due to the deficiency of selenium in ration and its conversion into insoluble form. Nano-particles are smaller and more active than larger particles. The importance of Selenium for rumen microorganisms are not entirely clear. Also, selenium is an essential trace element, and its importance for animal health and productivity has been well confirmed. Selenium has known to be involved in enzyme activity and preventing oxidative damage to body tissue. Selenium plays important roles in antioxidant systems, prevents cell damage and is necessary for growth, fertility, and immune system in farm animals. Recently, nano -elemental Se has attracted wide spread attention due to its high bioavailability and low toxicity, because nanometer particulates exhibit novel characteristics, such as great specific surface area, high surface activity, a lot of surface active centers, high catalytic efficiency and strong adsorbing ability and over and above the character of low toxicity of Se0. Dietary selenium is an essential trace element for animals and humans with a variety of biological functions. It plays important roles in the regulation of thyroid hormone metabolism, cell growth and antioxidant systems thus, together with alpha-tocopherol prevents cells against oxidative stress damage, also these compounds are necessary for growth, fertility, and immune system health in animals and humans. The objective of this research was to investigation the effects of different sources of selenium on digestion characteristics of concentrate mixture of diets in high producing lactating dairy cows using in vitro gas production technique.
Four male ruminally fistulated sheep, average 43±4.8 kg of BW, were used in a replicated 4×4 Latin square experiment. Sheep were fed twice daily (08:00 and 18:00 h) at maintenance nutrition requirements with a basal diet consisting of 400 g/kg (dry matter) DM of basal concentrates and 600 g/kg DM of forage. Sheep were placed in metabolic cages individually and fresh water was freely available during the experimental period. This experiment was conducted in four periods of 28 days with 21 d adaptation period and 7 d for data tacking. Treatments were: 1. Basal diet 2. Basal diet + 0.3 ppm nano selenium, 3. Basal diet + 0.3 ppm seleno methionine, 4. Basal diet + 0.3 ppm selenite sodium. The rumen fluid was mixed with artificial saliva (1:2 ratio, respectively) in lab, and then nano-Selevels and seleno methionine added to it. In gas production method, 300 mg of each treatment weighted and incubated for 2, 4, 6, 8, 12, 16, 24, 36, 48, 72, 96 hours. In order to determine the effects of different forms of selenium on rumen parameters, concentrations of VFA and NH4, value of pH and population of protozoa were examined. Samples of rumen fluid were collected through the cannula at 4 h after feeding on days 19 and 20 of each collection period for pH, NH3-N, and volatile fatty acids (VFAs) determination. Ruminal pH was immediately measured using an electric pH meter. The samples were subsequently stored frozen at −20 ◦C until analyses.
Potential of gas production (fraction A) of nano, organic and inorganic treatments were higher (201.9, 344.0, 321.7 and 319.8 ml in control, nano, organic and mineral treatments, respectively) compared to control treatment (P<0.05). The nano selenium treatment had higher VFA concentration (109.83, 98.00 and 89.83 mmol/l in nano, organic and mineral treatments, respectively) when compared with organic and inorganic treatments (P<0.05). Rumen NH4 concentration was not effected by treatments. The organic treatment caused a significant increase in total protozoa population when compared with nano and inorganic treatments (P<0.05).
The results indicated that selenium supplementation in ruminant diet improves ruminal nutrients degradability's compared to control. Therefore, the use of nano-Se resulted to increase digestibility and fermentation of nutrients resulted improved rumen microorganisms activities. Although nano and organic selenium was better than inorganic treatment in ruminal degradability and rumen parameters, however there was not any significant differences between these two treatments.
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